Symbiosis and Sociality in Ecology

Study Notes

Coevolution: Two or more species influencing each other's evolution through interactions like predation, competition, or mutualism
Mutualism: Both species benefit from the interaction, e.g., bees pollinating flowers while collecting nectar
Commensalism: One species benefits, the other is neither helped nor harmed, e.g., birds nesting in trees
Parasitism: One species (parasite) benefits at the expense of the other (host), causing harm but not immediate death, e.g., ticks feeding on mammals
Parasitoidism: A parasitoid (often an insect) lays eggs on/in a host, and developing larvae kill the host, e.g., certain wasps and caterpillars
Phoresy: One organism uses another for transportation, e.g., remoras on sharks
Obligate Mutualisms: Both species are entirely dependent on each other for survival
Facultative Mutualisms: Both species benefit but are not dependent on each other for survival

Cooperation: Individuals work together for a common benefit, e.g., hunting in packs, sharing resources
Altruism: An individual sacrifices its own fitness to help others, often relatives, e.g., animals warning their group of predators
Eusociality: Complex social organization with cooperative brood care, overlapping generations, and division of labor, e.g., ants and bees
Kin selection: Natural selection favoring altruistic behavior toward relatives, increasing the indirect fitness of the altruist by helping relatives pass on shared genes

Fitness: An organism's ability to survive, reproduce, and pass on its genes
Mutualisms enhance fitness for both species by providing benefits, such as food, protection, or other resources
Case study: A bee pollinating a flower benefits by receiving nectar (increasing its fitness), while the plant increases its fitness through successful reproduction
Mutualisms are a result of coevolution, in which both species evolve in response to the other and optimize their fitness
Plants and animals use various structures and behaviors to obtain food, shelter, and protection through mutualistic interactions

In 1859, two dozen rabbits were released in Australia.
Populations exploded due to abundant food, lack of natural predators, and competitors.
Myxoma virus, related to smallpox and carried by mosquitos, was introduced as a biological control.
The virus, initially highly deadly, caused a decline in rabbit populations.
Coevolution: Over time, virus and rabbits coevolved, with the virus becoming less deadly and rabbits developing some resistance.