Historical climate change and speciation: neotropical seasonally dry forest plants show patterns of both tertiary and quaternary diversification.
Historical climate changes have had a major effect on the distribution and evolution of plant species in the neotropics. What is more controversial is whether relatively recent Pleistocene climatic changes have driven speciation, or whether neotropical species diversity is more ancient. This question is addressed using evolutionary rate analysis of sequence data of nuclear ribosomal internal transcribed spacers in diverse taxa occupying neotropical seasonally dry forests, including Ruprechtia (Polygonaceae), robinioid legumes (Fabaceae), Chaetocalyx and Nissolia (Fabaceae), and Loxopterygium (Anacardiaceae). Species diversifications in these taxa occurred both during and before the Pleistocene in Central America, but were primarily pre-Pleistocene in South America. This indicates plausibility both for models that predict tropical species diversity to be recent and that invoke a role for Pleistocene climatic change, and those that consider it ancient and implicate geological factors such as the Andean orogeny and the closure of the Panama Isthmus. Cladistic vicariance analysis was attempted to identify common factors underlying evolution in these groups. In spite of the similar Mid-Miocene to Pliocene ages of the study taxa, and their high degree of endemism in the different fragments of South American dry forests, the analysis yielded equivocal, non-robust patterns of area relationships.
Pennington
R Toby
RT
Royal Botanic Garden Edinburgh, 20a Inverleith Row, Edinburgh EH3 5LR, UK. t.pennington@rbge.org.uk
Lavin
Matt
M
Prado
Darién E
DE
Pendry
Colin A
CA
Pell
Susan K
SK
Butterworth
Charles A
CA
D001483:Base Sequence; D001499:Bayes Theorem; D044822:Biodiversity; D002489:Central America; D002980:Climate; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D019143:Evolution, Molecular; D055593:Geological Phenomena; D005844:Geology; D016013:Likelihood Functions; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D010944:Plants / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013020:South America; D013045:Species Specificity; D013997:Time Factors
D021903:DNA, Ribosomal Spacer