Exam 6

biological evolution

a change in allele frequencies in a population over time

natural selection

the process by which individuals w/ advantageous inherited characteristics for a particular environment survive & reproduce at a higher rate than individuals w/ less useful characteristics

directional selection

most common pattern; individuals at one extreme of an inherited phenotypic trait have an advantage over other individuals in the population

ex of directional selection

peppered moth; antibiotic resistant bacteria; plants w/ pesticides

stabilizing selection

individuals w/ intermediate values of an inherited phenotypic trait have an advantage over other individuals in the population

ex of stabilizing selection

human birth weights: light & heavy babies are more likely to die, but babies w/ middle weights have a higher survival rate

disruptive selection

the least common pattern; individuals w/ either extreme of an inherited trait have an advantage over individuals w/ an intermediate phenotype

ex of disruptive selection

beak sizes: birds w/small beaks survived by eating soft seeds, birds w/ large beaks survived by eating the hard seeds, birds w/ inbetween beaks died off

What is the mechanism for how new alleles are generated?

DNA mutation

mutation

a change in the sequence of any segment of DNA in an organism

biological species concept

the idea that a species is defined as a group of natural populations that can interbreed to produce viable, fertile offspring & cannot breed w/ other such groups

Zygote

fertilized egg cell resulted from the fusion of two haploid gametes

prezygotic reprod. Barriers

prevent male gamete & a female gamete from fusing to form a zygote; act before zygote exists

ex of prezygotic reprod. barriers

booby's ritual dance; dance happens before mating, if the dance is not performed correctly then no mating occurs & no fusion of egg & sperm

ecological isolation

two closely related species w/in the same area are reproductively isolated by minor differences in habitat; mating is prevented

behavioral isolation

two species respond poorly to each other's courtship displays or other mating behaviors; mating is prevented

mechanical isolation

the two species are physically unable to mate; mating is prevented

gametic isolation

the gametes of the two species cannot fuse or they survive poorly in the reproductive tract of the other species; fertilization is prevented

temporal isolation

time of year/day

ex of postzygotic reprod. Barriers

mule; mating of horse and donkey, creating a zygote that survived and grew to adulthood but is unable to reproduce

zygote deaths

zygote fail to develop properly, miscarriage; no offspring are produced

hybrid sterility

zygote develops 3 is born, creating a hybrid but unable to reproduce; no

offspring produced hybrid performance

hybrids survive poorly or reproduce poorly

speciation

process by which one species splits to form two species, occurs b/c of genetic divergence

Sympatric speciation

the formation of new species in the absence of geographic isolation

ex of sympatric speciation

fruit flies living on an apple tree, some flies like to lay their eggs on the red apples, others on the green apples, over time, they diverge into two different fly species despite living in the same area

allopatric speciation

the formation of new species from geographically isolated populations

ex of allopatric speciation

one plant species is homed in an area, sea level rises, separates & isolates the plant species, over time, the two populations will grow & evolve on their own; sea levels will fall, both plants recolonize the area, but will be unable to breed

biotic factors

living organisms

ex of biotic factors

polar bears, narwhals, willow trees, ferns, seagrass

abiotic factors

nonliving

ex of abiotic factors

glaciers, bedrock beneath the ice, sunlight, air temperature

ecosystem

system formed by interactions of individual organisms w/ each other & their physical environment

climate

the prevailing weather of a specific place over relatively long periods of time (30+ years) determined by solar radiation, air currents, geographic features

greenhouse gases

a gas in Earth's atmosphere that traps heat heat in the atmosphere

how do greenhouse gases help to keep our planet warm?

absorb heat that radiates away from Earth's surface, preventing that heat from being released into space

ex of greenhouse gases:

