Biological Basis of Life

Biological Basis of Life - Asexual reproduction, called...

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Asexual reproduction, called parthenogenesis (where an unfertilized egg develops into a new individual) is rare among multicellular organism. Asexual populations can reproduce at double the rate of sexual ones. Those that do clone usually do so in addition to sexual reproduction (heterogamy). Asexual reproduction is far more common in plants than animals and many plants, like these dandelions, can reproduce either sexually or asexually. Sexual reproduction is the norm among virtually all higher order organisms. It involves many costs, which are risky to lose their life (female praying mantis eat male praying mantis after sexual reproduction) and STD. Main benefit: increases variation (different from 1 another/not look alike) among offspring (asexual organisms are vulnerable to pathogens and parasites). It’s longer to produce the egg (female) than sperm (male). Hermaphroditic species like the Banana Slug, Ariolimax dolichophallus, prefer to self-fertilization. Sexual cannibalism is paying the price (eat one of the species after reproduction). 3 species where sexual cannibalism is common: praying mantises, horned nudibranchs, and red back spiders. Male is extendable and female is more important than male. The red queen theory: Even species that appear to be stable are engaged in a continual evolutionary arms race with those species around them. Sex may produce an advantage for animals in this race because it makes it harder for parasites and pathogens to adapt to them. Mutualism = both benefit each other Males and females have different gametes (reproductive cells). Male gametes (sperm) are smaller, more mobile and more numerous; female (eggs) are larger and rarer. The nature of gametes determines which sex an individual is. Zigote = fertilized eggs from female to male. A pregnant male Pygmy Seahorse, Hippocampus bargibanti, has offspring to develop in the
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This note was uploaded on 05/25/2011 for the course ANTH 1 taught by Professor Jenny during the Fall '10 term at East Los Angeles College.

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Biological Basis of Life - Asexual reproduction, called...

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