Browsing by Autor "Raoul Van Damme"

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Consistency and variation in the bat assemblages inhabiting two forest islands within a neotropical savanna in Bolivia
(Cambridge University Press, 2003) Luís F. Aguirre; Luc Lens; Raoul Van Damme; Erik Matthysen
Neotropical bats occupy a large variety of trophic niches, and represent locally abundant, species-rich communities. As such, they are highly suited as a model group for the study of temporal and spatial dynamics of animal communities. However, despite this important research potential, data on the dynamics and turnover rates of Neotropical bat communities are lacking. We here study both aspects for bats inhabiting two natural forests surrounded by savanna in Bolivia. Over a period of 8 y, both bat communities showed high rates of species turnover. As predicted, species relying on fluctuating food resources were more likely to be absent in particular years, whereas species relying on more predictable food supplies were present in all years.
Ecomorphological analysis of trophic niche partitioning in a tropical savannah bat community
(Royal Society, 2002) Luís F. Aguirre; Anthony Herrel; Raoul Van Damme; Erik Matthysen
The exceptional diversity of neotropical bat communities is sustained by an intricate partitioning of available resources among the member species. Trophical specialization is considered an important evolutionary avenue towards niche partitioning in neotropical phyllostomid bats. From an ancestral insectivorous condition, phyllostomids evolved into highly specialized frugivorous, carnivorous, nectarivorous, piscivorous and even sanguivorous species. Previously, correlations between cranial morphology and trophic ecology within this group have been documented. Here, we examine the evolutionary relationships between bite force and head shape in over 20 species of bats from a single tropical savannah bat community. The results show that bite force increases exponentially with body size across all species examined. Despite the significant differences between large dietary groups using traditional analysis (i.e. non-phylogenetic) and the strong evolutionary correlations between body mass and bite force, phylogenetic analyses indicated no differences in bite performance between insectivorous, omnivorous and frugivorous bats. Comparisons of three species with highly specialized feeding habits (nectarivory, piscivory and sanguivory) with the rest of the species in the community indicate that specialization into these niches comes at the expense of bite performance and, hence, may result in a reduction of the trophic niche breadth.
The implications of food hardness for diet in bats
(Wiley, 2003) Luís F. Aguirre; Anthony Herrel; Raoul Van Damme; Erik Matthysen
Summary Neotropical bat communities are characterized by a broad species diversity, which can be achieved and maintained only through partitioning of the available resources. Here patterns of trophic resource utilization within a single neotropical savanna bat community are investigated. Moreover, the physical properties of food items (i.e. hardness), its variation with food size, and whether food hardness differs between items consumed by the bats in this community are investigated experimentally. The results show that food hardness increases with the size of the food item, and that distinct differences exist in the amount of force needed to crush different food items (beetles vs other insects vs fruits). Using previously published data on bite forces from species in the same community it is explored whether food hardness may play a role in shaping the diets of the bats in the community. The combined data on bite forces and food hardness indicate that food hardness can both directly and indirectly limit dietary diversity in bats. The results also indicate that dietary specialization may potentially result in a decrease in trophic breadth for some species through its effect on bite performance.