Interspecific Interactions and the Ecology of Communities Chapter 57

Biological Communities Community “all the living organisms and the environment they live in” Communities are characterized by: Species diversity “Number of different species present” Species composition “Number of individuals in each species” Primary productivity “Amount of energy produced”

Functional Roles of Living Organisms Two types: Autotrophs Heterotrophs

Functional Roles of Living Organisms Organisms are categorized by what they eat: Primary consumers Secondary consumers Tertiary consumers

Roles Outside the Trophic Pyramid Scavengers Detritivores Feed off detritus There are 2 types of detritivores Detritus feeders Decomposers

Trophic Level Pyramid

Ecological Niche Niche: “A species’ way of life or functional role in the ecosystem” There are two types of ‘niches’ Fundamental niche Realized niche

Niches - Competition Because of competition, realized niches are much smaller than fundamental niches. 2 Types of competition: Intraspecific competition Interspecific competition Exploitative competition

Ways to Avoid Competition Resource partitioning Morphological Temporal Spatial Morphological Spatial Temporal

Predator–Prey Predation and Coevolution

Predator–Prey Morphological and Chemical defenses:

Protect themselves both offensively and defensively. Prey Protect themselves both offensively and defensively.

Mimi c r y Wasp B a t e s I n Moth Honey bee Flower Fly

Mullerian Mimicry

Species Interactions Commensalism: “One species benefits. The other is neither hurt nor helped” Mutualism: “both species benefit” Parasitism: “one species benefits at the expense of another”

Commensalism Mutualism Parasitism

Ecological Succession and Disturbance Primary succession Secondary succession

Mt. St. Helen’s Succession After eruption 1980 1st plant - Lupines Today Shrubs

Succession and Disturbance Animal species in a disturbed community also change over time As vegetation changes, animal habitat changes Plants that need animals for pollination or to spread their seed take longer to return.