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58 Cards in this Set

  • Front
  • Back
evolution is the process of adaptation and change leading to genetic diversity and new life forms
evolution may be accomplished through
1. natural selection
2. mutation
3. genetic drift
4. genetic shift
evolution is a THEORY
lamarck's inheritance theory of acquired characteristics
concept of use/disuse
-things used extensively(organs) would develop
-those that were not used as much, would lead to atrophy
changes through time associated with use/disuse theory called acquired characteristics
darwins natural selection theory
1. organisms produce offspring, few to which survive to maturity
2. chance variations w/in individuals may be inheritable
-if give slight advantage, deemed favorable
darwins natural selection theory contd
3. individuals with more of these favorable variations are more likely to survive/reproduce
-process known as natural selection
4. over time, separation of traits will form new species
darwins natural selection theory contd
fitness is defined as reproductive success of an individual
-reproductive success linked to relative genetic contribution of individual to next generation
lamarck was proven wrong in theory...
natural selection is mechanism of evolution, not equivalent to evolution
-modern synthesis
differential reproduction
-more favorable mutations passed on while less favorable ones are not
punctuated equilibrium
suggests that changes in species occur in rapid bursts rather than evenly over time
evidence of evolution comes from -paleontology
-comparative anatomy
-comparative embryology
-molecular biology
use of radioactive dating of fossils
-help determine chronological succession of animals
divergence(island species once on mainland, but separated over time,,,develop into new species)
comparative anatomy
comparison of similar structures to determine relatedness
homologous structures
similar in structure and share a common evolutionary origin even if they dont have a similar appearance, shape or form

ex) bats vs humans
both have similar bone structures in wings/arms respectively
analagous structures
structures that serve a common
purpose but evolved separately in each species

ex) birds and insects...both can fly but developed ability to fly independent of one another

vestigial structures
remnants of organs that have lost their ancestral function

ex) appendix
-things not necessary for life
comparative embryology
analyze similarities between embryos of different species
molecular embryology
as species become distant taxonomically speaking, the amt of shared DNA will decrease
when gene frequencies of population are not changing, the gene pool is stable and no evolution occurs..
criteria for this to be true...
1. LARGE population
2. no mutations
3. random mating
4. no migration
5. genes in pool are equally successful at reproducing
hardy-weinberg EQ is when the following criteria mentioned is true
no net evolution
HW equation...
P^2 + 2PQ + Q^2
P + Q = 1
5 agents of microevolution...
1. natural selection
2. mutation
3. assortive mating
4. genetic drift
5. gene flow
natural selection
genotypes favorable are selected
-frequency of selected increases
-more offspring with gene
gene mutations change allele frequencies in population
assortive mating
when mates are selected
-non random mating
-proximity/phenotype driven
genetic drift
changes in the composition of the gene pool due to chance
----founder effect
founder effect = when small population of species finds itself isolated from other populations as a result of natural boundaries
gene flow
occurs from migration of individuals among populations
-loss/gain of genes
-changes gene pool composition
natural selection is the ONLY method capable of generating stable evolutionary changes over long periods of time
occurs through
-stabilizing selection
-directional selection
-disruptive selection
stabilizing selection
elimination of the extremes
-uniform bell curve
-ex) birth weights
directional selection
leads to majority being of one of the extremes
-ex) bell-curve shifted to the right
-EX) pathogen resistance
disruptive selection
both extremes are favored
-ex) males and females...no middle sex
altruistic behavior
-selfless care for the concern of others..
ants have many workers who are sterile and benefit the community through their services
kin selection
suggests that organisms behave altruistically if they are closely related to successfully reproducing organisms

ex) workers are related to the queen ant
inclusive fitness
the number of alleles that an individual passes on to the next generation, even if only indirectly through altruistic behavior
the emergence of a new species

defn: species
-a group of individuals who can interbreed freely with one another but not with members of other species
reproductive isolation
when two populations of same species isolated for long time to the point where they can breed with each other
reproductive isolation can occur prezygotically or postzygotically
prezygotic mechanisms...
prevent formation of zygote completely
postzygotic mechanisms...
allow for gamete fusion, but yield sterile offspring..

horse + donkey = sterile mule
prezygotic isolating mechanisms
1. temporal isolation
2. ecological isolation
3. behavioral isolation
4. reproductive isolation
5. gametic isolation
temporal isolation
time dependent
-species may breed during different times, seasons, day/night
ecological isolation
live in same territory, but different habits

ex) top of tree vs ground level
behavioral isolation
not sexually attracted due to pheromones, appearance, courtship etc
reproductive isolation
parts dont necessarily fit
gametic isolation
sex can occur, but fertilization can not
postzygotic isolating mechanisms
1. hybrid inviability
2. hybrid sterility
3. hybrid breakdown
hybird inviability
aborted hybrid, even if fertilized
-limited ability to mature to adult
hybrid sterility
able to reach maturity, but not capable of reproduction since sterile
hybrid breakdown
1st generation hybrids are viable and fertile

2nd generation hybrid offspring are inviable or infertile

-occurs when closely related but reproductively isolated species introduced
--occurs in plants more than animals
adaptive radiation
when a single ancestral species gives rise to a number of different species

each species diverges to the point that it is able to occupy a unique niche
--this decreases competition among species for food/homes
3 evolutionary patterns exist
1. divergent
2. parallel
3. convergent
convergent evolution
independent development of similar characteristics in two or more lineages not sharing a common ancestor

ex) fish/dolphins both swim in water and look similar, yet have no ancestral connections
divergent evolution
the independent development of dissimilar characteristics in two or more lineages sharing a common ancestor

ex)seals + cats belong to Carnivora, but have separate appearances/environments
parallel evolution
process where related species evolve in similar ways for a long pd of time in response to analogous environmental selection pressures