1. © 2011 Pearson Education, Inc. AP Environmental Science Mr. Grant Lesson 30 Species Interactions

2. © 2011 Pearson Education, Inc. Mastery Check How do predation, parasitism, and herbivory differ? Predation is the relationship in which one organism, a predator, consumes another, its prey. Parasitism is a relationship in which one organism, the parasite, depends on another, the host, for nourishment or some other benefit while simultaneously harming the host (but generally not killing it). Herbivory is the consumption of a plant or a portion of a plant by an animal, the herbivore.

3. © 2011 Pearson Education, Inc. Objectives: Define the term resource partitioning. Compare and contrast the major types of species interactions.

4. © 2011 Pearson Education, Inc. Resource partitioning: The process by which species adapt to competition by evolving to use slightly different, or to use their shared resources in different ways, thus minimizing interference with one another. Define the term resource partitioning.

5. © 2011 Pearson Education, Inc. Compare and contrast the major types of species interactions. Species interactions shape and define communities Natural species interactions: -Competition  relationship in which both species are harmed -Exploitative  one species benefits and the other is harmed -Predation, parasitism, and herbivory -Mutualism  relationship in which both species benefit

6. © 2011 Pearson Education, Inc. Competition results when individuals or species vie for limited resources. Like what? Food, space, water, shelter, mates, sunlight It can occur within or among species and can result in coexistence or exclusion. Within species… Intraspecific competition High population density leads to increased competition Among species… Interspecific competition It also can lead to realized niches, resource partitioning, and character displacement.

7. © 2014 Pearson Education, Inc.  Fundamental niche  the full niche of a species  Realized niche  the portion of the fundamental niche that is actually filled  Due to competition or other species’ interactions

8. © 2014 Pearson Education, Inc.

9.  Character displacement  competing species diverge in their physical characteristics due to the evolution of traits best suited to the resources they use Competition is reduced when two species become more different

10. © 2011 Pearson Education, Inc. In predation, an individual of one species kills and consumes an individual of another. Predation is the basis of food webs and can influence population dynamics and community composition. Predator–prey interactions can sometimes drive cyclical population dynamics

11. © 2011 Pearson Education, Inc. Natural selection leads to evolution of adaptations that make predators better hunters Individuals who are better at catching prey: -Live longer, healthier lives -Take better care of offspring Prey face strong selection pressures: they are at risk of immediate death -Prey have evolved elaborate defenses against being eaten

12. © 2011 Pearson Education, Inc. In parasitism, an individual of one species derives benefit by harming (but usually not killing) an individual of another. Some parasites are free- living Infrequent contact with their hosts Ticks, sea lampreys Some live within the host Tapeworms Others cause disease These are pathogens

13. © 2011 Pearson Education, Inc. Parasitoids  insects that parasitize other insects -Lay eggs in larva or adults of other species -Kill the host Coevolution  process in which hosts and parasites become locked in a duel of escalating adaptations -Has been called an evolutionary arms race -Each evolves new responses to the other -It may not be evolutionarily beneficial to the parasite to kill its host

14. © 2011 Pearson Education, Inc. Herbivory is an explorative interaction in which an animal feeds on a plant. -May not kill the plant, but affects its growth and survival Defenses against herbivory include: -Chemicals: toxic or distasteful -Thorns, spines, or irritating hairs -Other animals: protect the plant Like in parasitism, herbivore– plant interaction can result in coevolution.

15. © 2011 Pearson Education, Inc. In mutualism, species benefit from one another.

16. © 2011 Pearson Education, Inc. In some mutualistic and parasitic interactions, the participants are symbiotic, whereas in others they are free living. Symbiosis  mutualism in which the organisms live in close physical contact Each partner provides a service the other needs (food, protection, housing, etc.) Microbes within digestive tracts Mycorrhizae: plant roots and fungi Coral and algae (zooxanthellae) Pollination  interaction in which bees, bats, birds, and others transfer pollen from one flower to another, fertilizing its eggs

17. © 2011 Pearson Education, Inc. Central Case Study: Black and White and Spread All Over: Zebra Mussels Invade the Great Lakes In 1988, zebra mussels were accidentally introduced to Lake St. Clair in discharged ballast water By 2010, they had invaded 30 states -No natural predators, competitors, or parasites They cause millions of dollars of damage to property each year

18. © 2011 Pearson Education, Inc. Predators kill and consume prey Zebra mussels eat phytoplankton and zooplankton -Both populations decrease in lakes with zebra mussels Zebra mussels don’t eat cyanobacteria - Cyanobacteria increase in lakes with zebra mussels Predators may also be prey -Zebra mussels are being eaten by diving ducks, muskrats, crayfish, flounder, sturgeon, eels, carp, and freshwater drum

19. © 2014 Pearson Education, Inc. Competition can occur when resources are limited  Competitive exclusion  one species completely excludes another species from using a resource  Zebra mussels displaced native mussels in the Great Lakes  Species coexistence  neither species fully excludes the other from resources, so both live side by side  This produces a stable point of equilibrium, with stable population sizes  Species minimize competition by using only a part of the available resource (niche)