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Keywords:

  • angiosperms;
  • biogeography;
  • Brazil;
  • disjunction;
  • distribution patterns;
  • endemism

Abstract

  1. Top of page
  2. Abstract
  3. 1 Origin of tropical South American flora
  4. 2 Overview of main Brazilian phytogeographic domains
  5. 3 Patterns of distribution of Brazilian flora
  6. Acknowledgments
  7. References

Abstract  Molecular phylogenetic studies have become a major area of interest in plant systematics, and their impacts on historical biogeographic hypotheses are not to be disregarded. In Brazil, most historical biogeographic studies have relied on animal phylogenies, whereas plant biogeographic studies have largely lacked a phylogenetic component, having a limited utility for historical biogeography. That country, however, is of great importance for most biogeographic studies of lowland tropical South America, and it includes areas from a number of biogeographic regions of the continent. Important biogeographic reports have been published as part of phylogenetic studies, taxonomic monographs, and regional accounts for small areas or phytogeographic domains, but the available information is subsequently scattered and sometimes hard to find. In this paper we review some relevant angiosperm biogeographic studies in Brazil. Initially we briefly discuss the importance of other continents as source areas for the South American flora. Then we present a subdivision of Brazil into phytogeographic domains, and we cite studies that have explored the detection of biogeographic units (areas of endemism) and how they are historically related among those domains. Examples of plant taxa that could be used to test some biogeographic hypotheses are provided throughout, as well as taxa that exemplify several patterns of endemism and disjunction in the Brazilian angiosperm flora.

Brazil is the fifth largest country in the world, with more than 8.5 million km2, and one of the most diverse in vascular plant species, with an estimated 55,000–60,000 species (Prance, 1994; Giulietti et al., 2005). The territory occupied by Brazil encompasses most of the world's remaining areas of tropical rainforests (primarily in the Amazon), as well as considerable areas of tropical savannas (the central Brazilian Cerrado) and seasonally dry tropical forests (SDTFs; mostly in the Caatinga). The country is also one of the few that includes two hotspots for the conservation of biodiversity sensuMyers et al. (2000), the Atlantic Forest and the Cerrado.

Despite its unquestionable importance for the study of South American biogeography in general, there is a serious lack of biogeographic synthesis about Brazilian plants. Most studies so far have emphasized the detection of patterns of geographic distribution by mapping occurrence data, relegating the explanations on how these patterns were achieved to a somewhat speculative level. Because the vast majority of the available studies lack a phylogenetic perspective (e.g., Prance, 1979, 1988; Giulietti & Pirani, 1988; Acevedo-Rodríguez, 1990; Alves et al., 2003; Gonçalves, 2004; Cavalcanti, 2007; Fiaschi & Pirani, 2008), the information generated has been regarded as having little relevance for historical biogeography, as the detection of areas of geographic distribution correspond only to the very first step of any historical biogeographic analysis (Crisci et al., 2003; Santos & Amorim, 2007).

In this paper we aim to provide an overview of the main plant biogeographic studies in Brazil. First, we present some general information on the origin of tropical South American flora, based mostly on recent paleogeographic and phylogenetic studies. Second, we briefly describe the main Brazilian phytogeographic domains and discuss the relevant biogeographic studies from publications on several groups of organisms (mostly animals) in order to provide a framework for comparison with the few available plant studies. Finally, we also provide examples of angiosperm genera that could be used to test some biogeographic hypotheses in Brazil, and of plant distribution and disjunction patterns in and among the Brazilian phytogeographic domains.

1 Origin of tropical South American flora

  1. Top of page
  2. Abstract
  3. 1 Origin of tropical South American flora
  4. 2 Overview of main Brazilian phytogeographic domains
  5. 3 Patterns of distribution of Brazilian flora
  6. Acknowledgments
  7. References

The break-up of West Gondwana and the separation of South America from Africa ca. 100 mya resulted in a long period of isolation for South America, until the closure of the Isthmus of Panama ca. 3 mya (Burnham & Graham, 1999; McLoughlin, 2001). This long period of isolation as an island continent (approximately 97 my) led some authors to suggest that the South American flora has developed in situ, with little contribution of immigrant taxa (Raven & Axelrod, 1974; Gentry, 1982; Burnham & Graham, 1999). However, the idea of a “splendid isolation” leading to a unique South American biota does not seem to fit the many well-known examples of disjunct taxa shared with Africa, Oceania, Asia and North America. Thus, in addition to vicariance explanations derived from the split of formerly united continents, some of these general patterns of disjunction must invoke hypothesized land connections through presently submerged areas (Morley, 2003) and climatically unfavorable areas (Sanmartín & Ronquist, 2004), or episodic events of long-distance dispersal (Givnish & Renner, 2004; Pennington & Dick, 2004), as molecular dating of plant phylogenies have shown that the arrival of several lineages in South America are posterior to its separation from Africa (e.g., Sytsma et al., 2004; Trénel et al., 2007), or prior to the closure of the Panama Isthmus (e.g., Erkens et al., 2007; Cuenca et al., 2008). In the following paragraphs we present a brief overview of past connections and dispersal routes that may have accounted for the presence of some angiosperm lineages in tropical South America, especially in Brazil.

The evident floristic connection between the African and South American floras (Raven & Axelrod, 1974; Gentry, 1982, 1993) can hardly be explained by the break-up of West Gondwana alone, because the initial separation of these two continents took place much earlier than the appearance of many of their plant lineages (Givnish & Renner, 2004; Renner, 2004; Sytsma et al., 2004). After the initial development of the South Atlantic Ocean ca. 135 mya (McLoughlin, 2001), northern South America and Africa remained connected until 110–95 mya (Sanmartín & Ronquist, 2004), and some island chains may have permitted dispersal routes for floristic exchanges between the two continents during the Late Cretaceous/Early Tertiary boundary (∼65 mya) (Hallam, 1994; Morley, 2003; Pennington & Dick, 2004). Recent phylogenetic and paleontological evidence suggests these routes may have been effective for Arecaceae (Trénel et al., 2007) and Proteaceae (Morley, 2003; Barker et al., 2007). Long-distance dispersals also seem to have contributed significantly to floristic connections between Africa and South America (Renner, 2004). Phylogenetic studies of Neotropical plant taxa with just a few recent colonizers in Africa, such as Bromeliaceae, Cactaceae, Humiriaceae, Loasaceae, Mayacaceae, Rapateaceae, and Vochysiaceae are supportive of this view (Givnish et al., 2000; Renner, 2004; Sytsma et al., 2004).

The suggestion that most of lowland tropical South American flora was derived from a West Gondwanan stock (Raven & Axelrod, 1974; Gentry, 1982) does not seem to be supported by phylogenetic evidence (Pennington & Dick, 2004). Instead, some important lowland Amazonian angiosperm families, such as Annonaceae, Burseraceae, Lauraceae, Melastomataceae, Meliaceae and Moraceae seem to have had most of their Neotropical species derived from northern hemisphere ancestors through Laurasian migrations (Chanderbali et al., 2001; Renner et al., 2001; Pennington & Dick, 2004; Richardson et al., 2004; Weeks et al., 2005; Zerega et al., 2005; Muellner et al., 2006). This Laurasian route is supported by the widespread presence of tropical forests in the northern hemisphere during the Paleocene and Eocene (“boreotropical forests;” see Wolfe, 1975; Tiffney, 1985a, b), and the possible floristic exchange between North American and South American landmasses throughout parts of the Tertiary before the closure of the Isthmus of Panama (Iturralde-Vinent & MacPhee, 1999; Morley, 2003). Among the possible island chains that may have permitted such exchange are the Middle to Late Eocene Proto-Greater Antilles (Morley, 2003), the Eocene-Oligocene GAARlandia (Fritsch, 2001; Morley, 2003), and the Late Miocene/Pliocene formation of the Isthmus of Panama, which provided a land corridor for the significant faunal exchange known as the “Great American Interchange” (Burnham & Graham, 1999; Iturralde-Vinent & MacPhee, 1999). Following the predictions of Lavin and Luckow (1993), additional evidence for the boreotropical origin of tropical South American taxa has been obtained for Magnoliaceae (Azuma et al., 2001), Malpighiaceae (Davis et al., 2002), Sapotaceae (Smedmark & Anderberg, 2007) and Styracaceae (Fritsch, 2001). Other angiosperm families listed by Gentry (1982) as having a Gondwanan origin, such as Anacardiaceae, Araliaceae, Gesneriaceae, Illiciaceae and Menispermaceae may prove to constitute additional examples of groups that arrived in South America by this Laurasian route.

