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Abstract The role of hybridization as a formative process in evolution has received much attention in the past few decades. A particularly fascinating outcome of hybrid speciation is the formation of asexual hybrid species. The Amazon molly (Poecilia formosa) is such a hybrid and originated from aP. mexicanamother and aP. latipinnafather. Consequently, a heterospecific mating must have occurred leading to the Amazon molly, indicating a breakdown of any potential prezygotic isolation between parental species. Here we studied the female mate preferences of extantP. mexicanaandP. latipinnafrom several populations using standard binary choice tests with males of both sexual species that were matched for size.Poecilia mexicanaandP. latipinnacan be crossed in the lab, however, the offspring are not asexual, but sexual F1s. In our study, we generated F1s and tested their mating preferences with sexual males of bothP. mexicanaandP. latipinnaagainst F1males. Overall, our results show that in extantP. mexicanaandP. latipinnano female preference for conspecific males was detectable. Consequently, heterospecific matings are possible and not hindered by any apparent behavioral prezygotic isolation. If female preferences in these species were comparable around the time the Amazon molly originated as a hybrid species ca. 100,000 years ago, matings leading to hybrids would be very likely. F1females also have no discernable mating preferences for either sexual males or F1males. Such lack of prezygotic behavioral isolation could potentially lead to F2individuals, backcrosses, and introgression.
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This content will become publicly available on July 1, 2026
Converging or diverging? Shape coevolution between a sperm-dependent asexual and its sexual hosts
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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- PAR ID:
- 10655861
- Publisher / Repository:
- Royal Society
- Date Published:
- Journal Name:
- Proceedings of the Royal Society B: Biological Sciences
- Volume:
- 292
- Issue:
- 2050
- ISSN:
- 1471-2954
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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