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evolution
change in organisms over time
lamarck
french guy that proposed evolution resulted from inheritance of acquired characteristics
adaptation
evolutionary process; organism gets better to live somewhere
natural selection
organisms w/ certain traits live longer and have sex more
artificial selection
selective breeding to get better traits
descent w/ modification
species descended and changed from other species
homologous
organisms that are similar bc of shared ancestry
vestigial structure
feature that got worse over time
analogous
similar traits but no shared ancestry (convergent evolution)
convergent evolution
unrelated organisms evolved similarly bc of environment
biogeography
study of past and present geographic distribution of organisms
endemic
native/confined to region
phylogeny
evolutionary history of species or group of related species
binomial nomenclature
genus name (capitalized) species name (lowercase)
genus
similar, closely related species
species
similar living organisms that can reproduce
classification systen
domain, kingdom, phylum, class, order, family, genus, species
linnaeus
swedish guy who proposed biological nomenclature
phylogenetic tree
diagram showing evolutionary relationships of organisms w/ common ancestor
taxa
level of organization organisms are classified into
rooted tree
branch to show most common ancestor of all taxa in tree
cladistics
organisms placed into clades based on common descent
clade
group of species including ancestral species and all descendants
outgroup
taxon that diverged prior to main taxa
maximum parsimony
when considering multiple explanations for observation, first look at simplest one consistent with facts
3 domains
archaea, bacteria, eukarya
genetic variation
differences among individuals in their genes or other DNA
gene pool
all genes in a population
hardy-weinberg equilibrium
condition describing a non-evolving population (in genetic equilibrium)
genetic drift
change in allele frequency of population as result of chance events
founder effect
genetic drift that happens when few individuals separate from population and make a new population
bottleneck effect
genetic drift that happens when a population is reduced greatly (normally natural disaster) and new population is genetically different
adaptive evolution
increase in frequency of good alleles; decrease in bad alleles
gene flow
movement of alleles into/out of population due to migration of individuals to/out of population
fitness
ability of an organism to survive and reproduce
direction selection
natural selection where individuals at one end of phenotypic range have better fitness
disruptive selection
natural selection where individuals at upper and lower ends of curve have better fitness
stabilizing selection
natural selection where individuals in middle of curve have better fitness
sexual selection
natural selection where individuals with certain phenotypic traits more likely to reproduce
biological species concept
species are groups of interbreeding natural populations that are reproductively isolated from other such groups
reproductive isolation
separation of species/population so they cannot interbreed and have fertile offspring
hybrids
offspring of parents that differ in genetic traits. parents may be different species, genera, or families
prezygotic barriers
barriers that prevent the hybrid zygote from forming at all
postzygotic barriers
barriers that prevent the hybrid zygote from becoming a fertile adult (may die early, be weak, or be sterile)
allopatric speciation
formation of new species in population that are geographically isolated from one another
sympatric speciation
formation of new species in populations that live in the same geographic area
parapatric speciation
speciation within population where subpopulations are reproductively isolated
speciation
formation of new and distinct species in the course of evolution
speciation characteristics
population is separated. different populations experience different environmental pressures. populations diverse (mutations accumulate; genetic drift occurs; natural selection occurs). reproductive isolation is attained
polyploidy
chromosomal alteration where the organism has more than 2 complete chromosome sets
habitat differentiation
appearance of new ecological niches that can lead to speciation
hybrid zones
region in which members of different species meet and mate, producing at least some offspring of mixed ancestry
gradual model
speciation model in which species gradually change over time
punctual equilibrium
periods of abrupt changes in a species after a long period of time
radiometric dating
process of measuring the absolute age of geologic material by measuring concentrations of radioactive isotopes and their decay products
big five extinctions
extinction rates due to events with a probability of 5% or less:
end ordovician, late devonian, end permian, end triassic, end cretaceous
pangaea
large ancient supercontinent
adaptive radiation
rapid increase in number of species with a common ancestor characterized by great ecological and morphological diversity. driven by adaptation of organisms to new ecological contexts
morphological species
characterizes a species by body shape and other features
cryptic species
group of organisms that are genetically distinct and do not interbreed but are morphologically almost indistinguishable
sterile offspring
offspring that cant reproduce
fertile offspring
offspring that can reproduce
ecological isolation
species occur in the same area but occupy different habitats and rarely encounter each other
behavioral isolation
form of reproductive isolation where 2 populations have differences in mating rituals or other behavior that prevents breeding
temporal isolation
form of reproductive isolation where 2 populations reproduce at different times
mechanical isolation
morphological differences prevent successful mating
gametic isolation
form of reproductive isolation where sperm are immobilized and destroyed before fertilization
zygotic mortality
egg is fertilized, but zygote does not develop
hybrid inviability
a postzygotic barrier where hybrid zygotes fail to develop or reach sexual maturity
hybrid sterility
hybrid offspring can mature but are sterile as adults
evolutionary reversal
reversion of a derived character state to its ancestral state
differential survival
individuals with better traits are more likely to survive and reproduce
reproductive isolation
inability of a species to reproduce due to certain conditions
systematics
study of morphological and behavioral resemblances to make theories about relationships
taxonomy
classification of life-forms by their similarities and differences
genetic equilibrium characteristics
no mutations. no gene flow. random mating. no natural selection