As discussed above, evidence for vicariant patterns between tropical African/South American elements are restricted to a few lineages whose estimated time of split agrees with the separation of these continents, such as calamoid palms (Pennington & Dick, 2004). Additional examples of disjunction patterns invoking Gondwanan vicariance seem to apply to subtropical and montane taxa shared between southern South America and areas belonging to the Southern Temperate Gondwana Province, such as Australia, New Zealand and New Caledonia (Sanmartín & Ronquist, 2004). Land connections through west Antarctic terrains permitted some floristic exchange between Australia and South America until the late Eocene (∼35 mya) or even the early Oligocene (30–28 mya), when South America finally separated from Antarctica (McLoughlin, 2001; Sanmartín & Ronquist, 2004). The prevailing impact of this connection was to provide a stock of subtropical elements to South America, for example, Araucaria (authors of generic names used in this study can be found in Mabberley (2008)), Griselinia, Gunnera, Nothofagus, Podocarpus, Cunoniaceae, some Proteaceae, and Winteraceae. However, it also made it possible for some taxa to diversify along tropical mountain ranges, such as the Andes and the eastern Brazilian Serra do Mar and Serra da Mantiquera [e.g., Arecaceae-Ceroxyloideae (Trénel et al., 2007), Alstroemeria (Hofreiter, 2007), Escallonia, Weinmannia]. The view that floristic connections among areas in higher southern latitudes are due to the break-up of Gondwana has also been challenged, and it seems that long-distance dispersals were important in shaping current plant distributions in this region (Sanmartín & Ronquist, 2004; Trénel et al., 2007).

Upon arrival in South America by any of the above-mentioned routes (old vicariant events or more recent dispersals, whether long-distance or by land bridges), diversification of tropical plant lineages seem to have been strongly influenced by the following three main factors (Burnham & Graham, 1999): (i) the uplift of the Andes and associated changes in drainage patterns during the Miocene, resulting in the separation of cis- and trans-Andean biotas (Chanderbali et al., 2001; Trénel et al., 2007; Pennington & Dick, in press) and the creation of suitable montane habitats (Ritz et al., 2007; Smith et al., 2008); (ii) the closure of the Isthmus of Panama (3.5–3 mya), which resulted in considerable floristic exchanges between northern and southern landmasses, and accounted especially for the present composition of upland forests; and (iii) Quaternary climatic fluctuations, which might have been important in the recent diversification of large lowland tropical genera, such as Inga (Richardson et al., 2001) and Guatteria (Erkens et al., 2007). Other factors that may have driven speciation in South American rainforest taxa include ecological shifts associated with soil heterogeneity (Fine et al., 2005), altitudinal range (Givnish et al., 2000), and invasions of novel geographic areas and biomes (Pennington et al., 2004; Gonçalves et al., 2007; Saslis-Lagoudakis et al., 2008). A good overview on the diversification of tropical South American rainforest plants, focusing on Amazonian taxa, is presented by Pennington and Dick (in press). Additional examples of plant diversification in Brazil are presented in the sections dedicated to the main phytogeographic domains of the country.

2 Overview of main Brazilian phytogeographic domains

  1. Top of page
  2. Abstract
  3. 1 Origin of tropical South American flora
  4. 2 Overview of main Brazilian phytogeographic domains
  5. 3 Patterns of distribution of Brazilian flora
  6. Acknowledgments
  7. References

Because many Brazilian plant groups have a distribution mostly restricted to one of the main phytogeographic domains represented in the country (e.g., Perret et al., 2006) and several studies address domain-based, rather than taxon-based biogeographic hypotheses (e.g., Oliveira-Filho & Fontes, 2000; Queiroz, 2006; Ratter et al., 2006; Santos et al., 2007), we first present general information on the biogeographic divisions of Brazil and then provide separate discussions for each of these domains, including the relevant taxon-based studies. Geographic distribution patterns of Brazilian plants are also illustrated, aiming to account for observed patterns of disjunction.

The first attempt to classify Brazilian vegetation was made by Martius (1824), who divided the country into five floristic domains, each named after a Greek nymph. His system included the Amazon (Nayades), the cerrados of central Brazil (Oreades), the Atlantic rainforests (Dryades), the Araucaria forests and southern grasslands (Napeias), and the northeastern Caatinga (Hamadryades). Several authors have suggested changes to this system, but the basic features remain unaltered (Sampaio, 1940; Fernandes & Bezerra, 1990; Veloso et al., 1991). Regions and provinces recognized in all biogeographic systems of South America do not show any sharp difference from this general framework of domains (e.g., Cabrera & Willink, 1973; Morrone, 2001).

The most widely accepted classification system for Brazilian vegetation is that of Veloso et al. (1991), who separated the country into four biomes (see comment on biomes below): the Amazon Forest, the Atlantic Forest, the Savanna (= Cerrado), and the Steppe (= Caatinga + Campos sulinos). Joly et al. (1999) provide a good introduction to the phytogeographic divisions of Brazil, and Daly and Mitchell (2000) give a South American overview. We divided the country into five main phytogeographic domains: Amazon, Cerrado, Atlantic Forest (including the Araucaria forests), Caatinga, and Campos sulinos (Fig. 1). Here, instead of adopting a single Steppe biome for the northeastern Caatinga and the southern Campos sulinos (Veloso et al., 1991), we kept them separate due to their strong floristic and climatic differences. It is worth mentioning that the use of “biome” as a synonym of “phytogeographic domain” in Brazilian phytogeographic published works is incorrect (Coutinho, 2006). “Biome” refers to an area with physiognomic homogeneity regardless of the floristic composition, and the term “phytogeographic domain” implies physiognomic heterogeneity and takes the floristic composition as a very important component.

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Figure 1. Map of Brazil, showing the phytogeographic domains discussed in the text. The inset box shows the position of Brazil in South America.

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2.1 Amazon

The Amazon forests extend over an area of approximately 6 million km2 in northern South America (Daly & Mitchell, 2000), and account for most of the world's remaining rainforests. The limits of these forests have been variously defined (Daly & Prance, 1989), but they are somewhat congruent with the Amazon basin. The basin, however, extends north and eastward beyond the forested area, and the forests become replaced by savannas in most of eastern Bolivia and central-northern Brazil (Goulding et al., 2003). Amazon rainforests are among the most diverse in the world (Gentry, 1988a; Valencia et al., 1994). Recent estimates of Amazonian plant diversity range from 25,000 angiosperm species in the entire basin (Goulding et al., 2003) to 30,000 in the Brazilian part alone (Gentry, 1982), but these may represent a crude underestimation of the total diversity (Hopkins, 2007). Based on data compiled from monographs, Gentry (1982) estimated 76% of the Amazonian flora as endemic at the species level.

The geological history of the Amazon basin is marked by a major shift in drainage orientation, caused by the uplift of the Andean mountain range (Hoorn, 1993). Before the Andean uplift, most of the Amazon basin drained westward to the Pacific and was covered by westward deposition of low-fertility sediments from the pre-Cambrian Brazilian and Guiana Shields (Hoorn, 1993). With the subsequent uplift of the northern Andes, starting approximately 15 mya, the direction of sediment deposition shifted eastward, and most of the ancient sands were covered by deep clay sediments coming from the Andes (Burnham & Graham, 1999). During the Late Miocene (8–10 mya), the Pebasian Sea transgression created a marine seaway uniting the Caribbean to the South Atlantic and resulted in a dramatic landscape change leading to the current configuration of the Amazon basin (Räsänen et al., 1995; Webb, 1995). The presence of rainforests in the basin largely colonizes relatively recent Andean sediments. Earlier sandy sediments from the Guiana Shield cover approximately 3% of the Amazon (ter Steege et al., 2000) and are found in patches mostly in the upper Rio Negro of northwestern Brazil (Anderson, 1981; Prance, 1996), neighboring areas in Venezuela and Colombia (Daly & Mitchell, 2000), and the Iquitos region of northeastern Peru (Alonso & Whitney, 2003). These areas of white-sand soils do not support tall rainforests but rather several physiognomies varying from open scrublands to low forests, depending on the proximity of the water table (Anderson, 1981; Huber, 1995; Prance, 1996; Daly & Mitchell, 2000).

