Biology 2483A Lecture Notes - Lecture 1: Carcinus Maenas, Intertidal Zone, Appledore Island

• School: Western University
• Department: Biology
• Course: Biology 2483A
• Professor: Sheila Macfie

Document Summary

Flat periwinkle lives on seaweed on shores of intertidal zone. Histograms graphical distribution of data for a variable showing frequencies of values occurring in a population. Distribution a(cid:396)(cid:396)a(cid:374)ge(cid:373)e(cid:374)t of a (cid:448)a(cid:396)ia(cid:271)le"s (cid:448)alues that i(cid:374)di(cid:272)ate thei(cid:396) f(cid:396)e(cid:395)ue(cid:374)(cid:272)y of occurrence. Populatio(cid:374) i(cid:374) (cid:1005)(cid:1013)(cid:1012)(cid:1004)"s had the larger average of shell thickness (thicker shells) Population in 1971 had larger range from 1 to 13. With no differential survival, thin-shelled and thick-shelled snails disappear randomly and thickness is no longer a component towards snail survivability. Darwin: if a population contains, variation for some trait and, variation is partly heritable (due to differences in genes inherited by parents) When all three are in effect, we see evolution shifted towards thicker shells: Hypothesis of seeley flat pe(cid:396)i(cid:449)i(cid:374)kles of appledo(cid:396)e isla(cid:374)d e(cid:448)ol(cid:448)ed a(cid:272)(cid:272)o(cid:396)di(cid:374)g to da(cid:396)(cid:449)i(cid:374)"s theo(cid:396)y of. In lab offered 8 crabs thin-shelled snails, ave. time was 42 seconds to eat them.