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Abstract Detail


Finch, Geoffrey [1], Yang, Yang [1], Barker, Michael S. [1].

Is chromosome number positively correlated with post-zygotic reproductive isolation?

Chromosome number variation is a striking aspect of the structural diversity of eukaryotic genomes. Among flowering plants, numbers range from n = 2 in a few species to over 300 in Sedum sauveolens. Despite this variation, most chromosome numbers across plants and animals have a narrow distribution with similar medians at n ~ 9. It remains unclear why chromosome numbers are centered on this range, especially in flowering plants, in which polyploidy has repeatedly increased numbers followed by losses back to this range. This process of chromosome loss is one aspect of genomic diploidization of polyploids. A recently emerged hypothesis proposes that lineages with low chromosome counts are more likely to survive this process, due to a putative penalty of high chromosome numbers. More chromosomes should provide more opportunity for independent sets of reciprocally lost genes and other types of Bateson-Dobzhansky-Muller Incompatibility (BDMI) to evolve, decreasing fitness in these taxa relative to taxa with low chromosome counts. To test this hypothesis, we analyzed whether chromosome number in plants is positively correlated with the degree of post-zygotic isolation, such as that caused by BDMIs. We used crossability indices, chromosome counts, and mean Ks of the most recent whole genome duplication in each lineage to address whether chromosome number is associated with reproductive isolation and how this interacts with age of the polyploidy event. Our preliminary results suggest that there is no universal relationship between chromosome number and crossability.

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1 - University of Arizona, Ecology and Evolutionary Biology, 1041 E. Lowell St., Tucson, AZ, 85721, USA

chromosome number
Bateson-Dobzhansky-Muller Incompatibility

Presentation Type: Oral Paper
Session: MACROIII, Macroevolution III
Location: Virtual/Virtual
Date: Friday, July 23rd, 2021
Time: 11:00 AM(EDT)
Number: MACROIII005
Abstract ID:849
Candidate for Awards:None

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