Population Ecology 4 CHAPTER Placeholder opening page, but maybe we can duplicate the look of the SE chapter opener page by using the same fonts and colors (and maybe that Ch 14 icon?)

Levels of Ecological Organization Lesson 4.1 Studying Ecology Levels of Ecological Organization Everything on Earth is connected, so how do ecologists study anything? Ecology is the study of how organisms interact with each other and with their environments Scientists study ecology at various levels of organization.

Levels of Ecological Organization Individual Ecology involves describing relationships between individual organisms and their environment. Populations Individual organisms are classified - species Species = group of individuals that interbreed and produce fertile offspring Members of a species that live in the same area at the same time = a population.

Levels of Ecological Organization Communities All of the populations in a particular area. Ecology involves interactions among species. Ecosystems Include all the livings things and their physical environments within a particular area Living and nonliving things. Ecology involves studying the living and nonliving components of a system together.

Levels of Ecological Organization Biosphere Includes all parts of Earth that host life, with all of its organisms and environments. Ecology involves how matter and energy cycle through the biosphere and influence organisms worldwide.

Biotic and Abiotic Factors Lesson 4.1 Studying Ecology Biotic and Abiotic Factors Biotic factors: Parts of an ecosystem that are living or used to be living Ex: living tree, dead tree Abiotic factors: Parts of an ecosystem that have never been living Ex: oxygen, sunlight

Habitat The specific environment in which an organism lives Lesson 4.1 Studying Ecology Habitat The specific environment in which an organism lives Habitats consist of biotic and abiotic elements. Habitats provide an organism with resources—anything an organism needs to survive and reproduce, including food, shelter, and mates.

Lesson 4.2 Describing Populations From 1900 to 2000, the white-tailed deer population of New York state grew from about 20,000 to more than 1 million. Densities of more than 100 deer per sq mi occur in some metropolitan areas.

Lesson 4.2 Describing Populations Population Size The number of individuals in a population at a given time Sudden and dramatic decreases in population size can indicate an unhealthy population headed toward extinction. When population size increases or remains steady, it is often a sign of a healthy population.

Determining Population Size It is nearly impossible to count each individual in a population Population is estimated using sampling techniques. Count individuals in small sample area Use that to estimate number of individuals in large overall area Counting Laysan Albatross Nests

Population Density Measure of how crowded a population is Lesson 4.2 Describing Populations Population Density Measure of how crowded a population is Larger organisms generally have lower population densities. Low population density: More space, resources; finding mates can be difficult High population density: Finding mates is easier; tends to be more competition; more infectious disease; more vulnerability to predators Northern pintail ducks

Population Distribution Lesson 4.2 Describing Populations Population Distribution How organisms are arranged within an area: Random distribution: Organisms arranged in no particular pattern, resource are spread out Uniform distribution: Organisms evenly spaced; individuals hold territories/compete for space Clumped distribution: Organisms grouped near resources; most common distribution in nature

Population Distribution

Lesson 4.2 Describing Populations Age Structure Age structure describe the relative number of organisms of each age group within population Can be used to predict future population growth of a population Young individuals who have not yet reached the age where they can reproduce are called pre-reproductive Older individuals past the age of having offspring are called post-reproductive

Age Structure Population with even age distribution will likely remain stable (births = deaths). Population made up of mostly post-reproductive individuals will likely decline over time. Population made up of mostly pre-reproductive individuals will likely increase over time.

Age Structure Diagram Age  How will each population change over time?

Lesson 4.3 Population Growth From 1800 to today, the human population has grown from about 1 billion to more than 6.8 billion—an exponential rate of increase.

Lesson 4.3 Population Growth Biotic Potential An organism’s maximum ability to produce offspring in ideal conditions Many factors influence biotic potential, including gestation time (time to “be born”) and generation time (span from time of organism’s birth until time it has its own offspring). Organisms with high biotic potential can recover more quickly from population declines than organisms with low biotic potential.