Genetic Differences between Wild and Artificial Populations of Metasequoia glyptostroboides: Implications for Species Recovery

Authors

  • YUAN-YUAN LI,

    1. Department of Environmental Sciences, East China Normal University, Zhongshan Road (N.) 3663, Shanghai 200062, People's Republic of China
    Search for more papers by this author
  • XIAO-YONG CHEN,

    1. Department of Environmental Sciences, East China Normal University, Zhongshan Road (N.) 3663, Shanghai 200062, People's Republic of China
    2. Shanghai Key Laboratory for Ecological Processes and Restoration in Urban, Shanghai 200062, People's Republic of China
    Search for more papers by this author
  • XIN ZHANG,

    1. Department of Environmental Sciences, East China Normal University, Zhongshan Road (N.) 3663, Shanghai 200062, People's Republic of China
    Search for more papers by this author
  • TIAN-YI WU,

    1. Department of Environmental Sciences, East China Normal University, Zhongshan Road (N.) 3663, Shanghai 200062, People's Republic of China
    Search for more papers by this author
  • HUI-PING LU,

    1. Department of Environmental Sciences, East China Normal University, Zhongshan Road (N.) 3663, Shanghai 200062, People's Republic of China
    Search for more papers by this author
  • YUE-WEI CAI

    1. Department of Environmental Sciences, East China Normal University, Zhongshan Road (N.) 3663, Shanghai 200062, People's Republic of China
    Search for more papers by this author

‡ Address correspondence to X.-Y. Chen, email xychens@hotmail.com or xychen@des.ecnu.edu.cn

Abstract

Abstract: Information on population genetics is fundamental to developing in situ or ex situ conservation strategies. Few researchers, however, have compared the genetic structure of restored and natural populations of threatened plant species. Metasequoia glyptostroboides Hu & Cheng (dawn redwood) (Taxodiaceae), a living fossil endemic to China, may be the most successfully recovered threatened species, with many more individuals and a much wider distribution than fossil records indicate. We used random amplification of polymorphic DNA markers to compare the genetic structure of artificial populations with that of wild ones and to determine whether the genetic structure of M. glyptostroboides has been recovered as has its distribution. The genetic variation of wild populations of M. glyptostroboides was lower than the average of gymnosperms, indicating the effects of glaciations and recent habitat loss and fragmentation. Genetic variation in artificial populations was less, but not substantially, compared with wild populations. The unweighted pair group method with arithmetic mean revealed that the wild and the artificial populations formed two distinct groups. Artificial populations were more similar to each other (mean Nei's genetic distance = 0.0924) than to wild populations (mean distance = 0.2054). This might be the result of biased seed collection, vegetative propagation, or a mixture of propagules from different populations and an ultimate propagule source. These results suggest that although the quantity and distribution range have been successfully restored, the genetic structure of M. glyptostroboides has not recovered appropriately, given the loss of genetic variation and biased genetic composition in artificial populations. Therefore, in addition to protecting the wild populations, additional ex situ genetic reserves should be established based on genetic knowledge and via appropriate approaches. We suggest that population genetic and demographic indices should be considered when downlisting or delisting threatened species.

Abstract

Resumen: Es fundamental contar con información sobre genética poblacional para el desarrollo de estrategias de conservación in situ o ex situ. Sin embargo, pocos investigadores han comparado la estructura genética de poblaciones restauradas y naturales de especies de plantas amenazadas. Metasequoia glyptostroboides Hu & Cheng (Taxodiaceae), un fósil viviente endémico de China, puede ser la especie amenazada recuperada más exitosamente, con mucho más individuos y una distribución mucho mayor que la indicada por registros fósiles. Utilizamos amplificaciones aleatorias de marcadores de ADN polimórfico para comparar la estructura genética de poblaciones artificiales con la de poblaciones silvestres y para determinar si la estructura genética de M. glyptostroboides se ha recuperado como lo ha hecho su distribución. La variación genética de poblaciones silvestres de M. glyptostroboides fue menor que la del promedio de gimnospermas, lo que indica efectos de glaciaciones y pérdida y fragmentación reciente de hábitat. La variación genética en poblaciones artificiales fue menor, pero no sustancialmente, comparada con poblaciones silvestres. El método de grupos pareados con media aritmética reveló que las poblaciones artificiales y silvestres formaron dos grupos distintos. Las poblaciones artificiales fueron más similares entre si (distancia genética de Nei promedio = 0.0924) que con poblaciones silvestres (distancia promedio = 0.2054). Esto puede ser el resultado de la colecta sesgada de semillas, propagación vegetativa o mezcla de propágulos de diferentes poblaciones y una fuente terminal de propágulos. Estos resultados sugieren que aunque la cantidad y la distribución se han restaurado exitosamente, la estructura genética de M. glyptostroboides no se ha recuperado adecuadamente, dada la pérdida de variación genética y la composición genética sesgada de poblaciones artificiales. Por lo tanto, además de proteger a las poblaciones silvestres, se deben establecer reservas genéticas ex situ adicionales con base en conocimiento genético y por medio de métodos adecuados. Sugerimos que se deben considerar índices demográficos y de genética poblacional cuando se revise el estatus de especies amenazadas.

Ancillary