Interaction among species

Lecture 37

niche

set of physical and biological conditions a species requires for growth, survival and reproduction.

• two species cannot co-exist if their niches are identical

• can if they use slightly different resources —> ”resource partitioning”

Antagonism

one benefit, one is harmed

Mutualism

both benefit (not always equal)

competition

neither benefits

• different species can depend on same prey/resources

• Unstable: eventually one becomes locally extinct

• Competition drives one species to extinction

commensalims

one benefits, other is unaffected

• ex: orchids sitting, living on branch of large tree

amensalism

one is harmed, other is unaffected

Predation: antagonistic

• predators have affective traits (fast, strong, sharp claws etc.)

• Prey have protective traits (big ears, high reproduction rate, cryptic coloration)

• Both have adaptions that increase success in interaction

Aposematism

• producing toxins as defense has drawbacks (warming predators)

• Bright coloration —>warn predator of toxic prey

• Nontoxic species can mimic —> Batesian mimickry “pretending”

mimicry

• Batesian: harmless species match appearance of toxic species

  • harmless mimicking harmful

• Mullerian: both species are toxic

  • “harmful mimicking harmful”

herbivory

animals eat pants

what are plants defense mechanisms against herbivory?

• toxins, thorns, hairs, waxy cuticle

• Silica in cell walls

• production of attractants (for predators of herbivores when attacked)

parasitism

• draws nutrition form its host without killing it

• Host evolve defenses, parasites coevolve

Microparasites

• bacteria, viruses, protists

  • dwell inside hots, reducing vigor

macroparasites

• can live inside or outside host

  • worms, fleas/ticks

How are angiosperms and pollinators and example of unequal mutualism

• Angiosperms (3/4’s) and pollinators

  • pollinators get food (pollen, nectar)

  • plants has its male gametophytes directly delivered)

  • Flowers, insects coevolved

what is resource partioning among competing species?

selection drives changes in predation —> ex: owls hunt at night where hawks hunt by day

interference competition

• one species interferes with access to resource

exploitation competition

• one species is more effective in using resource

• can lead to resource allocation

competition can be equal for a resource but skewed if one species is preferentially preyed on by a shared predator