Trophic niche partitioning of cryptic species of long-eared bats in Switzerland: implications for conservation

Abstract

Dietary niche partitioning is postulated to play a major role for the stable coexistence of species within a community, particularly among cryptic species. Molecular markers have recently revealed the existence of a new cryptic species of long-eared bat, Plecotus macrobullaris, in the European Alps. We studied trophic niches as well as seasonal and regional variations of diet in eight colonies of the three Plecotus species occurring in Switzerland. Faeces were collected monthly from individuals returning to roost after foraging. Twenty-one arthropod categories were recognized from the faeces. All three species fed predominantly on Lepidoptera, which made up 41%, 87% and 88% (means across colonies) of the diet composition of P. auritus, P. macrobullaris and P. austriacus, respectively. The occurrence of numerous fragments of both diurnal and flightless insects in the diet of P. auritus (but rarely in the diet of the other two species) indicates that this species mostly gleans prey from substrates. P. austriacus and P. macrobullaris are more typical aerial feeders. The latter two species have narrow trophic niches, whilst P. auritus has a much broader diet. Comparison of intraspecific and interspecific niche overlaps in P. auritus and P. macrobullaris in sympatry suggests dietary niche partitioning between these two species. In contrast, the high similarity of the trophic niches of P. austriacus and P. macrobullaris, associated with a typical parapatric distribution, indicates competitive exclusion. The best conservation measures are preservation and restoration of habitats offering a high abundance of moths, the major prey of the three Plecotus species.

Porous barriers? Assessment of gene flow within and among sympatric long‐eared bat species

“…We thus confirm that the use of simple mitochondrial barcodes (typically COI) is perfectly suited to identify these long-eared bat species in Western Europe despite the existence of morphologically intermediate individuals . This concordance of genetic markers and lack of interspecific gene flow also validates previous genetic assignations that were exclusively based on mitochondrial markers (Ashrafi, Beck, Rutishauser, Arlettaz, & Bontadina, 2011;Mattei-Roesli, 2010). This clear-cut situation of strong barriers to gene flow among the three Plecotus contrasts with the situation of other pairs of cryptic species such as Myotis bats which hybridize and exchange both nuclear and mitochondrial genes (Berthier et al, 2006;Morales & Carstens, 2018;Morales et al, 2017).…”

Disease and community structure: white‐nose syndrome alters spatial and temporal niche partitioning in sympatric bat species

“…Given that insect availability varies both spatially and temporally across the northern hardwood region where our study occurred (Belwood & Fenton, ; Clare et al ., ), observation of a relaxation of temporal and spatial niche partitioning across species suggests that a dietary shift could be simultaneously occurring. Although beyond the scope of our study, in addition to spatial and temporal niche partitioning, dietary niche partitioning occurs in sympatric bat species (Arlettaz et al ., ; Patterson et al ., ; Ashrafi et al ., ). MYLU are smaller in size compared with the non‐ Myotis species present and have a generalized diet focused on small aquatic insects (Belwood & Fenton, ; Edythe & Kunz, ).…”

“…Sympatric bat species might compete for auditory bandwidth and alter their echolocation call structure (Habersetzer, ; Ratcliffe et al ., ) in what has been termed an ‘interspecific jamming avoidance response’ (Necknig & Zahn, ). Additionally, bats are highly mobile and exhibit some flexibility in prey and habitat use, enhancing the likelihood of interactions and interspecific competition among sympatric species (Kunz, ; Ashrafi et al ., ). To limit interspecific competition for prey and auditory bandwidth, spatial niche partitioning is believed to be common in sympatric bat species, particularly at foraging areas where individual species exploit specific, fine‐scale habitat conditions (Arlettaz, ; Arlettaz et al ., ; Patterson et al ., ; Nicholls & Racey, ; Razgour et al ., ).…”

“…Niche partitioning is most likely to occur in species assemblages that are diverse and highly structured by competition (Begon et al ., ), such as that displayed by insectivorous bat communities (Arlettaz et al ., ; Patterson et al ., ; Ashrafi et al ., ). Bats are among the most diverse and most recently expanded mammalian orders (Ray et al ., ).…”

Patterns of cranial size variation in two sibling species Plecotus auritus and P. austriacus (Chiroptera: Vespertilionidae) in a contact zone

“…P. auritus is a less specialized generalist, occupying a broader niche, while P. austriacus is a specialist with a narrow niche. This is supported by resource partitioning in an area of sympatry of three long‐eared bat species; differences in diet composition were found between P. auritus and other two species: P. austriacus and P. macrobullaris (Kuzyakin, ), which feeds in similar insects (Ashrafi et al ., ). Both M. evotis and P. auritus are generalists, with variable diets and, in consequence, have more variable cranial sizes than those of specialists.…”