The discordance of diversification: evolution in the tropical-montane frogs of the Eastern Arc Mountains of Tanzania



    1. University of Chicago, Committee on Evolutionary Biology, 1025 E. 57th St., Culver Hall 402, Chicago, IL 60637, USA
    2. Field Museum of Natural History, Zoology Department, 1400 S. Lake Shore Dr., Chicago, IL 60605, USA
    Search for more papers by this author

Lucinda P. Lawson, Fax: 312 665 7754; E-mail:


Species with similar geographical distribution patterns are often assumed to have a shared biogeographical history, an assumption that can be tested with a combination of molecular, spatial, and environmental data. This study investigates three lineages of Hyperolius frogs with concordant ranges within the Eastern Afromontane Biodiversity Hotspot to determine whether allopatric populations of co-distributed lineages shared a parallel biogeographical response to their shared paleoclimatic histories. The roles of refugial distributions, isolation, and climate cycles in shaping their histories are examined through Hierarchical Approximate Bayesian Computation, comparative phylogeography, and comparisons of current and past geographical distributions using ecological niche models. Results from these analyses show these three lineages to have independent evolutionary histories, which current spatial configurations of sparsely available habitat (montane wetlands) have moulded into convergent geographical ranges. In spite of independent phylogeographical histories, diversification events are temporally concentrated, implying that past vicariant events were significant at the generic level. This mixture of apparently disparate histories is likely due to quantifiably different patterns of expansion and retreat among species in response to past climate cycles. Combining climate modelling and phylogeographical data can reveal unrecognized complexities in the evolution of co-distributed taxa.