Consequences of natal philopatry for reproductive success and mate choice in an Alpine rodent

Abstract

Quantifying the interaction between dispersal, kinship, and genetic structure can provide insights into the factors that shape kinstructured mammal societies. Here, we first employ a combination of 8 years of capture-mark-recapture and molecular data to characterize the spatial and genetic relationships among female snow voles (Chionomys nivalis) in a population located in the Swiss Alps. Subsequently, we examine the individual-level consequences of kin structure in terms of fitness and mating patterns. Behavioral data, relatedness estimates, and spatial autocorrelation analyses indicate that females show strong philopatry, with spatially clustered females being characterized by high levels of genetic relatedness, leading to significant small-scale (<30 m) spatial genetic structure (SGS). In line with selection favoring female philopatry, dispersing females had a lower fitness compared with philopatric individuals. However, we found a negative association between female reproductive success and the number of neighboring females. This suggests that female kin clustering does not constitute an adaptive strategy in this species, but rather that site tenacity is a by-product of the costs of dispersal. Although dispersal is frequently invoked as a means to avoid inbreeding, our results provide no evidence for premating inbreeding avoidance, which is in line with previous studies on mammals. Instead, in the majority of years, we observed that pairs were more-closely related than expected by chance. However, we found that both males and females with related partners had reduced reproductive success, suggesting the existence of inbreeding depression and/or postmating inbreeding avoidance mechanisms. On the whole, our results show how quantification of SGS within populations can provide insights into individual dispersal behavior and its fitness consequences, and into the ways in which social and genetic structure interacts to shape the evolution of free-living populations.

Spatio-temporal genetic structure of the striped field mouse (Apodemus agrarius) populations inhabiting national parks in South Korea: Implications for conservation and management of protected areas

“…We further tested for temporal stability in the genetic structure by comparing genetic diversity and genetic composition of the Jirisan National Park population between 2015 and 2019. We hypothesized that A. agrarius populations show high dispersal ability but female philopatry, as suggested in previous studies (Clutton -Brock and Lukas, 2012;García-Navas et al, 2016;Jo et al, 2017). Therefore, we predicted that there would be elevated levels of population connectivity via high gene flow occurring across the BMR populations and also that maternally inherited mtDNA marker would exhibit more geographic structure than biparental microsatellites, due to female's home-site fidelity with male dispersal.…”

“…Some recent studies of mammalian species have suggested that several species may not discriminate against inbreeding and actually seek for inbreeding, particularly when the reproductive cost of inbreeding is low (Szulkin et al, 2009;Rioux-Paquette et al, 2010;Olson et al, 2012). Although the ultimate ecological and evolutionary explanations as to the mechanisms of inbreeding are uncertain, the significant IBD patterns only found in mtDNA would provide genetic evidence supporting the notion that especially female A. agrarius has a higher homing fidelity and therefore more tends to be sedentary (García-Navas et al, 2016;Jang et al, 2021). However, additional analysis using more microsatellite markers would be required to substantiate the findings, as larger number of microsatellite markers (e.g., N > 12) could provide more accurate results, although the number of markers needed may differ among species (Wang et al, 2021).…”

“…Small mammals might be susceptible to deteriorating population connectivity caused by habitat destruction and fragmentation (Streatfeild, 2009). Small social mammals may be even more vulnerable to the low habitat connectivity as they often show different behavioral patterns between sexes (female home-site fidelity and male-mediated dispersal; García-Navas et al, 2016;Jang et al, 2021). Because the connectivity largely affects dispersal of not only mice, but also other mammalian species across the national park habitats, large efforts need to be made to improve the connectivity for the purpose of sustaining regional biodiversity (Kahilainen et al, 2014;Almasieh et al, 2022).…”

“…Because small mammals have short lifespans, lessened generation time, and high turnover rates may lead to a change in the genetic structure of populations over a relatively short time period (Merritt, 2010). In addition, most small social mammals show the tendency for sex differences in philopatry and dispersal, e.g., female philopatry with male-biased dispersal (Clutton- Brock and Lukas, 2012;García-Navas et al, 2016).…”

The effects of food and parasitism on reproductive performance of a wild rodent

“…In wild, it is often necessary to perform parentage analysis on a breeding population to quantify individual reproductive performance. A breeding population can be substantially larger in area size than a population used for demographic studies even for small mammals with limited mobility (e.g., parentage studies: 0.5-23 ha, García-Navas, Bonnet, Waldvogel, Camenisch, & Postma, 2016;Gooderham & Schulte-Hostedde, 2011;Patterson & Schulte-Hostedde, 2011;Shaner, Yu, Ke, & Li, 2017; demographic studies: 0.05-0.5 ha, Forbes et al, 2014;Lo & Shaner, 2015;Pedersen & Greives, 2008;Vandegrift et al, 2008). Furthermore, individual reproductive success mainly reflects relative fitness, which is more meaningful in the context of a breeding population.…”