Geographical and temporal variation of multiple paternity in invasive mosquitofish (Gambusia holbrooki, Gambusia affinis)

Abstract

Multiple paternity (MP) increases offspring's genetic variability, which could be linked to invasive species' evolvability in novel distribution ranges. Shifts in MP can be adaptive, with greater MP in harsher/colder environments or towards the end of the reproductive season, but climate could also affect MP indirectly via its effect on reproductive life histories. We tested these hypotheses by genotyping N = 2,903 offspring from N = 306 broods of two closely related livebearing fishes, Gambusia holbrooki and Gambusia affinis. We sampled pregnant females across latitudinal gradients in their invasive ranges in Europe and China, and found more sires per brood and a greater reproductive skew towards northern sampling sites. Moreover, examining monthly sampling from two G. affinis populations, we found MP rates to vary across the reproductive season in a northern Chinese, but not in a southern Chinese population. While our results confirm an increase of MP in harsher/more unpredictable environments, path analysis indicated that, in both cases, the effects of climate are likely to be indirect, mediated by altered life histories. In both species, which rank amongst the 100 most invasive species worldwide, higher MP at the northern edge of their distribution probably increases their invasive potential and favours range expansions, especially in light of the predicted temperature increases due to global climate changes.

Integrative demographic study of the Iberian painted frog (Discoglossus galganoi): inter‐annual variation in the effective to census population size ratio, with insights on mating system and breeding success

“…In small and genetically depauperated populations, genetic compensation mechanisms may contribute to increase N b and N e via an increment in the average breeding success of individuals (Beebee 2009;Sánchez-Montes et al 2017), and this in turn may be related with higher polygamy rates (Byrne & Roberts 2012;Gao et al 2019). In our study population, we observed high polygamy rates in both males and females, according to inferred pedigrees.…”

“…2017), and this in turn may be related with higher polygamy rates (Byrne & Roberts 2012; Gao et al . 2019). In our study population, we observed high polygamy rates in both males and females, according to inferred pedigrees.…”

“…Modeling population turnover rates and the maintenance of genetic diversity also requires knowledge about the biology of target species (Balloux & Lehmann 2003; Holman & Kokko 2013; Gao et al . 2019), including mating system and variation in breeding success (Byrne & Roberts 2012). However, this information is lacking for most amphibian species in the wild (O'Brien et al .…”

High Degree of Multiple Paternity and Reproductive Skew in the Highly Fecund Live-Bearing Fish Poecilia gillii (Family Poeciliidae)

“…To minimize the potentially confounding effect of local conditions on multiple paternity, we randomly sampled 31 pregnant females from 8 different locations to characterize multiple paternity in P. gillii across its South-Western range in Costa Rica. Moreover, many studies on multiple paternity in species with large broods have analyzed only a fraction, or a set number of embryos, per brood (Travis et al, 1990;Greene and Brown, 1991;Girndt et al, 2012 but see Gao et al, 2019), potentially underestimating the absolute number of sires that may have contributed to the broods. To avoid this, we genotyped and analyzed all embryos (N = 1346) to quantify multiple paternity in our 31 P. gillii females.…”

“…Most earlier multiple paternity studies have focused on species with small broods, such as Poecilia reticulata (Kelly et al, 1999;Hain and Neff, 2007;Neff et al, 2008), Heterandria formosa, (Kelly et al, 1999;Soucy and Travis, 2003), Xiphophorus multilineatus (Luo et al, 2005), X. nigrensis (Smith, 2014), and X. birchmanni (Paczolt et al, 2015). Only a few earlier studies focus on species with large broods, i.e., Poecilia latipinna and Gambusia affinis, but most of these only analyze a small part of the actual brood (Travis et al, 1990;Greene and Brown, 1991;Girndt et al, 2012), except for a study by Gao et al (2019) that studied multiple paternity in whole broods of Gambusia affinis and G. holbrooki. Therefore, little is currently known about how the large variation in brood size affects multiple paternity, the number of sires per brood and male reproductive skew within species.…”