The “good gene” hypothesis is one of the main hypotheses regarding sexual selection by female mate choice. Sexual selection was first defined by Darwin as “the advantage which certain individuals have over others of the same sex and species, in exclusive relation to reproduction”. He devised sexual selection theory to account for the evolution of survival-decreasing traits, which nevertheless increase individual reproductive success by enabling individuals to acquire mates in competition with others. Sexual selection consists of two components, one arising when the members of one sex compete for mates (often called intrasexual selection) and the other occurring when members of the choosier sex determine which members of the other sex will have a chance to mate (often called intersexual selection). The good gene hypothesis is concerned with the latter or rather with the evolution of female preferences for male traits. First, I am going to outline the main components of the good gene hypothesis and then I am going to explore whether there is any evidence that females choose on the basis of “good genes”.
Table of Contents
1. SEXUAL SELECTION AND MATE CHOICE
Objectives and Topics
The primary objective of this text is to examine the "good gene" hypothesis within the context of sexual selection, specifically investigating whether empirical evidence supports the claim that females select mates based on the heritable viability of their genes. The work explores the theoretical foundations of these preferences and reviews various studies to determine if they provide conclusive proof of paternal genetic benefits.
- Theoretical definitions of sexual selection and the "good gene" hypothesis.
- The role of handicap principles and indicator models in mate choice.
- Empirical analysis of female preference and offspring viability.
- Comparison of "good gene" theory with "healthy mate" and "runaway selection" models.
- Limitations in measuring the heritability of fitness in diverse species.
Excerpt from the Book
SEXUAL SELECTION AND MATE CHOICE
The “good gene” hypothesis is one of the main hypotheses regarding sexual selection by female mate choice. Sexual selection was first defined by Darwin as “the advantage which certain individuals have over others of the same sex and species, in exclusive relation to reproduction”. He devised sexual selection theory to account for the evolution of survival-decreasing traits, which nevertheless increase individual reproductive success by enabling individuals to acquire mates in competition with others. Sexual selection consists of two components, one arising when the members of one sex compete for mates (often called intrasexual selection) and the other occurring when members of the choosier sex determine which members of the other sex will have a chance to mate (often called intersexual selection). The good gene hypothesis is concerned with the latter or rather with the evolution of female preferences for male traits. First, I am going to outline the main components of the good gene hypothesis and then I am going to explore whether there is any evidence that females choose on the basis of “good genes”.
The idea that conspicuous, costly male traits become targets of female choice because such traits indicate high heritable viability and that after mating with a highly ornamented male, a female would then bear offspring that survive well, was suggested by Fisher (1915) as well as by Williams (1966). Nevertheless neither developed the idea any further and Williams even came to doubt whether the heritability of fitness is high enough for such a process to work, but their versions of this idea gave rise to what has been termed “good genes”, “handicap” or “indicator” models. Zahavani’s (1975) handicap principle popularised the notion that females prefer to mate with males who have demonstrated their superior genetic quality for survivorship. He suggested that females can evaluate a male’s survaival ability by assessing the magnitude of the handicap with which he is able to survive. There is no disagreement that many sexually dimorphic traits can increase male mortality, and Zahavani suggested that these handicaps to survival evolve as honest signals, allowing females to assess male genetic quality; thus, the term female choice for
Summary of Chapters
1. SEXUAL SELECTION AND MATE CHOICE: This section introduces the theoretical framework of sexual selection and the "good gene" hypothesis, while reviewing empirical case studies—such as those on great tits, peacocks, and barn swallows—to evaluate the validity of female mate preferences based on genetic quality.
Keywords
Sexual selection, good gene hypothesis, female mate choice, heritability, survival, fitness, handicap principle, intersexual selection, offspring viability, indicator models, parasite load, evolutionary biology, paternal genetic effect, plumage, breeding success.
Frequently Asked Questions
What is the core focus of this publication?
The publication focuses on the "good gene" hypothesis within evolutionary biology, analyzing whether female mate selection is driven by the desire to secure superior genetic traits for their offspring.
What are the primary thematic fields covered?
The text covers sexual selection theory, the handicap principle, the heritability of fitness, and various empirical studies testing whether mate preferences correlate with offspring survival.
What is the main research question addressed?
The central question is whether there is credible empirical evidence that females choose mates based on the basis of "good genes" to enhance the viability of their offspring.
Which scientific methods are analyzed in the work?
The work reviews observational studies, cross-fostering experiments, and comparative analyses across different species to test predictions related to ornamentation, parasite resistance, and heritable viability.
What topics are discussed in the main body?
The main body examines the history of the "good gene" model, the limitations of measuring fitness heritability, and specific case studies involving birds and toads to highlight the complexities of these evolutionary mechanisms.
Which keywords characterize this work?
Key terms include sexual selection, good gene hypothesis, female mate choice, heritability, handicap principle, and offspring viability.
How does the author view the relationship between different evolutionary theories?
The author suggests that the "good gene" hypothesis often overlaps with the "healthy mate" theory, noting that it is difficult to isolate these effects and that they likely function in combination.
What role does the "handicap principle" play in the text?
The handicap principle is discussed as a mechanism where females assess male genetic quality by evaluating the costliness of specific survival traits, which act as honest signals of fitness.
What challenges does the author identify regarding empirical research?
The author notes significant challenges, such as the difficulty of measuring the heritability of overall fitness and the risk of confounding parental genetic effects with maternal environmental effects.
Do the findings suggest that the good gene hypothesis is universal?
No, the author concludes that while there is evidence supporting the hypothesis in specific cases like great tits and peacocks, it does not necessarily apply to all species and remains a subject requiring further investigation.
- Quote paper
- BA (Oxon), Dip Psych (Open) Christine Langhoff (Author), 2002, Sexual selection and mate choice - is there any evidence that females choose on the basis of “good genes”? , Munich, GRIN Verlag, https://www.grin.com/document/80252