CO2, water vapor (H20), methane(CH4), nitrous oxide (N2O)

hydrologic cycle

the movement of water as it circulates from the land to the sky & back again

stages of the hydrologic cycle:

evaporation, transpiration, condensation, precipitation

Evaporation

conversion of water to gas; warm moist air rises, begins to cool as it rises

transpiration

evaporative loss of water from plant tissues

condensation

cooling of water vapor; forms clouds

precipitation

rain, snow, sleet, hail

carbon cycle

the movement of carbon w/in biotic communities, between living organisms & their physical surroundings, & w/in the abiotic world

stages of the carbon cycle

photosynthesis, respiration, combustion, decomposition photosynthesis

respiration

organisms release CO2

decomposition

release of carbon

carbon sink

natural/artificial system that absorbs carbon dioxide

Population

a group of organisms of the same species in a defined area

population density

the number of individuals per unit of area

carrying capacity

the maximum population size that can be sustained in a given environment

biome

a large region of the world defined by shared physical characteristics, a distinctive community of organisms & unique climate

terrestrial biomes

categorized by temperature, precipitation, attitude

location of deserts

extremely arid region

description of deserts

high daytime, low nighttime temperatures

vegetation of deserts

plants w/ small leaves that minimize heat loss & store water in fleshy stems/leaves

animals of deserts

nocturnal animals such as tarantulas, kangaroo rats, owls, & coyotes hiding in burrows during day & emerging at night to feed

location of tropical rainforests

near equator

vegetation of tropical rainforests

rich variety that locks up nutrients (soil is nutrient poor)

animals of tropical rainforests

rich diversity: poison dant frogs, parrots, boa constrictors, jaguars

location of tundra

polar, mountaintops

animals of tundra

herbivores: rodents; carnivores: foxes, wolves; large mammals: bears, musk oxen

description of boreal forests

cold, dry winters & mild summers

vegetation of boreal forests

coniferous trees, low plant diversity

animals of boreal forests

large herbivores: elk, moose; small carnivores: weasels, wolverines, martens

location of grasslands

across latitudes in the middle of continents

description of grasslands

arid but less than deserts; many areas converted to agriculture

vegetation of grasslands

grasses, herbaceous plants w/ scattered trees

animals of grasslands

burrowing rodents: voles, prairie dogs

description of deciduous forests

snowy winters & humid, warm summers

vegetation of deciduous forests

greater diversity than tundra & boreal forest: oak, maple, hickory, beech, elm

animals of deciduous forests

herbivores: squirrels, rabbits, deer, racoons, beavers; carnivores: bobcats, mountain lions, bears, amphibians, reptiles

Producers

organism that creates its own food using sunlight/chemical energy; autotrophs

consumers

organisms that obtain energy by eating all or parts of other organisms

herbivore

animals that feed exclusively on plant material

Carnivore

animals that primary consume other animals

omnivore

animals that eat both animals & plants

Decomposer

a scavenger that uses enzymes to dissolve the dead bodies of other organisms to consume them for food

scavengers

eat dead/dying plants & animals

primary producer

capture energy from the sun & transforms it into fuel

primary consumer

eat producers; are heterotrophs often called herbivores

secondary consumer

eat primary consumers; are heterotrophs: carnivores that eat herbivores

tertiary consumer

eat secondary consumers; carnivores that eat carnivores

trophic level

each level of the energy pyramid, corresponding to a step in a food chain

Which trophic level of a food chain w/in an ecosystem has the most energy available to it?

the first level, consisting of producers

What are decomposers important?

responsible for nutrient flow from biotic to abiotic world

why is biodiversity important?

essential for maintaining ecosystem functionality & resilience, provides services that are crucial to both the environment's human well being (food security, clean air & water, climate regulation)

global warming

a significant increase in the average surface temperature of earth over decades or more

gene flow

the exchange of alleles between populations

ex of gene flow

flowers mixing genes through pollinators & pollen; migrating birds interbreeding w/ a population

genetic drift

a change in allele frequencies produced by random differences in survival & reprod. among the individuals in a population; more likely to cause evolution in small populations than in large ones

ex of genetic drift

walking in a field of flowers then killing the only blue flower; random chance genetic bottleneck

founder effect

a form of genetic drift that occurs when a small group of individuals establishes a new population isolated from its original larger population

how does gene flow & genetic drift lead to evolution?

when there are changes in allele frequencies over time

Coevolution

the tandem evolution of two species that results because interaction between the two so strongly influences their survival

tandem

the connecting of one object to another similar object behind it

Weather

short-term atmospheric conditions in a limited geographic area such as today's temperature, precipitation, wind, humidity, cloud cover

Combustion

burning of carbon-rich materials, living or not, fossil fuels 

convergent evolution

when distantly-related organisms evolve similar structures b/c they survive & reproduce under similar environmental pressures

climate change

a large-scale & long-term alteration in earth’s climate