Selection causes Microevolution Frequency of alleles (versions of a gene) changes in a population

Selection creates Adaptations Traits common to all members of a population Confer greater success

Selection can lead to Macroevolution Populations no longer interbreed Become more different over long periods of time micro macro Change on a grand scale

Selection can lead to Macroevolution = different species

Ensatina salamanders Inhabit the CA coast, and Sierra foothills, but not the hot, dry Central Valley From Microevolution to Macroevolution Geographic Isolation

Geographic isolation causes Reproductive isolation Interbreed Do not interbreed Functionally separate species

Species? Organisms that interbreed, producing viable, fertile, offspring A mule is neither horse nor donkey The evolution of a species is called speciation

Geographic isolation causes Reproductive isolation

Geographic isolation causes Reproductive isolation

Geographic isolation causes Reproductive isolation Grand Canyon

Other factors also cause Reproductive isolation Sexual selection

Other factors also cause Reproductive isolation Behavior Timing Lay eggs in green (early) fruit Lay eggs later, in ripe fruit Mature at different times, reproductively isolated

Once isolated, the populations become less and less alike Yes, via selection but also via unique genetic mutations Random mutation creates green phenotype

Once isolated, the populations become less and less alike Random chance event causing changes in allele frequencies Yes, via selection but also via genetic drift random changes, not directed

Genetic drift Most apparent in small populations Net loss of variation/diversity Ex: bottleneck event 20 Northern Elephant Seals 30,000 today Of 24 genes studied no allelic variation Hunted population

Genetic drift Ex: founders effect Small founding population with less genetic variation than the original During a Caribbean hurricane, Green iguanas are rafted to Anguilla from Guadeloupe

Gene Flow causes change (aka evolution) too Movement of genes - via individuals or gametes - between populations pollination spreads sperm

Gene Flow causes change (aka evolution) too Movement of genes, via individuals or gametes between populations immigration emigration More or less alike in time?

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Which type of event explains the high incidence of polydactylism found in the Amish population? Bottleneck, Gene Flow or Founder Effect? Founder Effect

Flower population: ww = white flower; WW and Ww = purple flower; a mud slide wipes out most of the white flowered plants. What type of event occurred? Bottleneck, Gene Flow or Founder Effect? Bottleneck

Genetic modifications from transgenic plants passed to neighboring populations of wild relatives. What type of event occurred? Bottleneck, Gene Flow or Founder Effect? Gene Flow

Millions of greater prairie chickens once lived on the prairies of Illinois. As these prairies were converted to farmland and other uses during the 19 th and 20 th century, the number of greater prairie chickens plummeted to less than 50 individuals. The few survivors have low levels of genetic variation. What type of event occurred? Bottleneck, Gene Flow or Founder Effect? Bottleneck

This event resulted in the world wide spread of several insecitcide-resistance alleles in the mosquito Cluex pipiens, a vector for West Nile virus and Malaria. What type of event occurred? Bottleneck, Gene Flow, or Founder Effect? Gene Flow

A few weeks after two major hurricanes swept through the Caribbean islands, fishermen on the island of The allele frequencies for the founding population on Anguilla differed from those on Guadeloupe. What type of event occurred? Bottleneck, Gene Flow or Founder Effect? Founder Effect