The Amazon phytogeographic domain is broadly defined here to include the Guianan lowlands (Gentry, 1982; Granville, 1988) and the Guiana Shield (Huber, 1995) (i.e., the Amazonian subregion of Morrone, 2006), in spite of strong evidence to the contrary (Mori, 1991; Berry et al., 1995; Kelloff & Funk, 2004; Berry & Riina, 2005). Thus, in addition to the large extension of lowland rainforests and white-sand forests, several other physiognomies are found in scattered patches across this domain. The most prominent of these patches are the Amazonian savannas (Prance, 1996; Daly & Mitchell, 2000), which are floristically linked to the Cerrado (see section 2.2), and the tepuis, which are remnant sandstone plateaus of the Guiana Shield (Huber, 1995; Prance, 1996; Daly & Mitchell, 2000; Berry & Riina, 2005). Most tepuis are restricted to Venezuela, but some extend to northern Brazil, eastern Colombia and the Guianas (Daly & Mitchell, 2000; Berry & Riina, 2005). The tepui vegetation is very diverse physiognomically (Huber, 1995; Daly & Mitchell, 2000), and 42% of the flora from areas above 1500 m (the Pantepui region) has been estimated as endemic (Berry & Riina, 2005).

Of major importance to Brazilian biogeography are floristic connections between the Guiana Shield with white-sand Amazonian habitats and/or eastern Brazil, as exemplified by Bonnetia (Bonnetiaceae), Caraipa (Clusiaceae), Potalia (Gentianaceae), Humiria (Humiriaceae), Chamaecrista and Eperua (Leguminosae), Marcetia and Microlicia (Melastomataceae), Biophytum (Oxalidaceae), Rapateaceae, Pagamea and Sipanea (Rubiaceae), Barbacenia and Vellozia (Velloziaceae), and Xyridaceae. Among the few phylogenetic studies focused on white-sand plant lineages, Struwe et al. (1998) suggested a general pattern where endemic white-sand taxa represent older lineages from which more recent lineages have been derived. Although this hypothesis has not been sufficiently tested with phylogenetic data, Frasier et al. (2008) provided additional support for the older ancestry of endemic white-sand taxa. Other studies, however, point to more complex scenarios, involving several shifts to white-sand areas from ancestors growing in more fertile clay or terrace soils (Fine et al., 2005), back and forth movements between lowland forests and tepui summits (Steyermark, 1986; Givnish et al., 2000), and shifts to habitats with different light conditions, flooding regimes and altitude (Vicentini, 2007).

Based on the detection of areas of bird endemism in the Amazon, Haffer (1969) proposed a model to explain the diversification of the Amazonian biota in terms of allopatric speciation driven by forest fragmentation during glacial events in the Quaternary. This Pleistocene refuge model predicted that areas with a greater number of endemic species were likely to have acted as refuges for rainforest taxa during the expansion of savannas in glacial times. These isolated patches of rainforest in a landscape of savannas and dry forests would have provided the reproductive isolation required for allopatric speciation. The same (or slightly modified) areas of endemism reported for birds were believed to have also accounted for the diversification of frogs, lizards, butterflies and several groups of plants (Vanzolini, 1970; Brown, 1982; Prance, 1982). However, the initial excitement to detect such refuges for several groups of organisms was accompanied by many attempts to test the model, most of which have largely refuted the assumptions based on collection bias (Nelson et al., 1990), hypothesized paleoecological conditions (Colinvaux et al., 2000, 2001; Bush & Oliveira, 2006), and molecular systematic data (e.g., Moritz et al., 2000; Patton & Silva, 2005). Several additional models have been proposed to explain Amazonian biodiversity, but none have achieved the same credibility (for a review of these models see Haffer, 1997, 2008; Marroig & Cerqueira, 1997). Current views on Amazonian diversification suggest that it is unlikely for the pattern to be adequately explained by the model of vicariance alone (Bush, 1994), requiring a mixture of pre-Pleistocene speciation events (Patton & Silva, 2005) and recent radiations (Richardson et al., 2001; Erkens et al., 2007). Geological processes and marine transgressions throughout the Amazon basin have been invoked as potential causes for currently observed vicariance patterns (Räsänen et al., 1995; Patton & Silva, 2005; Rossetti et al., 2005), whereas recent diversification of some plant groups appear to have been promoted by ecological shifts related to habitat (Prance, 1982, 1994; Gentry 1988b, 1989; Tuomisto et al., 1995; Fine et al., 2005), pollinator specialization (Gentry, 1982; Kay et al., 2005), and fluctuating temperatures and precipitation (Graham, 1997).

In order to investigate diversification of the Amazonian biota, attempts to detect areas of endemism have been made for several groups of organisms (Haffer, 1969; Vanzolini, 1970; Prance, 1982; Brown, 1982; Cracraft, 1985; Cracraft & Prum, 1988), although most studies have relied solely on the detection of such areas and the possible causes for their existence. The following areas of endemism have been consistently identified in the Amazon: Guiana (northern Brazil, Guyana, Surinam and French Guiana); Imeri (southern Venezuela and neighboring areas in Brazil and Colombia); Napo (Upper Negro-Uaupés rivers in Brazil, and Colombian, Ecuadorian and northern Peruvian Amazon); Inambari (southwestern Brazilian Amazon, eastern Peru and northwestern Bolivia); Rondônia (Madeira-Tapajós interfluvial areas, into northern Bolivia); Pará (southern Pará and northern Mato Grosso states in Brazil); and Belém (northeastern Brazilian Amazon). Most information on the historical relationships among Amazonian areas of endemism based on phylogenetic data comes from studies of birds (Cracraft, 1985; Cracraft & Prum, 1988; Marks et al., 2002; Eberhard & Bermingham, 2005; Ribas et al., 2005), butterflies (Hall & Harvey, 2002) and dipterans (Nihei & Carvalho, 2007 and references therein) and, to our understanding, the issue of how such areas are related to each other based on plant phylogenies has never been addressed.

There is evidence disputing the recognition of the Amazon as a biogeographic unit (Garzón-Orduña & Miranda-Esquivel, 2007; Nihei & Carvalho, 2007). Some studies suggest a composite nature where southeastern Amazonian taxa are historically linked to eastern Brazilian taxa, and northwestern Amazonian taxa are more proximally related to Central American, Caribbean and Chocoan ones (Amorim & Pires, 1996; Amorim, 2001; Ribas & Miyaki, 2004; Nihei & Carvalho, 2007). Other studies are supportive of the Amazon as a single historical unit, that is, with southeastern and northwestern areas sister to each other (Silva & Oren, 1996; Bates et al., 1998; Eberhard & Bermingham, 2005). As far as we are concerned, the historical separation of the Amazon in these two blocks (southeastern and northwestern) has never been tested with plant phylogenetic studies, but seems to agree, at least spatially, with the extension of a middle Miocene marine transgression that separated the Guiana and Brazilian shields (Räsänen et al., 1995; Webb, 1995; Nores, 1999). The hypothesis that the biota of the southeastern portion of the Amazon region is more closely related to that of the central Brazilian forests than to the northwestern Amazonian ones has already been suggested by floristic analyses (e.g., Oliveira-Filho & Ratter, 1995; Ivanauskas et al., 2008), and remains to be tested with plant phylogenetic studies.

Regardless of the methodology used, raw distributions or taxon phylogenies, relationships among Amazonian areas of endemism seem to show some degree of congruence (Ron, 2000; Hall & Harvey, 2002). The summary area cladogram (Guiana + (Rondônia + (Pará+ Belém))) + (Imeri + (Napo + Inambari)) presented by Hall and Harvey (2002) seems to be a good working hypothesis, because it combines data from several unrelated groups of organisms. According to this hypothesis two Amazonian blocks (S/SE and W/NW) are sister groups and, as a whole, sister to Guiana. Alternative scenarios have been proposed, especially regarding the position of Rondônia as part of the W/NW block (Cracraft & Prum, 1988; Eberhard & Bermingham, 2005), and Guiana as part of the S/SE block (Racheli & Racheli, 2004; Eberhard & Bermingham, 2005; Garzón-Orduña & Miranda-Esquivel, 2007). Large-scale phylogenetic studies of plant taxa with widespread distribution in the Amazon basin, but with limited dispersal ability, could be designed to test if these area relationships are supported.

