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Homework 2 due F 2/23 Bonus 1 due W 2/28 Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces. As DNA changes; traits change. DNA Traits Natural Selection: Individuals that are most successful at reproducing will pass on more of their genetic information. Reproductive success = evolutionary success Individuals are selected… But populations evolve via changes in DNA during reproduction. Who evolves?…Species. A. harrisi A. leucurus •A population that can produce fertile offspring •A population that does reproduce **A population sharing genetic information** CB 24.6 Evolution: A species’ genetic component changes as the individuals reproduce. These changes are based on how the DNA changes and who reproduces. Meiosis splits apart the pairs of chromosomes. X 23 in humans haploid X 23 in humans X 23 in humans diploid X 23 in humans Inheritance = The interaction between genes inherited from Mom and Dad. Asexual Reproduction Mitosis only: extremely low genetic diversity vs. Sexual Reproduction Meiosis and Mitosis: greater genetic diversity Asexual Reproduction genetically identical to parent (this tree can reproduce both sexually and asexually) Why does sexual reproduction exist? Cons: • Need two individuals • Hard to find mate • Diseases/Competition Pros: • Genetic diversity Voles Prairie Montane • Monogamous • Nonmonogamous • Both parents care • Mother cares for for young young briefly Why might these voles use different reproductive strategies? Prairie voles: Montane voles: Resource poor Resource rich habitat habitat • Monogamous • Nonmonogamous • Both parents care • Mother cares for for young young briefly How does evolution work for a behaviors such as monogamy? monogamous bye non-monogamous How does evolution work for a behaviors such as monogamy? monogamous bye non-monogamous How does evolution work for a behaviors such as monogamy? After several generations… monogamous non-monogamous How does monogamy work? from “The Myth of Monogamy” by Barash and Lipton Screw worm flies F M sterile Sterile male screw worm flies led to decreased populations because of screw worm monogamy. F M sterile In most other species, because females mate with multiple males, introduction of sterile males has little effect. Sterile male screw worm flies led to decreased populations because of screw worm monogamy. F M sterile In most other species, because females mate with multiple males, introduction of sterile males has little effect. Hi, want to study biology together? M F fertile F M sterile Mating pairs share genetic information and possibly help in child-rearing 10-40% of offspring in a socially monogamous bird species are fathered by an extra-pair male •Social Monogamy = pair lives/works together, but not “faithful” •Sexual Monogamy = pair raise young and only copulate with each other In mammals, child-rearing is most commonly done by the female. She provides milk. Less than 0.01% of mammals are monogamous 1.Would you have dinner with a boy/girl you met today? 1.Would you have dinner with a boy/girl you met today? 2.Would you go to a boy’s/girl’s house who you met today? 1.Would you have dinner with a boy/girl you met today? 2.Would you go to a boy’s/girl’s house who you met today? 3.Would you sleep with a boy/girl who you met today? Do Males and Females have different attitudes toward sex and relationships? On a college campus an attractive male or female asked the opposite sex: “I have been noticing you around campus. I find you very attractive…” Female answers: Male answers: …Would you go out …Would you go out with me tonight? with me tonight? = 50% yes = 50% yes On a college campus an attractive male or female asked the opposite sex: “I have been noticing you around campus. I find you very attractive…” Female answers: Male answers: …Would you go out with …Would you go out with me tonight? me tonight? = 50% yes = 50% yes …Would you come to …Would you come to my apartment my apartment tonight? tonight? = 6% yes = 69% yes On a college campus an attractive male or female asked the opposite sex: “I have been noticing you around campus. I find you very attractive…” Female answers: Male answers: …Would you go out with …Would you go out with me tonight? me tonight? = 50% yes = 50% yes …Would you come to …Would you come to my apartment tonight? my apartment tonight? = 6% yes = 69% yes …Would you go to bed …Would you go to bed with me tonight? with me tonight? = 0% yes = 75% yes Why do Males and Females have different attitudes toward sex and relationships? The male perspective on monogamy Eggs require large resource input. A clutch of bird eggs can be ~20% of bird’s weight. Sperm are cheap. Human Females: ~1 egg/month Human Males: 250,000,000 sperm/ ejaculation Mating pairs share genetic information and possibly help in child-rearing What are the consequences of the different male and female attitudes toward sex and relationships?