Biology 1001A Lecture Notes - Lecture 11: Plant Reproductive Morphology, Dioecy, Genetic Recombination
Document Summary
Sex conjures up ideas about copulation, reproduction, males and females: mutation creates new alleles, sexual reproduction creates new combination of alleles over multiple different loci. Sex, recombination, genetic diversity: reproducing sexually generates new multilocus combination of alleles, ex: ab, ab, ab, ab, offspring genetically distinct from either parents and (usually) from each other. Size-advantage model of sex change: protandry: m -> f. If females gain a little by being larger: make sense to be born as a female, reach threshold body size -> switch to male, biggest female will turn into male. Non-hermaphrodites also need to balance male and female function: adaptive sex ration manipulation, temperature determination, ex: turtle, x, y determination, ex: mammals, z, w determination, ex : birds. The first cells, and the first eukaryotes, reproduced asexually: asexually reproduction is older, most living thing -> asexual, most plants and animas -> sexual, asexual species of animals are rare and extinction-prone.
