EEB362H1 Lecture Notes - Lecture 5: Macroevolution, Symplesiomorphy, Sexual Dimorphism
26 Oct 2016
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We finished discussion about 3 theories of evolution. Concluded from last lecture that adaptation has 2 parts: Adaptation is a character that is more functionally efficient i. e. y is better adapted than x if y solves a problem posed by environment e more efficiently than x. Enhances fitness at its point of origin. Not all traits are adaptive: selection can"t solve every problem irrespective of time, evolution of adaptation can be disrupted by a lot of things. Trade-offs (costs vs benefits) in character evolution. Ex: distal end of our radius and ulna very thin and prone to fracture (cid:4666)cost(cid:4667) but allows us to have flexible (cid:498)wrist(cid:499) (cid:4666)benefit(cid:4667: selection and adaptation are slow. Environment always changes faster than organism = mismatch. If they didn"t would be like a lamarckian world. Phylogenetic comparison phylogenetic comparative approach: better to be adaptable than adapted and diversification for every character on tree. Phylogenetic tree shows you evolutionary relationships among taxa but also sequence of origin.
