--- title: "Sexual selection, mate choice and parental investment" description: "Parental investment can affect how quickly each sex returns to mating and how available partners are, influencing competition and choice. These are conditional tendencies. A heritable trait that lower" canonical: https://lightmysky.com/learn/science/sexual-selection-mate-choice-and-parental-investment-mt_6oTPGFw_p5 source: https://lightmysky.com/learn/science/sexual-selection-mate-choice-and-parental-investment-mt_6oTPGFw_p5.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Sexual selection, mate choice and parental investment Parental investment can affect how quickly each sex returns to mating and how available partners are, influencing competition and choice. These are conditional tendencies. A heritable trait that lowers survival can still be favoured if its mating benefits raise overall reproductive success. Subject: Science · Area: Ecology & Conservation · Ages 20 to 21 Page: https://lightmysky.com/learn/science/sexual-selection-mate-choice-and-parental-investment-mt_6oTPGFw_p5 ## Ready when they can - Predicts tendencies in mate competition and choice from parental investment and the availability of ready partners. - Explains how a costly ornament can be favoured despite lowering survival. - Uses a role-reversed case to test a conditional investment prediction without treating it as proof of a universal rule. ## Lesson: Mating success and parental investment Sexual selection arises from differences in mating success. Parental investment is effort spent producing or caring for offspring at a cost to other reproductive opportunities. Greater investment can delay returning to mating, making ready partners scarcer. This often favours more choice by that sex and more competition by the other. These are tendencies: partner availability and ecology also matter, and both sexes can compete and choose. **Example.** A heritable ornament may lower survival yet be favoured if its mating benefits increase overall expected reproductive contribution. Count both effects. For example, after survival costs are included, ornament carriers might average 8 surviving offspring rather than 6. Cost alone does not make an ornament an honest signal of condition. Honesty requires evidence that the signal reliably reflects condition. *(drawing: Hypothetical averages after survival costs: 6 surviving offspring without the ornament, 8 with it.)* Competition among individuals of the same sex for mating opportunities is called intrasexual selection. Mate choice between sexes is called intersexual selection. If males fight and females choose among them, the fights show competition and the choices show mate preference. Both processes can affect mating success. Suppose males invest more overall, brooding delays their next mating, and ready males are scarce relative to females. The investment argument predicts greater female competition and male choosiness. Male egg carrying alone does not establish these conditions. A matching role-reversed case supports the prediction but does not prove a universal rule. Measure total investment, readiness and mating behaviour. As in foraging, time and energy used for one action cannot also fund another. Hours spent displaying instead of feeding chicks have an opportunity cost: chick-feeding effort forgone. That does not tell us how many chicks will die. For reproductive decisions, compare expected reproductive contribution, including offspring survival and future opportunities, rather than energy gain alone. **Recap.** Investment and partner availability influence competition and choice. Heritable ornaments can be favoured despite survival costs, but cost alone does not establish signal honesty. *Lesson, questions and study cards written for this dataset.* ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Optimal foraging and the currency of a behavioural decision](https://lightmysky.com/learn/science/optimal-foraging-and-the-currency-of-a-behavioural-decision-mt_9iNYB7d1Rh) ## Optional connections - [Selection Coefficients and Predicting Allele Frequency Change](https://lightmysky.com/learn/science/selection-coefficients-and-predicting-allele-frequency-change-mt__JS2XJxOXV) ## Opens up - [Kin Selection, Relatedness and When Helping Pays](https://lightmysky.com/learn/science/kin-selection-relatedness-and-when-helping-pays-mt_scVf8G34WI)