bio 1b midterm 2

population

a group of individuals of a single species in a certain area

community

multiple species co-occurring in a place at a time, and possibly interacting with each other

ecosystem

various species + abiotic elements/environment

biosphere

various species + environment in the entire planet

life history

the suite of traits related to a species’ life cycle and the timing of major events

principle of allocation

individual organisms have a limited amount of resources to invest in different activities and functions

trade-off

resources invested in one function are not available for another

survivorship

the fraction of individuals surviving to a given age

fast-slow continuum

framework describing how species allocate resources between reproduction and survival; describes size, mortality rate, # of offspring, parental care, # reproduction and classifies as slow or fast

birth

production of individuals into a population

death

the irreversible cessation of biological functions that maintain an organism's life, leaving from the population

immigration

influx or movement of individuals from other locations into a new population, habitat, or area

emigration

one-way movement of individuals or groups out of a specific population or habitat to settle elsewhere

B-D model

model that calculates individuals in a population time t, simplified from BIDE model assuming no immigration and emigration (a closed population) for mathematical simplicity

exponential model

represents population growth where size increases at a constant, proportional rate over time, resulting in a J-shaped curve

logistic model

describes population growth that slows as resources become limited, resulting in an S-shaped (sigmoid) curve that stabilizes at the environment's carrying capacity

per capita population growth rate

rate of population growth divided by population size; a metric of the average rate of population change for an individual in the population

density dependence

changes in per capita population growth rate with population size

equilibrium population size

occurs when per-capita birth rate equals per-capita death rate

carrying capacity (K)

a constant variable; the population size at which N comes to equilibrium

intrinsic growth rate (r)

not a variable (constant number); describes how quickly population size will increase staring at very low density; intrinsic in relation to species biology & environment context

population fluctuation

the rise and fall in the number or density of individuals within a population over time

intraspecific competition

competition between individuals of the same species; mechanism behind density-dependent population growth

interspecific competition

competition between different species

predation

predators eat prey; predators are a species that kills its prey & eats it, while prey is a species that is killed by a predator

herbivory

eating plants; one species eats part (or all) of another species, which is a plant; the plant may or may not die, so herbivory is sometimes but not always predation

parasitism

A lives on/in B, may or may not kill B

mutualism

when both species benefit; many possible mechanisms

commensalism

when one species benefits and the other is unaffected; may actually be mutualistic/competitive

facilitation

one species benefits another; typically not specified whether the second species is impacted (positively or neutrally), but often the impact is positive; sometimes, it is “mutualism for plants”

defense

prey strategies to survive; ex. physical, chemical, escaping, avoiding by mimicry, fighting back

dishonest mimicry

appearing like an unpalatable species, even though it is palatable

honest mimicry

appearing like an unpalatable species and is unpalatable

exploitation competition

two predators (A, B) eat the same prey species C; if A consumes C better, then A indirectly harms B, because B gets less food

indirect mutualism

if three species (A, B, C) are herbivorized by the same species D, and both A and B are less palatable to D, so that C is a more attractive target for D, then A and B indirectly help each other

interaction network

diagram with arrows linking species that have a direct pairwise interaction; complex networks

coexistence

when several species co-occur together over time; ex. human gut lining & bacteria, Pt. Reyes shore, Michigan bog

scarcity

No resource occurs in unlimited quantities; therefore, resources can eventually become scarce and limited

Limited resources become allocated among individuals within species, and across species; not all individuals or species are able to complete their life cycle

fundamental niche

the full range of conditions or resources used in which a species could maintain a stable population in the absence of other species; niche limits are based on physiological tolerance limits and resource needs

realized niche

the actual set of conditions or resources used in which the species could maintain a stable population in the presence of other co-occurring species; limits usually set by competition/prediation or other negative interactions

niche partitioning

Competition is reduced through each species occupying a different realized niche

character displacement

an evolutionary response driving a reduction in competition and can further reduce niche overlap; ex. finches living on the same island (sympatric) have evolved different beak sizes compared to when they lived on separate islands (allopatric)

predator-prey system

one species becomes the resource for the other (species do not share a resource; there are three possible scenarios:

(1) Predator eats all the prey, so prey goes extinct, then predator goes extinct → 0 species exist

(2) Predator does not find enough prey, so predator goes extinct, then prey populations increase → 1 species exists

(3) Predator and prey coexist with each other → 2 species coexist

cycle

periodic increases and decreases in each population

Lotka-Volterra predator-prey model

• When prey populations are low, predator populations become low (low food) 

• When predator populations are low, prey populations become high (low predation) 

• When prey populations are high, predator populations are high (high food) 

• When predator populations are high, prey populations become low (high predation) 

