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Asexual species, despite lacking recombination, can evolve in response to environmental changes and influence the evolutionary trajectory of coexisting sexual species. Gynogenesis, where asexual females rely on sperm from males of a different species, offers a unique perspective on the eco-evolutionary dynamics between asexual females and their sexual hosts. The Amazon molly,Poecilia formosa, is a gynogenetic species that primarily uses sperm from two sympatric sexual species: the sailfin molly (P. latipinna) and the Atlantic molly (P. mexicana). To understand shape variation in an asexual species relative to their sexual hosts, we analysed shape variation among wild Amazon mollies and their sexual hosts. We tested three hypotheses: (i) Amazon mollies mimic their sexual hosts to enhance mating opportunities (sexual mimicry hypothesis); (ii) ecological interactions or male mate choice drive morphological divergence (character displacement hypothesis); and (iii) Amazon mollies exhibit random shape variation due to their asexual nature (null hypothesis). Our findings revealed significant shape variation in Amazon mollies, which differ from their sexual hosts in a host-specific manner (e.g. Amazon mollies withP. latipinnaresembleP. mexicanaand vice versa), supporting character displacement at the interspecific level in a sexual–asexual system.
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Sperm‐dependent asexual species and their role in ecology and evolution
Abstract Sexual reproduction is the primary mode of reproduction in eukaryotes, but some organisms have evolved deviations from classical sex and switched to asexuality. These asexual lineages have sometimes been viewed as evolutionary dead ends, but recent research has revealed their importance in many areas of general biology. Our review explores the understudied, yet important mechanisms by which sperm‐dependent asexuals that produce non‐recombined gametes but rely on their fertilization, can have a significant impact on the evolution of coexisting sexual species and ecosystems. These impacts are concentrated around three major fields. Firstly, sperm‐dependent asexuals can potentially impact the gene pool of coexisting sexual species by either restricting their population sizes or by providing bridges for interspecific gene flow whose type and consequences substantially differ from gene flow mechanisms expected under sexual reproduction. Secondly, they may impact on sexuals' diversification rates either directly, by serving as stepping‐stones in speciation, or indirectly, by promoting the formation of pre‐ and postzygotic reproduction barriers among nascent species. Thirdly, they can potentially impact on spatial distribution of species, via direct or indirect (apparent) types of competition and Allee effects. For each such mechanism, we provide empirical examples of how natural sperm‐dependent asexuals impact the evolution of their sexual counterparts. In particular, we highlight that these broad effects may last beyond the tenure of the individual asexual lineages causing them, which challenges the traditional perception that asexual lineages are short‐lived evolutionary dead ends and minor sideshows. Our review also proposes new research directions to incorporate the aforementioned impacts of sperm‐dependent asexuals. These research directions will ultimately enhance our understanding of the evolution of genomes and biological interactions in general.
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- Award ID(s):
- 1916519
- PAR ID:
- 10481956
- Publisher / Repository:
- Ecology and Evolution
- Date Published:
- Journal Name:
- Ecology and Evolution
- Volume:
- 13
- Issue:
- 10
- ISSN:
- 2045-7758
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/ece3.10522
