Ap bio: ecology

Photoperiodism

A plant's response to seasonal changes in length of night and day

- flower bloom according to amount of uninterrupted darkness

Tropism

A growth response of a plant toward or away from a stimulus

Gravitropism

A growth response to gravity

- negative: growing up, away from the pull of gravity

Auxins

Hormones involved in plant-cell elongation, shoot and bud growth, and rooting.

- promote growth on one side of the plant

- tip of plant

Gibberellins

A class of related plant hormones that stimulate growth in the stem and leaves, trigger the germination of seeds and breaking of bud dormancy, and stimulate fruit development.

cytokinins

promote cell division, leaf enlargement, slow aging of leaves

ethylene

plant hormone that stimulates fruits to ripen

abscisic acid

inhibits cell growth, helps close stomata

biosphere

part of Earth in which life exists including land, water, and air or atmosphere

ecosystem

A biological community of interacting organisms and their physical environment.

community

All the different populations that live together in an area and interact with each other

simpson’s diversity index

used to measure biodiversity of a habitat

the higher the index value, the more diverse a community is

1 - sum(n/N)²

trophic cascade

negative effect the removal of or decrease in a key species has on other trophic levels

niche partitioning

decrease in competition over limited resources between two similar species because each species is accessing the resource in different ways

population

A group of individuals that belong to the same species and live in the same area

biomes

a broad, regional type of ecosystem characterized by distinctive climate and soil conditions and a distinctive kind of biological community adapted to those conditions.

- tundra, taiga, temperate deciduous forest, grasslands, deserts, tropical rainforests

carbon cycle

The organic circulation of carbon from the atmosphere into organisms and back again

producers

Organisms that make their own food

gross productivity

the total gain in energy or biomass per unit area per unit time

net productivity

the gain in energy or biomass per unit area per unit time that remains after deductions due to respiration

consumers

An organism that obtains energy and nutrients by feeding on other organisms or their remains.

- macromolecules --> smaller monomers

primary consumers

animals that feed on producers; ex. herbivores

secondary consumers

carnivores/omnivores that eat herbivores

tertiary consumers

carnivores that eat other carnivores

keystone species

A species that influences the survival of many other species in an ecosystem

10% rule

Only 10% of the total energy produced at each trophic level is available to the next level. The amount of energy passed up to the levels of the food pyramid reduces as you go up.

bioaccumulation

The accumulation of a substance, such as a toxic chemical, in various tissues of a living organism.

- animal who eats prey with a high concentration of toxin dies

biomagnification

accumulation of pollutants at successive levels of the food chain

population ecology

The study of populations in relation to the environment, including environmental influences on population density and distribution, age structure, and variations in population size.

population growth

births - deaths / N

density independent factors

limiting factor that affects all populations in similar ways, regardless of population size

- natural disasters

density dependent factors

factor that limits a population more as population density increases

- resources

r strategists

species that grow exponentially when environmental conditions allow them to reproduce

k strategists

species where organisms tend to reproduce later in life, have a smaller number of offspring, and are long living

- due to their lack of competition

ecological succession

series of gradual changes that occur in a community following a disturbance

primary succession

An ecological succession that begins in an area where no biotic community previously existed

pioneer organisms

The first to colonize a barren environment in primary ecological succession.

Sere/seral stage

each phase of succession

secondary succession

Succession following a disturbance that destroys a community without destroying the soil

ozone depletion

thinning of Earth's ozone layer caused by CFC's leaking into the air and reacting chemically with the ozone, breaking the ozone molocules apart

acid rain

Rain containing acids that form in the atmosphere when industrial gas emissions (especially sulfur dioxide and nitrogen oxides) combine with water.

desertification

Degradation of land, especially in semiarid areas, primarily because of human actions like excessive crop planting, animal grazing, and tree cutting.

DDT

A colorless odorless water-insoluble crystalline insecticide that tends to accumulate in ecosystems and has toxic effects on many vertebrates; became the most widely used pesticide from WWII to the 1950's; implicated in illnesses and environmental problem; now banned in the US.

Populations consist of:

A single specifies that:

Occupy the same general area

Rely on the same resources

Are influenced by similar environmental factors

Have a high likelihood of interacting with one another

Population density

# of individuals per unit area/volume

- can directly count # of individuals or work out an estimate based on indirect indicators or signs

clumping dispersion

Individuals "flock together" in bunches; can indicate a heterogenous environment or social interactions between individuals; most common (i.e. fish swim in schools & birds migrate in groups to avoid predation).

-usually prey, to avert predators

uniform dispersion

The pattern in which individuals are equally spaced throughout a habitat.

- territories formed based on need for resources

Random dispersion

Random spacing of individuals of the same species within an area.

- usually plants, because of the way that seeds are distributed

Demography

The scientific study of population characteristics, and what can cause growth and decline

Addition to population

births and immigration

population elimination

Occur through deaths and emigration

Two important demographic features

Age and gender ratio

Life tables

Average life expectancy of an individual

Survivorship curves

a graph that represents the distinct patterns of species survival as a function of age

Type 1 survivorship curve

low death rates during early and middle life and an increase in death rates among older age groups

- humans

type 2 survivorship curve

fairly constant death rate at all ages (small mammals and large birds)

type 3 survivorship curve

a pattern of survival over time in which there is low survivorship early in life with few individuals reaching adulthood

- sharp drop

- marine invertebrates (bivalves)