• Process repeats

spatial refuge

Refuge for prey (space); enable prey to bounce back from rarity and increase their population size

fluctuation

the irregular, often rapid, rise and fall of plant or animal population sizes (density/abundance) around a mean over time

disturbance

a change in abiotic or biotic conditions in a community, happening all the time & everywhere; ex. changes in weather, species exclusion or extinction, species introductions, doctors prescribing antibodies

primary succession

following a disturbance, the community becomes empty, or approximately empty (ex. everyone killed by a volcano); any species that enters the community must first immigrate from another community

secondary succession

following disturbance to an existing community, populations decline or only individuals of some ife stages survive (ex. seeds, spores); species that become resident in the community represent either population growth from these individuals, or immigration from other communities

early-successional

initially-arriving species in secondary succession

late-successional

later-arriving species in secondary succession

species richness

total # of species

species evenness

relative similarity in abundance of species

species composition

identities of which species are present

alpha diversity

number of species in a local site

beta diversity

difference between alpha and gamma diversity

gamma diversity

number of species across all sites

spatial scale

how ecological patterns, processes, and biodiversity measurements change across different spatial dimensions

spatial grain

the characteristic scale at which measurements are reported (ex. 1x1 meter rectangle)

spatial extent

the overall region in which the measurements are made at the selected spatial grain (ex. an entire state)

latitudinal diversity gradient (LDG)

pattern of changes in species richness (gamma diversity) with latitude; generally highest species richness near the equator, lower richness towards North/South pole; observed to exist across taxonomic groups

species area relationship (SAR)

the number of species in a habitat increases with the size of the area surveyed

sublinear scaling

bigger areas have more species, but doubling the area yields less than double the number of species

island biogeography theory

predicts how many species should occur on "islands" (which can be oceanic islands, mountaintops, or isolated forest patches)

equilibrium richness

the number of species in a community or island where the rate of new species immigration equals the rate of species extinction

luxury effect

richer people have more access to biodiversity

redlining

denial of mortgages/homebuying to non-white people in certain neighborhoods, subsequently inequality in public investmenet in urban neighborhoods)

species distribution

the geographic range and spatial arrangement of individuals or populations of a species across an area over time; range

dispersal

the movement of individuals or gametes away from (and potentially back to) their original location; occurs via several mechanisms, such as mobile, wind, water, biotic vector (ingested/excreted or not ingested)

dispersal limitation

the inability of organisms to reach potentially suitable, unoccupied habitats due to movement restrictions, physical barriers, or inadequate dispersal mechanisms

environment

everything in an organism’s surroundings, including both biotic (living components) and abiotic (non-living components) elements; some parts of [this term], such as soil and natural waters, are a blend of both

biotic limit

include herbivory eating habits; ex. cattle herbivores eat some plant species, and reduce these plants’ geographic distribution

Another example: competition for similar resources; both species cannot persist in areas of overlap, so each species reduces range to an area where it persists successfully; ex. similar European hedgehog species that do not overlap in their geographic distributions

Related to realized niches; restrict a species to its realized niche

abiotic limit

include temperature; ex. heat tolerance in the California mussel, as high temperatures cause mortality

Related to fundamental niches, as they set the extremes of a species niche (ex. the lowest/highest temps a species can tolerate)

environmental gradient

a gradual, continuous change in abiotic (e.g., temperature, altitude, salinity) or biotic (e.g., predation, competition) factors across space or time; comprise of multiple factors; some physically continuous, others patchy

biome

a region experiencing similar environmental conditions, and therefore containing a similar “core” set of species

Hadley cell

large-scale, thermally driven atmospheric circulation loops spanning the tropics to subtropics (0–30° latitude)

• Tropical air heats up, moisture rises and air cools → cooler air precipitates moisture as rain in tropics → rising air is displaced either north or south, creating winds and air transport → transported air begins to cool down and sink → dry air falls in mid-latitudes

maritime climate

lower amplitude of seasonal temperature fluctuations

continental climate

higher amplitude of seasonal temperature fluctuations

ecosystem

all the organisms in a place, and the environment

photosynthesis

solar energy is captured by formation of C bonds in compounds that are stored in organismal bodies

respiration

metabolic reactions release chemical energy, and in doing so return carbon to the environment, and re-radiate thermal (heat) energy

gross primary productivity (GPP)

all the energy obtained from sunlight by autotrophic (photosynthetic) organisms

net primary productivity (NPP)

all the energy available to other organisms (e.g. as biomass) from autotrophs

energy flow

the unidirectional transfer of energy from the sun through producers to various consumer levels

ecological efficiency

the fraction of energy available to other organisms as growth (efficiency = growth/energy available)

assimilation fraction

the fraction of energy used by an organism for growth and respiration

trophic pyramid

graphical representation designed to show the biomass, productivity, or number of organisms at each feeding level (trophic level) within an ecosystem; less energy/biomass are available at higher trophic levels (only 10% energy transfers between stages)

trophic cascade

an effect on energy flow due to a change in the biomass of one trophic level

top-down control

amount of top predators/consumers determines energy flows of prey, which in turn limit other trophic levels

bottom-up control

amount of limiting resources determine energy available to producers, which in turn limit other trophic levels

sociometabolism

metabolism of humans accounting for bodily energy use and also indirect consumption through appropriation of ecosystems (agriculture and animals) as well as other energy sources (burning biomass with fire, fossil fuels, etc.)

fossil fuels

dead plants (biomass) produced by long-ago photosynthesis, becoming coal, oil, and natural gas; solar energy stored over deep time

stock/pool

amount in a compartment of the system; units = mass or mass/area

flux

rate of movement between compartments; units = mass/time or mass/area*time

net flux

the overall, quantitative balance of matter or energy (e.g., carbon, water, nutrients) moving into and out of a specific ecosystem or component over a set time. Equals zero when at equilibrium

residence time

how long something spends in a compartment, if the system is at equilibrium; units = time

average residence time

how long something spends in a compartment when at equilibrium, calculated as Stock / Flux; units = time

sink

a stock that is increasing due to a net flux

source

a stock that is decreasing due to a net flux