Bio 202 Unit 1

ecology

the study of the interactions between organisms and the environment

environment

other organisms and physical surroundings

organismal ecology

how an organism’s structure, physiology, and behavior meet the challenges of its environment

population ecology

factors that affect population size and how and why it changes over time

community ecology

how interactions between species (predation) affect community structure and organization

ecosystem ecology

energy flow and chemical cycling between organisms and the environment

landscape ecology

factors controlling exchanges of energy, materials, and organisms across multiple ecosystem

global ecology

how the regional exchange of energy and materials influences the functioning and distribution of organisms across the biosphere

most significant influence on distribution of land organisms

climate

climate includes:

temperature, precipitation, sunlight, and wind

intense solar radiation near equator

creates a pattern of global air circulation and precipitation

other factors that modify climate

large bodies of water and mountain ranges

seasonality

earth’s tilted axis of rotation and trip around the sun causes strong seasonal cycles in day length, solar radiation, and temperature

sun’s angle affects local environments

sun’s angle changes throughout the year

belts of wet and dry air move slightly north and south (wet and dry seasons for 20 degrees N- 20 degrees S)

upwelling

seasonal changes in wind patterns alter ocean currents→ cold water comes to the surface

nutrient rich water that stimulates growth of surface-dwelling phytoplankton and the organisms that eat it

very few spots in the ocean but 25% of fish caught globally

microclimate

fine, localized patterns in climatic conditions

an environmental feature

global climate change

large scale changes in Earth’s climate affect the biosphere

earth is warming, wind and precipitation patterns are shifting

more frequent extreme weather events

species’ ranges are already shifting as a result

climate change

a directional change to the global climate that lasts three decades or more

biome

major life zones characterized by vegetation type in terrestrial (physical environment in aquatic)

climograph

plot of the annual and mean temperature and precipitation in a particular region

shows the importance of climate on the distribution of biomes

terrestrial biomes

most are named for major climatic features and their predominant vegetation

also characterized by microorganisms, fungi and animals adapted to that environment

ecotone

areas where a terrestrial biome bleeds over into another

vertical layering of vegetation

forests: upper canopy → low tree layer → shrub understory → ground herbaceous plants → floor → roots

creates different habitats for different animals

dusturbance

an event (natural disaster or human activity) that changes a community, removing organisms and altering resource availability

biomes are dynamic, disturbance tends to be the norm

biomes are often patchy (several communities in 1 area)

even dominant plants depend on disturbance

abiotic factors

temperature, water, oxygen, salinity, sunlight, soil

if physical conditions at a site don’t let species reproduce, species won’t be found there

can fluctuate daily, seasonally, or annually

organisms can temporarily avoid stressful conditions through dormancy or hibernation

biotic factors

the presence/absence of pollinators, food resources, parasites, pathogens, and competing organisms

ability of a species to survive and reproduce is often reduced by interactions with other species (predators or herbivores)

dispersal

movement of individuals (or gametes) away from their areas of origin or centers of high population density

helps to understand the role of geographic isolation in evolution and modern species distribution patterns

adaptive radiation

rapid evolution of an ancestral species into new species that fit many ecological niches

long distance dispersal can lead to adaptive radiation

successful species transplant

some organisms must survive and successfully reproduce in the new area

if successful, potential range is greater than actual range

sometimes transplanted species disrupt their new communities and ecosystems

what controls climate at the global scale

latitudes affect intensity of sunlight

global air circulation and precipitation patterns

tilt creates seasons

what controls climate at the regional scale

mountains- moisture levels, air flow, rain-shadow effect

oceans and lakes tend to moderate the climate of lands near them (lake effect)

seasons- angle of the sun affects local environments

seasons

angle of the sun affects local environments

different regions have different seasonality's

middle to high latitudes have strong seasonal cycles, solar radiation and temps (polar regions)

species’ ranges are limited by physical environments

each species needs certain things from their environments (limits species to certain environments)

limits the amount of places a species can thrive

species’ ranges are limited by species interactions

predator vs. prey (prey won’t thrive in an environment with a larger number of predators, but predators need prey to live)

species’ ranges are limited by long-term history

species were segregated based off the separation of plate tectonics

evolutionary adaptation of species over time

pattern

elements repeat in a predictable way

qualitative observations (senses)

quantatative observations (numbers, measurable)

inference

idea about what’s happening based on evidence and reasoning

background knowledge plus clues

zonation

patterns observed across a habitat

based on distinct plants and animals

connected to gradients of abiotic factors and biotic interactions

population

group of individuals of a single species living in the same general area

described by their boundaries (natural or arbitrary) and site

density

the number of individuals per unit area or volume of a population

dispersion

pattern of spacing among individuals within the boundaries of a population

mark-recapture model

used to estimate population size when ecologists can’t count all the individuals in a population

capture a random sample of individuals (tag and release)

capture a second random set later on

see how many from the second set are already tagged

immigration

influx of new individuals from other areas

emigration

movement of individuals out of a population and into other locations

clumped dispersion

individuals are aggregated in patches (ex. mushrooms)

uniform

even spacing that may result from direct interactions between individuals in a population (ex. penguins)

can result from territoriality or chemical secretions

random

each individual’s position is independent of other individuals (ex. dandelions)

demography

study of key characteristics of populations and how they change over time

life table

summarizes the survival and reproductive rates of individuals in specific age-groups within a population

have to determine the proportion of the cohort that survives from one age group to the next (sometimes only includes females)

cohort

group of individuals of the same age

survivorship curves

survival rate data in a life table represented as a plot of the proportion in a cohort still alive at each age

reproductive rate

usually the number of females giving birth to females

exponential growth

when a population experiences ideal conditions increases in size by a constant proportion at each instant in time