2.2 Cerrado

The Cerrado domain originally covered ca. 2 million km2 of the central Brazilian Plateau, extending west into Bolivia, south to Paraguay, and east to the Caatinga, and with some isolated patches found scattered across the Amazonian and Atlantic forests, and the Caatinga (Prance, 1996; Daly & Mitchell, 2000). Most of the cerrado vegetation is characterized by savanna physiognomies with a grass-rich ground layer growing on nutrient-poor soils with high aluminum content (Eiten, 1972; Ratter et al., 1997, 2006). The woody flora is mostly composed of sclerophyllous evergreen plants adapted to periodic fires, and with well-developed root systems reaching underground water tables. Depending on the density of the woody component, the structure of the vegetation can vary from open grassland to forest with a closed canopy (Silva & Bates, 2002; Ratter et al., 2003, 2006).

The Cerrado flora is very rich, with an estimated vascular plant diversity ranging from 6,429 to approximately 10,500 species (Mendonça et al., 1998; Ratter et al., 2006). Approximately 35% of the trees and 70% of the herbaceous and shrubby plants that grow in the Cerrado are endemic to this domain (Pennington et al., 2006a; Ratter et al., 2006), whereas most of the non-endemic species are associated with the Atlantic Forest domain (Méio et al., 2003; Ratter et al., 2006; but see Gonçalves, 2004 for an Amazonian connection). Besides the high levels of diversity and endemism, the Cerrado has sufferred a high degree of disturbance, especially due to agricultural expansion, cattle ranching, and charcoal production (Ratter et al., 1997; Silva & Bates, 2002). There are estimates that less than 20% of the cerrado vegetation remains undisturbed, which has resulted in its recommendation as a biodiversity hotspot (Myers et al., 2000; Mittermeier et al., 2005).

Floristic comparisons among several sites in the Cerrado domain have led to the recognition of seven floristic provinces based on the presence/absence of woody taxa (Ratter et al., 1996, 2003, 2006). These studies have pointed to a previously unrecognized floristic heterogeneity mostly associated with soil type and geographic location. A few taxonomic based biogeographic studies (e.g., Simon & Proença, 2000; Fiaschi & Pirani, 2008) seem to corroborate these patterns, and phylogeographic studies of endemic Cerrado plant species are suggestive of genetic structuring among these floristic provinces following Quaternary climatic changes (e.g., Ramos et al. 2007).

The highest levels of endemism in the Cerrado domain are found along the mountains of the Espinhaço Range (Minas Gerais and Bahia states), and the Chapada dos Veadeiros (Goiás state) (Prance, 1994; Simon & Proença, 2000; Silva & Bates, 2002; Fiaschi & Pirani, 2008). Most of the endemic species grow in areas above 900–1000 m along these mountains, which are covered by a low, mostly herbaceous or shrubby vegetation on sandy or stony soils called campos rupestres (Giulietti & Pirani, 1988; Harley, 1995; Alves et al., 2007). The high level of endemism in the campos rupestres flora has been recognized by several authors (Joly, 1970; Giulietti & Pirani, 1988; Harley, 1995; Rapini et al., 2002), but the explanations proposed for these diversity patterns remain very speculative because most of the relevant studies lack phylogenetic hypotheses for the endemic taxa.

Studies exploring diversification patterns among endemic Cerrado plants using dated molecular phylogenies are just beginning. A few studies suggest recent (3–4.7 mya) diversification events in high-altitude clades including Viguiera (Asteraceae), Microlicieae (Melastomataceae), and Minaria (Apocynaceae) (Schilling et al., 2000; Fritsch et al., 2004; and Rapini et al., 2007, respectively). Further phylogenetic studies of the endemic flora of the Cerrado could provide additional data to evaluate whether most of the endemic flora is the result of recent radiations, as suggested by Pennington et al. (2006b). Several angiosperm groups are good candidates for this goal, such as: Eremanthus, Lychnophora and Richterago (Asteraceae), Encholirium (Bromeliaceae), Kielmeyera (Clusiaceae), Eriocaulaceae, Pseudotrimezia (Iridaceae), Eriope (Lamiaceae), Chamaecrista and Mimosa (Leguminosae), Diplusodon (Lythraceae), Byrsonima (Malpighiaceae), Microlicia and Trembleya (Melastomataceae), Sauvagesia (Ochnaceae), Declieuxia (Rubiaceae), Barbacenia and Vellozia (Velloziaceae).

2.3 Atlantic forest

The Atlantic forests originally occupied approximately 1.5 million square kilometers, extending from Rio Grande do Norte to Rio Grande do Sul states along the Brazilian coast. The width of this forest strip is very variable, and it extends far inland in some areas of southeastern Brazil, eastern Paraguay, and Misiones Province of Argentina (Galindo-Leal & Câmara, 2003; Oliveira-Filho et al., 2006). The Atlantic coastal forests are separated from the Amazonian forests by a northeast–southwest diagonal swath of open or dry formations (Prado & Gibbs, 1993; Prado, 2000; Silva et al., 2004), which are believed to act as a current barrier to floristic exchange between these two forest blocks (Mori et al., 1981; but see Oliveira-Filho & Ratter, 1995; Costa, 2003). Because the Atlantic forests harbor a unique biota that is very rich in endemic species, and because of the high level of habitat destruction the region has been suffering – only approximately 7.5% of the original vegetation remains – it is considered one of the world's priorities for biodiversity conservation (Myers et al., 2000; Mittermeier et al., 2005).

The Atlantic Forest domain is characterized mostly by evergreen tropical forest but SDTFs (Oliveira-Filho et al., 2006) and subtropical forests (the Paranaense Province of Cabrera & Willink, 1973, including Araucaria forest) are also usually considered part of the domain (Oliveira-Filho & Fontes, 2000; the Parana Subregion of Morrone, 2006). In addition to forest physiognomies, mangroves and shrubby restinga vegetation are widespread in sea-level sandy areas (Scarano, 2002), and patches of high altitude grasslands and rocky outcrops are usually found above 2000 m along the Serra do Mar and Serra da Mantiqueira mountain ranges (Safford, 1999, 2007). The archipelago-like open formations found along the montane areas of the Atlantic forests harbor a highly endemic flora (over 20%) that has strong floristic connections with other South American montane areas such as the Andes (Safford, 2007), and the aforementioned campos rupestres of the Espinhaço Range (Giulietti & Pirani, 1988; Di Maio, 1996; Safford, 1999; Calió et al., 2008). The fragmented distribution of these open areas, coupled with episodic dispersal events, appear to have favored allopatric speciation in Sinningieae (Gesnericaeae) (Perret et al., 2007), and suggest that habitat heterogeneity may have played an important role in the diversification of the endemic Atlantic forest flora.

Vascular plant diversity and endemism in the Atlantic rainforests are among the highest in the world (Martini et al., 2007), but information on the geographic distribution of many taxa is lacking. There are approximately 20,000 species of vascular plants in the Atlantic forests (Myers et al., 2000), with estimated levels of endemism varying from 33% of the pteridophytes to more than 81% of the 803 species of bromeliads (Martinelli et al., 2008), and 41.6–44.1% of the total number of vascular plants from two reserves at southern Bahia (Thomas et al., 1998). Among the angiosperm genera, 159 are endemic to the Atlantic forests and approximately half of those are monotypic (Stehmann et al., in press). Many others groups are represented better there than anywhere else in the Neotropics, such as Hornschuchia (Annonaceae), many Bromeliaceae genera, Nematanthus and Sinningia (Gesneriaceae), Huberia and Pleiochiton (Melastomataceae), Dorstenia (Moraceae), Calyptrogenia and Myrceugenia (Myrtaceae), Oxalis subg. Thamnoxys (Oxalidaceae), Atractantha and Merostachys (Poaceae), Coccocypselum (Rubiaceae), Conchocarpus and Galipea (Rutaceae).

