Sex differences in relationships between habitat use and reproductive performance in Soay sheep (Ovis aries)

Abstract

The role of habitat use in generating individual variation in fitness has rarely been examined empirically in natural populations of long-lived mammals, particularly for both sexes simultaneously. This is the case despite the increase in studies attempting to understand evolutionary change in such populations. Using data from the St. Kilda Soay sheep population, we quantified the association between lifetime reproductive performance (lifetime breeding and reproductive success) and the proportion of the home range covered by a key grass species, H. lanatus, for 490 females and 304 males. Increased H. lanatus cover was associated only with increased female lifetime reproductive success, but increased lifetime breeding success for both sexes, arising through increased male longevity and increased female fecundity. This work suggests that improved understanding of the causes and consequences of fitness differences will likely require us to better account for habitat-derived individual variation, and to do so for the sexes appropriately.

Declining home range area predicts reduced late‐life survival in two wild ungulate populations

“…There has been no detectable change in botanical composition within the communities since detailed botanical recording began in 1993 (Regan et al . ).…”

“…; Regan et al . ). We estimated the annual core home range area in hectares for each individual in each of the 100 sampling runs, and calculated the repeatability for each individual–year to get an idea of sampling error.…”

“…lanatus in a female's lifetime home range is positively correlated with her lifetime reproductive success in this population (Regan et al . ). The percentage cover of H .…”

“…; Regan et al . ). One previous study looked at annual home ranges, and found that home range area declined with age in adult female Soay sheep, whereas a metric of habitat quality increased with age (Hayward et al .…”

“…An individual's home range is therefore driven by a combination of habitat selection and intraspecific competition (Albon et al 1992;Coulson et al 1999). Previous studies of space use in these systems focused on lifetime estimates of home range or resource selection, and found considerable heterogeneity among individuals (McLoughlin et al 2006;Stopher et al 2012;Regan et al 2015). One previous study looked at annual home ranges, and found that home range area declined with age in adult female Soay sheep, whereas a metric of habitat quality increased with age (Hayward et al 2015).…”