BIO 1B ECOLOGY PT1

ecology

the study of the relationship between organisms and their environment

organisms

individuals

population

multiple organisms of the same species on a certain area

community

multiple species

ecosystem

multiple species and the ecosystem

biosphere

all of earth

life histories

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

examples of life history traits

avg lifespan, age of first reproduction, ect.

principle of allocation

individual organisms have a limited about of resources to invest in different activities and functions, Resources invested in one function are not available for another(trade-off)

trade-off

in life cycle, resources must be allocated among growth, survival, and reproduction

reproduction size-number tradeoffs

species can have more smaller or fewer bigger offspring

cost of reproduction trade-off

more reproduction in on year means less reproduction the next year

survivorship

fraction of individuals surviving to a given age

type I curve

most individuals reach old age(humans)

type II curve

some individuals reach old age, somewhat random(squirrels)

type III curve

very few individuals reach old age (trees)

fast-slow continuum

species with smaller body sizes reproduce quickly and dont live for too long while larger bodied species live for longer and may reproduce more than one time

fast species

reproduce early, short life span, short maturation, many offspring per episode, few reproductions per lifetime, no parental care, and small offspring/eggs

slow species

reproduce late, long life span, long maturation, few offspring per episode, many reproductions per lifetime, extensive parental care, and large offspring/eggs

demography

the study of how a population changes over time

births

new individuals being created

deaths

existing individuals dying

immigration

individuals coming from a separate area to join a population

emigration

individuals leaving a population to go to a separate area

BIDE model

a model accounting for all birth, immigration, death, emigration

N_t = number of individuals in a population at a time

B-D equation

N_t+Δ = N_t + B - D

r > 0

exponential positive growth

r = 0

the population will not change

r < 0

exponential negative growth

per capita population growth rate

rate of population growth divided by population size

a metric of the average rate of population change for an average individual in the population

density dependance

observation about whether or not the per capita growth rate changes with population size

no density dependence

slope is constant

negative density dependence

the per capita population growth rate decreases when the population is larger- this is neccesary for population control

slope in negative

positive density dependence

slope is positive

population equilibrium

per capita birth rate equals per capita death rate, (1/N)(dN/dt) = 0

Why is negative density dependence common?

fewer resources per individual, more competition among individuals, fewer available mates. more disease/parasites, more predation risk

logistic model

derived by adding negative density to the exponential model

r

intrinsic growth rate: constant number that will describe how quickly population size will increase starting at a very low density

K

carrying capacity: a constant number describing the population size at which N comes to equilibrium

density independent effects

N is limited by something unrelated to the size of the population

examples of density independent factors

changes in temperature, changes in water availability, changes in land area

interaction defintion 1

individual of species A influences the behavior or life events of an individual of species B

interaction defintion 2

an individual of species A incuenceis the growth, survival, or reproduction of an individual of species B

interaction definition 3

a population of species A influences the growth rate (dN/dt) of a population of species B

competition

A and B both try to acquire the same limited resource

effect A→ B: -

effect B → A: -

intraspecific competition

competition between individuals of the same species

interspecific competition

competition between individuals of different species

predation

A kills B

effect A→ B:-

effect B→ A; +

prey strategies

physical defenses( porcupine quills), chemical defenses(poison in dart frogs), escape( moth ears detecting bats so they can drop out of the bats path ), mimicry, and fighting back

dishonest mimicry

appears like an unpalatable species, even though it is palatable

honest mimicry

appears like an unpalatable species, and it is unpalatable

herbivory

A eats B(plant), may or may not kill B

plants sometimes (but not usually) benefit

effect A →B: -

effect B→ A: +

mutualism

A and B help each other

effect A → B: +

effect B → A: +

mutualism examples

disperse seeds, pollinate flowers, defend against herbivores, gather nutrients, photosynthesize and respire, ect.

commensalism

B helps A, no impact on B

effect A → B: 0

effect B→ A: +

facilitation

general term for either mutualism or commensalism

parasitism

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

effect A →B: -

effect B → A: +

exploitation competition

when individuals interact indirectly as they compete for common resources, like territory, prey or food

indirect mutualism

positive effects on two consumer species when each negatively impacts a competitor species of the other predator's main prey species

interaction network

diagram with arrows linking species that have direct pairwise interaction

human interactions with non human species

agriculture, livestock, and unintentional introduction

community

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

coexistence

when several species co-occur together over time

scarcity

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

competition

two species looking for the same resources in the same location

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( 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 stable population in the presence of other co-occurring species( limits are usually set by competition/ predation or other negative interactions)

niche partitioning

when realized niche is different than the fundamental niche. completion is reduced though each species occupying a different realized niche which increases coexistence

predator- prey systems

species do not share a resource - one is the resource for the other

predator- prey cycles

periodic increases and decreases in each population. predator population increases after the prey population increases

simple environment cycle

with no refuges for prey, predator kills prey then goes extinct after in runs out of food

complex environment cycle

with refuges for prey, prey are killed by predator, but can colonize fast enough to escape the predator and persist in the overall environment

spatial refuges

places with prey but no predators which allow the prey population to bounce back

disturbance

a change in abiotic or biotic conditions in a community(not rare)

disturbance examples

changes in weather, species introductions, species exclusion, antibiotics

primary succession

following a disturbance, the community becomes empty, or approx empty. any species that enters the community must first immigrate from another community

primary succession example

everyone is killed by a volcano

secondary succession

following disturbance to an existing community, populations decline or only individual of some life stages survive. species that become resident in the community represent either population growth from these individuals , or immigration from other communities

early-successional species

intirially-arriving species. outcompeted by late-successional species

late-successional species

later arriving species. usually outcompete early-successional species

spatial grain

characteristic scale at which measurements are reported

spatial extent

the overall region in which the measurements are made at the selected spatial grain

spatial abundance

number of individual

spatial richness

total number of species

spatial eveness

relative similarity in abundance of species

spatial composition

identities of which species are present

latitudinal diversity gradient

diversity is generally highest in species richness near the equator and lower toward the north/South Pole

explanation for LDG

more land/resources, environments are less stressful, more annual solar radiation (energy), higher temp = higher mutation rates, more time to evolve new species in tropics

larger area

higher richness