In:
Philosophical Transactions of the Royal Society B: Biological Sciences, The Royal Society, Vol. 375, No. 1806 ( 2020-08-31), p. 20190535-
Abstract:
Cichlid fishes are exceptionally species-rich, speciated at explosive rates and, hence, are a model system in speciation research. Yet, their reproductive isolating barriers have, so far, not been comprehensively studied. Here, we review current knowledge on pre- and postzygotic mechanisms in cichlids. While premating isolation is the norm in cichlids, its strength varies across lineages and with the geographical setting. Moreover, manipulations of ambient conditions tended to reduce assortative mating among closely related species, suggesting that premating isolation in cichlids is often fragile and context dependent. The observed lack of complete reproductive isolation is supported by past and present hybridization events that have contributed to diversity by creating novel allelic combinations. On the other hand, our meta-analysis highlights that intrinsic postzygotic isolation might accumulate faster than assumed. Mild forms of genetic incompatibilities, such as sex ratio distortion, can already be observed among closely related species. Therefore, cessation of gene flow by strong reproductive isolation in cichlids requires a combination of premating prezygotic isolation supplemented with intrinsic and extrinsic postzygotic barriers. Further, we suggest crucial next steps to improve our knowledge about reproductive barriers in cichlids to understand the evolutionary dynamics of pre- and postzygotic isolation mechanisms during adaptive radiations. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers'.
Type of Medium:
Online Resource
ISSN:
0962-8436
,
1471-2970
DOI:
10.1098/rstb.2019.0535
Language:
English
Publisher:
The Royal Society
Publication Date:
2020
detail.hit.zdb_id:
1462620-2
SSG:
12
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