Interactions with Living Organisms

Competition

  • Competition happens when multiple organisms attempt to acquire the same essential resources within the same habitat.
  • It regulates population size by restricting the number of organisms that can thrive on available resources.
  • Animals compete for resources similarly to plants.
  • Limited resources lead to mortality or relocation for some animals.
  • Example: Plants close together compete for water, sunlight, and nutrients.
  • Species in the same area compete for grasses and plants, especially during shortages.

Symbiotic Relationships

  • Symbiosis involves interactions between different species where at least one benefits.
  • Three types of symbiosis:
    • Mutualism
    • Parasitism
    • Commensalism
  • Examples:
    • Cattle egrets eating bugs off cows
    • Cowbirds laying eggs in other birds' nests.

Mutualism

  • Mutualistic relationships are a type of symbiosis where both participating species benefit.
  • Example: Birds eat ticks off rhinoceroses, cleaning them and flying off when danger approaches.
  • The rhinoceros provides a perch and food source for the birds (Obligate Mutualism).

Parasitism

  • Parasitic relationships involve one animal benefiting while the other is harmed.
  • Example: Starlings and cowbirds lay eggs in other birds' nests (Brood Parasitism).
  • The cowbird chick hatches early and removes other eggs, then gets more food because it calls the loudest, leading to starvation of the other chicks.

Commensalism

  • Commensalism is a relationship where one organism benefits, and the other is neither helped nor harmed.
  • One animal benefits without causing harm or cost to the other.
  • Example: Birds nesting in trees (Inquilinism).
  • The tree provides shelter, but the bird's nest does not affect the tree.

Chart Examples

  • Box 1: Cuckoo removes two eggs and lays two of its own.
    • Parasitism (Brood parasitism)
  • Box 2: Mongoose picks through a warthog’s fur for ticks.
    • Mutualism (Facultative)
  • Box 3: Jaeger steals food from a gull.
    • Parasitism (Kleptoparasitism)
  • Box 4: Ethiopian wolf searches for rodents in gelada monkey territory.
    • Commensalism (Inquilinism)
  • Box 5: Arum lily attracts bugs and provides seeds eaten by wall lizards.
    • Mutualism (Facultative)
  • Box 6: Golden jackal waits for tiger to finish eating and takes leftovers.
    • Commensalism (Scavenging)
  • Box 7: Remora fish attaches to a shark for transportation.
    • Commensalism (Phoresy)

Predation

  • Ecosystems have predators and prey.
  • Predation is essential for maintaining food balance.
  • Predators occupy higher levels in the food web, while prey occupy lower levels.
  • This creates a balance in the number of predator and prey species.
  • Imbalance leads to extinction due to either a decline or rise in population on one side, outcompeting the other.
  • Loss of food sources results in extinction for both.
  • Predator: Animal that hunts other animals for food.
  • Prey: Animal that is hunted by predators.