ecology; unit 3

Competition

An interaction with negative effects on both species that require the same limited resource to survive, grow, and reproduce

Interspecific competition

occurs between different species

intraspecific competition

involves competition between individuals of the same species

Exploitative Competition

Individuals consume and drive down the abundance of a resource to the point that other individuals cannot persist

- ex. squirrels foraging for nuts

Interference Competition

• Competitors directly defend resources from other individuals

• Aggressive interactions between individuals

Apparent Competition

• Two species appear to compete for a shared resource but in fact cause a negative effect on each other due to mechanisms that are not competition

Competitive Exclusion Principle

• Two species cannot coexist indefinitely when they are both limited by the same resource

Competing Species

• Competing species are more likely to coexist when there is a difference in their niche

• May preferentially use different subsets of available resources

• May be better adapted to different conditions (e.g., soil types, climate conditions, etc.)

Mutualism

A mutually beneficial interaction between individuals of different species

- Alpheid shrimp and goby fish,

mycorrhizal fungi, ants and acacia trees, nitrogen-fixing bacteria

Pollination

Pollinating insects pollinate flowers as they forage for pollen and nectar

- pollinator gets a source of food

- plant increases chances of successful fertilization

scopa

- hair on bees to carry pollen

- on hind legs or abdomen

corbicula

a flat structure on honey bees hind legs to carry pollen

Herbivory

Eating tissue or internal fluids of living plants or algae

Predation

Killing and eating other organisms (prey)

specialist herbivores

Feed on one or two plant species only

specialist predators

predators that show a strong preference for certain prey species

generalist predators

predators that eat a great variety of prey species

generalist herbivores

can feed on many plant species

What types of relationships do the Lotka-Volterra equations model?

interactions between predator and prey populations

coevolution

When two or more species affect each other's evolution

bottom-up controls

Availability of resources

top-down controls

Predation, parasites, or disease

Armor/Deterrents

Physical adaptations include large size, speed, and body armor or modifications

Venom

injected (active)

Poison

ingested or absorbed (passive)

Crypsis

Camouflage that lets an individual match its environment or breaks up its outline to blend in better with its background

aposematism

When distastefulness evolves in association with very conspicuous colors and patterns

Batesian mimicry

When palatable species evolve warning coloration that resembles unpalatable species-butterfly

Müllerian mimicry

When several unpalatable species evolve a similar pattern of warning coloration-frogs

Parasite

an organism that lives in/on another organism, usually without killing it

Host

the organism a parasite lives in/on

Vector

an organism a parasite uses to move between hosts

Ectoparasite

lives on the outside of an organism

Endoparasite

lives inside an organism

Hemiparasitic plants

photosynthetic, contain chlorophyll

• mistletoe

• Depend on host for water and nutrients carried in the water

Holoparasitic plants

non-photosynthetic

• dodder

• Completely dependent on host for survival

Why are Black-Footed Ferrets endangered?

use previous knowledge, talk out loud

Allee Effect

A type of density-dependent factor that leads to a lower population growth rate in small populations

• Difficulty finding mates

• Inbreeding depression

Environmental Stochasticity

Random variation in birth and death rates due to variation in environmental condition

Demographic Stochasticity

Random variation in birth and death rates due to variation among individuals

community

composed of all populations living together in a particular area

Ecotone

A boundary created by sharp changes in environmental conditions over a relatively short distance, accompanied by a major change in the composition of species

Interdependent Communities

Communities in which species depend on each other to exist

Independent Communities

Species do not depend on each other to exist

Species Richness

the number of species in a community

Species Evenness

a comparison of the relative abundance of each species in a community

Keystone Species

Species with high community impact relative to number of individuals

- often top predators, sea stars removing oysters

Ecosystem Engineers

Keystone species that affect communities by influencing the structure of a habitat

- beavers, structure their dams

Food webs

A complex diagram representing the many energy pathways in an ecosystem

Producer

An organism that can make its own food.

- plants, bacteria

Primary Consumer

An organism that eats producers

- rabbits, cows

Secondary Consumer

An organism that eats primary consumers

- snakes, fox

Tertiary Consumer

An organism that eats secondary consumers

- lions, sharks

Explain how a trophic cascade works

occur when predators limit the density and/or behavior of their prey and thereby enhance survival of the next lower trophic level

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

secondary succession

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

What are some characteristics that early- and late-successional stage species tend to have?

- early successional species; fast-growing, short-lived, and good at colonizing disturbed areas

- late-successional species; larger, slower-growing, and long-lived, often thriving in more stable environment