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13.1 Ecologists Study Relationships KEY CONCEPT Ecology is the study of the relationships among organisms and their environment. 13.1 Ecologists Study Relationships Ecologists study environments at different levels of organization. • Ecology is the study of the interactions among living things, and between living things and their surroundings. Fig. Salmon are a primary food source for many species, including grizzly bears. If salmon disappeared, species dependent on them would also suffer. 13.1 Ecologists Study Relationships • An organism is an individual living thing, such as an alligator. Organism Organism 13.1 Ecologists Study Relationships • A population is a group of the same species that lives in one area. Population Population Organism Organism 13.1 Ecologists Study Relationships • A community is a group of different species that live together in one area. Community Community Population Population Organism Organism 13.1 Ecologists Study Relationships • An ecosystem includes all of the organisms as well as the climate, soil, water, rocks and other nonliving things in a given area. Ecosystem Ecosystem Community Community Population Population Organism Organism 13.1 Ecologists Study Relationships • A biome is a major regional or global community of organisms characterized by the climate conditions and plant communities that thrive there. Biome Ecosystem Ecosystem Community Community Population Population Organism Organism 13.1 Ecologists Study Relationships Ecological research methods include observation, experimentation, and modeling. • Observation is the act of carefully watching something over time. • Observations of populations can be done by visual surveys. – Direct surveys for easy to spot species employ binoculars or scopes. – Indirect surveys are used for species that are difficult to track and include looking for other signs of their presence. Fig. Much of the data gathered by ecologists results from long hours of observation in the field. This ecologist is using radio telemetry to track coyotes. 13.1 Ecologists Study Relationships • Experiments are performed in the lab or in the field. – Lab experiments give researchers more control. – Lab experiments are not reflective of the complex interactions in nature. – Field experiments give a more accurate picture of natural interactions. – Field experiments may not help determine actual cause and effect. 13.1 Ecologists Study Relationships KEY CONCEPT Every ecosystem includes both living and nonliving factors. 13.1 Ecologists Study Relationships A Brief Review from August: • Biodiversity is the assortment, or variety, of living things in an ecosystem. • Biodiversity increases as you travel from the poles to the equator. 13.1 Ecologists Study Relationships Biotic factors are living things. – plants – animals – fungi – bacteria 13.1 Ecologists Study Relationships • Abiotic factors are nonliving things. – moisture – temperature – wind – sunlight – soil 13.1 Ecologists Study Relationships • A keystone species is a species that has an unusually large effect on its ecosystem. keystone 13.1 Ecologists Study Relationships • Keystone species form and maintain a complex web of life. creation of wetland ecosystem increased waterfowl Population keystone species increased fish population nesting sites for birds 13.1 Ecologists Study Relationships Every organism has a habitat and a niche. 13.1 Ecologists Study Relationships A habitat differs from a niche. • A habitat is all aspects of the area in which an organism lives. • This includes all biotic and abiotic factors 13.1 Ecologists Study Relationships A habitat differs from a niche. • An ecological niche is – The role and position a species has in its environment – How it meets its needs for food and shelter – How it reproduces – Its behavior – All its interactions with the biotic and abiotic factors of its environment 13.1 Ecologists Study Relationships Example: The niche of black bears • Ecological role: Helps carry seeds of berries (in their digestive systems) and expels them, allowing the berries to grow • Finds shelter in the forest • Feeds on nuts, berries, insects, and small animals • Fed on by blood-sucking insects and parasites 13.1 Ecologists Study Relationships Resource availability gives structure to a community. • Species can share habitats and resources. – This leads to competition 13.1 Ecologists Study Relationships • Two species can NOT share the same niche – This is known as competitive exclusion • Competitive exclusion has different outcomes. –One species is better suited to the niche and the other will either be pushed out or become extinct. –The niche will be divided. –The two species will further diverge 13.1 Ecologists Study Relationships • Ecological equivalents are species that occupy similar niches but live in different geographical regions. Madagascar South America