Evidence for Natural Selection

Patterns There are 4 main patterns for natural selection Two are directly tied to speciation rate Gradualism—happens slowly (millions to billions of years) Punctuated equilibrium—happens fast with long periods of stability The other two are mostly used for comparing why organisms are the way they are. Divergent evolution—differentiation from a single species A specific type of divergent evolution would be adaptive radiation Convergent evolution—developing something similar because of a need and not a common ancestor.

6 types of accepted evidence for evolution. Structural adaptation This is going to be an actual change in physical appearance Usually happens slow (gradualism) Ex: mimicry and camouflage Physiological adaptations This is going to be a change in physiology (how the body works) Usually happens relatively quickly Ex: bacteria resistant to antibiotics

Fossils Provide a record of early life and evolutionary history The record while helpful is incomplete Anatomy Anatomy is the structure and function of physical parts Homologous structure Structure with common evolutionary origin, similar in arrangement, function, or both Analogous structures Structures that serve the same purpose but do not share an evolutionary origin. Vestigial structures A structure that in present day no longer serves a purpose but is there because it was useful to an ancestor.

Embryology Biochemistry Embryo is the earliest stage of growth and development of an organism When comparing how all organisms look in the beginning of an embryo to the end the similarities cause scientists to believe that all organisms are related. Biochemistry All the tiny parts that make up life such as DNA, ATP, RNA, enzymes, proteins, etc. Because all life has this and they are all roughly the same shape and type scientists think it is strong evidence for all living organism to be related in some way.