Good Genes Models

Good-genes models

These models assume that mates are chosen based on characteristics that reflect "good genes" of the mate. An extension of this considers characteristics that correlate with the viability of the offspring resulting from the mating.

The good-genes irony--strong mate choice based on a trait is sexual selection and should render the trait non-informative; there will be no significant heritability for the trait.

The good-genes criminals--my genes may not be good but I can use deceptive practices to mimic the trait being used to measure good-genes

Honest signalling--honest signals are resistant to deception and have a high heritability. (see the handicap principle).

Moller and Alatalo (1999) present a meta-analysis of 22 previously published papers dealing with the correlation between male traits and offspring survival. The mean correlation coefficient was 0.122, which significantly differs from 0 (but r squared = 0.0148, or only 1.5%!!). The authors argue that while small, the effect may be substantial over extended evolutionary time-scales. (interesting aside: the authors found a significant effect of publication year on the results of the original studies; this could be due to biases in the studies resulting from paradigm shifts in the field!!) Why isn¹t the same mate chosen every time? This question applies both within individuals and between individuals within a species. If good genes are good, then why vary mating choice. (note: these mechanisms preserve additive genetic variation). From Widemo and Saether's (1999) table 1: causes of variation in mating preferences

ADVANTAGE	MECHANISM
genetic compatibility	meiotic drive avoidance
genetic complementarity	MHC
	heterozygosity
	heterosis
	parasite resistance
phenotypic compatibility	mating facilitation
remating avoidance	quality assortative mating
different optimal offspring phenotypes	fixed alternative strategies
rare offspring advantage	frequency dependent success

Jennions, M. D. and M. Petrie. 1997. Variation in mate choice and mating preferences: a review of causes and consequences. Biol. Rev. 72:283-327.

Widemo, F. and S. A. Saether. 1999. Beauty is in the eye of the beholder: causes and consequences of variation in mating preferences. Trends in Ecology and Evolution. 14:26-31.

Iyengar, V. K. and Eisner, T. 1999. Heritability of body mass, a sexually selected trait, in an arctiid moth (Utetheisa ornatrix). P. N. A. S. (USA). 16:9169-9171.

Moller, A.P. and Alatalo, R. V. 1999. Good genes effects in sexual selection. Proceedings of the Royal Society of London (B) 266:85-91.