1. Relationships in the Ecosystem

2. Predation
Predation = the act of one organism consuming another organism for food
Predator = the organism that pursues another organism
Prey = the organism that is pursued
Lizardfish & Gobey

3. Predation Predators evolve adaptations to capture prey and vice versa
Predator Adaptations: spider webs ; tiger stripes
Prey Adaptations: mimicry, plant toxins

4. Predator/Prey Population Sizes
Predator/Prey population sizes are closely linked (# Prey effects # Predators!)
Larger animals have longer population cycles because they live longer and reproduce more slowly than smaller animals
Large prey populations = more predators!

5. Species Interactions
Symbiosis: the close relationship that exists when two or more species live together
Types of Symbiosis: Parasitism, Mutualism, Commensalism

6. Mutualism
Mutualism = the relationship between two or more organisms that live closely together and benefit from each other
-Example: Lichens = mutualism between fungi and algae
Algae provide food for the fungi
Fungi provide a habitat for the algae

7. Mutualism
Humming bird (nectar) and flower (pollen is spread)

8. Commensalism
Commensalism = relationship in which one organism benefits and the other organism is not helped or harmed
Egrets on cattle = cattle stir up egrets’ food (insects)

9. Commensalism
Barnacles and whales = barnacles transported to new areas of food

10. Parasitism
Parasitism = a symbiotic relationship in which one organism benefits at the expense of another organism
Ectoparasite – external (ex: tick, lice)
Endoparasite – internal (ex: tapeworm, bacteria, roundworms)
Adaptations of a parasite vs. host?

11. Parasitism Host = the organism on which a parasite feeds
Parasite depends upon host for many functions (cannot live without host!!!)
Population size of a parasite is related to the population size of its host ( more individuals = more hosts!!!!)

12. Brood Parasitism
Brown-headed cowbirds demonstrate brood parasitism because they rely on other bird species to:
build their nests
incubate their eggs
Baby cowbirds push the host’s eggs or young from the nest
Lower population of songbirds