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Lecture 19

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Western University
Biology 1001A
Tom Haffie

Lecture 19 November-15-12 10:39 AM Parent-offspring conflict before birth • Fetus selected to ‘demand’ more resources from mother than mother selected to give ○ fetal tissue in placenta secretes allocrine hormones to manipulate maternal blood pressure and blood sugar; maternal sensitivity to these signals drops ○ conflict of interest endangers both parties Unrelated individual may have similar, but not overlapping interests • Tragedy of the Commons; social dilemma (conflict) over use of shared resource ○ 10 farmers each own their own cows; but all share "the commons (land the cows graze on)" ○ As more cows are added; cost of overgrazing shared by all the farmers ○ Benefits of owning another cow are not shared ○ Rational decisions by individuals overexploitation of shared resource Summary: cooperation and conflict • Altruism, like sex, is puzzling • Many 'altruistic' traits can be explained by shared genetic interests; others by reciprocity; but rational decisions by individuals may delete shared resources • Even when genetic interests overlap (family groups) they can be different enough to induce conflict Morphological species concept • BIOLOGICAL SPECIES CONCEPT Biological species concept • Species: interbreeding (or potentially interbreeding) group of individuals, reproductively isolated from other such groups Limitations to Biological species concept • Has troubles when species are geographically separate from each other • Reproductive isolation has no meaning (reproducing asexually) One species or two? • Tough to tell if we deal with more than one species or not Achieving reproductive isolation: Prezygotic
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