Evolutionary Mechanisms Part 2 Flashcards
microevolution
change in a population!
macroevolution
speciation
-extinction of dinosaurs
mutation
- only mechanisms that produce new alleles
- random but natural selection edits them
quantitative
- traits on a continuum
- ex. height and weight
qualitative
- yes/no traits
- either you have it or you don’t
- dimples, albinism, widow’s peak
natural selection
differential survival and reproduction of individuals in a population based on heritable variations in their phenotypes
gene
a section of DNA that codes for a trait
phenotype
observable traits
genotype
genetic make-up
allele
versions of a gene
gene pool
all genetic information within a population
recessive
allele masked by a dominant gene
dominant
allele that if inherited, is always expressed
population
all individuals of a single species that live together in one place and time
species
group that can potentially interbreed and produce viable offspring
mechanisms of evolution
- mutations
- gene flow
- genetic drift
- natural selection
- nonrandom mating (sexual selection and artificial selection
Genetic drift
a totally random event that causes the allele frequency in a population to change unpredictably
genetic drift key point:
- totally random:as opposed to natural selection, which is not random
- although genetic drift is an evolutionary mechanism it doesn’t produce adaptation
- reduces genetic variation
- the fewer copies of an allele present in a population (the more rare the alleles) then the greater effect genetic drift will have
True or false:
small population size means the loss of just a small number of alleles means the loss of a large amount in diversity
true
circumstances in genetic drift
- founder effect
- bottleneck effect
population bottleneck
when the population goes through a huge change that drastically reduces population, there will be a change in the frequency of alleles
-caused by catastrophes, manmade or natural
founder effect
a special type of bottleneck when a small number of a population splinter off
-can be a driving force in development of new species
gene flow
- the movement of alleles from one population to another
- new genes flow into existing populations
- migration
- pollen dispersal
- one population becomes 2 populations
- natural barriers
- manmade barriers
cladogenesis
evolution that results in the splitting of a lineage
anagenesis
evolution within a lineage
speciation
the generation of a reproductively isolated species
artificial selection
- when humans mess with nature
- humans breeding certain plants or animals for certain traits
- domesticity, food production, size, type
- bred for work
inbreeding
breeding of related organisms, tends to multiply recessive
out crossing
breeding of completely unrelated organisms
line breeding
milder form of inbreeding, a fluid term depending on species
hybrid vigor
strength in selective outcrossing
sexual selection
non random mating
hermaphrodite
both sexes in one organism
gender
the behavior, appearance, and life history of a sexed body
sex
refers to size of the gametes.
- male sperm=small
- female egg= big
sexual dimorphism
distinct difference in size or appearance between the sexes of an animal in addition to difference between the sexual organs themselves
why do organisms have sex?
- facilitates sharing
- is used for reconciliation of disputes
- helps integrate new members to a society
- used to form coalitions
- is a commodity that can be traded
- used for reproducing
how does sex benefit organisms?
- maintains variability in a population
- DNA repair
- allows for mutation which leads to variations like crossing over, independent assortment, and sexual reproduction
2 ways sexual selection is mediated
- intrasexual selection
- intersexual selection
intrasexual selection
- fight each other, within one sex
- sperm competition to make more sperm
- prolonged copulation: stay hooked to females so no other male can get access
- sperm is cheap and eggs are to take care of
- females can be choosy
intersexual selection
interaction between sexes
infanticide
kill the other males’ offspring
copulatory plugs
plug females to prevent other males from copulating
alternative strategies to doing it
- small males sneak in and deposit sperm
- males will act like and/or look like a female to sneak past other males
hypotheses for choosy females
- sexy son hypothesis: they want their sons to be good looking
- good gene hypothesis: their offspring will have a better chance at survival and reproducing
