All-offspring dispersal in a tropical mammal with resource defense polygyny

Abstract

In polygynous mammals, males are usually responsible for gene flow while females are predominantly philopatric. However, there is evidence that in a few mammalian species female offspring may disperse to avoid breeding with their father when male tenure exceeds female age at maturity. We investigated offspring dispersal and local population structure in the Neotropical bat Lophostoma silvicolum. The mating system of this species is resource defense polygyny, with the resource being active termite nests, excavated by single males, which are then joined by females. We combined field observations of 14 harems during 3 years and data about the genetic structure within and between these groups, calculated with one mitochondrial locus and nine nuclear microsatellite loci. The results show that both male and female offspring disperse before maturity. In addition, we estimated life span of excavated termite nests and the duration they were occupied by the same male. Our findings suggest that long male tenure of up to 30 months is indeed a likely cause for the observed dispersal by female offspring that can reach maturity at a low age of 6 months. We suggest that dispersal by offspring of both sexes may occur quite frequently in polygynous tropical bats and thus generally may be more common in mammals than previously assumed.

Neither genetic nor observational data alone are sufficient for understanding sex‐biased dispersal in a social‐group‐living species

“…Mammals with these characteristics often exhibit dispersal by both sexes (e.g. Equus zebra zebra : Lloyd & Rasa 1989; Procolobus verus : Korstjens & Schippers 2003; Lophostoma silvicolum : Dechmann et al . 2007), presumably because females would otherwise face inbreeding in their natal groups.…”

“…2005), so other methods for examining within‐ and among‐group relatedness were also necessary. We did not use male and female F ST values to examine sex‐biased dispersal ( sensu Dechmann et al . 2007) because the number of adult males and females per group were too few in most cases to reliably calculate F ST and all samples came from the same study population.…”

“…1998), leading to an interest in inferring dispersal patterns from genetic patterns, sometimes with little or no corresponding observational data on dispersal in that population (Di Fiore & Fleischer 2005; Hammond et al . 2006; Dechmann et al . 2007).…”

Social organization and genetic structure: insights from codistributed bat populations

“…In polygynous taxa, males tend to disperse more, to avoid inbreeding and/or competition, while females are more philopatric (Greenwood 1980; McCracken & Wilkinson 2000), although exceptions are not uncommon (e.g. Dechmann et al. 2007; Nagy et al.…”

Verhaltensbiologie

“…Die wichtigsten Nahrungsressourcen der betreffenden Arten sind von einer solchen Qualität oder so in Raum und Zeit verteilt, dass deren gemeinsame Verteidigung nicht möglich oder nicht ökonomisch ist (Isbell u. van Vuren 1996), so dass die typischen Vorteile der weiblichen Philopatrie reduziert sind. Schließlich wandern junge Weibchen auch ab, um Inzucht mit ihren Vätern zu vermeiden, wenn dominante Männchen eine lange Residenzzeit haben (Dechmann et al 2007). Weibchen können unter bestimmten Bedingungen auch abwandern, um Konkurrenz um Ressourcen mit residenten Verwandten zu vermeiden, oder um sich einem Männchen anzuschließen, das sie effizient vor fremden, potentiell infantizidalen Männchen schützen kann.…”