PACKET #81 CHAPTERS #54 & #50 Community Ecology

Review & Introduction Community  Assemblage of populations, of different species, that live and interact in the same place at the same time Community Ecology  Description and analysis of patterns and processes within the community

Introduction II Communities are difficult to study  Large number of organisms and many different species that interact with one another and are interdependent in a variety of ways  Species compete for food, water, living space and other resources  Communities vary in size  Lack precise boundaries  Rarely completely isolated  Within a community, no species exists independently of other species.

COMMUNITY STRUCTURE & FUNCTIONING Community Ecology

Niche The role of a species within a community Describes all aspects of an organism’s existence  Not only habitat, but much more Fundamental Niche  Niche that an organism would occupy in the absence of competition Realized Niche  Niche that an organism occupies in the presence of competition

Niche II Limiting resources restrict the ecological niche of a species  Soil composition  Climatic extremes  Any environmental resource that is scarce or unfavorable Biotic and abiotic factors may influence an organism’s niche

Competition Intraspecific  Competition between members of same species Interspecific  Competition between members of different species Competition between two species with overlapping niches may lead to competition exclusion  Results in the exclusion of one species due to interspecific competition  Coexistence occurs when overlap between niches is reduced

Natural Selection Shapes the body forms and behaviors of both predator and prey  Pursuit and ambush  Chemical protection  Plant defense  Varied defense adaptations of animals to avoid predators  Fleeing  Hiding Warning colors Batesian mimicry Resemblance of a harmless organism to a harmful or unpalatable organism Mullerian mimicry Similar morphology of a group of harmful or unpalatable organism Monarch & Viceroy butterflies  Living in large groups

DEFENSE MECHANISMS Community Ecology

Defense Mechanisms Hiding Use of warning colors  Aposmatic Colors  A warning coloration such as a 'striking' color pattern designed to attract attention and to warn predators away.

Defense Mechanisms Hiding Batesian mimicry  Resemblance of a harmless organism to a harmful or unpalatable organism

Defense Mechanisms Hiding Mullerian mimicry  Similar morphology of a group of harmful or unpalatable organism  Monarch & Viceroy butterflies

Symbiosis Any intimate relationship or association between members of two or more species  Greek sym = together  Greek bios = life

Types of Symbiosis I Mutualism  Benefits are shared  Nitrogen fixing bacteria & legumes  Zooxanthellae and reef- building coral  Mycorrhizae facilitate mutalistic relationships between fungi and the roots of a wide variety of plants

Types of Symbiosis II Commensalism  Taking without harm  Epiphytes living on tropical tress benefit from the habitat of the host, but the host is not harmed or benefited

Types of Symbiosis III Parasitism  Taking at another’s expense  Parasite benefits while host is harmed  Well adapted parasite does not kill the host  Parasite that causes the death of the host is a pathogen

Keystone Species Affect the character of the community Have a great effect on other species in the community  Commonly are the top predators Dominant species influence the community as a result of their greater size or abundance  Trees are the dominant species in forests because they change the local environment  Coral, an animal, in coral reefs

COMMUNITY DEVELOPMENT Community Ecology

Succession Process of community development over time, with one species being replaced by another

Succession II Primary Succession  Occurs when a community develops in a “lifeless” environment  Occurs on bare rock when rock is eventually transformed into soil  Occurs on newly formed volcanic larva and recently glaciated rock

Succession III Secondary Succession  Occurs when a community develops where a previous community existed  Occurs where soil already exists  Areas denuded or modified by fire or agriculture  Abandoned farmland Keep in mind that disturbances impact succession

Studying Succession Ecologists continue to study community structure Clements  Developed organismic model  Emphasizes the interdependence of species within the community Gleason  Developed individualistic model  Emphasizes species individually Most research is conducted here

Review

Students are encouraged to place their own questions and charts on the following slides.