SBI 3U November 7 th, 2012

 Recall: story of the peppered moths Process whereby the characteristics of a population of organisms change because individuals with certain heritable traits survive specific local environmental conditions and pass on their traits to their offspring

 There must be diversity within a species for natural selection to occur  Look around your own classroom  Individuals do not change during their lifetime, rather the population shifts over time

 Artificial Selection: a plant or animal breeder selects individuals to breed for the desired characteristics he or she wishes to see in the next generation  Ex: dogs  Ex: overpoaching of elephants in the 1970s-80s

What is the key difference between natural selection and artificial selection?

 The Origin of Species by Means of Natural Selection  published in 1859  Did not use the word “evolution” in the original edition of “The Origin of Species”  Word ‘evolution’ implied progress  why might this view be incorrect?

 What is a fossil record?  Ex: animal remains preserved in the Burgess Shale (British Columbia)  some are ancestors of present-day animals, some are extinct

 Fossils from more recent geological periods  more similar to species living today  Fossils appear in chronological order  Changes are slow  Picture of Ostracoderm  Ex: oysters

 Transitional fossils – show intermediary links between groups of organisms. These organisms share characteristics common to two separate groups  Ex: Archaeopteryx  link between reptiles and birds  Archaeopteryx had feathers and first true-flier

 Biogeography: the study of the geographical distribution of species  Populations adapting over time to adjust to the environmental conditions of their new home

 Geographically close environments are more likely to be populated by related species than are locations that are geographically separate  Ex: Australia (marsupials) and New Zealand (flightless birds)  Populations endemic to these islands evolved

 Example: Madagascar  Madagascar  90% of its land birds are endemic to it  Lemurs and monkeys

 Anatomy gives evidence for _________?  Homologous structures: bones have the same origin, but differ in structure and function

 Analogous structures: body parts of organisms that do not have a common evolutionary origin but perform similar functions  Ex: insect and bird wings

 How do analogous structures support natural selection?

 Vestigial structures: structures that were functional in the organism’s ancestors yet have no current function  Ex: ostriches