Ecology Lesson 9.1

Lesson Objectives Distinguish between abiotic and biotic factors. Describe ecological levels of organization in the biosphere. Define organism, population, community, ecosystem, biome, and biosphere as the term are used in ecology and other ecological concepts. Compare and contrast exponential and logistic growth. Compare and contrast niches and habitats.

Introduction

Levels of Organization Ecologists study organisms and their environments at different levels of organization:

–Organisms: are individual living things. This is the lowest level of organization that ecologists study. Biologists study organisms, organ systems, organs, tissues, cells, organelles, and molecules. Chemists study atoms and subatomic particles.

Organisms and the Environment Organisms: life form consisting of one or more cells; has characteristics of life. Environment includes both living (biotic) and nonliving things (abiotic).

Biotic and Abiotic Factors Biotic  living organisms Abiotic  nonliving or physical factors Together determine productivity of the ecosystem in which organisms’ live

What Is a Population? In biology, a population is a group of organisms of the same species that live in the same area, interact with one another, and produce fertile offspring.. How large a population is and how fast it is growing are often used as measures of its health.

What Is a Community? Communities are made up of populations of different species that live in the same area and interact together.

What Is an Ecosystem? An ecosystem is a unit of nature and the focus of study in ecology. It consists of all the biotic and abiotic factors in an area and their interactions. Ecosystems can vary in size. A lake could be considered an ecosystem. So could a dead log on a forest floor. Both the lake and log contain a variety of species that interact with each other and with abiotic factors.

Ecosystem Components Niches Habitats Competitive Exclusion Principle

The Niche Niche  organism’s occupation (role), where it lives, and way in which organism’s use conditions they exist in –Food it eats –Place in food web –How it gets food –Range of temperatures needed for survival –When and how it reproduces

The Habitat Physical environment to which an organisms has become adapted and survives in.

Competitive Exclusion Principle Two different species cannot occupy the same niche in the same geographic area. If they do they will compete with one another for the same food and other resources. Eventually, one species will out compete the other.

What Are Biomes? A biome is a group of similar ecosystems with the same general abiotic factors and primary producers. Biomes may be terrestrial or aquatic.

What Is the Biosphere? The biosphere is the global sum of all ecosystems; integrating all living beings and their relationships, including their interactions with the elements of the lithosphere, hydrosphere, and atmosphere.

Lesson Summary Ecology is the study of how living things interact with each other and with their environment. The environment includes abiotic (nonliving) and biotic (living) factors. Organisms are dependent upon their environments for energy and matter. Population growth rate is how fast a population changes in size over time. It is determined by rates of birth, death, immigration, and emigration. Under ideal conditions, populations can grow exponentially. The growth rate increases as the population gets larger. Most populations do not live under ideal conditions and grow logistically instead. Density-dependent factors slow population growth as population size nears the carrying capacity. A community is the biotic part of an ecosystem. It consists of all the populations of all the species that live in the same area. It also includes their interactions. An ecosystem consists of all the biotic and abiotic factors in an area and their interactions. A niche refers to the role of a species in its ecosystem. A habitat is the physical environment in which a species lives and to which it is adapted. Two different species cannot occupy the same niche in the same place for very long. The biosphere is composed of all the ecosystems on Earth.