Ecology and Population Dynamics What is Ecology Ecology

Ecology and Population Dynamics

What is Ecology? • Ecology is the study of interactions between organisms (biotic) and their nonliving (abiotic) environment • Habitat is the place a plant or animal lives, while its niche is its total way of life

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

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 • Energy in an ecosystem originally comes from the sun • Energy flows through ecosystems from producers to consumers

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 (energy flows from producers to various levels of consumers) • 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

• Amount of available energy decreases for higher consumers • It takes a large number of producers to support a small number or primary consumers

Ecological Pyramids • Biomass pyramid- amount of matter at each trophic level

Pyramid of Numbers • Shows the number of organisms at each trophic level

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 + 0 - + Mutualism Commensalism Parasitism/Predation 0 Commensalism Neutralism - Parasitism/Predation Competition

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 • Competition – Intraspecific (between same species) – Interspecific (between different species) – Competitive Exclusion Principle: no two species will have the same niche in an ecosystem

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

Factors that Limit Population Growth • Density-independent factors – Limit population growth regardless of population density – Ex: weather, natural disasters, human activities

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

Keystone Species • A species that influences the survival of many other species • Bats are considered keystone species of many ecosystems