When challenged by similar environmental conditions, phylogenetically distant taxa often independently evolve similar traits (convergent evolution). Meanwhile, adaptation to extreme habitats might lead to divergence between taxa that are otherwise closely related. These processes have long existed in the conceptual sphere, yet molecular evidence, especially for woody perennials, is scarce. The karst endemic , and its only congeneric species, . , which is widely distributed in the mountains in East Asia, provide an ideal model for examining the molecular basis of both convergent evolution and speciation. Using chromosome-level genome assemblies of both species, and whole genome resequencing data from 207 individuals spanning their entire distribution range, we demonstrate that . and . form two species-specific clades, which diverged around 2.09 million years ago. We find an excess of genomic regions exhibiting extreme interspecific differentiation, potentially due to long-term selection in . , likely contributing to the incipient speciation of the genus . Interestingly, our results unveil underlying karst adaptation in both copies of the calcium influx channel gene in . . has previously been identified as a selective target in certain karst-endemic herbs, indicating a convergent adaptation to high calcium stress among karst-endemic species. Our study reveals the genic convergence of among karst endemics, and the driving forces underneath the incipient speciation of the two lineages.
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http://dx.doi.org/10.1093/molbev/msad121/7175457 | DOI Listing |
Evolution
December 2024
School of Biological Sciences, Institute of Ecology and Evolution, Edinburgh, UK.
Most studies investigating the genomic nature of species differences anticipate monophyletic species with genome-wide differentiation. However, this may not be the case at the earliest stages of speciation where reproductive isolation is weak and homogenising gene flow blurs species boundaries. We investigate genomic differences between species in a postglacial radiation of eyebrights (Euphrasia), a taxonomically complex plant group with variation in ploidy and mating system.
View Article and Find Full Text PDFMol Phylogenet Evol
December 2024
Department of Biological Sciences Boise State University Boise, ID 83725 USA. Electronic address:
Delimiting species boundaries is a perennial challenge in the field of systematics. Resolving whether morphological variation is the result of environmental parameters, incipient speciation, or complete speciation is especially challenging when the variation is subtle. Within the perennial endemic North American clade of Apiaceae (PENA) there are numerous examples in which widespread species have subtle geographically defined morphological variants that have typically been recognized at the subspecific rank.
View Article and Find Full Text PDFPLoS One
November 2024
Laboratory for Amphibian Systematics and Evolution, College of Biology & the Environment, Nanjing Forestry University, Nanjing, China.
Evolution
November 2024
Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, 0316 Oslo, Norway.
Are differences between species the long-term consequence of microevolution within species, or does speciation involve fundamentally different processes? We analyzed brain and body sizes of present-day primate species using a novel phylogenetic comparative method that decomposes the phenotypic covariance of these traits into speciational and anagenetic components. We estimated that approximately half of speciation events are accompanied by accelerated phenotypic change. Equivalent in magnitude to approximately 7 million years of gradual microevolution, such speciational changes in brain and body size account for about 58% of the phenotypic variation among extant species.
View Article and Find Full Text PDFSyst Biol
October 2024
Department of Biochemistry and Molecular Biology, Faculty of Medicine, Dalhousie University, Halifax, NS B3H 4R2, CA, Canada.
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