BIOL 2001 Lecture Notes - Lecture 1: Cambrian Explosion, Ernst Haeckel, Synapomorphy
12 Nov 2018
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Homologous structures: have similar morphology, embryology and anatomy etc. but are dissimilar in their functions. Analogous structures: structures in different species which perform the same function, have similar appearance and structure but are not evolved together; therefore do not share a common ancestor. Possible rst appearance of early forms of molluscs, arthropods, and echinoderms, but this is still under debate. Three sources of phylogenetic information (ways of knowing how characters vary): The developmental history of an organism from fertilization to gestation or hatching. A derived character that is shared by members of a clade. Recapitulation theory: (by ernst haeckel) hypothesis that the development of the embryo of an animal, from fertilization to gestation or hatching (ontogeny), goes through stages resembling successive stages in the evolution of the animal"s remote ancestors. Includes the most recent common ancestor and all descendants of that ancestor.
