How Populations Evolve

Front 1

Darwin

Back 1

-voyage of HMS Beagle

-Galapagos islands

he saw: species immigrated from the mainland, similar to, but different from mainland

-published: "descent with modification"

Front 2

natural selection observations and inferences

Back 2

observations: members of a population differ in inheritable traits, "overproduction" of offspring

inferences: some individuals leave more offspring than others, based on traits/ unequal production of offspring, leads to accumulation of favorable traits over generations

Front 3

important points and misconceptions

Back 3

populations evolve, not individuals

natural selection can only modify heritable traits

evolution is not "goal directed"

Front 4

evolution

Back 4

change in allele frequency in a population over successive generation

-evolution acts on genetic variation

-genetic variation b/t populations, within populations

Front 5

fossils

Back 5

imprints or remains of organisms that lived in the past

Front 6

homology

Back 6

similarity due to common ancestry

Front 7

population

Back 7

group of individuals same species, love in same area and interbreed

Front 8

gene pool

Back 8

total collection of genes in a population at one time

Front 9

what causes genetic variation

Back 9

mutations (change in nucleotide sequence of DNA)

sexual reproduction: independent assortment, crossing over, random fertilization

Front 10

5 mechanisms of evolution

Back 10

1) mutation

2) migration (gene flow)

3) non-random mating (convenience, inbreeding, preferences)

4) genetic drift (bottleneck and founders effect, smaller populations)

5) natural selection

Front 11

bottleneck effect

Back 11

results from natural disasters usually

Front 12

founders effect

Back 12

Amish people have a higher rate of polydactylism

Front 13

genetic drift summary

Back 13

1. important in small populations

2. causes allele frequencies to change at random

3. can lead to a loss of genetic variation

4. can cause harmful alleles to become more common

Front 14

natural selection

Back 14

-occurs because all individuals are not equally likely to reproduce

-higher relative fitness contributes more to the gene pool of the next generation

-acts on phenotype, not the genotype

-only mechanism that consistently leads to adaptive evolution

Front 15

why isn't survival of the fittest not a good explanation of evolution by natural selection

Back 15

just because an organism is surviving doesn't mean it is reproducing

Front 16

modes of natural selection

Back 16

stabilizing selection

directional selection

disruptive selection

Front 17

stabilizing selection

Back 17

favors intermediate phenotype (middle)

ex. birth weight in humans

Front 18

directional selection

Back 18

shift towards one of the extremes

ex. perhaps fire darkened the environment, now darker mice are more camoflauged

Front 19

disruptive selection

Back 19

shift towards both of the extremes

Front 20

sexual selection

Back 20

individuals with certain traits are more likely to obtain mates, leads to sexual dimorphism

Front 21

types of sexual selection

Back 21

intrasexual selection (within): fights displays, harems- when one males gets a lot of females

intersexual selection/mate choice: individuals of one sex are choosy in selecting their mates (good gene hypothesis- female frogs prefer males with long calls)

Front 22

antibiotic resistance

Back 22

antibiotics- drugs that kill infectious microorganisms

-chance mutation leads to resistance

-resistant bacteria have higher fitness

Front 23

what causes antibiotic resistance

Back 23

livestock producers add to animal feed

doctors over prescribe

patients misuse