-Evidence for Evolution Notes-
I. Fossil Record
A. The fossil record is all fossils that have been collected over time
B. Organisms have changed over time according to fossil record
1. Evolution is gradual change in organisms over time.
II. Comparative Anatomy
A. Basic body plans can be compared
1. Fish, amphibians, reptiles, birds, and mammals- similar internal skeleton and backbone- “Vertebrates”
2. Presumably, All 5 groups inherited these similarities from an early common, ancestor
B. Homologous Structures- structures that related species have inherited from a common ancestor
1. dolphin flipper, dog’s leg, bird’s wing- all bones are arranged in a similar way
C. Vestigial Structures- reduced forms of functional structures inherited from a common ancestor.
1. Evolutionary theory predicts that features of ancestors that no longer have a function for that species over time will become smaller until they are lost.
(ex. Snake pelvis, human appendix, kiwi wings)
D. Analogous Structures – structures that can be used for the same function and can be superficially similar, but not inherited from a common ancestor. (ex. Wing of an eagle, and wing of a beetle)
III. Similarities in Early Development
A. Organisms have similarities in embryonic development
1. Chickens, turtles, rats all have tails and gill slits- suggests that vertebrates share a common ancestor.
IV. Similarities in Biochemistry
A. DNA is hereditary material- organisms closely related would have similar DNA
1. DNA analysis shows common ancestory
a. ex. elephant shrew more similarities in DNA to elephants, not rodents
B. DNA shows more reliable evidence of common
ancestory than similarities in body structure or early development
- Geographic Distribution- distribution of plants and animals around world. Organisms in a particular area are more likely to share a common ancestor.
(ex. Mara- same niche as English rabbit, but more closely related to S. Amer. Animals than rabbit because they shared a common ancestor)
VI. Adaptation- trait shaped by natural selection that increases an organism’s reproductive success.
(ex. Finches of Galapagos adapted to individual islands, creating variation of beaks, antimicrobial resistance of bacteria to antibiotics)
VII. Combining the Evidence-
A.Scientists combine all types of evidence for evolution to determine relationships- fossil, similarities in body structure and early development, and DNA!!
B. Phylogenetic tree- diagram that shows how scientists think different groups of organisms are related based on evidence.