ZOOL 4133 1st Edition Lecture 10 Sexual Selection I. A special case of natural selectiona. The ability to obtain mates varies, which results in differential reproductionb. Requires heritable variationi. In regards to characteristics that affect reproductive successc. The sources of selection are always relevant phenotypic variation that is always within-sex and conspecificsi. This is in contrast to natural selectiond. Sexual selection is able to select for characteristics which increase the reproductive success of an organismi. This is at the expense of survival and is also in contrast to natural selectionReproductive asymmetries: males vs. femalesII. Males and females have different investments in their gametesa. Males – spermi. Smallb. Females – eggsi. Largec. He choosier sex should be the one that has the most to investi. Females are the ones that invest more in gametesIII. Reproductive potentiala. Malesi. Limiteless amounts of spermii. The ability to attract females is a limiting factoriii. Can increase fitness with multiple matesb. Femalesi. Finite number of eggsii. Time and resources are the limiting factors1. Must invest wisely for each offspringiii. Only one mate needed to reach maximum reproductive outputc. High inconsistency in male reproductive achievementd. Low inconsistency in female reproductive achievementi. Bateman gradientIV. Bateman gradient seen in experimentsa. Rough-skinned newt experimenti. All of the females produced offspringThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.ii. About 70% of the males did not propagate offspringb. Sex role-reversed pipefishi. About 40% of the females did not produce offspringii. About 14% of the males did not propagate V. Bateman gradient in regards to modern behavioral ecologya. Sexual selection is not always stronger in males than it is in femalesi. It often is though – but not alwaysii. Males become the choosy sex when they invest more than femalesb. There are many species in which females mate with multiple males, even though only one mating session is enough to fertilize all eggsc. Choosy females are not passive femalesIntrasexual vs. intersexualVI. Within-sexa. Various mating strategiesb. After-mating competition such as sperm competitionc. Infanticided. Territorial fightinge. Ritual fightingf. Defending of resourcesVII. Between-sexa. Elaborate shows/displaysb. intricate phenotypesVIII. intrasexuala. the evolution of alternative mating strategies can be promoted by intense male-male competitioni. Coho salmonii. Plainfin midshipmaniii. Copulatory plugs1. The first male is advantageousb. Sperm competitiveness in a mammal shown in experimenti. House mouse1. Polygamous line males were seen to produce more sperm with better motility after 8 generations versus monogamous males2. Higher paternity