What is Ecology?

What is Ecology? * Ecology is the study of interactions among organisms and between organisms and their environment.

Levels of Organization Biosphere – contains the combined portions of the planet in which all of life exists, including land, water, and air/atmosphere. It is our planet as a whole and where ecology takes place. Biome – a group of ecosystems that have the same climate and similar dominant communities. Ecosystem – a collection of organisms that live in a particular place along with their non-living, or abiotic, environment. Communities – assemblages of different populations living together in a defined area. Populations – groups of individuals that belong to the same species and live in the same area. Organism – an individual living thing. Example: Whole Planet ↓ Temperate Forest Pond, plants, animals, water, O2, rocks Pond, frogs, fish, plants, algae All bullfrogs in pond Bullfrog Biotic Factor = living organisms influencing the environment Abiotic Factor = non-living influences on environment

Ecological Levels of Organization

A Hierarchy of Interactions Ecology can be divided into four increasingly comprehensive levels: organismal ecology, population ecology, community ecology, and ecosystem ecology.

(a) Organismal ecology (b) Population ecology (c) Community ecology (d) Ecosystem ecology

A Hierarchy of Interactions Organismal ecology is concerned with evolutionary adaptations that enable individual organisms to meet the challenges posed by their abiotic environments.

A Hierarchy of Interactions Population ecology addresses populations, groups of individuals of the same species living in a particular geographic area and concentrates mainly on factors that affect population density and growth.

A Hierarchy of Interactions Community ecology is concerned with communities, all the organisms that inhabit a particular area and focuses on how interactions between species affect a community’s structure and organization.

A Hierarchy of Interactions Ecosystem ecology is concerned with ecosystems, all the abiotic factors in addition to the community of species in a certain area and focuses on energy flow and the cycling of chemicals among the various abiotic and biotic factors.

Feeding Relationships Trophic structure is the feeding relationships among the various species in a community. A community’s trophic structure determines the passage of energy and nutrients from plants and other photosynthetic organisms to herbivores and then to predators.

Feeding Relationships Autotrophs – Producers – produce their own food using sun or chemicals Plants and algae - by photosynthesis (sun’s energy) Some bacteria – by chemosynthesis (chemical energy) Heterotrophs – Consumers – rely on autotrophs for food Herbivore – eat autotrophs directly (primary consumers) Secondary consumers and up: Carnivore – eat herbivores Omnivore – eat both autotrophs and heterotrophs Scavengers – feed on carcasses Detritivores – eat decaying plant and animal material Decomposers – break down organic material and release nutrients

A terrestrial food chain An aquatic food chain Quaternary consumers Carnivore Carnivore Tertiary consumers Carnivore Carnivore Carnivore Secondary consumers Carnivore Herbivore Primary consumers Zooplankton Plant Phytoplankton Producers A terrestrial food chain An aquatic food chain

Food Chains Food Chains – show the sequence of food transfer between trophic levels algae → zooplankton → small fish → squid → shark (notice direction of the arrowheads!!!) This food chain idea works for simple food chains but....

Food Webs …Food webs are able to show the complexity of more complicated ecosystems Food webs link all food chains in a community together

Quaternary, tertiary, and secondary consumers Tertiary and secondary consumers Secondary and primary consumers Primary consumers Producers (plants)

A Marsh Food Web

Biological Magnification Organisms can’t metabolize many of the toxins produced by industrial wastes or pesticides Toxins become concentrated as they pass through a food chain in a process called biological magnification.

Biological Magnification Magnification of DDT Concentration Fish-Eating Birds 10,000,000 Large Fish 1,000,000 100,000 Small Fish 10,000 Zooplankton 1000 Producers Water 1

Energy Flow **** Sunlight is the main energy source for life on Earth.**** *Energy flows through an ecosystem in one direction, from the sun or inorganic compounds to autotrophs (producers) and then to various heterotrophs (consumers). Energy is NOT reused. Chemical cycling is the use and reuse of chemical elements such as carbon and nitrogen within the ecosystem.

C m a c i e h l y n g Energy flow Light energy Chemical energy Heat energy Bacteria, protists, and fungi Chemical elements

Primary Production and the Energy Budgets of Ecosystems The amount, or mass, of living organic material in an ecosystem is the biomass. The rate at which an ecosystem’s producers convert solar energy to the chemical energy stored in biomass is primary production and yields about 165 billion tons of biomass per year. Different ecosystems vary considerably in their primary production.

Average primary production (g/m2/yr) Open ocean Estuary Algal beds and coral reefs Desert and semidesert scrub Tundra Temperate grassland Cultivated land Northern coniferous forest (taiga) Savanna Temperate broadleaf forest Tropical rain forest 500 1,000 1,500 2,000 2,500 Average primary production (g/m2/yr)

Ecological Pyramids ****Pyramid of production (aka energy pyramid) – only roughly 10% of energy can be transferred to next trophic level because organisms use energy for respiration (breathing), movement, and reproducing. More levels between a producer and a top-level consumer means less energy remains from original amount = limited food chain length supported and more room needed for top level consumers****

Tertiary consumers 10 kcal Secondary consumers 100 kcal Primary consumers 1,000 kcal Producers 10,000 kcal 1,000,000 kcal of sunlight

Ecological Pyramids Biomass Pyramid – shows amount of potential food for each trophic level (grams per unit area) Pyramid of Numbers – shows number of individuals at each trophic level.

Ecological Pyramids Energy Pyramid Shows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat. Pyramid of Numbers Shows the relative number of individual organisms at each trophic level. Biomass Pyramid Represents the amount of living organic matter at each trophic level. Typically, the greatest biomass is at the base of the pyramid.