Ecology and Populations

What is ecology?

Ecology is the scientific study of interactions between organisms and their environment.

Ecology

Ecological systems have both biotic and abiotic components.

What are a few examples of biotic and abiotic factors?

Populations

Individuals of the same species, at the same place, at the same time.

Demography- the study of populations and population processes

Populations

All populations have 3 characteristics: distribution, density, and growth rate or age structure.

Distribution- the range a population covers

Density- The number of individuals per unit area; measured by sampling or census Sampling- measuring a portion of a population

to estimate the whole population Census- a full count of the population

Populations

Growth and Age Structure- Population sizes vary year by year. Members of a population are organized into an age structure, which separates members by gender and age.

Measuring growth- Growth= Beginning pop+(birth-deaths)+

(immigration-emigration) Immigration= the number of individuals entering

a population Emigration= the number of individuals leaving a

population

Practice Problem

Suppose a population of cows with 523 members has 124 births, 94 deaths, 13 emigrations and 24 immigrations. What is the new size of the population?

A population of 307 sparrows lives in the fields surrounding the school. The following summer, the population was re-counted and there were 270 sparrows. Assuming there were 57 births, 0 immigrations, and 14 emigrations, how many deaths were there during the winter?

Population Growth

Age structure diagrams help to give a visual representation of how the population is made up in terms of age and gender.

•There are 4 different types: • Rapid growth• Slow growth• Zero growth• Negative growth

Population Growth

Population Growth

There are two types of growth models for populations: exponential and logistic.

Exponential: unregulated growth- the population can grow forever. (Ideal)

Logistic: limited growth with limiting factors. The population grows until it reaches the carrying capacity

Population Growth

Growth factors: Density dependent: factors that depend on how

many individuals are in a given area. Density independent: factors that are not

affected by how dense the population is.

Population Growth

Which of the following are density dependent? Density independent? Food Natural disaster Weather and Climate Disease Predators Human Activity Living space

Population Growth

Survival curves: Help to show the survivorship rates through different ages and stages of life.

3 types: Type I: High juvenile and adult survival,

parental care, and low fecundity (numbers of offspring)

Type II: Constant survival/death rates throughout life

Type III: low juvenile survival rates, high fecundity, no parental care.

Population Growth

Human Population

How does this all relate to the human population? What growth

pattern does the human population follow? What will limit our

growth eventually?

Human Population

The human population exhibits all 4 types of age structure:

Human Population

Consequences? Ecological footprint is huge- too many demands

with limited resources in the environment? What are some of these ecological demands?

Resources

There are many resources I have posted online if you would like to, or need, more review. www.sciencerules2.wikispaces.com www2.onu.edu/~k-morris.1