quiz 1 ch 4 Flashcards
Charles Drawin
went on a journey around the world which convinced him that various populations evolve from ancestral form.
theory of evolution by natural selection states:
organisms give rise to live organisms.
chance variation btwn individuals that are heritable.
more offspring will be produced each generation that survives.
some individuals have higher chance of survival tan others in the same population.
evolution
change in allele frequency in population over time
variation within a population
phenotypic variation among individuals in population is a result of combined effects of genes environment
ecotype
subspecies or race adapted to certain set of environmental conditions
Gregor Mendel
discovered that characteristics pass from parent to offspring in form of discrete pockets (genes)
*phenotypic plasticity
variation in phenotype due to different environment
Hardy Weinberg Equilibrium states
in population there is random mating and an absence of evolutionary forces causing allele frequency to remain constant from generation to generation
gene pool
sum of alleles in a population
allele frequency
related proportions of 2 alleles
genetic frequency
proportion of genotypes of an individual organism
phenotypic frequency
relative proportions of traits
p+q=1
sum of all alleles in a population
p^2+2pq+q^2=1
genotypic proportions
conditions for H-W equilibrium*
random mating.
no mating.
large population size = no genetic drift.
no immigration/emigration = no gene flow.
equitable fitness btwn all genotypes = no NS.
~1 will not be met and allele frequency changes.
non random change due to natural selection
natural selection can favor, disfavor, or conserve genetic makeup of a population.
by stabilizing selection, directional selection, or disruptive selection
stabilizing selection
intermediate forms are favored and extremes eliminated.
does not result in evolutionary change and preserve average.
ex: human infant birth weight.
directional selection
change phenotype to favor extreme phenotype over others.
lead to evolutionary change.
ex: antibiotic resistance in bacteria
disruptive selection
bimodal distribution by favoring 2 or more extreme phenotypes over average in population.
ex: seed cracker finches in Africa
change due to chance
random process;
genetic drift changes gene frequencies especially in small populations
concern of habitat fragmentation
reduces habitat availability to where genetic drift reduces genetic diversity in natural population.
endemic
not found anywhere else
inbreeding in small population leads to
high extinction rates
inbreeding leads to
reduced fecundity.
depressed juvenile survival.
shorten life span.
case study: variation in plant populations
hypothesis
evidence of genetic adaptation by ecotype to local environmental conditions of 3 clones from common gardens at 3 elevations at (lowland, midland, and alpine).
if there is no genetic difference then they wold grow equally as well
case study: variation in plant populations
result
did not support hypothesis.
different ecotypes = diff genotypes even if they were genetically identical.
case study: variation in animal populations (chuckwalla)
hypothesis
genetic variation of young when they grow in regions with different elevation and rainfall
case study: variation in animal populations (lizard)
results
raised in common garden experiment with controlled variables at different elevation.
lizards at higher elevation grew larger because the increased rainfall leading to more food for young.
case study: adaptive change in island colonizing lizards
hypothesis
physical change in hind limbs depending on vegetation once they are translocated
case study: adaptive change in island colonizing lizards
results
less morphological change in hind limbs in areas where vegetation is the same to OG island.
greater morphological change in areas with new vegetation
case study: rapid adaptation by soapberry bugs
hypothesis
document adaptations of herbivore beak length to the distance from fruit walls to seeds vary to see if there are any genetic differences in populations or by chemical factors for host plants
case study: rapid adaptation by soapberry bugs
result
raised juvenile on alt host plants and they maintained beak length
case study genetic drift in chihuahua spruce
hypothesis
did population lose its genetic diversity after the glacial Pleistocene; looked at diversity of enzymes for 24 genes
case study genetic drift in chihuahua spruce
result
there was a population size and diversity, smaller populations = low heterozygosity than larger populations
case study: genetic variation in island populations
hypothesis
look at genetic variation in animal and plant populations of an island and the mainland
case study: genetic variation in island populations
result
genetic variation was lower in isolated and smaller island populations that are endemic.
indicates low potential for population to evolve
isolated areas
less genetic variation = less variation for NS to act on
case study: Glanville fritillary butterflies
hypothesis
inbreeding of 42 heterozygous populations in patchy environments
case study: Glanville fritillary butterflies
results
higher inbreeding (low heterozygosity) had higher probability of extinction due to few offspring with lower survival rate
natural selection*
heritable characteristics that are favorable and give an advantage.
allows for variation in a population.
gives a higher chance of survival and reproduction at an individual level.