In addition to its highly endemic flora, the Atlantic forests harbor early diverging lineages of some angiosperm groups, such as the Poaceae subfamily Anomochlooideae (Judziewicz & Clark, 2007), Goniorrhachis and Barnebydendron, which correspond to the first diverging branches of the Detarieae clade of Leguminosae (Bruneau et al., 2008), and the Harleyi clade of Pagamea (Rubiaceae), which point to a possible arrival through dispersal from African ancestors (Vicentini, 2007). Based on the presence of presumably “primitive” species in the Atlantic forests, Gentry (1982) suggested that it could be a “source area” of Gondwanan taxa for other phytogeographic regions, such as the geologically recent Amazon lowlands and the Andes, although Prance (1982) discounted the floristic contribution of the Atlantic forests to the Amazon flora due to their early isolation. The basal placement of Atlantic forest taxa in several phylogenetic hypotheses of Neotropical organisms seems to support the contribution of early diverging lineages to the Atlantic Forest biota (Cracraft & Prum, 1988; Bates et al., 1998; Eberhard & Bermingham, 2005). In other cases, however, the presence of some lineages in these forests seems to result from more recent colonization from other South American source areas (Cracraft & Prum, 1988; Costa, 2003; Vicentini, 2007). Thus, as suggested by Silva and Castelletti (2003) and Pennington et al. (2006b), it seems more prudent to view the Atlantic Forest biota as having contributions from both old and recently diverged lineages.

Multiple centers of endemism based on several groups of organisms have been proposed for the Atlantic Forest domain (Prance, 1982; Cracraft, 1985; Soderstrom et al., 1988; Costa et al., 2000; Silva et al., 2004; Santos et al., 2007). The number of such centers varies depending on the organisms under consideration and the specific questions being addressed, both of which influence the selection of areas. Thus, although some studies point to a northern/southern separation in just two blocks (Cracraft, 1985; Soderstrom et al., 1988), finer-scale studies using low-vagility organisms suggest more numerous and smaller areas (e.g., Pinto-da-Rocha et al., 2005). Regardless of the study group and methodology used, most studies agree that there is an historical separation between the northern and southern parts of the domain, whose limits are more or less coincident with the Rio Doce valley (northern Espírito Santo state) (Cracraft & Prum, 1988; Amorim & Pires, 1996; Costa, 2003; Silva et al., 2004; Pinto-da-Rocha et al., 2005; Perret et al., 2006). Several examples of plant taxa restricted to either one of these areas are known, resulting in a strong floristic differentiation between the northern and southern Atlantic forests (Oliveira-Filho & Fontes, 2000; Oliveira-Filho et al., 2005).

The northern Atlantic forest (NAf) ranges from Rio Grande do Norte (ca. 5° S) to northern Espírito Santo (ca. 19° S) states, and comprises mostly a narrow strip of forest bounded to the west by the Caatinga domain (Thomas & Barbosa, 2008), as well as some inland areas, such as the “brejos nordestinos” (Rodal & Sales, 2008) and the Chapada Diamantina forests (Funch et al., 2008). Two centers of endemism are usually recognized in the NAf: Pernambuco (ca. 8° S), and Bahia (“central corridor”, from approximately 13° to 19° S) (Thomas et al., 1998). The NAf shows some floristic influence from the Amazonian forests, presumably due to historical connections through the Cenozoic (Rizzini, 1963; Andrade-Lima, 1966; Prance, 1979; Mori et al., 1981; Costa, 2003). Although the extension of these forest connections are unknown, three main routes for floristic exchange between the Amazonian and Atlantic rainforests have been proposed (Costa, 2003): a southern route through the Paraná River basin, a northeastern route through the Caatinga domain (Rizzini, 1963; Andrade-Lima, 1966), and a route by way of gallery forests across the central Brazilian cerrado (Oliveira-Filho & Ratter, 1995). The closer biogeographic relationship of the Pernambuco center plus the brejos nordestinos to the Amazon rather than to southern Atlantic forests is supportive of the northeastern route (Prance, 1979, 1982; Silva et al., 2004; Santos et al., 2007). In addition, evidence is provided by the disjunct occurrence of several genera in the NAf and the Amazonian forests that are lacking in the southern Atlantic forests such as Lacmellea and Macoubea (Apocynaceae), Anthodiscus (Caryocaraceae), Glycydendron (Euphorbiaceae), Gustavia and Lecythis (Lecythidaceae), Macrolobium and Parkia (Leguminosae), Roucheria (Linaceae), Adelobotrys and Graffenrieda (Melastomataceae), Anomospermum and Orthomene (Menispermaceae), Naucleopsis and Pseudolmedia (Moraceae), Aptandra (Olacaceae), Atractantha and Pariana (Poaceae), and Pagamea and Remijia (Rubiaceae).

The southern part of the domain [southern Atlantic forests (SAf)] ranges from Espírito Santo (ca. 19° S) to southern Santa Catarina (ca. 29° S), and it includes a large western extension of seasonally dry forests in southeastern Brazil, eastern Paraguay, and Misiones in Argentina (Oliveira-Filho & Fontes, 2000; Oliveira-Filho et al., 2006), and the Araucaria angustifolia Forest Province (Morrone, 2006). The seasonally dry forests of the Paranaense and Misiones nuclei are currently considered a distinct phytogeographic unit (Prado, 2000; Pennington et al., 2006a), whereas the subtropical Araucaria forests are sometimes considered on their own as the Paranaense Province (Cabrera & Willink, 1973) or the Araucaria angustifolia Forest Province (Morrone, 2006). The SAf block comprises an extensive center of endemism that seems to coincide well with the Serra do Mar and Serra da Mantiqueira mountain ranges (Prance, 1982; Silva et al., 2004; Pinto-da-Rocha et al., 2005). Here we adopt the delimitation of the Serra do Mar center of endemism as proposed by Silva et al. (2004), which is congruent with a group of historically related areas ranging from southern Espírito Santo to northern Santa Catarina (Pinto-da-Rocha et al., 2005). Instead of sharing a high number of taxa with Amazonia, the SAf seems to be influenced more strongly by elements of other regions. As an example, some Andean-centered taxa can be found in the SAf but are usually absent in the NAf (A. Amorim, pers. comm., 2009), such as Oreopanax (Araliaceae), Clethra (Clethraceae), Gaultheria (Ericaceae), Escallonia (Escalloniaceae), Gordonia (Theaceae), Macrocarpaea (Gentianaceae), Hypericum (Clusiaceae), Meriania (Melastomataceae), Calyptrogenia and Myrceugenia (Myrtaceae), Fuchsia (Onagraceae), Aulonemia, Chusquea and Colanthelia (Poaceae), Euplassa (Proteaceae), Meliosma (Sabiaceae), and Valeriana (Valerianaceae). As discussed in section 1, other floristic elements of the SAf are probably remnants of a southern Gondwanan land connection (Sanmartín & Ronquist 2004), such as A. angustifolia, Canellaceae, Weinmannia (Cunoniaceae), Crinodendron (Elaeocarpaceae, Crayn et al., 2006), Griselinia (Griseliniaceae), Podocarpus (Podocarpaceae), some Proteaceae (Barker et al., 2007), and Drimys (Winteraceae).

The floristic differences between the northern and southern blocks of the Atlantic forests are supported by the available phylogenetic data. Most biogeographic studies point to the Atlantic Forest domain as a composite biogeographic area where the southern and northern areas are not sister groups (e.g., Cracraft & Prum, 1988; Costa, 2003; Perret et al., 2006; Nihei & Carvalho, 2007; Santos et al., 2007), however, in others the same two blocks form a monophyletic Atlantic Forest (e.g., Amorim & Pires, 1996; Costa et al., 2000). Although rare, the exchange of floristic elements between the NAf and SAf has been proposed by Perret et al. (2006) and seems to account for the presence of typical elements of the SAf in montane areas of southern Bahia (A. Amorim, pers. comm., 2009) and the Chapada Diamantina (Funch et al., 2008).

