Module 1, p2

Species interactions

Ways species affect each other, including competition, predation, parasitism, herbivory, mutualism, and commensalism.

Competition

Interaction where species share a limited resource, harming both.

Resource partitioning

Evolutionary change reducing overlap in resource use through space, time, or morphology.

Predation

Interaction where one animal kills and consumes another.

Predator effects

Can regulate prey populations and drive evolution of prey defenses.

Predator-prey example

Wolves and moose on Isle Royale; predator decline caused moose overpopulation and starvation.

Parasitoid

Specialized predator laying eggs inside a host, whose larvae consume it.

Prey defenses

Behavioral, morphological, or chemical adaptations to avoid predation.

Camouflage

Morphological adaptation hiding prey, such as the satanic leaf-tailed gecko.

Spines

Physical defense in porcupines, stingrays, and plants to deter consumers.

Chemical defenses

Toxins or distasteful chemicals deterring predators, as in poison dart frogs.

Mimicry

Harmless species evolve to resemble toxic species for protection.

Parasitism

Interaction where one organism lives on or in a host, usually not killing it.

Pathogen

Parasite causing disease, such as viruses, bacteria, fungi, or protists.

Herbivory

Interaction where animals consume plants or algae.

Herbivore impacts

Can greatly reduce plant abundance and change community composition.

Plant defenses

Spines or chemicals that deter herbivores.

Mutualism

Interaction benefiting both species by improving survival or reproduction.

Pollination

Mutualism between plants and pollinators like bees, birds, and bats.

Fig-fig wasp

Example where each fig species is pollinated by a unique wasp species.

Acacia-ant mutualism

Ants live in acacia thorns and protect trees while feeding on nectar.

Coral-algae mutualism

Corals provide shelter; algae provide sugars via photosynthesis.

Lichen mutualism

Fungi supply nutrients; algae supply carbohydrates through photosynthesis.

Photosynthesis

Process using sunlight to convert CO₂ and water into glucose and oxygen.

Commensalism

Interaction where one species benefits and the other is unaffected.

Commensalism example

Birds nesting in trees; fish hiding in coral reefs.

Interaction summary

Competition harms both; predation, parasitism, and herbivory benefit one and harm the other; mutualism benefits both; commensalism benefits one, no effect on other.

Native species

Species living in its historical range for thousands or millions of years.

Exotic species

Species living outside its historical range, also called alien species.

Invasive species

Exotic species spreading rapidly and harming native species.

Invasive spread

Occurs because they lack natural enemies in new regions.

Rat invasion

Rats introduced to islands caused extinctions of ground-nesting birds.

Fungal invasion

Exotic fungi killed most American elm and chestnut trees in North America.

Avian malaria

Exotic protist in Hawaii drove many bird species to extinction.

Ecosystem boundaries

Distinctions between ecosystems, sometimes defined by topography or administrative criteria.