BIOB38H3 Lecture Notes - Lecture 2: Wild Type, Abscission, Outcrossing
27 Oct 2016
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Natural selection: happens on all organisms, selection by the environment, no purpose of goal. Artificial selection: on cultivated plants and animals, selection by humans, has a purpose or goal, do(cid:373)esti(cid:272)ated ra(cid:272)es sho(cid:449) adaptatio(cid:374), (cid:374)ot i(cid:374)deed to the a(cid:374)i(cid:373)al"s or pla(cid:374)t"s o(cid:449)(cid:374) good, (cid:271)ut to (cid:373)a(cid:374)"s use or fa(cid:374)(cid:272)(cid:455) (cid:894)charles dar(cid:449)i(cid:374)(cid:895) Altered plant traits: reduction of seed dispersal. Without seed dispersal adaptations, most seeds/fruits are deposited close to the mother plant: lead to competition. Grass architecture: spikelets (seeds) are attached to the ranchis, wild type plants shatter (disperse seeds) and leaves a smooth edge at the spikelet. Non-shattering mutant: two genes that control shattering (naturally occurring recessive mutations, early farmers slowly selected non-shattering genotypes, characterized by absence of abscission layer at spikelet base. Impact of sickles selects for tough ranchis (all brittle ones lose their seeds due to the force of impact)
