evolution Flashcards
hypothesis
an idea about how observed phenomenon works
theory
an explanation of large bodies of collected data and facts
natural selection
the process by which a selective force causes some individuals in a population to survive and reproduce to a greater degree than others, which can lead to evolutionary change
fitness
the level of ability to survive and reproduce
evolution
a change in genotype frequencies in a population over time
selective force
predator, parasite, abiotic feature
necessary aspects of natural selection to cause the evolution of traits over time
genetic variation
selective force
this causes differential survival that leads to differential reproduction, that some individuals are more successful at reproduction for a reason
leads to genotype frequency alterations in a population
genetic variation
mutation, sexual reproduction
selective force
alteration in background, parasite presence
natural selection generally happens to individuals and evolution happens to populations
natural selection leads to adaptive evolution
adaptation
any trait that makes the organism more likely to survive and reproduce
individuals within populations that have adapted to their environment generally have a higher…
fitness
what is fitness measured in
terms of survival or reproductive success
fecundity
reproductive success is usually measured by counting the number of surviving offspring
divergent evolution
when two species or more evolved from a common ancestor
convergent evolution
similar conditions can cause the evolution of similar traits even in unrelated organism
misconceptions of evolution
evolution is just a theory
individuals evolve
evolution explains the origins of life
organisms evolve on purpose
evidence for evolution
fossils
anatomy and embryology
biogeography
molecular biology
vestigial structures
structures that have no apparent function and are likely due to evolution from an ancestor that had a function for that structure
anatomy and embryology
shared and conserved embryological development
levels of evolution
microevolution and macroevolution
microevolution
changes within a species
pocket mouse coat evolution
macroevolution
formation of a new species from pre-existing species
modern-day species- reproductively isolated from ancestral wolf species
biological species concept
group of populations whose members have potential to interbreed in nature and produce fertile offspring
morphological species concept
defines species by physical traits; doesnt require mating
ecological species concept
defines species by their role within the environment
phylogenetic species concept
any group of organisms that have shared common ancestry, also may use morphology(physical traits)
medical/micro species concept
species, groups of similar organisms within a genus, are designated by biochemical and other phenotypic criteria and by DNA relatedness, which groups strains on the basis of their overall genetic similarity
speciation
how one species become two
- when one group of organisms become isolated and evolves enough to become their own species
speciation
allopatric speciation- different environment
- geographic isolation –> reproductive isolation
sympatric speciation - the same environment
- reproductive isolation–> prezygotic barriers and postzygotic barriers
geographic isolation
allopatric speciation
when two populations are physically separated
speciation ha[[ens gradually
sympatric speciation
when populations live in the same habitat but gene flow has been eliminated through reproductive isolation
reproductive isolation
when two populations are no longer able to reproduce with each other
causes rapid speciation
can be broken up into prezygotic barrier and postzygotic barriers
prezygotic barriers
mating behavioral differences
breeding at different times
live indifferent habits
mechanical isolation
gametic isolation
postzygotic barriers
hybrids- offspring between populations cannot survive or are not able to reproduce
hybrid zones
regions in which two species have the opportunity meet, mate, and produce some offspring
reinforcement
fusion
stability
reinforcement
when hybrids are less fit than parental species -maintains species
fusion
when hybrids are more fit than parental species causing two species to fuse into one
stability
when hybrids continue to be produced and are maintained
equilibrium
population does not change with regard to the trait in question
such as coat color and beak size
allele vs locus
an allele is the type of gene
and locus is the location on the chromosome
who discovered dominance
Gregor Mendel and monk
what did the four men do
their work laid down the foundations of evolutionary biology which led huxley to his book on evolution
evolution
occurs when genotype frequencies change over time in a population
what does population genetics investigate
how the genotype frequencies in an offspring population are related to the genotype frequencies in a parental population
null model
tells us what happens when evolutionary change is not occurring
if in HW equilibria then…
frequencies a1 and a2 do not change over time
given allele frequencies and random mating, we can predict the equilibrium genotype frequencies in a population in which evolutionary processes are not acting(h-w equilibrium frequencies)
if no evolutionary processes are operating, a locus that is initially not at hw equilibrium will reach hw equilibrium in a single generation
assumption of hw equilibria
natural selection is not operating on the traits affected by the locus in question
individuals have no preferences for each other(random mating) with respect to the locus in question
no mutation is occurring
no migration in/out of populations
population size is infinite, so that fluctuations in allele frequencies are negligible(genetic drift is not occurring)
what are the four mechanisms by which populations can evolve
genetic drift
migration
mutation
natural(sexual) selection (splits into different sections)
what are the sub-types of natural selection
frequency-dependent
directional
stabilizing
diversifying
genetic drift
the tendency for sampling error among genes in small populations
fixation–> entire population has one allele
what causes bottleneck population
earthquakes, tsunamis/ chance events
migration
tends to homogenize populations but asymmetry can occur
natural selection and sexual selection
natural selection is when a selective force causes the alteration in genotype frequencies within a population
sexual selection is a form of natural selection, where the selective force is either choice in mates or competition for mates
what are the two sections of sexual selection
intrasexual and intersexual
intrasexual
competition between members of the same sex
intersexual
choice in one sex for mates in the opposite sex
stabilizing selection
genetic diversity decreases as the population stabilizes on a particular trait/ favors an average phenotype and selects against extreme variations
directional selection
a single phenotype is favored causing the allele frequency to continuously shift in one direction
diversifying selection
frequency-dependent selection
red queen hypothesis
parasites limit the proliferation of asexual lineages
especially if parasites can evolve to be efficient at infecting common genotypes
asexually reproducing lineages have limited capability in generating genetic diversity
