Ecology and Populations

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

Ecology Ecological systems have both biotic and abiotic components. Ecological systems have both biotic and abiotic components. What are a few examples of biotic and abiotic factors? What are a few examples of biotic and abiotic factors?

Populations Individuals of the same species, at the same place, at the same time. Individuals of the same species, at the same place, at the same time. Demography- the study of populations and population processes Demography- the study of populations and population processes

Populations All populations have 3 characteristics: distribution, density, and growth rate or age structure. All populations have 3 characteristics: distribution, density, and growth rate or age structure. Distribution- the range a population covers Distribution- the range a population covers Density- The number of individuals per unit area; measured by sampling or census 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 Sampling- measuring a portion of a population to estimate the whole population Census- a full count of the 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. 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- Measuring growth- Growth= Beginning pop+(birth- deaths)+(immigration-emigration) Growth= Beginning pop+(birth- deaths)+(immigration-emigration) Immigration= the number of individuals entering a population Immigration= the number of individuals entering a population Emigration= the number of individuals leaving 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? 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? 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. 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

There are two types of growth models for populations: exponential and logistic. There are two types of growth models for populations: exponential and logistic. Exponential: unregulated growth- the population can grow forever. (Ideal) Exponential: unregulated growth- the population can grow forever. (Ideal) Logistic: limited growth with limiting factors. The population grows until it reaches the carrying capacity Logistic: limited growth with limiting factors. The population grows until it reaches the carrying capacity

Population Growth Growth factors: Growth factors: Density dependent: factors that depend on how many individuals are in a given area. 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. Density independent: factors that are not affected by how dense the population is.

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

Population Growth Survival curves: Help to show the survivorship rates through different ages and stages of life. Survival curves: Help to show the survivorship rates through different ages and stages of life. 3 types: 3 types: Type I: High juvenile and adult survival, parental care, and low fecundity (numbers of offspring) Type I: High juvenile and adult survival, parental care, and low fecundity (numbers of offspring) Type II: Constant survival/death rates throughout life Type II: Constant survival/death rates throughout life Type III: low juvenile survival rates, high fecundity, no parental care. Type III: low juvenile survival rates, high fecundity, no parental care.

Population Growth

Human Population How does this all relate to the human population? How does this all relate to the human population? What growth pattern does the human population follow? What growth pattern does the human population follow? What will limit our growth eventually? What will limit our growth eventually?

Human Population The human population exhibits all 4 types of age structure: The human population exhibits all 4 types of age structure:

Human Population Consequences? Consequences? Ecological footprint is huge- too many demands with limited resources in the environment? Ecological footprint is huge- too many demands with limited resources in the environment? What are some of these ecological demands? 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. There are many resources I have posted online if you would like to, or need, more review www2.onu.edu/~k-morris.1 www2.onu.edu/~k-morris.1