Evolution

• small changes and short term that occur in populations
• IE antibiotics insecticides

Understandingand application of the mechanisms of evolutionary change to biological problems

organisms never changed

organism changed through time based on acquired characteristics in one’s lifetime passed on

1809- Lamarck

Species change over time

Divergent species share a common ancestor

Mechanism for change is called natural selection

• Certain traits are selected for survival
• Overtime the desirable traits would be seen- natural selection

1850- Darwin and Wallace-

man determines which traits are passed in offspring

• Process by which traits evolve
• Trait more likely for organism to reproduce and survive

Darwin was unable to prove in lab but could give examples in nature

study of genetic variation and causes within populations

Natural variation needs to occur otherwise extinction

Explain patterns/organization of genetic variation

Origin/maintenance of genetic variation

Understand the mechanisms that cause changes in allele frequencies in pops

- relative proportion of alleles, measure genetic variation X1X2 X3

• Allele freq-measured in Mendelian interbreeding pop
• p=2NAA + NAa/(2N)
• q=2Naa + NAa/(2N)

• - how genetic variation is distributed
• X1X1,X1X2, X2X2

• --Shows mathematically genetic variation
• --Genetic makeup will remain same in population remaining the same
• --Useful for predicting the approx genotype freq from it
• allele freq
• --Describes the conditions required for there to be no evolution in a pop

• Random mating
• No mutations in genetic material
• Large population size
• No emigration/immigration
• All genes/alleles have to have equal chance

• -Differential mate selection- nonrandom mating -Mutations occur all the time
• -There are individual that can leave and enter populations- ---gene flow
• -Certainalleles are advantageous and likely passed on in favor of lesser
• -Certain chance events can reduce populations
• ---genetic drift
• ----Populationbottleneck
• ----Prairiechicken-low genetic variation due to man

• --Fitness-how well one phenotype is passed on compared to another phenotype
• --Determined by relative rates of success and reproduction of individuals w/ that phenotype

• - traits closer to the mean are selected for
• IE birth weight

• - traits at an extreme are favored for
• - mean will shift towards it

• - traits at both extremes are favored for
• - bimodal
• IE beak sizes-large for breaking hard seed, small for soft seeds

- characteristics that help either better compete or more attractive for mates

• IEbrighter colors, bigger horns, taller crests
• ---zebra finches bills
• ---male widowbirds long tails

Sexualdimorphism

Thereare benefits and tradeoffs with reproduction

• Neutral allele
• sexual recombination-meiosis
• mutations
• frequency dependent selection- stable polymorphism
• heterozygote advantage
• geographically isolated sub species of a species-clinal

• Breaksup adaptive combinations of genes
• Sex reduces rate at which females pass genes Dividing offspring into separate genders greatly reduces overall rate

• Two forms of the allele
• Butterflies in rockies are tolerant to wider ranges of temp in am/pm

Only alleles already in existence will help in adaptation --

• Development processes
• IEscathes rays- bodies shift to dorso-ventrally compressed to be bottom-dwellers

Trade-offs--TTX resistent