Ecology and Population Dynamics

Ecological Organization Levels of organization: Organism- individual living thing Population- group of the same species in one area Community- group of different species in one area Ecosystem- living (biotic) and nonliving (abiotic) factors in an environment Biome- regional or global community of organisms

Biomes Tundra Taiga- coniferous forest (pine trees) Deciduous forest- temperate climate Rainforest Desert Grasslands Freshwater Marine- ocean (saltwater) Estuary- mix of saltwater and freshwater

Energy Flow Producers (autotrophs)- make their own food Consumers- get energy by eating other plants and/or animals Heterotrophs Carnivore- meat eater Herbivore- eat plants Omnivore- eat both plants and animals Detritivore- eat detritus (dead organic matter) Decomposer- break down dead organic matter

Food Chains Food chains show a sequence of feeding relationships Trophic levels- levels in a food chain

Food Web Shows complex network of feeding relationships One organism may have multiple feeding relationships and roles within the food web

Energy Pyramid Energy pyramids show energy flow among trophic levels Only about 10% of energy is transferred from one trophic level to the next

Community Interactions Competition Two organisms fight for same resources Predation One organism captures and feeds on another organism

Symbiosis Symbiosis- close ecological relationship between organisms of different species Mutualism- both organisms benefit (ex: bat and saguaro cactus) Commensalism- one organism benefits; the other neither benefits nor is harmed (ex: cattle egret and water buffalo) Parasitism- one organism benefits; the other is harmed (ex: dog and flea)

Ecological Relationships + - Mutualism Commensalism Parasitism/Predation Neutralism Competition

Name the Relationship! A certain kind of bacteria lives in the intestines of humans and many other animals. The human cannot digest all of the food that it eats. The bacteria eat the food that the human cannot digest and partially digest it, allowing the human to finish the job. The bacteria benefit by getting food, and the human benefits by being able to digest the food it eats. Barnacles are sedentary crustaceans. Barnacles live by using long, feathering appendages to sweep the surrounding water for small, free-floating organisms. The critical resource for barnacles is a place to stay. Barnacles attach to rocks, ships, shells, whales, and just about anywhere else they can gain a foothold. Occasionally, barnacles will attach to the shell of a scallop. The barnacle gains a place to live and, presumably, the scallop is not harmed by the presence of the barnacles.

Name the Relationship! Wolves are reintroduced into a habitat with a large coyote population. The wolves and coyotes both fight for the same food source. Braconid wasps lay their eggs inside caterpillars. When the eggs hatch, wasp larvae eat their way out of the host caterpillar. An owl population’s diet is made up mostly of field mice.

Population Dynamics Survivorship Curve “K selected”- low birth rate, low infant mortality “r selected”- high birth rate and mortality

Population Growth Patterns Exponential growth Unlimited resources

Population Growth Patterns Logistic growth Population levels off at carrying capacity (maximum number of individuals the environment can support) Carrying capacity

Factors that Limit Population Growth Density-dependent factors Affected by the number of individuals in an area Ex: competition, parasitism, predation, disease Density-independent factors Limit population growth regardless of population density Ex: weather, natural disasters, human activities

Predator-Prey Interactions Density-dependent As hare population grows, so does lynx Eventually the lynx eat too many hares and populations decrease again Cyclic pattern

Ecological Succession Succession: gradual regeneration or creation of a community Primary vs. secondary succession

Primary Succession Establishment of an ecosystem in a previously uninhabited area Ex: new island formation after a volcano erupts Pioneer species- first organisms that live in the are (often lichens and mosses)

Secondary Succession Reestablishment of an ecosystem after a disturbance (such as fire) Takes less time than primary succession Climax community- stable, mature community