Abstract Detail


Frost, Laura [1], Olmstead, Richard [2].

Comparing effects of niche conservatism and niche evolution in Citharexylum (Verbenaceae).

Much of our understanding of Neotropical diversification relates to recent, rapid radiations in a single biome (e.g. the paramo or cloud forests). We sought to investigate patterns of biogeography and diversification in an older Neotropical lineage inhabiting multiple biomes in order to understand relative contributions of niche conservatism and niche evolution on diversification. Citharexylum comprises ca. 70 species of flowering trees and shrubs distributed from northern Mexico to southern Brazil and Argentina in low-elevation tropical moist forest, mid-elevation moist forest, high alpine biomes, tropical dry forests and deserts. Citharexylum originated in Mesoamerica in the mid-Miocene, but the crown radiation occurred in the late Miocene to early Pliocene. Early diversification occurred in mid-elevation montane forests with some temperate elements. Dispersal to South America was followed by separate radiations in open, Andean biomes and low to mid-elevation forest. In Mesoamerica, species repeatedly colonized xeric, seasonally dry, and moist forest biomes. Both niche conservatism and niche evolution have played important roles in the diversification of Citharexylum. The Mesoamerican clade exhibits a pattern of radiation within the ancestral biome with more recent, independent colonization events, whereas the South American clade exhibits a pattern of early colonization and radiation within biomes. Despite differences in biogeographic patterns and diversification rates, both clades have produced similar taxonomic diversity in the same amount of time.

1 - Louisiana State University, Department Of Biological Sciences, 202 Life Sciences Building, Baton Rouge, LA, 70803, United States
2 - University Of Washington, Department Of Biology, Campus Box 355325, Seattle, WA, 98195, United States

Niche Conservatism
niche evolution

Presentation Type: Oral Paper
Abstract ID:1064
Candidate for Awards:George R. Cooley Award

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