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
- Sexual Selection and Mate Choice
- The Good Gene Hypothesis
- Empirical Studies Investigating the Good Gene Hypothesis
- Norris (1993): Great Tits
- Petrie (1994): Peacocks
- Howard et al. (1994): Toads
- Hamilton and Zuk (1982): Parasites and Plumage
- Moller (1990): Barn Swallows
Objectives and Key Themes
This text examines the "good gene" hypothesis within the broader context of sexual selection and female mate choice. It aims to explore whether empirical evidence supports the claim that females select mates based on superior genetic qualities that enhance offspring viability. The text reviews existing research and analyzes its strengths and limitations.
- Sexual selection and its components (intrasexual and intersexual selection).
- The "good gene" hypothesis and its various models (handicap principle, condition-dependent handicap).
- The heritability of fitness and its implications for the good gene hypothesis.
- Empirical evidence for and against the good gene hypothesis from various studies.
- Comparison and potential integration of the good gene hypothesis with alternative hypotheses, such as the healthy mate theory and runaway selection.
Chapter Summaries
Sexual Selection and Mate Choice: This introductory section defines sexual selection according to Darwin's original concept, differentiating between intrasexual and intersexual selection. It introduces the "good gene" hypothesis as a central focus, explaining its core premise: females choose mates based on traits indicating high heritable viability, leading to offspring with enhanced survival prospects. The section lays the groundwork for the subsequent exploration of empirical evidence supporting or refuting this hypothesis.
The Good Gene Hypothesis: This chapter delves into the theoretical underpinnings of the good gene hypothesis, tracing its origins to Fisher (1915) and Williams (1966). It details Zahavi's (1975) handicap principle, highlighting how costly male traits, despite potentially reducing survival, can serve as honest signals of superior genetic quality. The chapter then discusses variations of this principle, including the condition-dependent handicap model. A key challenge addressed is the difficulty in accurately measuring the heritability of total fitness, which is crucial for validating the hypothesis. The complexities of heritability, including potential negative correlations between fitness components, are explored, underscoring the need for further empirical investigation.
Empirical Studies Investigating the Good Gene Hypothesis: This section presents a critical review of several key empirical studies that investigate the good gene hypothesis. It summarizes studies on great tits (Norris, 1993), peacocks (Petrie, 1994), toads (Howard et al., 1994), and barn swallows (Moller, 1990), highlighting both supporting and contradictory findings. The analysis includes a discussion of methodological limitations and potential confounding factors (e.g., maternal effects, alternative hypotheses like the healthy mate theory). The chapter concludes by acknowledging the complexities of disentangling the effects of the good gene hypothesis from other theories of mate choice, suggesting that a combination of factors might be at play.
Keywords
Sexual selection, mate choice, good gene hypothesis, handicap principle, heritability of fitness, female preferences, offspring viability, empirical studies, great tits, peacocks, toads, barn swallows, parasites, healthy mate theory, runaway selection.
Frequently Asked Questions: A Comprehensive Language Preview on Sexual Selection and the Good Gene Hypothesis
What is the main topic of this text?
This text focuses on the "good gene" hypothesis within the context of sexual selection and female mate choice. It examines whether empirical evidence supports the idea that females select mates based on superior genes that improve offspring survival.
What are the key themes explored in this text?
The key themes include sexual selection (intrasexual and intersexual), the "good gene" hypothesis and its models (handicap principle, condition-dependent handicap), the heritability of fitness, empirical evidence from various studies (including those on great tits, peacocks, toads, and barn swallows), and comparisons with alternative hypotheses like the healthy mate theory and runaway selection.
What are the objectives of this text?
The text aims to review existing research on the "good gene" hypothesis, analyze the strengths and limitations of this research, and explore whether empirical evidence supports the hypothesis. It seeks to provide a comprehensive understanding of the topic by examining both supporting and contradictory findings.
Which studies are reviewed in the text?
The text reviews several key empirical studies, including Norris (1993) on great tits, Petrie (1994) on peacocks, Howard et al. (1994) on toads, Hamilton and Zuk (1982) on parasites and plumage, and Moller (1990) on barn swallows. These studies are analyzed to assess their contribution to understanding the "good gene" hypothesis.
What is the "good gene" hypothesis?
The "good gene" hypothesis proposes that females choose mates based on traits that signal superior genetic quality, leading to offspring with enhanced survival and reproductive success. The text explores this hypothesis in detail, including its theoretical underpinnings and various models, such as the handicap principle.
What is the handicap principle?
The handicap principle, proposed by Zahavi (1975), suggests that costly male traits, even if detrimental to survival, can serve as honest signals of superior genetic quality. Only males with superior genes can afford the cost of such traits, making them reliable indicators of fitness.
What are the limitations and challenges in testing the good gene hypothesis?
The text highlights the challenges in accurately measuring the heritability of total fitness, which is crucial for validating the good gene hypothesis. It also discusses methodological limitations in empirical studies and the potential influence of confounding factors, such as maternal effects and alternative hypotheses of mate choice.
How does the text compare the good gene hypothesis to other theories?
The text compares the good gene hypothesis with alternative explanations for mate choice, such as the healthy mate theory and runaway selection. It acknowledges that a combination of factors might contribute to female mate preferences.
What are the key takeaways from the chapter summaries?
The chapter summaries provide concise overviews of the introduction to sexual selection, a detailed explanation of the good gene hypothesis and its theoretical foundations, and a critical analysis of several empirical studies investigating the hypothesis, including discussion of both supporting and contradictory evidence and methodological limitations.
What are the keywords associated with this text?
Keywords include: Sexual selection, mate choice, good gene hypothesis, handicap principle, heritability of fitness, female preferences, offspring viability, empirical studies, great tits, peacocks, toads, barn swallows, parasites, healthy mate theory, runaway selection.
- 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
