Intro to Ecology Unit 2

Interspecific competition

Interspecific competition

________ can lead to directional selection that reduces niche overlap.

Alarm call

________: to bring in a mob (crows), or alert others to hide (ground squirrels)

Symbolic relationships: Commensalism

________: One benefits, the other is not harmed, but does not.

Allopatric

________- live in different areas- do not overlap.

small scales

On ________, individuals within a population may show clumped, uniform, or random distribution.

Symbolic relationships: Parasitism

________: one is harmed and the other benefits.

Müller

________ hypothesized populations maintained through balance of downstream and upstream dispersal.

Mullerian Mimicry

________: two or more species that are harmful and look similar.

Cryptic coloration

________: Blend in with the background (Camouflage)

Batesian mimicry

________: A harmless species looks like a harmful species.

Niche

________: An organisms ecological role plus its habitat.

Gause

________ (1934) studied interspecific competition in two closely related species of paramecium.

State Endangered

threatened with extirpation from the state

State threatened

may become endangered with continued stress

Batesian mimicry

A harmless species looks like a harmful species

Paratisitim

one is harmed and the other benefits

Random Distribution

• Resources typically uniform in distribution

• Individuals not attracting, nor repelling each other

Uniform Distribution

• Common when resources are scarce, and individuals are competing for them

• Individuals avoid/repel each other

• Maximizes resource use

Clumped Distribution

• Resources tend to be clumped

• Better protection from predators

• More likely to eat

• Easier for mating and nurturing

Plant Distribution and Abundance

Typically clumped, with decreasing numbers on extreme ends of environmental variable gradient

Constant Dispersal of Aquatic Macroinvertebrates

Doesn’t matter the time of day, they will move whenever

Catastrophic Dispersal of Aquatic Macroinvertebrates

Moved by a flood or big event

Behavioral Dispersal of Aquatic Macroinvertebrates

Move or stay in place at specific times on purpose (i.e., predators)

Rarity I

• Extensive Range, Broad Habitat Tolerance, Small Local Populations

  • Peregrine falcon

Rarity II

• Extensive Range, Large Populations, Narrow Habitat Tolerance

  • Passenger pigeon

Rarity III

• Restricted Range, Narrow Habitat Tolerance, Small Populations (rarest of rare)

  • California condor

Community

a group or association of populations of two or more different species occupying the same geographical area at the same time

Population

a group of individuals belonging to one species, living together in on area

Competition

an interaction between individuals of the same or different species, in which the fitness of one is lowered by interaction with the other over a limited resource

Mechanisms of Competition: Inference competition

Direct, aggressive interaction between individuals

Mechanisms of Competition: Exploitation competition

Indirect interaction between individuals through limited resource (i.e., compete through mutual effects on resource)

Intraspecific Competition

• Competition with members of own species

• May involve interference or exploitation

Interspecific Competition

• Competition between individuals of different species

• May involve interference or competition

Principle of Competitive Exclusion

• Two species with identical niches cannot coexist indefinitely

One will be a better competitor, have higher fitness, and exclude the other

Fundamental niche

represents the range of conditions and resources within which a species can persist (ideally)

Realized niche

Competitors can resist distribution of a species to some smaller part of the fundamental niche

Competition; predation

___________ and ____________ restrict fundamental niche to smaller realized niche

Two possible outcomes of competition between species with identical niches:

1. Extinction, or exclusion of one species

2. Change in one species to use different resources (“Ghost of competition past”)

Species can become resource specialists, minimize niche overlap Species can be generalists with high overlap, and competition

Competition

_____: Can result in evolution of niches