Abstract Detail

Systematics

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

Is it faster to move or evolve? Comparing effects of niche conservatism and niche evolution on diversification rate 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, high alpine biomes, tropical dry forests and deserts. The genus originated in Central America in the Oligocene, during a period of global cooling and aridification. Early diversification occurred in seasonal, semi-arid environments. Dispersal to South America was followed by separate radiations in high alpine biomes and low to mid-elevation humid forest. A subsequent dispersal to Central America resulted in the largest radiation of the genus into arid, seasonal, and moist forest biomes. Each major radiation comprises a seasonal or dry adapted clade sister to a predominantly moist forest clade, and a moist forest ancestor is inferred for each radiation. Diversification rates are higher in moist forest clades. Niche evolution is a common pattern in the evolutionary history of Citharexylum-there seem to be few barriers to adaptation to different biomes-but niche conservatism may be the greater contributor to diversification.

1 - Department Of Biology, Box 351800, Seattle, WA, 98195, United States
2 - University of Washington, Department of Biology, Box 351800, Seattle, WA, 98195, USA

Keywords:
Citharexylum
Verbenaceae
Biogeography
Niche Evolution
phylogenetic niche conservatism
microfluidic PCR.

Presentation Type: Oral Paper
Session: 26, ASPT Cooley Awards II
Location: 110/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 1:30 PM
Number: 26001
Abstract ID:728
Candidate for Awards:George R. Cooley Award