66 terms


pg. 129-140
changes in populations, species, or group of species
the details of how populations of organisms change from generation to generation and how new species originate
describes patterns of changes in groups of related species over broad periods of geologic time
patterns determinate phylogeny
the evolutionary relationships among species and groups of species
theory of evolution had 3 important ideas
1. use/disuse
2. inheritance of acquired characteristics
3. natural transformation of species
-one of the 3 important ideas in Lamarck's theory of evolution
-described how body parts can develop with increased usage while unused parts weaken
inheritance of acquired characteristics
-one of the 3 important ideas in Lamarck's theory of evolution
described how body features acquired during the lifetime of an organism could be passed on to offspring
natural transformation of species
organisms produced offsprings with changes.
species didn't become extinct nor did they split and change into two or more species
each generation had a slightly diferent from toward some higher order of complexity
Evidence for Evolution
1. Paleontology
2. Biogeography
3. Embryology
4. Comparative Anatomy
5. Molecular Biology
provides fossils that reveal the prehistoric existence of extinct species
describes the distribution of species
reveals similar stages in development
Comparative anatomy
describes two kinds of structures: homologous and analogous
homologous structures
body parts that resemble each other in different species because of common ancestors
analogous structures
body parts that resemble one another in different species because they are adaptations to similar environments
molecular biology
examines the nucleotide and amino acid structures of DNA and proteins from different species
natural selection
differences in survival and reproduction among individuals in a population as a result of their interaction with the environment
ability to suvive or leave offspring
stabilizing selection
eliminates individuals with extreme or unusual traits
favors the middle
directional selection
favors traits that are at one extreme
traits at the opposite extreme are selected against
disruptive selection
occurs when environment favors extreme or unusual traits
doesn't favor the middle
sexual selection
differential mating of males and sometimes females in a population
female vs male
female choice
make a greater energy investment into producing offspring
can increase their fitness by increasing the quality of their offspring by choosing superior males
male competition
contribute little energy to the production of offspring
miximize the quantity of offspring produced
artificial selection
form of directional selection carried out by humans
sources of variation
1. mutations
2. sexual reproduction
3. diploidy
4. outbreeding
5. balanced polymorphism
provdes raw material for new variation
sexual reproduction
creates individuals with new combinatins of alleles
includes crossing over, independent assortment of homologoues, and random joining of gametes
presence of two copies of each chromosome in a cell
mating with unrelated partners
balanced polymorphism
maintenance of different phenotypes in a population
includes heterozygote advantage, hybrid vigor, and frequency dependent selection
heterozygote advantage
occurs when the heterozygous condition bears a greater selective advantage than either homozygous condition

ex: sickle cell carrier -- partial immunity to malaria
hybrid vigor
the superior quality of offspring resulting from crosses between two different inbred strains of plants

ex: corn hybrid produces larger ears of corn and is more disease resistant than either inbred species
frequency dependent selection
minority advantage
when the least common phenotypes have a selective advantage
causes of changes in allelic frewuencies
natural selection
gene flow
genetic drift
nonrandom mating
gene flow
describes the introduction or removal of alleles from the population when individuals leave or enter the population
genetic drift
random increaes of decrease of alleles
two kinds: founder effect and bottleneck
founder effect
occurs when allele frequencies in a group of migrating individuals are, by chance, not the same as that of their population of origin
occurs when the population undergoes a dramatic decrease in size
the small population becomes severely vulnerable to genetic drift
nonrandom mating
occurs when individuals choose mates based upon their particular traits
*inbreeding and sexual selection occurs
occurs when individuals mate with relatives
the formation of new species
can occur through:
1. allopatric
2. sympatric
3. adaptive radiation
allopatric speciation
when a population is divided by a geographic barrier so there's no interbreding
due to natural selection, if the geographic barrier was removed, there'd still be no mating between the two
sympatric speciation
formation of new species without geographic barriers
includes: balanced polymorphism, polylpoidy, and hybridization
the possesion of more than 2 set of chromosomes in diploid cells
when 2 distinctly different forms of a species mate and produce offspring
adaptive radtion
relatively rapid evolution of many species from a single ancestor
occurs when the ancestral species is introduced to an area where diverse geographic or ecological conditions are available for colonziaation
prezygotic isolating mechniasms
mechanisms that prevent fertilization
1. habitat isolation
2. temporal isolation
3. behavioral isolation
4. mechanical isolation
5. gametic isolation
habitat isolation
occurs when species do not encounter one another
temporal isolation
when species mate or flower at different times/seasons
behavioral isolation
when species do not recognize another species as a mating partner because they don't perform the correct rituals or give out the same signals, or relase the proper chemicals
mechnical isolation
occurs when male and female genitalia are structurally incompatible or when flower structures select for different pollinators
gametic isolation
occurs when male gametes do not survive in the environment of the female gamete or female gametes don't recognize the male gametes
postzygotic isolating mechanisms
prevents the formation of fertile offspring
1. hybrid inviability
2. hybrid sterility
3. hybrid breakdown
hybrid inviability
occurs when the zygote fails to develop peroperly and aborts ot dies
hybrid sterility
hybrids become functional adults, but are reproductively sterile
hybrid breakdown
occurs when hybrids produce ofspring that have reduced fertility/viability
Patters of evolution
1. divergent evolution
2. convergent evolution
3. parallel evolution
4. coevolution
divergent evolution
describes two or more species that originate from a common ancestor and become increasingly different over time
can happen because of allopatric/sympatric speciation or adaptive radiation
convergent evolution
describes two unrealted species that share similar traits
each species has developed these traits because they live in similar envrionments
*called analogous traits
parallel evolution
describes 2 related species or two related lineages that have made similar evolutionary changes after their divergence from a common ancestor
evolution of a species in response to new adaptations that appear in another species

ex: prey species gains an advantage, some variants in the predator population will be succesful in getting the prey despite the advantage. those that get the prey pass down the favorable trait to its offspring
descibes patterns of evolution for groups of species over extended periods of geologic time
includes phyletic gradualism and punctuated equilibrium
phyletic gradualism
evolution occurs by the gradual accumlation of small changes. individual speciation eventts or major changes in lineages occur over long periods of geologic time
punctuated equlibirum
evolution consists of geologically long periods with little or no evolution, then interrupted by geologically short periods of rapid evolution
chemical evolution
study of how life began