Handedness in scale-eating cichlids: is it in the bones?


Scale-eating cichlids from Lake Tanganyika offer an inspiring example of frequency-dependent selection in action. Adults of P. microlepis are either left-handed, with a beak oriented towards the left, or right-handed, with their beak towards the right.

Lef-handed fish attack the right flanks of prey, right-handed fish the left flanks. Frequency dependence is caused by the prey: when one scale-eating morph is rare, the prey doesn't expect attacks from the corresponding side, giving a rarity advantage.



It is believed that handedness is caused by one major gene with dominance-recessivity. In our lab, however, we discovered that that cannot be true. We also find many rather symmetric fish, such that handedness in scale-eating cichlids might just be another example of fluctuating asymmetry.

Our measures of handedness so far are based on morphometric analysis of head outlines (contours). Old papers on P. eccentricus claim that there was a clear handedness in the jaw bones.


We now want to complement our contour morphometrics with an analysis of jaw bone variation, to check whether they are concordant or not, whether jaw bone asymmetry is more discrete than our contour measures, and whether jaw bone asymmetry correlates with differences in attack behaviour.


This is a six-month project for a Msc student. The student will do attack preference experiments, morphometrics from digital photographs of heads, and from x-ray photographs.

Supervision is by Tom JM Van Dooren (t.j.m.van.dooren@biology.leidenuniv.nl) and Frans Witte.


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This page contains a single entry by administrator published on August 30, 2008 9:58 PM.

Life-history trade-offs between developmental time, longevity and fecundity was the previous entry in this blog.

Ossification and behaviour, do they interact? is the next entry in this blog.

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