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Absence of female preference and the origin of a unisexual species, the Amazon molly (Poecilia formosa)
Journal article   Peer reviewed

Absence of female preference and the origin of a unisexual species, the Amazon molly (Poecilia formosa)

Caden Smith, Waldir Miron Berbel-Filho, Montrai Spikes, Frederic Fyon, Francisco Ubeda and Ingo Schlupp
Ethology, Vol.130(8), e13469
08/2024
DOI: https://doi.org/10.1111/eth.13469
Web of Science ID: WOS:001217114500001

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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 a P. mexicana mother and a P. latipinna father. 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 extant P. mexicana and P. latipinna from several populations using standard binary choice tests with males of both sexual species that were matched for size. Poecilia mexicana and P. latipinna can be crossed in the lab, however, the offspring are not asexual, but sexual F(1)s. In our study, we generated F(1)s and tested their mating preferences with sexual males of both P. mexicana and P. latipinna against F-1 males. Overall, our results show that in extant P. mexicana and P. latipinna no 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. F-1 females also have no discernable mating preferences for either sexual males or F-1 males. Such lack of prezygotic behavioral isolation could potentially lead to F-2 individuals, backcrosses, and introgression.

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