Raphaël Arlettaz

Is the Gibraltar Strait a barrier to gene flow for the bat Myotis myotis (Chiroptera: Vespertilionidae)?

Because of their role in limiting gene flow, geographical barriers like mountains or seas often coincide with intraspecific genetic discontinuities. Although the Strait of Gibraltar represents such a potential barrier for both plants and animals, few studies have been conducted on its impact on gene flow. Here we test this effect on a bat species (Myotis myotis) which is apparently distributed on both sides of the strait. Six colonies of 20 Myotis myotis each were sampled in southern Spain and northern Morocco along a linear transect of 1350 km. Results based on six nuclear microsatellite loci reveal no significant population structure within regions, but a complete isolation between bats sampled on each side of the strait. Variability at 600 bp of a mitochondrial gene (cytochrome b) confirms the existence of two genetically distinct and perfectly segregating clades, which diverged several million years ago. Despite the narrowness of the Gibraltar Strait (14 km), these molecular data suggest that neither males, nor females from either region have ever reproduced on the opposite side of the strait. Comparisons of molecular divergence with bats from a closely related species (M. blythii) suggest that the North African clade is possibly a distinct taxon warranting full species rank. We provisionally refer to it as Myotis cf punicus Felten 1977, but a definitive systematic understanding of the whole Mouse‐eared bat species complex awaits further genetic sampling, especially in the Eastern Mediterranean areas.

Low-Frequency Echolocation Enables the Bat Tadarida teniotis to Feed on Tympanate Insects

The European free-tailed bat, Tadarida teniotis, forages in uncluttered airspace by using intense narrowband echolocation calls with low frequency (11–12 kHz), and feeds on relatively large flying insects, mainly (90% by volume) of the tympanate orders Lepidoptera and Neuroptera. The use of low-frequency echolocation calls without strong harmonics appears to be a specialization for long-range detection of large, tympanate insects, which are less well represented in the diet of most other aerial-hawking bats. The results provide evidence in support of the allotonic frequency hypothesis, i. e. that use of echolocation calls with frequencies above or below the best hearing of tympanate insects is an adaptation to increase the availability of these insects.

PHYSIOLOGICAL TRAITS AFFECTING THE DISTRIBUTION AND WINTERING STRATEGY OF THE BAT TADARIDA TENIOTIS

The ability to enter torpor at low ambient temperature, which enables insectivorous bats to survive seasonal food shortage, is often seen as a prerequisite for colonizing cold environments. Free-tailed bats (Molossidae) show a distribution with a maximum latitudinal extension that appears to be intermediate between truly tropical and temperate-zone bat families. We therefore tested the hypothesis that Tadarida teniotis, the molossid species reaching the highest latitude worldwide (46° N), lacks the extreme physiological adaptations to cold that enable other sympatric bats to enter further into the temperate zone. We studied the metabolism of individuals subjected to various ambient temperatures in the laboratory by respirometry, and we monitored the body temperature of free-ranging individuals in winter and early spring in the Swiss Alps using temperature-sensitive radio-tags. For comparison, metabolic data were obtained from Nyctalus noctula, a typically hibernating vespertilionid bat of similar body siz...

Feeding Habits of the Long-Eared Desert Bat, Otonycteris hemprichi (Chiroptera: Vespertilionidae)

We studied food habits of the long-eared desert bat, Otonycteris hemprichi , in a subdesert area of Kirghizstan (central Asia) by fecal analysis and light-tagging. The bulk of the diet of 13 individuals in September consisted of arachnids (Solifugae, Scorpiones, and Araneae; 49.9% of total volume) and orthopterans (Acrididae, Gryllidae, and Tettigoniidae; 34.7%). Visual nocturnal observations confirmed that this species captures its prey from the surface of the ground.