BIO 214 M12 and M13

ecology

study of how organisms interact with each other and the environment; biotic + abiotic

biotic

organisms (live)

abiotic

non-living physical aspects that impact biotic factors

population

group of individuals of the same species that occupy a particular location at a given time; form a gene pool

characteristics of a population (3Ds)

• Density

• Demography

• Dispersion

Density

number of individuals in a given area

demography

statistical study of the processes that change a population’s size and density through that time

• most useful: age structure of population

dispersion

spatial distribution of organisms; clumped, random, uniform

clumped dispersion

individuals grouped into patches; typically caused by clumped distribution of resources (most common form of dispersion)

random dispersion

not arranged in any particular pattern; occurs when there is an equal distribution of resources

uniform dispersion

individuals equally distributed in an environment; result of limited resources

organism level

focus on how individuals of the same species interact with each other and the environment; focus is behavior

population level

focus on whether a population is growing or declining and why

species level

focus on why species have evolved or are evolving

community level

focus on how species live in a particular area and how they interact

community

group of species present in the same area at the same time

ecosystem level

how changes in abiotic condition change the communities present or how energy and matter flow through organisms and the environment

levels of organization in ecology

• organisms

• population

• species

• communities

• ecosystem

demographic characteristics

• age structure

• birth rate

• death rate

• life expectancy

mortality rate

probability of individuals dying before their next birthday

2 models of population growth

1. geometric growth

2. exponential growth

geometric growth

all organism

exponential growth

growth of a population under ideal conditions with infinite resources

dN/dt = rN

logistic model

describes how populations grow when resources are limited, starting with exponential growth and slowing to a stable maximum capacity

dN/dt = rN(K-N)/k

carrying capacity

the size of a population that a particular habitat can support over the long term, is a function of the resources available

growth rate when a population size equals the carrying capacity

0; population size remains stable

population growth rate

increase or decrease in the number of individuals in a population

finite rate of population growth

the growth rate over a defined period

= e^instantaneous rate

instantaneous rate of population growth (r)

growth rate of a population at any moment

life history traits

biological characteristics of a species that determine its schedule of growth, survival, and reproduction; associated trade offs between age/size of reproductive maturity, number of lifetime breading events, lifespan and aging, number and size of offspring

k-selected species

thrive in stable conditions

• slow growth

• late reproduction

• long lifespan

r-related species

adapted to function well in changing conditions

• rapid growth

• early reproduction

• short lifespan

• numerous tiny offspring in single reproductive event

density-independent factors

influence populations evenly regardless of size (ex: natural disaster)

density-dependent factors

influence dependent on density (generally more impactful)

• crowding

• interspecific competition

• predation

• parasitism and disease

• includes non feeding interactions

crowding

decreases individual growth rate, adult size and survival of plants and animals, negative effect on reproduction; stimulates developmental and behavioral changes

survivorship curve

graphs showing the proportion of individuals in a population surviving at each age

type I survivorship

high % of offspring in early years; death prominent in older individuals; high amount of parental care (humans and primates)

type II survivorship

die equally at each age interval; relatively few offspring, provide significant parental care (birds)

type III survivorship

very few organisms survive early years; lots of offspring, little parental care (trees)

intraspecific competition

competition between members of the same species for resources

energy budget

allocation of energy resources for body maintenance, reproduction and parental care

early reproduction

higher chance of producing offspring at expense of growth and their own health (life history)

late reproduction

higher feudency and greater parental care at risk of not surviving to reproductive age (life history)

semelparity

species reproduces once during its lifetime then dies (life history)

heroparity

species that reproduce repeatedly during their lives (life history)

energy budget

allocation of energy resources for body maintenance, reproduction and parental care

fecundity

potential reproductive capacity of an individual; INVERSELY related to amount of parental care given

interspecific competition

competition between species for resources in a shared habitat or environment; occurs when populations of different species use the same limiting resource; causes increased mortality and decreased reproduction in the two populations

species diversity

number of species occupying the same habitat and their relative abundance

predation

consumption of prey by its predator

herbivory

consumption of plants by insects and other animals

camoflauge

avoiding detection by blending in with the background (type of physical defense mechanism)

climax community

the final, stable, and self-perpetuating stage of ecological succession, where a community of plants, animals, and fungi exists in equilibrium with local environmental condition

Batesian mimicry

harmless species imitates naming coloration of a harmful one

Mullerian mimicry

multiple species share the same warning coloration (all of them have defense)

Emsleyan (or Mertensian) mimicry

highly deadly, or "lethal," species mimics a less dangerous, "moderately venomous" model (Very rare)

community dynamics

changes in community structure and composition over time

niche

range of abiotic and biotic conditions a species lives in

fundamental niche

defines the locations where it is physically possible for a particular species to live in

realized niche

range of conditions and resources a species occupies and uses in an ecosystem

demographic-based population model

modern model of population dynamics incorporating many features of the r- and k- selection theory

primary succession

newly exposed/formed land is colonized by living things

secondary succession

part of ecosystem is distributed and remnants of the previous community remain

pioneer species

first species to appear

competitive exclusion principle

two species cannot occupy the same niche in a habitat; different species cannot coexist in a community if they are competing for all the same resources

symbioses

close interactions between individuals of different species over an extended period of time which impacts the abundance and distribution of the associating populations

commensal relationship

one species benefits from close, prolonged interaction while the other neither benefits nor is harmed

mutualism

two species benefit from their interaction

parasitism

an organism (parasite) that lives in or on another living organism (host) and derives nutrients from it

foundation species

“base of a community”; forms the majoral structural portion of a habitat

species richness

number of different species in a community

relative species abundance

absolute population size of a particular species relative to the population sizes of other species

keystone species

species whose presence is key to maintaining biodiversity in an ecosystem and to upholding an ecological community’s structure

limiting resources

required for there to be competition

interference competition

direct interaction of competitors; includes include territorial defense, chemical inhibition (allelopathy), and direct physical aggression

allelopathy

plants release chemicals to their environment to inhibit the growth, gemination or reproduction of neighboring plants

exploitative competition

indirect form of competition where organisms deplete shared resources faster than their competitor (not physically interacting with each other)

habitat partitioning

species coexist by dividing habitats (occupying different distinct niches)

character displacement

evolutionary divergence of traits between similar species when they occur

optimal foraging theory

predicts that an animal’s diet is a compromise between the costs and benefits associated with different types of food; maximizing energy intake is a balance between time and energy in capturing food and energy gain of food; food abundance affects food choice

quantification of selectivity (D)

D = (r-p)/[(r+p)-2rp] where r is proportion of food in the gut and p is relative proportion of good food in the environment

Lotka Voltera Model

model of logistic growth modified to show the impact of competition

Guase

wrote The Struggle for Existence, established the competitive exclusion principle, stating that two species with identical niches cannot coexist indefinitely; validated this concept experimentally, showing that competing microorganism species (e.g., Paramecium) cannot share limited resources