Animal Reproduction

Animal Reproduction - Animal Reproduction & Development...

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Tuesday, April 14, 2009 9:34 AM 1. Sexual reproduction o Results in new genetic combination 2. Marine organisms spawning is sexual reproduction 3. Not just limited to physical contact 4. Axexual o 1 parent => genetically identical offspring o Not much input of energy o Many offspring rapidly o Budding, fission, fragmentation/regeneration o Hydra- Sessile aquatic o Corrals, Starfish (fragmentation) o Plants Runners, shoots o Animals 5. Why Sex? 6. Sexual Reproduction o Fusion of gametes from 2 parents: genetic variation o Evolutionary Speculation o Sex Brings about Variation New genetic combination o In environment that is changing new combination may give advantage o Co-evolution between parasite and host. If some of host have slightly different makeup species will persist o Red Queen Hypothesis o Run faster and faster to keep up. Evolutionary arms race o Sex takes more energy, more structures 7. Parthenogenesis o The development of an egg without benefit of sperm. o Female has cells that undergo meiosis and one of meiotically produced cells develop into organism without sperm o Not like the mother. Half the mothers genetic material and random genetic material via meiosis. 8. Hermaphroditism o Both female and male systems o Reproductive parts o Some plants do o Some animals o Some factors that discourage or prevent self fertilization o Worms. Cannot self fertilize Why? Increases the change of rare harmful mutations
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If do mating with close relative are more likely to get rare harmful mutations Situations that prevent self mating o Humans being Hermaphrodites Both ovaries and testis NO. Generally But, yes rarely. Person that represented two individuals in development fused. Technically met hermaphrodites characteristics but not functional o Generally sex organs come from same tissue. Either go ovary way or testis way o Person with primary sex characteristic and secondary opposite sex characteristic No Y or multiple Y. Still makes male or female Testosterone. Path can foul up. Genes turned on or off Must be receptors on cells for testosterone. Can mess up 9. External fertilization: Release gametes into environment => fertilization o Frogs 10.Human Reproduction 11.Male o Testes (gonads) from abdomen => o At birth move from Inguinal Canal => o Scrotal Sacs o Very weird to carry something so important in such little protective sac. o Temperature is evolutionary advantage. No much evidence o In some species of animals. Sometimes testis only in sacs in mating season o If prostate enlarged, presses against urinary bladder. Increased frequency of urination. o
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This note was uploaded on 11/05/2011 for the course BIOL 101 taught by Professor Hogan during the Fall '08 term at UNC.

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Animal Reproduction - Animal Reproduction & Development...

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