Mr Hugo Vitorino Rebelo
School of Biological Sciences, University of Bristol, Woodland Road, Bristol, BS8 1UG.
phone: +44 (0)117 95 46386 (Internal 46386)
fax: +44 (0)117 331 7985
Tree-dwelling bat species are among Europe 's most threatened mammal groups, yet there is a great lack of knowledge about their ecology. I started my PhD in February 2005, where I propose to investigate the ecological characteristics of one of the least known and most threatened species of this group ( Barbastella barbastellus ), and also consider other tree-dwelling species like Plecotus auritus , Nyctalus leisleri and N. lasiopterus . This study will focus on developing habitat-suitability maps that highlight areas of likely occupancy by these bats in mainland Portugal . Subsequently, new trapping techniques will be tested in these areas to improve capture efficiency. From captured individuals a non-lethal biopsy punch will be collected for genetic analysis to characterize the population structure and species' evolutionary history. Individuals will be released and followed to their roosts by radio-tracking. Located roosts will then be characterized, and I will test whether bats select roost trees. My research will try to identify patterns of resource utilization and demographic structure that can be used in effective conservation strategies for tree-dwelling bats.
My objectives are:
- To develop habitat-suitability models for the focal species and to determine which ecogeographical variables influence their distribution.
- To investigate and improve current methodologies of trapping bats in Europe. This will consist on developing acoustic lures that could increase the efficiency of mist-netting by testing the use of distress calls playbacks to attract bats.
- To describe roost characteristics, namely morphology, thermal behaviour and localization, in order to determine optimal roost conditions. Trees in the vicinity of occupied roosts will also be measured to determine if there is selection.
- To investigate the genetic structure of the populations by measuring the levels of gene flow among sampled populations.
This work also has a partnership with CIBIO, University of Porto ( http://cibio.up.pt/ ) where genetic analyses are conducted with the supervision of Prof. Nuno Ferrand.
In-depth knowledge of distribution is of prime interest for conservation management (Jaberg & Guisan 2001). Modern conservation ecology crucially relies on multivariate, spatially explicit models that describe and/or predict a species' distribution (Hirzel et al. 2002). Ecological-Niche Factor Analysis (ENFA) methods introduce a new multivariate approach to the study of geographic species distribution, using presence data only. This analysis is robust enough so it can process scarce (the case of rare species) and scattered data (Hirzel et al . 2002), obtained for example, from museum collections or databases. Therefore, the use of this methodology seems to be more appropriate for modelling the distribution of tree-dwelling bat species.
This experiment will test the use of playbacks of social calls, since this type of calls seem to have a strong attractive function to other bats (Hill & Greenaway 2005). The playback experiments of these calls will be done during mist-netting sessions using a Sussex AutoBat device.
The aim was to locate bat roosts with captured individuals tagged with radio-transmitters. Several studies have located roosts with this method (e.g. Brigham et al. 1997, Russo et al. 2004).
After roost detection several parameters are measured whenever possible. In order to investigate roost selection by bats, trees in the vicinity of the located roosts that may be potentially available for roosting bats are chosen for study. Their features are compared with those of trees occupied by bats using similar methodology by Russo et al. (2004).
Studies of population structure require a sufficient number of populations (=5) with a minimum of 10-20 individuals each (Burland & Worthington Wilmer 2001). It is intended to capture individuals during mist-netting sessions and from colonies on discovered roosts (see below). A small piece from the tail or wing membranes will be collected from each captured individual using a non-lethal method described in Worthington Wilmer & Barratt (1996).
Microsatellite DNA markers will be employed to investigate the extent of genetic differentiation and estimate gene flow among sampled populations. Microsatellite primer pairs designed for Plecotus auritus, Nyctalus noctula , Myotis myotis and Myotis bechsteinii will be tested in the rare Barbastella barbastellus . Sequencing mtDNA will be used to assess the degree of female philopatry and phylogeographic issues, namely to investigate possible genetic discontinuity between Portuguese and European populations.
DNA will be amplified by PCR in a thermal cycler. PCR products will be run in a Sequencer.
The University of Bristol acknowledges the financial support of Fundação para a Ciência e Tecnologia.
Brigham, R. M., Vonhof, M. J., Barclay, R. M. R., & Gwilliam, J. C. 1997. Roosting behaviour and roost-site preferences of forest-dwelling California bats ( Myotis californicus ). Journal of Mammology , 78 , 1231-1239.
Burland, T.M. & Worthington Wilmer, J. 2001. Seeing in the dark: molecular approaches to the study of bat populations. Biological Reviews , 76 , 389-409.
Hill, D. & Greenaway, F. 2005. Effectiveness of an acoustic lure for surveying bats in British woodlands. Mammal Review , 35 , 116-122.
Hirzel, A.H., Hausser, J., Chessel, D. & Perrin, N. 2002. Ecological-Niche Factor Analysis: how to compute habitat-suitability maps without absence data?. Ecology ,, 83 , 2027-2036.
Jaberg, C. & Guisan, A. 2001. Modelling the distribution of bats in relation to landscape structure in a temperate mountain environment. Journal of Applied Ecology , 38, 1169-1181.
Russo, D., Cistrone, L., Jones, G. & Mazzoleni, S. 2004. Roost selection by barbastelle bats ( Barbastella barbastellus , Chiroptera: Vespertilionidae) in beech woodlands of central Italy : consequences for conservation. Biological Conservation , 117 , 73-81.
Worthington Wilmer, J. & Barratt, E. 1996. A non-lethal method of tissue sampling for genetic studies of chiropterans. Bat Research News , 37 , 1-3.