Four characters in a trade-off: dissecting their phenotypic and genetic relations

Citation
G. Stirling et al., Four characters in a trade-off: dissecting their phenotypic and genetic relations, OECOLOGIA, 120(4), 1999, pp. 492-498
Citations number
46
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
OECOLOGIA
ISSN journal
0029-8549 → ACNP
Volume
120
Issue
4
Year of publication
1999
Pages
492 - 498
Database
ISI
SICI code
0029-8549(199909)120:4<492:FCIATD>2.0.ZU;2-Q
Abstract
Phenotypic characters may covary negatively because they are in a trade-off or positively because they contribute to a single function. Genetic correl ations can be used to test the validity and generality of these functional relationships by indicating the lever of genetic integration and checking t he conditions under which they are expressed. Phenotypic correlations indic ate that there is a widespread trade-off between flight capability and earl y fecundity in insects. Different wing morphs (long and short wing) are tho ught to have a suite of reproductive and right capability traits. In a half -sib mating experiment, we estimated phenotypic relationships between two f light-capability-related characters (flight muscle condition, wing morph) a nd two components of early fecundity (number of eggs in the ovaries, number of eggs laid), as well as genetic correlations relating wing morph and bot h components of fecundity in the wing-dimorphic cricket, Gryllus firmus. Th e number of eggs in the ovaries and the number of eggs laid were negatively correlated phenotypically and genetically with wing length morph (i.e., lo ng wings associated with low fecundity). Both fecundity characters differed between wing morphs, but only if flight muscle was present and not histoly zed. The phenotypic and genetic correlations between fecundity characters w ere not significant. This suggests that the phenotypic relationship between ovary development and eggs laid is complex, they are not genetically integ rated, and they may evolve independently. However, both early fecundity cha racters are functionally and genetically integrated within the trade-off to a similar degree. Finally, the trade-off affects early fecundity of both w ing morphs suggesting that the functional relationship depends on flight mu scle size.