Dispersal and group formation dynamics in a rare and endangered temperate forest bat (Nyctalus lasiopterus, Chiroptera: Vespertilionidae)

Abstract

For elusive mammals like bats, colonization of new areas and colony formation are poorly understood, as is their relationship with the genetic structure of populations. Understanding dispersal and group formation behaviors is critical not only for a better comprehension of mammalian social dynamics, but also for guiding conservation efforts of rare and endangered species. Using nuclear and mitochondrial markers, we studied patterns of genetic diversity and differentiation among and within breeding colonies of giant noctule bats (Nyctalus lasiopterus), their relation to a new colony still in formation, and the impact of this ongoing process on the regionwide genetic makeup. Nuclear differentiation among colonies was relatively low and mostly nonsignificant. Mitochondrial variation followed this pattern, contrasting with findings for other temperate bat species. Our results suggest that this may indicate a recent population expansion. On average, female giant noctules were not more closely related to other colony members than to foreign individuals. This was also true for members of the newly forming colony and those of another, older group sampled shortly after its formation, suggesting that contrary to findings for other temperate bats, giant noctule colonies are not founded by relatives. However, mother–daughter pairs were found in the same populations more often than expected under random dispersal. Given this indication of philopatry, the lack of mitochondrial differentiation among most colonies in the region is probably due to the combination of a recent population expansion and group formation events.

Nest-site competition and killing by invasive parakeets cause the decline of a threatened bat population

“…The two closest colonies are located in Doñana National Park and Jerez de la Frontera, 60 and 77 km from María Luisa Park, holding a maximum of 40 and 150–200 individuals across years, respectively. Although genetic studies showed no differentiation between these colonies [ 26 ], our long-term monitoring of the three colonies does not support this idea. While many of the more than 300 females marked in María Luisa Park were recaptured within the same park across years [ 22 ], only one of these females visited Doñana (in 2001, 2003 and 2004), while two females marked in Doñana and Jerez visited María Luisa Park (2007 and 2017) and three females marked in Jerez visited Doñana (2004–2016), all for short periods of time.…”

“…Their annual survival rates were similar to those of other long-distance aerial-hawking bat species [ 25 ]. Genetically, this population is closely related to the two closest colonies of the species found in Jerez de la Frontera and Doñana National Park [ 26 ], located 60 km and 75 km from María Luisa Park, respectively.…”

Kin structure and roost fidelity in greater noctule bats

“…(2009) further reported that females were loyal to their groups for at least five years, and that juveniles returned to their natal roosting areas along the study period. In a recent genetic analysis encompassing the region of Andalusia, Spain, and including four maternity colonies, we found that at least 31% of the females sampled shared their nursery colonies with mothers or daughters (Santos et al, 2016). However, the reasons for this high level of philopatry (despite the species' high dispersal ability, Burns & Broders, 2014) remain unclear.…”

“…All individuals were genotyped at 11 nuclear microsatellite loci: Nle 2, 3 and 6-11 (developed for Nyctalus leisleri, see Boston et al 2008); EF4 (developed for Eptesicus fuscus, Vohnof et al 2002); P20 and P217 (Kaňuch et al, 2007). All were tested in muscle tissue prior to genotyping (see Supplementary Methods for a detailed description of DNA extraction, amplification, sequencing, and microsatellite genotyping) and successfully employed in our previous study (Santos et al, 2016). Labelling followed Schuelke's procedure (2000).…”

“…Western Andalusia, Spain, is unique for harboring several known maternity colonies of giant noctules in three main breeding areas (Santos et al, 2016). Females consolidate colonies in spring to breed, and remain until late August, when they disaggregate and disperse, presumably to mating and hibernation sites , although some cases of permanent residency have been observed (C. Ibáñez and J. Juste, unpublished data).…”