Phenotypic plasticity and the possible role of genetic assimilation: Hypoxia-induced trade-offs in the morphological traits of an African cichlid

Citation
Lj. Chapman et al., Phenotypic plasticity and the possible role of genetic assimilation: Hypoxia-induced trade-offs in the morphological traits of an African cichlid, ECOL LETT, 3(5), 2000, pp. 387-393
Citations number
20
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
ECOLOGY LETTERS
ISSN journal
1461-023X → ACNP
Volume
3
Issue
5
Year of publication
2000
Pages
387 - 393
Database
ISI
SICI code
1461-023X(200009)3:5<387:PPATPR>2.0.ZU;2-H
Abstract
In this study we investigate the possible role of phenotypic plasticity and genetic assimilation in the process of adaptation and evolutionary change in the cichlid Pseudocrenilabrus multicolor victoriae. In the field we comp ared a population of a stable hypoxic habitat with one of a stable well-oxy genated habitat. In the laboratory, we compared individuals from the same m other raised under hypoxic or well-oxygenated conditions to examine phenoty pic plasticity. Morphological parameters of three categories were measured: (a) the gill apparatus, (b) the surrounding structural elements, and (c) t he outer shape of the fish. Swamp-dwelling fish had a 29% greater total gil l surface area than fish from the well-oxygenated habitat due to their larg er gill filament length and greater lamellar area. In the plasticity experi ment, total gill surface area was 18% greater in the hypoxia group due to a larger number of longer filaments. Surrounding elements and outer shape al so differed between the field populations and between fish grown under hypo xic and well-oxygenated conditions, but there was disparity between the fie ld results and the plasticity experiment. The disparity between field and e xperimental fish may be due to: (a) differences in selection pressures betw een populations, (b) different constraints for genetic and plasticity chang es, or (c) selection against plastic responses to hypoxia. Our results sugg est that both (a) and (c) are involved.