Chapter 16 and 26 Exam 1 Bio 102

michelleburkee2's version from 2016-02-18 07:21

Section 1

Question Answer
before Darwin species were classified based onappearance
speciesa gorup of interbreeding natural populations that are reproductively isolated from other groups
reproductively isolatedunable to successfully breed outside the group
3 problems with the definition of speciesleaves out asexual organisms, often difficult to observe whether members of two different groups interbreed, and species of fossils cannot be determined
does similar appearance always mean same species?no
Can organisms that differ in appearance belong to the same species?yes Ex. variation in color but can still interbreed
how is reproductive isolation between species maintained (2 reasons)premating isolating mechanisms and postmating isolating mechanisms
5 premating isolation factorsgeograpical, ecological, behavioral, and mechanical incompatibility
3 postmating isolation factorsgametic incompatibitily, hybrid inviability, and hybrid infertility
speciationthe process by which new species are born
what two factors cause speciationisolation of population and genetic divergence of populations
what causes sympatric speciation?ecological isolation can reduce gene flow until species diverge or because of mutations
what cause allopatric speciation?a geographical barrier
polyploidymultiple copies of a chromosome

Section 2

Question Answer
premating isolating mechanismsmechanisms that prevent mating between species
postmating isolating mechanismsmechanisms that prevent mating to result in a healthy fertile hybrid between species
geographical isolationspecies don't mate because they don't come into contact. They are not necessarily distinct species.
ecological isolationspecies don't mate because they live in different habitats or niches. They use different resources therefore they do not meet.
temporal isolationspecies don't mate because they breed at different times
beharioal isolationspecies can't mate because they have different mating rituals
mechanical isolationspecies can't mate because their reproductive structures are incompatible
gametic incompatibilitysperm from one species cannot fertilize eggs of another
hybrid inviabilityhybrid offspring fail to survive to maturity, hybrid may abort early in development, hybrid may die shortly after birth, hybrid may be unable to reproduce due to behavior
hybrid infertilityhybrid offspring are sterile (i.e. the mule). gametes never develop
isolation of populationsprevents gene flow between populations
genetic divergence of populationsdriven by genetic drift or natural selection
allopatric speciationisolating mechanisms is a geographical barrier
sympatric speciationisolation occurs without geograpical seperation
what is the most common form of speciationallopratric speciation
polyploids cannotmate successfully with normal diploid individuals. This is more common in plants than animals
3 examples of environmental change that can cause extinctionhabitat destruction, increased competition among species, and human activities

Section 3

Question Answer
what is a common source of sympatric speciation?polyploidy
how can many new species arise in a short period of time?when the population of one species invades a varity of new habitats with few competitors. Ex. finch colonization of Galapagos islans
adaptive radiationrise of many new species over relatively short period of time. This differs from speciation and reproductive isolation. Ex. the finches of the galapagos
adaptive radiation tree showsone line then many lines coming from it. this represents than multiple speciation events occured rapidly
extinctiondeath of all members of a species
how many of all species that ever existed are now extinct?99.9%
what is the immediate cause of extinction?environmental change
populationall the members of a particular species that live within an ecosystem
communitygroups of interacting populations within ecosystems. all living and nonliving components of a defined area
biosphereenormous ecosystem that encompasses all of earth's habitable surface
ecologystudy of the interrelationships of organisms with each other and with the nonliving environment
what two factors do population size depend on?natural increase (births and deaths) and net migration(immigration and emigration)
growth ratechange in population size per unit of time. growth rate= birth rate-death rate
birth ratenumber of births per unit of time
death ratenumber of deaths per unit of time
population growth# of individuals added to a population per unit of time
formula for growth rateG= growth rate * the origonal poulation size

Section 4

Question Answer
what two factors determine population sizebiotic potetial and environmental resistance
biotic potentialthe maximum rate at which a population could grow
environmental resistanceany factor that tends to couteract biotic potential therefore limiting population growth.
example of environmental resistancepredation and famine
what five factors influence biotic potentialthe age at which the organism first reproduces, the frequency at which reproduction occurs, the average number of offspring produced each time, the length of the organism's reproductive life span an the death rate of individuals
what would a graph look like with exponential growth?J curve
when does exponential growth occur?only in unusual conditions: in populations with "boom and bust cycles", when environmental resistance is reduced, and when individuals invade a new habitat
What happens to many populations that exhibi exponential growth?they eventually stabilize as resoucres decome depleted
carrying capacitymaximum population size that can be sustained for extended period of time without damge to ecosystem. If exceed carrying capacity there are severe consequences
what does the graph of logistic growth look likeS shaped
restriced growthlogistic growth
unrestricted growthexponential growth
logistic growththe growth pattern of a population that stabilizes at a set level of size that is compatible with the environment and resources.
what happens if environmental resistance increases?population growth slows
density independent factorslimit size regardless of the population density i.e. climate and weather
density dependent factorslimit population size more as the population inceases i.e. predation, parasitism, and competition

Section 5

Question Answer
maintains populations at or below carrying capacityenvironmental resistance
what two factors limit population sizedensity independent factors and density dependent factors
predation as a limiter of population sizepredators populations grow as their prey become more abundant. result in predatory-prey population cycles
parasites as a limiter of population sizeparasites spread more rapidly among dense populations (i.e. the bubonic plague)
interspecific competitionbetween different species
intraspecific competitionbetween same species
scramble competitionfree for all scarmble as individuals try to beat others for limites resources. Competitors don't interact they just try to reach the resources first
contest competitionsocial or chemical interactions determine access to limited resources. i.e. only the fittest wolf defends its territory or bigger wolf becomes alpha male and only he reproduces
clumpedlive in groups. protection from prey and method to prey
uniformmaintain relatively constant distance between individuals. usually a resuly of competition for resources
randomindividuals that do not form social groups. usually where resources are plentiful
which type of spatial distriubution is the most commonclumped
which type of spatial distribution is the least commonrandom
late loss populationslow juvenile death rates and most survive to old age
constant loss populationsindividuals have equal chance of dying at any time during their life
early loss populationsproduce large number of offspring and lots of early loss
how have humans increased the carrying capacity of Earth?technical advances, agricultural advances and industrial and medical advances

Section 6

Question Answer
demographic transitionexplains trends in population size
Replacement level fertilitypopulations eventually stabilize if parents have just the number of children to replace themselves
why is the world's population growth unevenly distributed?developing countries still have rapidly growing populations
pre-industrial stagehigh birth and death rates. population relatively small and stable
transitional stagedeath rates drop but birth rates remain (pop. growth)
industrial stagelower birth rates due to contraceptives.
post-industrial stagelow birth and death rates. population relatively stable