Abstract Detail


Tribble, Carrie [1], José Ignacio, Márquez Corro [2], Mike R., May [3], Escudero Lirio, Antonio Marcial [4], Hipp, Andrew [5], Rosana, Zenil-Ferguson [6].

The influence of chromosome evolution on diversification rates in Carex (Cyperaceae).

Recent studies of angiosperm diversification have focused on the role of polyploidy as a driver of diversification. A less studied aspect in this field is the role of aneuploidies, single chromosomal changes that can enhance or hinder speciation and extinction of lineages by instantaneously modifying species fitness and potentially inducing reproductive isolation. From the modeling perspective, studying aneuploidy linked to diversification is mathematically and computationally challenging because of the large number of states and parameters to track single chromosome changes. Carex is a megadiverse genus in the sedge family (Cyperaceae: Poales; ca. 5600 spp.). Members of Carex possess holocentric chromosomes, leading to highly variable chromosome numbers across — and sometimes within — species; chromosome numbers vary from 2n = 12 to 2n = 124. We construct a graphical model of chromosome number evolution linked to diversification rates with a large number of states. Our model includes parameters that functionally link diversification rates to chromosome number change, differentiates between anagenetic and cladogenetic aneuploidy changes, and allows for variation in diversification rate not due to chromosome number change (hidden states). We apply our model to the most recent Cyperaceae time-calibrated phylogeny with chromosome number data from over 700 taxa. We report very fast rates of chromosome gains and losses across Carex. However, when we add diversification rate variation not linked to chromosome number change, we find that these chromosomal gains and losses do not affect diversification rates in Carex. Our inferences demonstrate the importance of including hidden rates in diversification rate analyses to identify real processes linked to speciation and extinction. We highlight the remarkable pliability of chromosome number in Carex; despite fast rates of gains and losses of chromosomes, single chromosome changes do not appear to cause reproductive barriers leading to speciation at macroevolutionary scales.

1 - University Of Hawaii At Manoa, Department Of Biology, 2538 McCarthy Mall, Edmondson Hall 216, Honolulu, HI, 96822, United States
2 - Universidad Pablo de Olavide, Department of Molecular Biology and Biochemical Engineering, Seville, Spain
3 - University of California, Berkeley, Integrative Biology, University of California, Berkeley, Berkeley, CA, 94720, United States
4 - Universidad de Sevilla, Departamento de Biología Vegetal y Ecología, Seville, Spain
5 - The Morton Arboretum, 4100 Illinois Route 53, Lisle, IL, 60532, United States
6 - University of Hawaii at Manoa, School of Life Sciences, 2538 McCarthy Mall, Edmondson Hall, Room 216, Honolulu, HI, 96822, United States

state-dependent speciation and extinction
hidden states.

Presentation Type: Oral Paper
Number: MACRO II015
Abstract ID:767
Candidate for Awards:None

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