lecture 2 evidence Flashcards
what are some ways evolution has evidence backing it up
experiment biogeography the fossil record homology, vestigial structures and homoplasy embryology comparative behaviour and biochemistry hierarchical organisation of life
what was the experiment
john endlers guppies
they have variation in the spot patterns that appeara after maturing. and there is i n t e n s e male competition. females prefere the more orange ones
he did some experiments with guppies in encolsures. the ones with predators of adult guppies in had less orange after a few generations, and the ones with predators of junior guppies had increased population of orange guppies. the one that was all guppy was extemely orange bc of selection from the females
so the direct evidence of the experiment is
evolution and change seen in a short time
effect of predation decreases orange colouration in population and the average of orange spotted guppies goes down
how does biogeography provide evidence for evolution
The distribution of animal and plant forms across the world is consistent with our
understanding of evolutionary processes and tectonic plate movements over the life of the earth. For
example, ratites (ostriches, emus and rheas) stem from a common ancestor but were separated when the
continent of Pangaea broke up
how does fossil record provide evidence for evolution
Although the record is incomplete and patchy, fossils provide a direct record of past organisms and can be put into their appropriate time-frame by an understanding of how rock layers stratify. Fossils are more common from aquatic environments due to the nature of their formation, and so gaps are to be expected but are certainly not fatal to the theory of evolution.
how does homology, vestigial structures and homoplasy provide evidence for evolution
Homology is the similarity in form between structures on different species: as they become more distantly related they differ more, but the origins can still clearly be seen, which supports the idea that they have a common ancestor. Vestigial structures similarly provide evidence for common ancestry, but also for the evolutionary process as unnecessary traits are ‘lost’ or reduced. Homoplasy can be seen in structures which have evolved independently but serve similar functions, e.g. insect and bird wings.
eg horses human turtle and seal have similar bones so maybe a common ancestor
how does embryology provide evidence for evolution
Similarities in embryo structure point to common origins across taxonomic groups. E.g. gill slits in embryo vertebrates.
how does comparative behavior and biochemistry provide evidence for evolution
Similarities in traits such as haemoglobin structure can be used to show phylogenetic links between groups. Similarity is lowest between more distantly related
groups – consistent with evolutionary theory.
how does heirachical organisation of life provide evidence for evolution
Phylogenies or trees showing relationships between species, show a
hierarchical structure, with branching and divergence consistent with species having shared origins.
