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Standing chromosomal variation in Lake Whitefish species pairs: the role of historical contingency and relevance for speciation
Author(s) -
DionCôté AnneMarie,
Symonová Radka,
Lamaze Fabien C.,
Pelikánová Šárka,
Ráb Petr,
Bernatchez Louis
Publication year - 2017
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1111/mec.13816
Subject(s) - biology , coregonus clupeaformis , sympatric speciation , allopatric speciation , coregonus , reproductive isolation , evolutionary biology , species complex , genetic algorithm , genetics , sympatry , karyotype , chromosome , population , gene , demography , fishery , sociology , fish <actinopterygii> , phylogenetic tree
The role of chromosome changes in speciation remains a debated topic, although demographic conditions associated with divergence should promote their appearance. We tested a potential relationship between chromosome changes and speciation by studying two Lake Whitefish ( Coregonus clupeaformis ) lineages that recently colonized postglacial lakes following allopatry. A dwarf limnetic species evolved repeatedly from the normal benthic species, becoming reproductively isolated. Lake Whitefish hybrids experience mitotic and meiotic instability, which may result from structurally divergent chromosomes. Motivated by this observation, we test the hypothesis that chromosome organization differs between Lake Whitefish species pairs using cytogenetics. While chromosome and fundamental numbers are conserved between the species (2 n = 80, NF = 98), we observe extensive polymorphism of subtle karyotype traits. We describe intrachromosomal differences associated with heterochromatin and repetitive DNA , and test for parallelism among three sympatric species pairs. Multivariate analyses support the hypothesis that differentiation at the level of subchromosomal markers mostly appeared during allopatry. Yet we find no evidence for parallelism between species pairs among lakes, consistent with colonization effect or postcolonization differentiation. The reported intrachromosomal polymorphisms do not appear to play a central role in driving adaptive divergence between normal and dwarf Lake Whitefish. We discuss how chromosomal differentiation in the Lake Whitefish system may contribute to the destabilization of mitotic and meiotic chromosome segregation in hybrids, as documented previously. The chromosome structures detected here are still difficult to sequence and assemble, demonstrating the value of cytogenetics as a complementary approach to understand the genomic bases of speciation.