Studied by 16 peoplebiogeography
the geographic distribution of species
evolution
change in the genetic makeup of a population overtime; descent with modification
natural selection
a process in which individuals that have certain traits tend to survive and reproduce at higher rates than other individuals because of their traits
artifical selection
the selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits
population
a group of individuals of the same species that live in the same area and interbreed to produce fertile offspring
gene pool
a population genetic makeup; consists of all copies of every type of allele
microevolution
small scale genetic changes in a population
genetic drift
chance events that cause a change in allele frequency
bottleneck effect
when a large population is drastically reduced by a non-selective disaster
founder effect
when a few individuals become isolated from a large population and establish a small population with a gene pool that differs from the large population
gene flow
the transfer of alleles into or out of a population due to fertile individuals or gametes
relative fitness
the number of surviving offspring that an individual produced compared to others left in population
directional selection
selection on the extreme towards one phenotype
stabilizing selection
selection towards the mean away from extremes
disruptive selection
selection against the mean and towards the extremes
sexual selection
a type of natural selection that explains why many species have showy unique traits; selection for mating based on certain traits (affects fitness)
Hardy-Weinberg Equilibrium
a model used to assess whether natural selection or other factors are causing evolution at a particular locus
Hardy-Weinberg principle
frequency of alleles and genotypes in a population will be remain constant from generation to generation provided that ONLY Mendelian segregation and recombination of alleles are at work
five conditions of Hardy-Weinberg equlibrium
No mutation
No gene flow
No natural selection
Random mating
Large population size
fossils
remains or traces of past organism
fossil record
gives a visual of evolutionary change overtime
comparative morphology
analysis of the structure of living and extinct organisms
homology
characteristics in related species that have similarities even if structures differ
vestigial structures
structures that are conserved even though they no longer have a use
molecular homology
similarities in DNA and AA sequencing between species
homologous structures
characteristics that are similar in 2 species because they have a common ancestor
convergent evolution
similar adaptation that have evolved in distantly related organisms due to similar selection presures
analogous structures
structures that are similar but have separate evolutionary origins
biogeography
the distribution of animals and plants geographically
systematics
classification of organisms and determining their evolutionary relationships
taxonomy
naming and classifying species
phylogentic trees
diagrams that represent the evolutionary history of a group of organisms
node
branching point; represents common ancestors
sister taxa
two clades that emerge from the same node
bassal taxum
a lineage that evolved from the root and remains unbranched
synapomorphy
a derived trait shown by clade member
derived charateristic
similarly inherited from the most recent common ancestor of an entire group
ancestral characteristic
similar trait that arose prior to common ansestor
outgroup
a lineage that is least closely related to the rest of the organisms
monophyletic group
includes the most recent common ancestor of the group and all its descendants (clade)
paraphyletic group
includes the most recent common ansestor but not all of it’s desendents
polyphyletic group
does not include most recent common ancestor of all members of the group
species
a group able to interbreed and produce viable offspring
speciation
formation of a new species
allopatric speciation
physical barrier divides population or a smaller group of the population is separated from the main population preventing gene flow
sympatric speciation
a new species evolved while still inhabiting the geographic regions of the ancestral species, usually due to the exploration of a new niche
2 types of reproductive isolation
prezygotic and postzygotic barriers
prezygotic barriers
prevent mating or hinder fertilization
habitat isolation
species live in different areas or occupy different habitats in the same area
temporal isolation
species breed at different times of the day, year or season
behavioral isolation
unique behavioral patterns and rituals separate species (sexual selection)
mechanical isolation
the reproductive anatomy of species does not fit the anatomy of another
genetic isolation
proteins on the surface of gametes do not allow for sperm and egg to fuse
reduced hybrid viability
the genes of different parent species many interact in a way that impair the hybrids development or survival
reduced hybrid fertility
a hybrid can develop into a healthy adult but is sterile
hybrid breakdown
the hybrid of the first generation may be fertile, but when they mate with a parent species or one another, their offspring will be sterile
microevolution
change in allele frequencies within a single species or population
macroevoltion
large evolutionary patterns
stasis
no change over long periods of time
punctuated equilibrium
when evolution occurs rapidly after long periods of statis
gradualism
when evolution occurs slowly over hundreds, thousands or millions of years
divergent evolution
groups with the same common ancestor evolve and accumulate differences resulting in the formation of new species (homologous traits)
adaptive radiation
if a habitat or niche becomes available, species can diversify rapidly
convergent evolution
two different species develop similar traits despite having different ancestors (analogus traits)
extinction
the termination of a species
Note
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