Browsing by Author "Teixeira, David"
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- Genetic identity of Pipistrellus maderensis from the Madeira archipelago: a first assessment, and implications for conservationPublication . Jesus, José; Teixeira, Sérgio; Freitas, Tamira; Teixeira, David; Brehm, AntonioAccording to the IUCN global Red List, Pipistrellus maderensis is among the most endangered bat species in Europe. Its populations are scattered across some islands of the Atlantic Ocean, particularly Madeira and the Canary archipelagoes. This geographical pattern is likely to result in significant genetic differences between populations which would have important implications to set conservation priorities. To test this hypothesis, we analyze cytochrome b sequences and compared populations from Madeira and the Canary islands. Five sequences from Madeiran individuals were analysed and compared to 30 sequences extracted from GenBank from Pipistrellus maderensisfrom the Canary islands and Pipistrellus kuhli. Our results indicate a significant divergence between the two groups, smaller than between true species, but higher that intra-group divergence. However, further research on the Madeiran popula tion is needed, including the use of sequences of other mitochondrial markers and nuclear marker and microsatellites
- Social calls are subject to stabilizing selection in insular batsPublication . Russo, Danilo; Teixeira, Sérgio; Cistrone, Luca; Jesus, José; Teixeira, David; Freitas, Tamira; Jones, GarethAim Bats communicate by emitting social calls, and these often elicit reactions in conspecifics. Many such vocalizations are species-specific so that unambiguous signals can be transmitted and interpreted by conspecifics. In species-rich assemblages, evolutionary pressures might prompt interspecific diversification of call structure so that communication with heterospecifics is avoided. In species poor island communities, where no risk of miscommunication occurs, stabilizing selection should prevail and preserve call structure and function. Call structure in island bats might be inherited from colonizers from the mainland and be maintained with little change in the absence of selection from heterospecifics. To test this hypothesis we studied Pipistrellus maderensis, an insular taxon occurring on the Madeira Archipelago, the Canary Islands and the Azores. It is closely related to one of the most widespread European pipistrelles, Pipistrellus kuhlii. Pipistrellus maderensis most probably evolved from a common ancestor shared with P. kuhlii, or from founders of that taxon that colonized the islands. We hypothesized that on Madeira Island, where no risk of ambiguous communication with heterospecifics exists, the structure and function of social calls should have been preserved by stabilizing selection. Echolocation calls, subject to different selection pressures, may instead show more pronounced differences between P. maderensis and P. kuhlii. Location Madeira Island (Portugal, Atlantic Ocean), central and southern Italy. Methods We recorded social and echolocation calls from allopatric populations of the two pipistrelles and explored interspecific differences in time and frequency characteristics. We also conducted playback experiments by broadcasting recordings of social calls from P. kuhlii and P. maderensis (taken respectively in peninsular Italy and on Madeira) and monitoring the bats’ responses. Results Social call structure showed a strong similarity between species, whereas echolocation calls were markedly different and exhibited a mean divergence of over 6 kHz in their frequency of maximum energy. On Madeira, P. maderensis significantly reduced flight activity when we broadcast P. kuhlii signals, as did P. kuhlii in Italy in response to P. maderensis calls. Main conclusions Reliable interpretation of social calls provides benefits to both the signaller and the receiver because signals help to optimize food exploitation at foraging sites. In the absence of closely related species that can emit similar calls, this advantage may have acted as a strong evolutionary pressure, stabilizing social call structure in P. maderensis in insular ecosystems with limited foraging resources.