Local adaptations in populations of rock–dwelling haplochromines (Pisces:Cichlidae) from southern Lake Victoria

Abstract

The radiation of cichlid ¢shes in the African great lakes is often described as adaptive, because, at a super¢cial level, cichlid ¢shes seem adapted to the ecological niches they occupy. However, adaptiveness has rarely been studied. We investigated to what extent island populations of three species of the rockdwelling genus Neochromis, endemic to Lake Victoria, are adapted anatomically to exploit locally abundant resources. Speci¢cally, we asked whether di¡erent resource environments were re£ected in di¡erences in the feeding apparatus, both within species and between species. In populations of two specialized biters, the algae scrapers N. rufocaudalis and N. omnicaeruleus, the biting force of the lower jaw increased with increasing amount of items that require biting in the diet. N. greenwoodi is a less specialized biter; we found di¡erences between two populations in the hyoid position and in the premaxilla that enhance suction feeding. These adaptations were related to the amount of items requiring suction. Comparing across three sympatric pairs of species, in each case di¡erent diets were re£ected in di¡erences in anatomy.

No trade-off between biting and suction feeding performance in clariid catfishes

“…Our modelling of the volume increase of the buccal cavity during expansion in Clariidae supports this: if only ventral expansion occurred (on average) 74% of the total observed volume increase would still had been reached, whereas lateral expansion only would result in 20% of the total expansion (the remaining 6% is due to the interaction between both directions of expansion). Clariidae differ in this aspect from the more laterally flattened cichlid fishes, the group for which the trade-off between biting and suction has been studied most intensively (Barel, 1983;De Visser and Barel, 1996;De Visser and Barel, 1998;Bouton et al, 1998;Bouton et al, 1999). It has been proposed for cichlid fishes that in order to accommodate thicker jaw adductor muscles (increasing bite force) the cichlid's head has to widen, which implies a lateral displacement of the touching point between the hyoid and the suspensorium.…”

“…scraping algae or picking molluscs off the substrate with the oral jaws). It is hypothesised that biting a prey or sucking it directly into the mouth are two functionally conflicting ways of getting food into the buccal cavity (Barel, 1983;Bouton et al, 1999;Sibbing and Nagelkerke, 2001). It is therefore assumed that suction feeding and biting can be combined only to a certain extent, It is generally assumed that biting performance trades off with suction performance in fish because both feeding types may place conflicting demands on the cranial musculo-skeletal system.…”

Significance of pre-Quaternary climate change for montane species diversity: Insights from Asian salamanders (Salamandridae: Pachytriton)

“…The hyobranchial skeleton of Pachytriton is specialized for underwater suction feeding (Özeti and Wake, 1969). Reconfiguration of the skeleton in P. archospotus implies a modified feeding habit in this species, which in turn may reflect novel prey availability (Bouton et al, 1999).…”

Integration and evolution of the cichlid mandible: The molecular basis of alternate feeding strategies

“…Several coral reef fish lineages exhibit extensive ecological diversity, often associated with elaborate accentuations of biting and suction feeding (3)(4)(5). Cichlids have diverged rapidly along this functional axis with the repeated evolution of alternate biting͞sucking morphologies that are characteristic of both deep cladogenic events and contemporary fine-scale ecological niche partitioning (6)(7)(8)(9)(10)(11)(12). Understanding the molecular basis of changes that differentiate biters from suction feeders will lend significant insight into the adaptive evolution of fish species.…”