Biology Chapter 2 - Evolution of Populations

what is a population?

group of animals usually form the same species

what does a population consist of?

individuals with slightly varying characteristics

A population is composed of _____ alleles

multiple

_______ will have an impact on specific alleles

time and location

________ will select for best alleles in the population

natural selection

During a drought, birds with larger beaks can eat larger seeds but smaller birds will….

die out

if large beaks are better for survival…

those alleles will be selected over several generations

evolution is a change in the….

population

an individual is unable to change his beak shape….

during its lifetime

alleles are selected over…

several generations

adaptation occurs over time with…

every generation, in that environment, at that time

microevolution

a change in allele frequencies in a
population over generations

microevolution is evolution on its…

smallest scale

larger beaks alleles increased over time due to…

more diverse range of food

natural selection causes allele frequencies to…

change over time

allele frequencies change every….

generation

new alleles result from…

random mutations

new patterns are created and passed on to…

offspring

allele frequency changes (3 main mechanisms)

natural selection, gene flow, and genetic drift

natural selection as allele frequency changes

consistently selects best adapted individuals

gene flow as allele frequency changes

transfer of alleles between populations

genetic drift as allele frequency changes

chance events that alter allele frequency (bottle neck effect and founder effect)

gene flow definition

process of alleles going from one population to another

genetic drift definition

alteration of allele frequency in a gene pool

gene flow cause of gene alteration

migration or geographical isolation

gene flow cause of gene alteration

random sampling with two mechanisms (bottle effect or founder effect)

gene flow cause of movement

founder effect

founder effect

breaking away of a few members and forming their own group

genetic drift cause of movement

transferring of organisms to an already existing population

gene flow alterative names

gene migration and allele flow

genetic drift alternative names

allelic drift and sewall wright effect

gene flow chances of genetic variation

most likely ensures genetic variation

genetic drift chances of genetic variation

less likely ensures genetic variation as it is mainly due to luck

gene flow is caused by ____ or _____

migration, geographical isolation

gene flow’s new mutations are shared…

between populations

gene pool

collection of all the different genes within a population

genetic drift is the variation in…

the relative frequency of different genotypes in a small population

genetic drift is owing to the chance ___of particular genes as individuals die or do not reproduce

disappearance

major event causing gene migration/flow

transfer of alleles in and out of gene pools

major event causing genetic drift

alteration of allele frequencies of a population due to random sampling

genetic drift is essentially…

a chance event

mechanisms of evolution so far

mutation, gene flow, genetic drift, and natural selection

genetic variation

differences among individuals in the composition of their genes or other DNA sequences

alleles represent _____ of specific genes

variations

genetic variability is quantified as the average….

percentage of loci that are heterozygous

heterozygous has ______ alleles for a given locus

two different

nucleotide variability

variations result in little phenotypic variation

variations result in little _____ variation

phenotypic

why do variations result in little phenotypic variation?

many of the nucleotide variations occur within introns

nonheritable variation

phenotypic variation does not result from genetic differences
among individuals

nonheritable variation difference example

what an animal eats leads it to turning into a different color

you look like what you eat =

camouflage

phenotype is the product of…

an inherited genotype and many environmental
influences

_______ of phenotypic variation can have evolutionary consequences

only the genetically determined part

_________ provides the raw material for evolutionary change

genetic variation

without genetic variation,…

evolution cannot occur

________, evolution cannot occur

without genetic variation

genetic variation originates from…

mutations, gene duplication, etc.

results of genetic variation are…

new alleles and new genes

genetic variation can be produced rapidly by…

organisms with short generation times

sexual reproduction

existing genes can be arranged in new ways

mutation

a change in the nucleotide sequence in DNA

errors in dna replication are caused by..

UV light, radiation, or chemicals

point mutation

one base change in a gene

new mutations are usually ______

slightly harmful

in many cases, ______ are hidden from selection

harmful recessive genes

diploid genes can ____ recessive genes

mask

allele frequency

refers to how common an allele is in a population

allele frequency equation

number of alleles in a population / total number of copies of genes

harmful mutations

non-adaptive and eliminated by selection

beneficial mutuations

adaptive, selected and persist

neutral mutations

neither adaptive or non-adaptive, may or may not persist in gene pool

dna →

rna

rna →

protein

dna → rna

transcription

rna → protein

translation

chromosomal changes that delete, disrupt, or rearrange…

many loci are usually harmful

chromosomal changes that _______ many loci are usually harmful

delete, disrupt, or rearrange

genes are left intact →

phenotypes may be unchanged

chromosomal rearrangements…

may link genes in a way that produces a positive effect

duplication of genes in small segments can…

accumulate

rapid reproduction has ___ mutation rates

low

rapid reproduction average mutations per generation

1/100,000

mutations stack up _____ in a population

quickly

HIV has an _____ genome

RNA

an RNA genome has a _____ mutation rate than DNA

higher

in virus mutations, ______ treatments are ineffective

single drug

in virus mutations, _____ are more efficient

cocktails

sexual reproduction genetic variation

occurs from the unique combination of alleles that each individual receives from its parents

sexual reproduction alleles resulted from…

past mutations

reproduction shuffles….

existing alleles and deals them at random to produce individual genotypes

genetic shuffling causes

crossing over, independent assortment of chromosomes, and fertilization.

genetic shuffling and fertilization

brings together gametes that have different genetic backgrounds

endless possible combinations of ______ based on the
______ formed

phenotypes, genotypes