2.4 Caatinga

The Caatinga domain of northeastern Brazil is the largest continuous area of SDTFs of South America, originally covering an area of approximately 850,000 km2 (Queiroz, 2006). The vegetation varies from an open thorny scrub to low dry forests; it is conditioned by a prevailing semiarid climate, with high evapotranspiration potential (1500–2000 mm/year) and low precipitation (300–1000 mm/year) concentrated during a short period of 3–5 months (Sampaio, 1995; Queiroz, 2006). Floristic diversity in the Caatinga is relatively low (Sampaio, 1995), especially when compared to that of the Atlantic rainforests and the Cerrado (e.g., Castro et al., 1999; Myers et al., 2000); however, 46% endemic species have been reported for the tree flora (Pennington et al., 2006a), and 52.5% for the family Leguminosae (144 of 274 species endemic to this domain, Queiroz, 2006). Likewise, Giulietti et al. (2002) have listed 18 angiosperm genera and 318 species as endemic to the Caatinga.

The floristic composition of the Caatinga shows strong links with other nuclei of South American SDTFs, such as Misiones, Piedmont, the Caribbean coast of Colombia and Venezuela, and the dry inter-Andean valleys, but not to the mostly subtropical South American dry forests of the Chaco domain (Prado & Gibbs, 1993; Prado, 2000; Pennington et al., 2000, 2006a). The recent recognition that SDTFs represent an archipelago-like biogeographic unit (Prado, 2000) has stimulated interest in the historical processes that may have shaped current distributions of SDTF-centered taxa (Pennington et al., 2000, 2004; Lavin, 2006; Ritz et al., 2007), not to mention their importance as repository areas for the conservation of the highly threatened Neotropical dry forest flora (Gentry, 1995).

Few studies have specifically focused on the Caatinga (Pennington et al., 2006a). In a first attempt to examine the historical biogeography of the Caatinga, Queiroz (2006) used distribution data of Leguminosae species, which account for approximately one-third of the total number of plant species found in the biome (Giulietti et al., 2002). By plotting the known geographic distributions of 274 species in the area occupied by the biome, he found that despite sharing an overall physiognomic similarity, the flora of the Caatinga could be divided into two distinct floristic blocks. One of these blocks is associated with soils derived from the crystalline basement and accounts for most of the floristic link of the Caatinga with the remaining areas of SDTFs (Prado, 2000). Genera characteristic of these areas include Amburana, Apuleia and Pterogyne (Leguminosae), as well as Balfourodendron (Rutaceae), Quiabentia (Cactaceae), Astronium (Anacardiaceae), and Patagonula (Boraginaceae) (Queiroz, 2006). The second group corresponds to plants growing on sandy sedimentary areas scattered across the domain, and these accounts for most of the endemic taxa of Leguminosae found in the Caatinga.

The historical development of this scenario was proposed as the result of a widespread process of pediplanation during the early Quaternary that uncovered the Precambrian crystalline bedrock in the region. According to this hypothesis, the earlier continuous sedimentary surfaces became dissected, leading to allopatric differentiation of their taxa. The exposed areas derived from the crystalline bedrock were occupied by elements typical of the SDTF flora (Queiroz, 2006), which were postulated as having evolved during the Miocene–Pliocene (Pennington et al., 2004; Saslis-Lagoudakis et al., 2008) and may have migrated later to the Caatinga. Phylogenetic analyses of taxa with multiple species centered in the Caatinga would be critical to test this scenario. Some good candidates for this purpose are groups within Croton and Jatropha (Euphorbiaceae), several Leguminosae genera such as Vachellia (Acacia s.l.), Aeschynomene, Bauhinia, Calliandra, Centrosema, Chamaecrista, Lonchocarpus, Macroptilium, Mimosa, Senna, Stylosanthes, and Zornia, as well as genera with several species endemic to the Caatinga, such as Melocactus and Pilosocereus (Cactaceae), Apodanthera (Cucurbitaceae), Hyptis (Lamiaceae) and Piriqueta Aubl. (Turneraceae) (Giulietti et al., 2002).

2.5 Campos sulinos (southern grasslands)

Extensive areas of southern Brazil are covered by open grassy formations generally called campos, which have been used as natural pastures (see Overbeck et al., 2007 for an overview on South Brazilian campos). In Brazil alone it is possible to distinguish between the campos do Planalto Meridional, which have a patchy occurrence within the Atlantic Forest domain and range from Paraná to northern Rio Grande do Sul states (Araucaria angustifolia Forest Province of Morrone, 2006), to the continuous pampas or campos da Campanha Gaúcha, which covers the largest part of Rio Grande do Sul and neighboring areas of Uruguay and Argentina (Pampa Province of Morrone, 2006). The patchy distribution of the campos do planalto is a consequence of its dynamics with the Araucaria Forest, which tends to advance over the campos– young Araucaria plants cannot grow in shade – with forest expansion being controlled by fire and other human activities (Klein, 1960; Behling et al., 2004; Overbeck et al., 2007).

Within the pampas, some authors further separate the southern Brazilian and Uruguayan grasslands (north of Rio da Prata) from the Argentinian pampas based on floristic differences (e.g., Soriano et al., 1992). The word “pampa” itself has a Quechua origin meaning “flat region.” In this sense, it includes all low, flat areas of the Rio da Prata basin northward to the Serra Geral. In this section we use the term pampas in this broad definition, which agrees with Morrone's Pampa Province (Morrone, 2006).

Floristic and physiognomic differences between the campos do planalto and the pampas are evident. Among the grasses, the relative importance of megathermic groups, such as Andropogoneae, Chlorideae, Eragrosteae and Paniceae in the campos do planalto is much higher than in the pampas, which in turn have a higher contribution of microthermic elements, including Agrostis, Aristida, Briza, Bromus, Calamagrostis, Danthonia, Piptochaetium, and Stipa (Burkart, 1975; Longhi-Wagner & Zanin, 1998; Boechat & Longhi-Wagner, 2000; Overbeck et al., 2007). In fact, the grass flora of the pampas consists of a mixture of both megathermic and microthermic grasses, which have distinct phenological phases (Burkart, 1975). Also noteworthy is the common presence of palms (mostly small species of Butia) in the campos do planalto, and its rarity or absence in the pampas.

Plant diversity in the Campos sulinos has been estimated as between 3,000 and 4,000 species (Overbeck et al., 2007), and some studies point to these grasslands as among the most species-rich in the world (Overbeck et al., 2006). The flora is dominated by species of sedges and grasses, but also includes shrubs and subshrubs of several families, such as Apiaceae (mostly Eryngium), Asteraceae (several species of Baccharis), Leguminosae, Myrtaceae, Malvaceae, Oxalidaceae and Rubiaceae (Joly, 1970; Soriano et al., 1992; Overbeck et al., 2007). The flora of the Campos sulinos in general has links to other open formations of South America. Several elements from the herbaceous flora of the Cerrado domain have their southern limits in the Campos sulinos (e.g., Boechat & Longhi-Wagner, 2000), where many elements of temperate/subtropical floras are fairly common. At the same time, some of these southern elements have their northernmost occurrence in this same region (e.g., Longhi-Wagner & Zanin, 1998). The apparent transitional nature of the Campos sulinos flora is even more evident in the state of Rio Grande do Sul, where the campos de planalto are replaced by the pampas at about 30° S (Smith, 1962; Burkart, 1975; Waechter, 2002; Ritter & Waechter, 2004; Overbeck et al., 2007).

Many examples of Andean-derived taxa are known from southern Brazil (Rambo, 1956; Smith 1962). A good example of connection with the Andean flora is provided by the presence of Gunnera manicata (Gunneraceae) in the wet hills and swamps of the high eastern planaltine areas of Santa Catarina and Rio Grande do Sul states. Dispersals of Andean genera both through Argentina to southern Brazil (Klein, 1960; Leite, 2002) and from the Paraná basin grasslands to the Andes (Katinas & Crisci, 2008) have been reported. The resulting disjunct pattern (see section 3.2.2.) is supported not only by similar mild climatic conditions, but also by former Quaternary connections that could have taken place during interglacial wetter periods (Ortiz-Jaureguizar & Cladera, 2006).

