Marcial Escudero1, Marlene Hahn2, Bethany H Brown2, Kate Lueders2, Andrew L Hipp3. 1. The Morton Arboretum, 4100 Illinois Route 53, Lisle, Illinois 60532 USA Department of Botany, The Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, Illinois 60605 USA Department of Plant Biology and Ecology, University of Seville, Reina Mercedes sn 41010 Seville, Spain. amesclir@gmail.com. 2. The Morton Arboretum, 4100 Illinois Route 53, Lisle, Illinois 60532 USA. 3. The Morton Arboretum, 4100 Illinois Route 53, Lisle, Illinois 60532 USA Department of Botany, The Field Museum of Natural History, 1400 S. Lake Shore Drive, Chicago, Illinois 60605 USA.
Abstract
PREMISE OF THE STUDY: Understanding the drivers of speciation is a central task of evolutionary biology. Chromosomal rearrangements are known to play an important role in species diversification, but the role of rearrangements of holocentric chromosomes-chromosomes without localized centromeres-is poorly understood. METHODS: We made numerous artificial crosses between Carex scoparia individuals of different diploid chromosome numbers and, for comparison, between individuals of the same chromosome number. We studied chromosome pairing and chromosomal rearrangements in the F1 individuals using light microscopy. We then estimated germination rates as a function of geographic distance, genetic distance, chromosome number differences in parents, and pairing irregularities in F1 individuals, using generalized least squares to fit alternative regression models. KEY RESULTS: The most informative predictors of germination rates in the F1 generation are chromosome number differences and minimum number of chromosome pairing irregularities in the F1 individuals. Genetic and geographic distances between parents are not significant predictors. CONCLUSIONS: Holocentric chromosomal rearrangements play an important role in postzygotic reproductive isolation in Carex through F1 hybrid inviability and sterility. Hybrid dysfunction seems to be a suitable model for chromosomal speciation when there are several chromosomal rearrangements between parents. However, we have not tested the hypothesis that genome rearrangements may also play an important role in suppressing recombination between cytogenetically divergent populations.
PREMISE OF THE STUDY: Understanding the drivers of speciation is a central task of evolutionary biology. Chromosomal rearrangements are known to play an important role in species diversification, but the role of rearrangements of holocentric chromosomes-chromosomes without localized centromeres-is poorly understood. METHODS: We made numerous artificial crosses between Carex scoparia individuals of different diploid chromosome numbers and, for comparison, between individuals of the same chromosome number. We studied chromosome pairing and chromosomal rearrangements in the F1 individuals using light microscopy. We then estimated germination rates as a function of geographic distance, genetic distance, chromosome number differences in parents, and pairing irregularities in F1 individuals, using generalized least squares to fit alternative regression models. KEY RESULTS: The most informative predictors of germination rates in the F1 generation are chromosome number differences and minimum number of chromosome pairing irregularities in the F1 individuals. Genetic and geographic distances between parents are not significant predictors. CONCLUSIONS: Holocentric chromosomal rearrangements play an important role in postzygotic reproductive isolation in Carex through F1 hybrid inviability and sterility. Hybrid dysfunction seems to be a suitable model for chromosomal speciation when there are several chromosomal rearrangements between parents. However, we have not tested the hypothesis that genome rearrangements may also play an important role in suppressing recombination between cytogenetically divergent populations.
Authors: Jurriaan M de Vos; Hannah Augustijnen; Livio Bätscher; Kay Lucek Journal: Philos Trans R Soc Lond B Biol Sci Date: 2020-07-13 Impact factor: 6.237
Authors: Jose Planta; Yu-Ya Liang; Haoyang Xin; Matthew T Chansler; L Alan Prather; Ning Jiang; Jiming Jiang; Kevin L Childs Journal: G3 (Bethesda) Date: 2022-09-30 Impact factor: 3.542