Four characters in a trade-off: dissecting their phenotypic and genetic relations |
| |
Authors: | Gray Stirling Derek Roff Daphne Fairbairn |
| |
Institution: | (1) Department of Biology, McGill University, 1205 ave. Dr. Penfield, Montreal, Quebec, H3A 1B1, Canada e-mail: stirling@bio1.lan.mcgill.ca, Tel.: +1-514-3986450, Fax: +1-514-3985069, CA;(2) Department of Biology, Concordia University, 1455 de Maisonneuve Blvd. West, Montreal, Quebec, H3G 1M8, Canada, CA |
| |
Abstract: | Phenotypic characters may covary negatively because they are in a trade-off or positively because they contribute to a single
function. Genetic correlations can be used to test the validity and generality of these functional relationships by indicating
the level of genetic integration and checking the conditions under which they are expressed. Phenotypic correlations indicate
that there is a widespread trade-off between flight capability and early fecundity in insects. Different wing morphs (long
and short wing) are thought to have a suite of reproductive and flight capability traits. In a half-sib mating experiment,
we estimated phenotypic relationships between two flight-capability-related characters (flight muscle condition, wing morph)
and two components of early fecundity (number of eggs in the ovaries, number of eggs laid), as well as genetic correlations
relating wing morph and both components of fecundity in the wing-dimorphic cricket, Gryllus firmus. The number of eggs in the ovaries and the number of eggs laid were negatively correlated phenotypically and genetically
with wing length morph (i.e., long wings associated with low fecundity). Both fecundity characters differed between wing morphs,
but only if flight muscle was present and not histolyzed. The phenotypic and genetic correlations between fecundity characters
were not significant. This suggests that the phenotypic relationship between ovary development and eggs laid is complex, they
are not genetically integrated, and they may evolve independently. However, both early fecundity characters are functionally
and genetically integrated within the trade-off to a similar degree. Finally, the trade-off affects early fecundity of both
wing morphs suggesting that the functional relationship depends on flight muscle size.
Received: 1 December 1998 / Accepted: 20 May 1999 |
| |
Keywords: | Trade-off Genetic correlation Functional integration |
本文献已被 SpringerLink 等数据库收录! |
|