Biological Interactions and Distribution

January 21st

Predation

• Predation – when one organism consumes another– Animal-animal predation– Animal-plant predation

• Stenophagous – selective predators– 80% of butterfly species– 90% of plant-eating insects

• Euryphagous – non-selective predators– Most terrestrial birds and mammals

Reasons for Stenophagy

• Optimal foraging theory

• Toxins

• Microenvironment

• Neural capabilities

• Lotka-Volterra model – explains the fluctuations in populations of stenophagous predators and their prey species

Keystone Species

• A keystone species is a species whose very presence contributes to a diversity of life and whose extinction would consequently lead to the extinction of other forms of life.

• Keystone species help to support the ecosystem (entire community of life) of which they are a part.

Keystone Species

Competition

• Interspecific competition

• Intraspecific competition

• Two forms of competition– Resource exploitation– Interference competition

• Allelopathy

Allelopathy

Creosote

Black Walnut

Competition

Competition

Competition

Diffuse Competition

Predator Medicated Competition

Mutualism

• Both species benefit

• Pollinators

• Ants and aphids

• Acacias and ants