ZOO 206

• -derived recent trait
• ex.

• -shared derived traits between lineages
• -all synapomorphies are homologous but not all homologies are synapomorphies

ex. Mitochondria is a synapomorphy for all eukarya but not for humans/chimps

-Genetic code (DNA, RNA, ribosomes, transcription/translation, proteins)-metabolic pathways-membrane

• -Same trait in different group but it's not due to common ancestry
• ex. crocodile and hippopotamus have eyes on top of their head

• -No Mutation
• -No Selection
• -No Migration
• -No chance events
• -Random Mating
• Violation of the assumptions results in evolution!

1.) allele frequencies in a population will not change throughout generations

2.) if allele frequencies are given by p and q, then the genotype frequencies will be given by p², 2pq, and q².

S: categorizing that reflects evolutionary history

T: categorizing/naming

• -the maintenance of 2 alleles in a population if each allele is advantageous when it is rare
• -fitness depends on the commonality of the genotype
• ex. elderflower orchids: the less common color has higher fitness because it recieves the most visits from pollinators.

• -heterozygotes have higher fitness than either homozygote.
• -lethal alleles in heterozygotes have selective advantage at equilibrium because disadvantages, like in lethal homozygotes, are balanced.

Empirical evidence that natural selection can cause change in allele frequencies.

When ethanol was added to their food, the allele that allowed for quick breakdown of ADH rapidly increased and gave the flies greater fitness.

-Malaria/sickle cell (overdominance) (SS, Ss, ss)

• -V and L alleles in fruit flies
• (L is lethal, homozygous L individuals die)

• ex. Kuru/Fore population had prion (PrP) disease from cannibalism
• -resulted in wrong folding of cells and brain shrinkage/spongiform encephalopathy (?)
• -survivors had strong selection for heterozygote

ex. lethal alleles in flour beetles

• -alone, mutation is a weak evolutionary force and it's changes are not evident in the population until much later.
• -normal mutation rate 1/10,000
• -important when combined w/ selection

def: movement of alleles b/n populations(gene flow/dispersal/colonization)

ex.Water snakes in Lake Erie (King)

• -Random change in allele frequencies
• -Sampling error=chance difference b/n allele freq. in subset population vs. whole population
• ex. founder effect and bottleneck are chance events

• Clegg Study: Colonization of Silvereyes from Australia/Tasmania
• -steady decline in allelic diversity
• -furthest island had <.5 of mainland

ex2. identical immune alleles in cheetahs

• -example of founder effect/drift
• -isolated human population (3,000) with high frequency of achromatopsia allele due to chance
• -loss of function of cone cell protein=color blindness/poor vision/sensitivity