Plasticity of Jaw and Skull Morphology in the Neotropical Cichlids Geophagus brasiliensis and G. steindachneri

Abstract

I examined plasticity of jaw and skull morphology induced by feeding different diets in two species of the neotropical cichlid genus Geophagus. The two species possess different modes of development, which affect the size at which young begin feeding. I hypothesized that the difference in size at first feeding could lead to a difference in the amount of change inducible in the two species. The young of the substrate-spawning species, G. brasiliensis, which begin feeding at a smaller size, were predicted to be more plastic than those of the mouthbrooding species, G. steindachneri. The two diets used to induce differences were brine shrimp nauplii and chironomid larvae. Numerous measures of the jaw and skull differed significantly between groups fed the two diets but the amount of plasticity induced was small and would not present a problem for taxonomists. Contrary to my prediction, both the magnitude and pattern of plasticity induced in the two species was similar. Thus, mode of parental care and the size at which young begin feeding do not affect the degree of plasticity. Fish fed brine shrimp nauplii were longer in oral jaw region, but were shorter and shallower in the area behind the oral jaws. An additional group of G. brasiliensis was fed flake food to compare the results of this study to other studies. The differences in measures between fish fed brine shrimp diets and flake food diets were greater than those between fish fed brine shrimp and chironomid larvae. A possible role of plasticity for enhancing rather than retarding morphological evolution is discussed.

Morphology and Genetics of the Ciscoes (Actinopterygii: Salmoniformes: Salmonidae: Coregoninae: Coregonus) from the Solovetsky Archipelago (White Sea) as a Key to Determination of the Taxonomic Position of Ciscoes in Northeastern Europe

“…We mentioned earlier the relation between the temperature during embryogenesis and the number of the vertebrae (Eckmann 1987, Lindsey 1988, Etheridge et al 2012). Many of the head features could be changed by the diet composition of fish (Men′šikov 1951, Meyer 1987, Balon 1989, Wimberger 1991. Body shape and position of the fins likely indicate ability to long-term migration (Belâeva 1951, Burmakin 1953.…”

Aspects structurels et fonctionnels de la biodiversité des peuplements de poissons

“…Whereas faunal studies examine field évidence, functional morphology is performed mosty in the lab. In addition to interfaunal and interspecific comparisons, within-population morphological diversity has been documented for a variety of attributes and species (MEYER, 1990 ;MOODIE, 1972 ;WAINWRIGHT et al, 1991 ;WIMBERGER, 1991).…”

Gene(s) and individual feeding behavior: Exploring eco‐evolutionary dynamics underlying left‐right asymmetry in the scale‐eating cichlid fishPerissodus microlepis

“…However, this technique has also various limitations, the most critical of which are, in our case, that it reflects only feeding during short periods immediately before capture (Menzel, 1959; Michener & Schell, 1994; Vander Zanden & Rasmussen, 1999). Morphological changes associated with feeding plasticity involve bone and soft‐tissues remodeling, which require some months to show plastic divergence in fish (e.g., Gunter et al., 2013; Schneider, Li, Meyer, & Gunter, 2014; Wimberger, 1991; Witten & Huysseune, 2009). Hence, differences in diet (such as feeding on more scales or alternative prey) should not be sporadic to induce a plastic change and produce different phenotypes (such as more or less asymmetrical mouths) through plasticity.…”