Ecomorphological individual variation in a population of Haplochromis nyererei from the Tanzanian part of Lake Victoria

Publisher Website
Google Scholar
Abstract
Intraspecific morphological variation among a population of Haplochromis nyererei (Teleostei, Cichlidae) from Lake Victoria was investigated. Three main groups of variables were used: general shape, outline of the head, and trophic group (intestinal length, stomach contents, teeth and jaw shape, lower jaw length and width). Fishes were arranged into four groups: G1, large males with a prominent bump on the head, a thickset body and anatomical structures related to a strictly insectivorous diet; G2, large males lacking a bump on the head but more or less thickset and showing anatomical structures related to omnivorous feeding habits, though favouring insects; G3, males and a few females with a slight bump on the head, a slender body shape and showing anatomical structures related primarily to a herbivorous tendency; and G4, females and a few small males without a bump on the head, a slender body and showing anatomical structures related to an omnivore with herbivorous tendencies. Several hypotheses related to behaviour are presented partly to explain the intraspecific variation observed. Differences between individuals could arise as a result about the establishment of dominance and territory in males.