(J shaped growth curve)

carrying capacity (k)

the maximum population size that a particular environment can sustain

varies over space and time with the abundance of limiting resources

logistic growth model

per capita rate of population growth approaches zero as the population size nears the carrying capacity (k)

K-N is the number of additional individuals the environment can support

(K-N)/K is the fraction of K that is still available for population growth

logistic model and real populations

populations in nature rarely match the predictions of the logistic model as closely as laboratory populations

model assumes that populations adjust instantaneously to growth and approach carrying capacity smoothly

there’s often a delay before the negative effects of an increasing population are realized

density independent

a birth rate or death rate that doesn’t change with population density

density dependent

death rate that increases with population density or a birth rate that falls with rising density

mechanisms of density dependent population regulation

competition for resources (reduces reproductive rates)

disease (transmission rate increases as population becomes more crowded, disease’s impact is density dependent)

territoriality (limit population when space becomes the resource individuals are competing for)

intrinsic factors (intrinsic psychological factors sometimes regulate population size)

toxic wastes (can contribute to density-dependent regulation of population size)

population dynamics

fluctuations in populations from year to year or place to place influenced by many factors and affect other species

metapopulation

a number of linked local populations

local populations occupy discrete patches of suitable habitat in a sea of otherwise unsuitable habitat

an individual’s ability to move between populations depends on many factors (including genetics)

interspecific interactions

an organism’s interactions with individuals of other species in the communities

competition

when individuals of different species each use a resource that limits the survival and reproduction of both individuals

can occur between members of the same species (intraspecific competition)

competitive exclusion

the local elimination of the inferior competitor due to even a slight reproductive advantage (of the superior species)

two species cannot coexist permanently in the same place

ecological niche

specific set of biotic and abiotic resources that an organism uses in its environment

two species cannot permanently coexist in a community if their niches are identical

resource partitioning

the differentiation of niches that enables similar species to coexist in a community

allopatric

geographically separate

sympatric

geographically overlapping

character displacement

the tendency for characteristics to diverge more in sympatric than allopatric populations of two species

exploitation

any type of (+/-) interaction in which individuals of one species benefit by feeding on (and thereby harming) individuals of the other species

predation

a (+/-) interaction in which an individual of one species, the predator, kills and eats an individual of the other species, the prey

aposematic coloration

often found in animals with effective chemical defenses

cryptic coloration

camouflage

batesian mimicry

a palatable or harmless species mimics an unpalatable or harmful species to which it isn’t closely related

Mullerian mimicry

2 or more unpalatable species resemble each other (cuckoo bee and yellow jacket)

herbivory

an exploitative (+/-) interaction in which an organism (herbivore) eats parts of a plant or algae, therefore harming it but not actually killing it

herbivores have specialized adaptations (chemical sensors, strong sense of smell, teeth)

parasitism

an exploitative (+/-) interaction in which one organism (parasite) derives its nourishment from another organism (its host), which is harmed in the process

endoparasites

live within their hosts (ex. tapeworms)

ectoparasites

feed on the external surface of a host (ticks and lice)

mutualism

interaction that benefits individuals of both the interacting species (+/+)

typically, both partners incur costs and benefits

commensalism

interaction that benefits individuals of one of the interacting species but neither harms nor helps the individuals of the other species (+/0)

species diversity

the variety of different kinds of organisms that make up the community

species richness

number of different species in the community

relative abundance

the proportion each species represents of all individuals in the community

biomass

total mass of all organisms in a habitat

higher in more diverse areas

trophic structure

feeding relationships between organisms of the community

food chain

the transfer of chemical energy from its source in plants and other autotrophs through herbivores to carnivores and eventually to decomposers

trophic level

the position and organism occupies in a food chain

food web

a group of food chains linked together

(a given species may weave into the web at more than 1 trophic level)

arrows on a food web go from a species to a species that eats it

energetic hypothesis

length of a food chain is limited by the inefficiency of energy transfer along the chain (10% rule)

foundation species

species that have strong effects on their communities as a result of their large size or high abundance

keystone species

not usually abundant in a community but exert strong control on community structure through their pivotal ecological roles

ecosystem engineers

species that create or dramatically alter their environment (ex: beaver)

bottom-up control

abundance of organisms at each trophic level is limited by nutrient supply or the availability of food at lower trophic levels

limited supply of producers

top-down control

abundance of organisms at each trophic level is controlled by the abundance of consumers at higher trophic levels

predators limit herbivores, herbivores limit plants

stability

a community’s tendency to reach and maintain a relatively constant composition of species

balance of nature view

competition is a key factor in determining the composition and stability of communities

the community of plants at a site has only one stable equilibrium

climax community controlled solely by climate

biotic interactions caused the species in the community to function as an integrated unit (superorganism)

other ecological view

communities can be viewed as chance assemblages of species found together because they have similar abiotic requirements

disturbance

an event (natural disaster or human activity) that changes a community by removing organisms from it or altering resource availability

keeps many communities from reaching equilibrium in species diversity or composition

nonequilibrium model

most communities are constantly changing after disturbance

the norm for most communities