Chapter 47 Community Ecology Community Ecology Outline The

Chapter 47 Community Ecology

Community Ecology Outline The Concept of the Community Diversity and Composition Models The Structure of Communities Island Biogeography Habitat and Ecological Niche Competition Between Populations Predator-Prey Interactions Symbiotic Relationships Community Development Community Biodiversity 2

Community Ecology Community Concept An assemblage of populations interacting with one another within the same environment Composition is a listing of various species in the community Diversity includes both species richness and species diversity 3

Community Structure 4

Community Ecology 5 Diversity and Composition Models Gleason - Individualistic Model Each population is there because its abiotic requirements are met Clements - Interactive Model Community is the highest level of organization Dependent on biotic interactions

Species Richness of Communities 6

Community Ecology Island Biogeography Mac. Arthur and Wilson Developed a general model of island biogeography Explains and predicts how the community diversity of an island is affected by Distance from the mainland, and Size of the island 7

Model of Island Biogeography 8

Community Ecology 9 Community Structure Competition When two species compete, the abundance of both species is negatively impacted Predation (or parasitism) Expected to increase the abundance of the predator (or parasite) And reduce the abundance of the prey (or host)

Community Ecology 10 Habitat and Ecological Niche Habitat The area an organism lives and reproduces in Ecological niche The role a species plays in its community Includes its habitat, and Its interactions with other organisms Fundamental niche - All conditions under which the organism can survive Realized niche - Set of conditions under which it exists in nature

Feeding niches for Wading Birds 11

Community Ecology 12 Competition Between Populations Interspecific competition Members of different species require the same resource The supply of the resource is limited Competitive Exclusion Principle No two species can occupy the same niche at the same time Resource Partitioning decreases competition Can lead to character displacement

Competition Between 13 Two Laboratory Populations of Paramecium

Character Displacement in Finches on the Galápagos Islands 14

Niche Specialization Among Five Species of Coexisting Warblers 15

Competition Between Two Species of Barnacles 16

Community Ecology Predator-Prey Interactions Predation One living organism, the predator, feeds on another, the prey Predator is larger Predator has lower reproductive rate Prey usually entirely consumed Presence of predators can decrease prey densities, and vice-versa 17

Predator-prey Interaction Between 18 Paramecium caudatum and Didinium nasutum

Predator-prey Interaction 19 Between a Lynx and a Snowshoe Hare

Community Ecology Prey Defenses Prey defenses Mechanisms that thwart the possibility of being eaten by a predator Spines Tough Epidermis Poisonous Chemicals Camouflage Bright Coloration Flocking Behavior 20

Camouflage in the Anglerfish 21

Anti-predator Defenses 22

Community Ecology 23 Mimicry One species resembles another species Mimicked species possesses an overt antipredator defense Batesian Mimicry - Mimic lacks defense of the organism it resembles Müllerian Mimicry - Mimic shares same protective defense

Mimicry Among Insects with Yellow and Black Stripes 24

Community Ecology 25 Symbiotic Relationships Symbiosis Interactions in which there is a close relationship between members of two species Parasitism Parasite derives nourishment from a host, and may use host as habitat and mode of transmission w Endoparasites w Ectoparasites

The Life Cycle of a Deer Tick 26

Community Ecology 27 Commensalism Symbiosis, cont. Commensalism A symbiotic relationship in which one species benefits and the other is indifferent w Remoras and Sharks Many supposed examples may turn out to be mutualism or parasitism Inferred amount of harm or benefit two species do to one another is subject to investigator bias

Clownfish Among Sea Anemone’s Tentacles 28

Community Ecology 29 Mutualism Symbiosis, cont. Mutualism A symbiotic relationship in which both members of the association benefit Need not be equally beneficial to both species w Cleaning Symbiosis Often help each other obtain food or avoid predation w Bacteria in human intestinal tract

Mutualism Between the Bullhorn Acacia Tree and Ants 30

Cleaning Symbiosis 31

Community Ecology Community Development Ecological Succession A predictable pattern of change in species replacements following a disturbance Primary Succession occurs in areas where there is no soil formation Secondary Succession begins in areas where soil is present w Pioneer Species 32

Secondary Succession 33

Secondary Succession in a Forest 34

Community Ecology Succession Models Facilitation Model Each stage facilitates invasion and replacement by organisms of the next stage Succession in a particular area will always lead to the same type of community Climax Community 35

Community Ecology 36 Succession Models Inhibition Model Colonists remain and inhibit growth of other plants until the colonists are damaged or die Tolerance Model Different types of plants can colonize an area at the same time Chance determine which seeds arrive first

Community Ecology Community Diversity Community stability can be recognized in three ways Persistence through time Resistance to change Recovery once a disturbance has occurred 37

Community Ecology 38 Intermediate Disturbance Hypothesis If widespread disturbances occur frequently, diversity will be limited If diversity is high, only moderate disturbances have been occurring with moderate frequency

The Intermediate Disturbance Hypothesis 39

Community Ecology 40 Predation, Competition, and Biodiversity Predation by a particular species may reduce competition and increases diversity Such predators are referred to as keystone predators Exotic species May lead to unbridled competition Resultant reduction in biodiversity

Effect of a Keystone Species 41

Community Ecology Review The Concept of the Community Diversity and Composition Models The Structure of Communities Island Biogeography Habitat and Ecological Niche Competition Between Populations Predator-Prey Interactions Symbiotic Relationships Community Development Community Biodiversity 42

Ending Slide Chapter 47 Community Ecology