unit 2 Flashcards
biodiversity
number, variety, and variability of earth’s organisms; genetic, species, and ecosystem
genetic diversity
richness of gene pool within a single species, high variability necessary for long-term species survival
why is high variability necessary for survival?
improves resistance to disease/pests, increases likelihood a species can adapt to changes in an environment
diversity of a species
number of difference species + abundance of individuals within each species
species richness
number of different species in an ecosystem; 1st
species eveness
comparison of abundance of individuals in each species
ecosystem/habitat diversity
variety of ecosystems on earth, variety of species and species interactions
factors affecting species diversity in communities
latitude, net primary productivity, habitat diversity, habitat disturbance, time, pollution, biogeography
latitude
species diversity highest in ecosystems closest to equator
net primary productiviy
higher NPP (like tropical rainforests and estuaries) = high biodiversity
habitat diversity
habitat are sources of food, shelter, mating grounds, and protection; more niches = more support for species diversity
habitat disturbance
loss of available resources = decline in diversity
time
habitats become more mature overtime = can support more organisms and greater species variety
pollution
degrades air, water, soil, resources, some species may not be supported
biogeography
more widespread species = higher genetic diversity
ecosystems with greater species diversity
more likely to recover from disruptions to ecosystems
how do humans impact biodiversity
agriculture, exploitation of species, habitat destruction, pollution, climate change, introduction of invasive species
provisioning ecosystem services
products directly obtained from ecosystems
regulating ecosystem services
benefits obtained from regulation of ecosystem processes
cultural ecosystem services
nonmaterial benefits obtained from ecosystem
supporting ecosystem services
services necessary for the production of all other ecosystem services
how do humans disrupt ecosystem services
overexploitation of resources, combustion of fuel sources, habitat destruction, pollution, agriculture, urbanization
island biogeography
species diversity is a balance of how many immigrate ONTO an island and how many emigrate AWAY or go EXTINCT
island features affecting immigration and emmigration/extinction rates
island size and island distance from a mainland
island settlers with high rate of survival from mainland
plants, insects, birds, bats - able to travel long distances and survive trip from mainland to island
island settlers with low rate of survival from mainland
mammals, reptiles, amphibians
size of island
larger island = more space for species to spread, less competition, more potential niches
distance from island
closer islands = more likely to be colonized more frequently
resources available
more resources = more likely colonizers will survive
presence or absence of predators
predators keep prey populations down
genetic adaptations and ecological tolerance of immigrant species
greater genetic diversity = greater ecological tolerance = more likely species will have adaptations to survive
weather/geologic events
can wipe out whole populations
habitat island
tropical island, or isolated habitats and ecosystems
ecological succession
transition in species composition over ecological time
primary succession
bare rock - lichens - mosses - seeds/grasses - small shrubs - trees
secondary succession
soil - pioneer species - intermediate species - climax community
ecological tolerance
the range of conditions an organism can endure before injury or death; temp, salinity, flow rate, sunlight, pH
disruptions
any event affecting structure and function of an ecosystem, human caused or natural
earth’s Milankovitch cycles
tilt ranges from 22.1 - 24.5, orbit shape changes from circular to elliptical every 90,000-100,000 years
effects of earth’s Milankovitch cycles
changes lead to glacial and interglacial periods every 40,000 years
plate tectonics
movement of plates over millions of years
continental drift
environments have changed over time, plates broke apart and shifted; ex, antarctica used to have forests
periodic disruptions
short-term, occur with highly consistent frequency
episodic disruptions
short-term, occasional, may have a regular season, but no frequency within season
random disruptions
short-term, no particular frequency at all
impacts of natural disturbances
may have greater impact than human disturbances, result in habitat change, fragmentation, or loss, influence animal behaviors, influence species diversity
migration
seasonal long-distance movement of animals from one location to another for a period of time
reasons for migration
to find food, to find favorable living conditions, find breeding grounds, lay eggs, hibernate
keystone species
help determine types and numbers of species in a community, much larger affect than number of keystones in a community
loss of keystone species
population crashes, extinction of other species in a community, no regulation of predators and prey
indicator species
serve as warning of damage or danger to a community
example of indicator species - trout and estrogen in water
high levels of estrogen lead to decreasing numbers of male fish born
example of indicator species - canary in a coal mine
canary is sensitive to toxic gases, like CO
example of indicator species - amphibians and ozone
amphibians are sensitive to UV radiation
example of indicator species - oysters in salt marshes
oysters are natural water filters and indicate water quality
example of indicator species - e. coli in water
indication of contaminated water
example of indicator species - lichens
sensitive to air pollution and disappear in in poor air quality
5 causes of evolution
variation, natural selection, non-random mating, migration, genetic drift
variation
gene pool consists of different alleles for the same gene; more variation in gene pool = greater likelihood for species to survive
natural selection
more individuals born than can survive, species with adaptations and favorable traits are more likely to survive and reproduce
disruptive natural selection
extremes selected over intermediates
stabilizing natural selection
intermediates selected over extremes
directional natural selection
one extreme is favored over all others
non-random mating
competition for mates, indication of good genes
migration
natural events form boundaries between populations, prevent mating between species, lead to fomation of new species
genetic drift
change in the frequency of allele within a population over time
population bottleneck
disaster occurs and reduces population = gene pool is reduced and what is left of population has decreased genetic and phenotypic variability
founder’s effect
sudden decline in population = decline in genetic variability, putting species at greater risk of eventual extinction
allopatric speciation
two species evolve due to geographic separation
peripatric speciation
small groups of individuals break from larger group to form new species
parapatric speciation
species is spread out over a large geographic area, but mainly reproduces with individuals in local area
sympatric speciation
development of many similar species in a single habitat, each with a different specialization