3 Patterns of distribution of Brazilian flora

  1. Top of page
  2. Abstract
  3. 1 Origin of tropical South American flora
  4. 2 Overview of main Brazilian phytogeographic domains
  5. 3 Patterns of distribution of Brazilian flora
  6. Acknowledgments
  7. References

As previously discussed, many angiosperm genera present in Brazil are also found on other continents. The most common patterns of intercontinental disjunctions include: (i) Africa, for example, Duguetia (Annonaceae), Pitcairnia (Bromeliaceae), Rhipsalis baccifera (Cactaceae), Chrysobalanus icaco (Chrysobalanaceae), Conceveiba and Pogonophora (Euphorbiaceae), Symphonia globulifera (Clusiaceae), Sacoglottis (Humiriaceae), Dalbergia ecastophyllum (Leguminosae), Aptandra and Ptychopetalum (Olacaceae), and Paullinia pinnata (Sapindaceae) (Thorne, 1973; Prance, 1979; Renner, 2004); (ii) other southern lands derived from Gondwana breakup (Sanmartín & Ronquist, 2004); and (iii) tropical and subtropical Asia, e.g., Anaxagorea (Annonaceae), Dendropanax (Araliaceae), Hedyosmum (Chloranthaceae), Rourea (Connaraceae), Caryodaphnopsis (Lauraceae), Schoepfia (Olacaceae), and Gordonia (Theaceae) (Good, 1974).

The geographic distribution patterns of Brazilian plant species are in general agreement with the main geomorphological domains and their vegetation types. Most species are either endemic to one domain or found in a regional subdivision or small portion of each domain; several species, however, are widespread in the Neotropics or disjunct between two of these domains. In addition to the genera previously mentioned as candidates for biogeographic studies of the Brazilian flora using a phylogenetic approach, we provide here examples of species and genera that illustrate geographic distributions endemic to one domain and disjunct between domains. We have tried to represent all life habits among these examples, but it is worth mentioning that we have a relative paucity of data on the geographic distribution of vines when compared to that of the other life habits. There are few recent monographs on important Neotropical vine groups, such as Bignoniaceae, Celastraceae (subfam. Hippocrateoideae), Cucurbitaceae, Menispermaceae, Sapindaceae and Vitaceae.

3.1 Endemic to one domain

Each of the above-mentioned Brazilian phytogeographic domains has its own set of endemic genera and species. Some genera and species have a geographic distribution somewhat similar to that of the domain where they occur, and can serve as an indicator of domain limits. Because the number of species endemic to each domain is very extensive, we mention just a few as examples.

3.1.1 Amazon  We estimate that the number of angiosperm genera endemic to the Amazon may be approximately 300–350, in addition to the 80 endemic genera of the Guiana Shield flora (Berry & Riina, 2005). It is difficult to estimate how many of the Amazonian genera are restricted to Brazil, because many of them are found in poorly explored areas close to the Venezuelan, Colombian and Peruvian borders (e.g., Yanomamua, Grant et al., 2006). In addition, many new genera have been recently described for the Amazonian flora but are not yet recorded in Brazil (Zuloaga & Judziewicz, 1993; Londoño et al., 1995; Woodward et al., 2007; Fernández-Alonso & Arbeláez, 2008). Examples of Amazonian endemic genera are: Polygonanthus (Anisophylleaceae), Leopoldinia (Arecaceae), Hevea (Euphorbiaceae), Goupia (Goupiaceae), Asteranthos and Bertholletia (Lecythidaceae), Dinizia and Eperua (Leguminosae), Huberodendron (Malvaceae), Brachynema and Curupira (Olacaceae), Parachimarrhis (Rubiaceae), Adiscanthus (Rutaceae), Duckeodendron (Solanaceae), Phenakospermum (Strelitziaceae), and Thurnia (Thurniaceae). Endemic species are numerous, many of which extend their ranges beyond Brazilian frontiers; selected examples are Mauritia carana (Arecaceae), Protium calendulinum (Burseraceae), Caryocar microcarpum (Caryocaraceae), Hirtella physophora (Chrysobalanaceae), Parkia decussata (Leguminosae), and Zanthoxylum djalma-batistae (Rutaceae).

3.1.2 Cerrado  We estimate that ca. 60 angiosperm genera are endemic to the Cerrado domain, including Klotzschia (Apiaceae), Diplusodon (Lythraceae), and Salvertia (Vochysiaceae). As already mentioned, 35% of the tree species and 70% of the herbaceous and shrubby plants found in the Cerrado are believed to be endemic. These include Schefflera macrocarpa (Araliaceae), Butia archeri and Syagrus petraea (Arecaceae), Tabebuia ochracea (Bignoniaceae), Caryocar brasiliense (Caryocaraceae), Kielmeyera coriacea (Clusiaceae), Connarus suberosus (Connaraceae), Andira cujabensis, Dimorphandra mollis and Hymenaea stigonocarpa (Leguminosae), Oxalis hirsutissima (Oxalidaceae), Esenbeckia oligantha (Rutaceae), Styrax martii (Styracaceae), Piriqueta tamberlikii (Turneraceae), Stachytarpheta gesnerioides (Verbenaceae), and Qualea grandiflora and Q. parviflora (Vochysiaceae).

3.1.3 Atlantic Forest  Stehmann et al., (2009) reported 159 angiosperm genera and 3,364 species as endemic to the Atlantic Forest. Most of the endemic species are not found across the entire range of the domain, and the ones listed below are illustrative of many distinct distribution patterns: Carpotroche brasiliensis (Achariaceae), Hippeastrum reticulatum (Amaryllidaceae), Schefflera angustissima (Araliaceae), Allagoptera arenaria (Arecaceae), Tabebuia elliptica (Bignoniaceae), Maytenus aquifolium (Celastraceae), Stephanopodium blanchetianum (Dichapetalaceae), Sloanea obtusifolia (Elaeocarpaceae), Nematanthus lanceolatus (Gesneriaceae), Cariniana legalis (Lecythidaceae), Poecilanthe falcata (Leguminosae), Leandra melastomoides (Melastomataceae), Trichilia pseudostipularis (Meliaceae), Mollinedia engleriana (Monimiaceae), Ficus organensis (Moraceae), Virola gardneri (Myristicaceae), Hindsia glabra (Rubiaceae), Conchocarpus insignis (Rutaceae), Chrysophyllum inornatum (Sapotaceae), and Vochysia schwackeana (Vochysiaceae).

3.1.4 Caatinga  A comprehensive list of endemic angiosperm genera from the Caatinga can be found in Giulietti et al. (2002). The following are examples of endemic genera and species are illustrative. Genera: Apterokarpos (Anacardiaceae); Alvimiantha (Rhamnaceae); Anamaria (Scrophulariaceae); Barnebya and Mcvaughia (Malpighiaceae); Facheiroa (Cactaceae); Fraunhofera (Celastraceae); Blanchetiodendron (Leguminosae); and Rayleya (Malvaceae). Species: Cyrtocarpa caatingae and Spondias tuberosa (Anacardiaceae), Annona vepretorum (Annonaceae), Aspidosperma pyrifolium (Apocynaceae), Copernicia prunifera (Arecaceae), Tabebuia spongiosa (Bignoniaceae), Patagonula bahiensis (Boraginaceae), Encholirium spectabile (Bromeliaceae), Arrojadoa rhodantha and Discocactus bahiensis (Cactaceae), Colicodendron yco (Capparaceae), Mimosa paraibana and Hymenaea eriogyne (Leguminosae), Ceiba glaziovii (Malvaceae), Ruprechtia glauca (Polygonaceae), Pilocarpus sulcatus (Rutaceae), and Averrhoidium gardnerianum (Sapindaceae).

3.1.5 Campos sulinos  To our knowledge, Onira (Iridaceae) is the only angiosperm genus restricted to the Brazilian sector of the Campos sulinos. According to Katinas et al. (2008), many genera of Asteraceae found in the campos are shared with neighboring areas in Argentina, Paraguay, and Uruguay, such as Criscia, Holocheilus, Ianthopappus, and Pamphalea. Lists of common species from the Brazilian campos de planalto and pampas were provided by Overbeck et al. (2007), including 10 endemic to the former and nine to the pampas. A few selected examples include E. megapotamicum and E. urbanianum (Apiaceae), Mangonia tweedieana (Araceae), Butia yatay (Arecaceae), Mikania oreophila, Panphalea araucariophila, and Trichocline humilis (Asteraceae), Kelissa brasiliensis (Iridaceae), Aristida teretifolia, Eragrostis acutiglumis, and Stipa charruana (Poaceae), Mimosa cruenta (Leguminosae), and Oxalis eriocarpa (Oxalidaceae).

