BSsqans-lect21 fishes

BSsqans-lect21 fishes - BIS 1B(Winter 2008 Study question...

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BIS 1B (Winter 2008) Study question answers: Fishes Lecture 21 1. How do you account for the fact that there are more species of fishes than of any other group of vertebrates? They are the first of the major chordate lineages to initially diversify into the marine environments, followed by diversification into fresh water habitats. They ecologically preoccupy these major ecosystems. Fresh water ecosystems offer frequent geographic isolation mechanisms to aquatic organisms causing spatial separation of populations and encouraging subsequent speciation events. Clades thus formed may successfully re-invade the marine environment equipped with new competitive advantages enriching the diversity of marine fishes. 2. What do you think are the two most important innovations developed by the Gnathostome fishes and other "higher" vertebrates? Why did you choose the two traits you did? Paired fins and lungs (in the sense of lung fish). These two characteristics are found in one form or another in all subsequent lineages and are only lost in a few relatively highly derived taxa. Other possibilities exist and can be defended. 3.
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This note was uploaded on 04/07/2010 for the course BIS 2 taught by Professor Schwartzandkeen during the Fall '09 term at UC Davis.

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BSsqans-lect21 fishes - BIS 1B(Winter 2008 Study question...

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