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87 Cards in this Set

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natural selection
states that a population can change over the course of time if individuals with certain heritable traits produce more viable offspring thatn the other individuals
evolutionary adaptation
tendency of the characteristics of a spiecies to change over generations to enable that species to better fit the environment, because of natural selection
sector of biology dedicated to the naming and classification of all forms of life (binomial nomenclature)
found in sedimentary rock, impressions of organisms that are no longer living. proof of evolution
study of fossils
geologic theory that states that profound changes in earth's features over the course of geologic time is the result of slow, continuous processes.
the idea that the geologic processes that have shaped the planet have not changed over the course of the earth's history
Jean Baptiste Lamarck
published an early theory of evolution, which stated that characteristics acquired during an organism's lifetime could be passed on to the next generation.
Charles Darwin
voyage on the Beagle in 1831 was the impetus for the development of his theory of evolution
descent with modification
refers to Darwins idea that all living organisms are related by descent from an unknown common ancestor n the past
Darwin's 3 theories
1. Natural selection is the result of differing reproductive success that is due to the unequal ability of individuals to survive to reproduce.
2. The process of natural selection occurs through interactions between the environment and organisms that vary in their genotype in a population
3. The result of natural selection is the adaptation of a population to its environment.
artificial selection
the process by which species are modified by humans. Plants and animals are specifically chosen to breed with the desired goal of producing offspring with specific characteristics
defined as a group of interbreeding individuals that live in a certain geographic area- it is the smallest unit that can evolve
heritable traits
natural selection only works on this
since organisms are related evolutionarily, species that share common ancestry should have similarities. A phenomenon, in which related species share characteristics
vestigial organs
historical remnants of structures that were functional in ancestors
embryological homologies
most prominent during development
molecular homologies
occur when organisms share characteristics on the molecular level, such as using the same method for reproducing DNA
refers to the geographic distribution of species. species that live closer to one another tend to be more closely related than those who do not.
species in a certain geographic location that are found nowhere else
natural selection acts on blank but evolution acts on blank
natural selection, evolution
population genetics
study of the genetic variation that exists within populations and of how it changes
is a group of populations of individuals that can interbredd successfully and produce a viable offspring. Populations of the same species may be geographically isolated and only exchange genetic material rarely.
gene pool
total aggregate of genes in a population at any one time.
all members of a population are homozygous for the same copy of an allele
Hardy-Weinberg theory
used to describe a population that is not evolving. States that the frequencies of alleles and genes in a population's gene pool will remain constant over the course of generations unless they are acted upon by forces other than mendelian segregation and the recomination of alleles
hardy-weinberg equilibrium
situation in which the allele frequencies within a population are not changing
Hardy-weinberg equation
p squared + 2pq + q squared
5 criteria in order for a population to be in Hardy-Weinberg equilibrium
1. large population
2. no migration in a population, gene flow - transfer of alleles between populations
3. no mutations
4. mating must occur randomly
5. natural selection may not be taking place
organisms that deviate from the hardy-weinberg equilibrium
defined as a generation to generation change in allelic frequency in a population. Main causes are genetic drift, natural selection, gene flow, and mutation.
genetic drift
refers to a change in a population's allele frequencies due to chance
the bottleneck effect
occurs when natural disaster or some other event causes a drastic reduction in the size of a population, which in turn causes genetic drift. Reduces genetic variability in a population, since some alleles are lost form the gene pool.
the founder effect
occurs when a few members of a population colonize an isolated location-the smaller number of founders the more limited the variability of the gens in the population
genetic variation
exists naturally in populations. Quantitative characters, such as height, vary in a continuum in a population.
a character in a population in two or more discrete forms, such as a plant bearing two different kinds of flowers in a population.
geographic variation
differences in gene pools between population or parts of populations
graded change in a trait along a geographic axis.
two processes leading to variation in a gene pool
1. mutation (only on gametes)
2. sexual recombination (most genetic differences)
diploidy (factor contributing to preservation of genetic variation)
fact that most eukaryotes are diploid means that they are capable of hiding genetic variation (recessive alleles) from selection
balanced polymorphism (other factor contributing to preservation of genetic variation)
the ability of natural selection to keep stable the frequencies of two or more phenotypes in a population
heterozygote advantage
individuals with heterozygous at a certain locus that confers to them an advantage (cycle cell ammenia)
origin of new taxonomic groups
process by which a new species arise.
two barriers to speciation
1. prezygotic barriers - prevent mating or hinder fertilization
2. postzygotic barriers - those that prevent a fertilized egg from developing into a fertile adult
5 examples of prezygotic barriers:

