Other Forces of Evolution

The forces of evolution

1. Natural Selection

2. Mutations

3. Gene flow

4. Genetic Flow

First Slide

Mutation

-heritable change in genetic information

-mutations in gametes are passed to offspring

-changes in DNA → RNA → Proteins → inherited more new alleles

-+variation

-depending on when the mutation separates and what the last common ancestor there was, there will be more similarities

-without mutations, you may go extinct

Gene Flow

Change in allele frequencies that occurs when individuals move into or out of a population

-more genetic diversity and alleles when interbreeding happens

-with time interbreeding creates a mixed party and selective pressures against the new traits creates natural selection

Reproductive Isolation

stopped or no contact between the two populations, reproduce alone

Genetic drift

random change in allele frequencies between generations due to chance

-bottle neck effect

-founder effect

-nothing to do with selective advantage

Bottlenecking effect

-population reducing event that has nothing to do with survival of the fittest

-hurricane or natural disaster

Founder effect

-population founding

-one bug founds whole island in its image

Macroevolutionary Patterns

grand transformations in anatomy, phylogeny, ecology, and behavior taking place in clades

-surviving species such as crocodile

-speciation

-extinction

Speciation

formation of a new species

Extinction

the dying out of an entire species

Background extinction

ongoing extinction caused overtime

Mass extinction

dramatic, probably caused by combination: volcanic eruptions, moving continents, and changing sea levels

End of cretaceous

end of dinosaurs and then start of mammals

Biogeography

the study of where organisms live now and where they and their ancestors lived in the past.

• Patterns in the distribution of living and fossil species tell us how modern organisms evolved from their ancestors

The two patterns

-closely related but different

-distantly related but similar

Closely related but different

-radial adaptation

-common closely related ancestor

-example is the finches

Distantly related but similar

-convergent evolution

-rhea,ostrich,emu

-similar environment can sometimes be a cause of this

• African euphorbia , Mexican/ US cactus, arid climate

Earth age

4.5 billion years old

Fossils form a _____ that ___________

Fossils form a series that trace evolution from ancestors to modern species.

Artodactyl to odontocetes

Homologous structures

structures that are shared by related species and that have been inherited from a common ancestor

-clue to common descent is common structure not function

Analogous structures

body parts that share common function but not structure or origin

-wing of bee (exoskeleton and chitin) vs bird (feather and bone)

Vestigial structures

inherited from ancestors but have lost much or all of their original function due to different selection pressures acting on the descendant.

Embryology

conserved developmental genes (HOX) → common ancestors

All living cells use

information coded in DNA and RNA to carry information from one generation to the next and to direct protein synthesis.

– bacteria, yeasts, plants, fungi, and animals

Homologous protein (molecule)

– cytochrome c (functions in cellular respiration)

• similar versions found in almost all living cells, from

cells in baker’s yeast to cells in humans