3.2 Disjunct

Several patterns of disjunction have been described for the Brazilian flora (e.g., Prance, 1979, 1988; Giulietti & Pirani, 1988; Mori, 1988; Pirani, 1990; Granville, 1992; Prado & Gibbs, 1993). In many cases they appear to be the result of dispersal events rather than a consequence of the fragmentation of a wider ancestral distribution, as the distinct areas of occurrence have asymmetric species diversity (Lavin et al., 2000; Givnish et al., 2000); in others cases the disjunct distribution may be adequately explained by vicariance. For example, studies of paleoclimate and paleovegetation in northeastern Brazil point to the previous existence of extensive moist forests in the area presently occupied by the dry Caatinga domain. The current presence of scattered islands of montane forests (“brejos”) in this domain is believed to represent relicts of these once more widespread moist forests in the region (Andrade-Lima, 1982; Oliveira et al., 1999).

Besides the fact that disjunct geographic distributions provide cases well suited for historical biogeographic studies, the geographic separation of biological entities is also suggestive of an interruption – or at least reduction – of genetic flow, thus promoting opportunities for allopatric speciation. The examples provided below are well-known cases of disjunct distribution patterns that are unlikely to be due to sampling artifacts. As most of the disjunct taxa listed below are species or small genera, we suggest that both species-level (phylogeographic) and phylogenetic studies of higher taxa must be carried out. By adopting a multi-level approach we believe that a better understanding of the intricate interactions among geographic isolation, genetic differentiation, and eventually speciation can be achieved.

3.2.1 Amazon–Atlantic Forest  As mentioned in section 2.3, several studies point to former connections between the Amazonian and the Atlantic forests (e.g., Andrade-Lima, 1966; Prance, 1979; Mori et al., 1981; Oliveira & Daly, 1999; Santos et al., 2007). Many examples of disjunct taxa found in these two forest blocks are known, such as Philodendron ornatum (Araceae), Anthodiscus amazonicus (Caryocaraceae), Parinari excelsa (Chrysobalanaceae), Glycydendron (Euphorbiaceae), Couratari macrosperma and Eschweilera ovata (Lecythidaceae), Sextonia (Lauraceae), Byrsonima laevigata (Malpighiaceae), Adelobotrys (Melastomataceae), Trichilia lepidota (Meliaceae), Elvasia (Ochnaceae), Peperomia rhombea (Piperaceae), and Pouteria venosa (Sapotaceae).

3.2.2 Southern Brazil–Andes  The occurrence in southern Brazil of a few species belonging to genera best represented in the Andes (or even in the Holarctic region, like Berberis L.) has been pointed out by several authors (e.g., Rambo, 1956; Smith, 1962; Clark, 1995; Waechter, 2002; Berry et al., 2004). In a floristic survey of the Aparados da Serra, in the northeastern part of Rio Grande do Sul state, Rambo (1956) listed 742 seed plant species, and ascribed an “Andean origin” to 197 (26%) of them. In most cases of this distribution pattern, the Brazilian extension is restricted to subtropical or tropical high-altitude areas. Selected examples (some mentioned in section 2.3) include: Araucaria (Araucariaceae, with only two species in South America, Araucaria araucana in Chile and Araucaria angustifolia in Brazil); Holocheilus, Mutisia and Perezia (Asteraceae), Berberis (Berberidaceae), Hedyosmum (Chloranthaceae), Clethra scabra (Clethraceae), Hypericum (Clusiaceae), Crinodendron (Elaeocarpaceae), Acca and Myrceugenia (Myrtaceae), Fuchsia (Onagraceae), Chusquea (Poaceae), Quillaja (Quillajaceae), Acaena (Rosaceae), and Viviania (Vivianiaceae).

3.2.3 Campos rupestres–Restinga  The term restinga refers to low scrubs and forests on sandy areas of recent origin along the Brazilian coast (Daly & Mitchell, 2000; Thomas & Barbosa 2008). Some studies have suggested a floristic connection between these lowland restinga areas and the campos rupestres vegetation of the Espinhaço Range usually found above 1000 m (Giulietti & Pirani, 1988; Harley, 1988), as reported for species of Lagenocarpus (Cyperaceae), Leiothrix (Eriocaulaceae), Eriope (Lamiaceae), Mimosa (Leguminosae), Marcetia (Melastomataceae), Phyllanthus (Phyllanthaceae), Eragrostis (Poaceae), and Vellozia (Velloziaceae). Among 56 plant taxa presumably representative of this pattern, Alves et al. (2007) have confirmed only nine (16%) as truly disjunct. Most of the remaining species have also been found in lowland Cerrado and Atlantic rainforests.

3.2.4 Eastern Brazil–Guiana Shield  This pattern was mentioned by several authors (Steyermark, 1982; Giulietti & Pirani, 1988; Berry & Riina, 2005). It is representative of groups with high diversity in the Guiana Shield, and just one species in the Espinhaço Range, such as the Schefflera group “Crepinella” (Araliaceae), Bonnetia (Bonnetiaceae), and Cottendorfia (Bromeliaceae), or groups with highest diversity in the Espinhaço Range and just a few species in the Guiana Shield, such as Leiothrix (Eriocaulaceae), Chamaecrista (Leguminosae), Marcetia and Microlicia (Melastomataceae), Declieuxia (Rubiaceae) and Vellozia (Velloziaceae). The occurrence of asymmetric diversity in both directions is suggestive that these patterns were achieved by recent dispersal events, either westward (e.g., Chamaecrista, Declieuxia, Leiothrix), or eastward (e.g., Bonnetia, Cottendorfia, Schefflera group Crepinella).

3.2.5 Disjunct among SDTFs  This pattern is characteristic of species associated with two or more of the SDTFs nuclei (Pennington et al., 2000, 2006a; Prado, 2000; Queiroz, 2006), among which the Caatinga, Paranaense, Misiones and Piedmont account for most of the species found in Brazil. It fits the Pleistocenic arc pattern proposed and richly illustrated by Prado and Gibbs (1993). A few selected examples include Schinopsis brasiliensis (Anacardiaceae), Carica quercifolia (Caricaceae), Amburana cearensis, Geoffroea spinosa and Poeppigia procera (Leguminosae), Ruprechtia laxiflora (Polygonaceae), and Galipea ciliata (Rutaceae).

3.2.6 Disjunct among rock outcrops in Atlantic Forest and/or Cerrado mountains  Several genera and species are shared among the “islands” of montane open formations found across the Atlantic Forest and Cerrado domains (Giulietti & Pirani, 1988; Di Maio, 1996; Safford, 1999; Safford & Martinelli, 2000; Calió et al., 2008). Some examples of plant taxa either restricted to areas within one of these domains or disjunct between the two domains include: Wunderlichia (Asteraceae), Prepusa and Senaea (Gentianaceae), Pseudotrimezia (Iridaceae), Crotalaria claussenii (Leguminosae), Luxemburgia (Ochnaceae), Aulonemia effusa, Chusquea pinifolia and Glaziophyton mirabile (Poaceae), Bradea and Hindsia (Rubiaceae), Physocalyx (Scrophulariaceae), Vellozia (Velloziaceae), Stachytarpheta glabra (Verbenaceae), and Xyris (Xyridaceae).

Acknowledgments

  1. Top of page
  2. Abstract
  3. 1 Origin of tropical South American flora
  4. 2 Overview of main Brazilian phytogeographic domains
  5. 3 Patterns of distribution of Brazilian flora
  6. Acknowledgments
  7. References

Acknowledgements  We wish to thank Jun WEN for inviting us to contribute to this volume. We also thank Douglas C. DALY, Robyn J. BURNHAM, and Hong QIAN for their reviews. Luciano P. QUEIROZ and Toby PENNINGTON provided valuable comments and critical references. Juliana OTTRA helped digitalizing the map. PF greatfully acknowledges Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; Grant No. 200682/2006-7) and the Integrative Life Sciences PhD Program from Virginia Commonwealth University for financial support. JRP is grateful to CNPq for financial support.

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  5. 3 Patterns of distribution of Brazilian flora
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