Habitat isolation
two species can live in the same geographic area, but not in the same habitat; this will prevent them from mating.
behavioral isolation
some use certain signals or types of behavior to attract mates, the signals are unique to their species, members of other species will not recognize them preventing mating
temporal isolation
species may breed at different times of the day, different seasons, or different years, and this can prevent them from mating
mechanical isolation
species may be anatomically incompatible
gametic isolation
gametes may not be able to form zygote
postzygotic barriers:

Reduced hybrid vitality
when a zygote is formed, the fact that the two species are genetically incompatible may cause development to cease.
reduced hybrid fertility
even if the two species produce viable offspring, reproductive isolation is still occurring if the offspring are sterile
hybrid breakdown
if the two different species produce offspring that are viable and fertile, these hybrids may mate to produce weak or sterile offspring
allopatric speciation
a population forms a new species because it is geographically isolated from the parent population, small newly isolated pops are more likely to have their gene pools significantly changed, occurs when it is no longer able to mate with parent population
sympatric speciation
a small part of a population becomes a new population without being geographically isolated from parent pop
geologic events or processes
can fragment a population, formation of land bridge, evaporation of large lake to smaller lakes
adaptive radiation
occurs when many new species arise from a single common ancestor
can be an example of sympatric speciation, species gets 4n chromosomes through nondisjunction and are unable to breed with the parent pop, but can with other tetrads
polyploid speciation
occurs in animals, but not common, instead, in animals, sympatric speciation can result from part of the population switching to a new habitat, food source, or other resource.
punctuated equilibrium model
species diverge in relatively quick spurts rather than slowly and gradually.
the field where evolutionary biology and developmental biology meet
allometric growth
different growth rates of various parts of an organism's body during development
homeotic genes
determine the location and organization of body parts. Hox genes are one class of homeotic genes
evolutionary history of a species or a group of related species
study of biological diversity in an evolutionary context.
fossil record
sequence in which fossils appear in the layers of sedimentary rock that constitute the earth's surface.
study the fossil record
sedimentary rock
formed from layers of minerals settling out of water Dead organisms settle along with the sediments and are compacted and sometimes preserved as fossils.
relative dating
can be used to date fossils. The fossils in each layer of sedimentary rock repersent certain time periods;
index fossils
found in more than one location that can be used to correlate information about the strata in both locations
geologic time scale
shows a consistent sequence of periods and events in the history of earth, divided into four eras, precambian, paleozoic, mesozoic, and cenozoic
absolute dating
refers to fossils' age given in years, rather than given in reference to one another.
radiometric dating
involves measuring the level of certain radioactive isotopes in fossils or rocks to determine their ages
of an isotope is the length of time it takes for 50% of the original sample of the isotope to decay.
are not fixed; rather , they move slowly on tetonic plates of the earth's crust, which in turn float on the liquid mantle of the earth.
about 250 million years ago, all of the major landmasses were brought together in a supercontinent which shaped much of biological evolution
geographic isolation
the brakeup of pangaea caused this
two major extinctions
permian extinction and the cretaceous extinction
study of biological diversity in the context of evolution, and it includes taxonomy, which is the naming and classification of species and groups of species.
used to describe species, consists of the genus and the species
8 taxons
domain, kingdom, phylem, class, order, family, genus, species
phylogenic trees
show the hierarchical classification of taxonomic levels for organisms
each branch of the diagram is called a clade. the sequence of branches on cladogram is based on shared anscestry
convergent evolution
takes place when two organisms become alike because they adapted to similar environmental challenges, likenesses the result from convergent evolution are called analogies instead of homologies
mollecular systematics
of different organisms allows us to determine evolutionary relationships on a molecular level, allowing for new breakthroughs
dictates that theories should be kept as simple as possible while still being consistent with the evidence, this way of thinking is used to create phylogneies
molecular clocks
methods used to place the origin of taxonomic groups more precisely in time