The effects of phylogenetic differences on resource partitioning between the cryptic species whiskered bat (Myotis mystacinus) and Brandt's bat (M. brandtii)
Location: United Kingdom
Cryptic species are defined as “species which are morphologically similar (i.e. similar in physical appearance), but reproductively isolated (Allaby 1996). Recently much attention has been given to the ecology of cryptic species because they provide us with an excellent oppurtunity to study whether ecological differences occur among morphologically similar species.
Bat species with similar morphologies are assumed to be ecologically similar, thus making it difficult to explain their coexistance. Although large morphological differences appear to have a profound influence on the foraging ecology of bats, the influence of smaller differences is unknown, and the mechanisms that allow similar species to coexist have yet to be determined. When similar species coexist, we would expect that this can only take place if there are differences in the species' ecologies that reduce competition. Studies of the resource partitioning of cryptic bat species support this theory (e.g. Arlettaz et al. 1993, Barlow 1997).
However, previous studies have only looked at bats with similar evolutionary histories. Interestingly, a study carried out in 2001 on a great number of bat species, discovered that unlike the other study animals, the cryptic species Brandt's bat ( Myotis brandtii ) and the whiskered bat ( M. mystacinus ) have different evolutionary histories and are more closely related to other Myotis species than each other (Ruedi and Mayer 2001). Brandt's bat and the whiskered bat therefore give us the perfect opportunity to study the outcomes of convergent evolution. I am therefore wanting to answer the question:
What is the resource partitioning between two species which are morphologically almost identical, but have different evolutionary histories?
Little research has been directed towards the ecology of whiskered and Brandt's bats. The species are morphologically very similar and the difficulties in telling them apart, even in the hand, makes the identification of their behaviour and ecology also difficult. This is probably a contributing factor to the lack of research on their biology.
As mentioned above, much attention has recently been given to the use of cryptic speices as a tool to study community ecology. However, cryptic species with different evolutionary histories are uncommon and a study of the ecology of whiskered and Brandt's bats could therefore provide us with some very interesting results.
Like many other British bat species, whiskered and Brandt's bats are at the limit of their range in the UK . Frequently management decisions in the UK are based on studies of bat populations on the continent, which may have different ecologies compared to the British bats. This study will therefore yield important information for the conservation of bat species at the limit of their range.
Most importantly, both species are currently regarded as “Vulnerable” in the UK (Hutson 1993) and unlike many of the other British bats, there is currently no Species Action Plan for either species. In order to make the best management recommendations it is important to obtain further information on diet, habitat use and range requirements of the bats. This is because successful conservation programmes for bats also need to develop measure to conserve the prey and foraging areas of the bats.
Allaby, M. 1996. Concise Dictionary of Zoology . Oxford University Press, Oxford
Arlettaz, R., Ruedi, M. and Hausser, J. 1993. Trophic ecology of two sibling species and sympatric species of bats- Myotis myotisand Myotis blythii (Chiroptera, Vespertilionidae)- first results. Mammalia 57: 519-531
Barlow, K.E. 1997. The diets of two phonic types of the bat Pipistrellus pipistrellus in Britain . Journal of Zoology , London 243: 597-609
Hutson, A.M. 1993. Action Plan for the Conservation of Bats in the UK . Bat Conservation Trust, London .
Ruedi, M. and Mayer, F. 2001. Molecular systematics of bats of the genus Myotis (Vespertilionidae) suggests deterministic ecomorphological convergences. Molecular Phylogenetics and Evolution 21: 436-448
PhD Thesis: Resource partitioning between the cryptic species Brandt's bat (Myotis brandtii) and the whiskered bat (M. mystacinus)in the UK
Dr Lene Berge
Professor Gareth Jones
The project would also not have been possible without the help and co-operation from roost owners, field assistants, colleagues and other bat workers.