Ecosystem Relationships & Population Growth How do relationships impact a population growth?

Vocabulary Species- a group of individuals that can freely interbreed and produce fertile offspring. Species- a group of individuals that can freely interbreed and produce fertile offspring. A population is just one species living in one area. A population is just one species living in one area. Community -Several different populations (species) living in a given area. Community -Several different populations (species) living in a given area. Ecosystem- The community (all populations) and how they interact with the environment (abiotic). Ecosystem- The community (all populations) and how they interact with the environment (abiotic).

Biotic factor a living thing, as an animal or plant, that influences or affects an ecosystem Biotic factor a living thing, as an animal or plant, that influences or affects an ecosystem Abiotic factor a nonliving condition or thing, as climate or habitat, that influences or affects an ecosystem and the organisms in it. Examples: Abiotic factor a nonliving condition or thing, as climate or habitat, that influences or affects an ecosystem and the organisms in it. Examples: Sun, temperature, rainfall, rocks Abiotic factors can determine which species of organisms will survive in a given environment. whichwillenvironmentwhichwillenvironment

Habitats and Niche Habitat is the location where a species lives. Habitat is the location where a species lives. It’s their address. It’s their address. Niche includes the habitat and the relationships – both biotic and abiotic that the species requires. Niche includes the habitat and the relationships – both biotic and abiotic that the species requires. It’s their “Job” It’s their “Job”

Community Because one species cannot live alone. They must interact with their community. Because one species cannot live alone. They must interact with their community. Symbiotic Relationships Symbiotic Relationships a) Mutualism: Both species benefit b) Parasitism: One benefits the other is harmed c) Commensalism: One benefits and the other is not affected. d) Predation: predator benefits, the prey individual dies but the prey species benefits

Mutualism

Commensalism

Parasitism

Predation

Community Because of the relationships in a community, one population (species) will always affect the population size of its symbiotic partner. Because of the relationships in a community, one population (species) will always affect the population size of its symbiotic partner. Examples: Examples: Wolf – Elk Wolf – Elk Fish- Eagle Fish- Eagle Aspen Tree – Deer Aspen Tree – Deer Sage Brush – Rabbit Sage Brush – Rabbit

Symbiotic Populations

Growth Exponential Growth: The rate of population growth in each new generation is a multiple of the previous. Exponential Growth: The rate of population growth in each new generation is a multiple of the previous. Few die and most survive to reproduce Few die and most survive to reproduce J-shaped curve J-shaped curve

Growth Rate Natural Growth rate is not as simple Natural Growth rate is not as simple Equation: Equation: Growth rate = Change in # of individuals Time Period Growth rate = Change in # of individuals Time Period

Growth Rate

Factors Influencing Growth a) Birth Rate b) Death Rate c) Migration 1. Immigration- movement into a population 2. Emigration- movement out of a population

Human Population Histograms indicate the population’s distribution & overall status

Population Growth Most population growth is in the developing countries (Latin America, Asia & Africa) Most population growth is in the developing countries (Latin America, Asia & Africa) Some countries are actually dropping dramatically (many European countries & Japan) Some countries are actually dropping dramatically (many European countries & Japan) The total population in the USA would have dropping without immigration. The immigrant population has increased 57% since The total population in the USA would have dropping without immigration. The immigrant population has increased 57% since The economic system of a country needs “consumers” and now they must consider the “quality of life” and long term sustainability. The economic system of a country needs “consumers” and now they must consider the “quality of life” and long term sustainability.

Limiting Factors Anything biotic or abiotic in the environment that limits the size of a population Anything biotic or abiotic in the environment that limits the size of a population Causes an increase in death rate or decrease in birth rate Causes an increase in death rate or decrease in birth rate Effects of these factors depends upon the size and density (individuals per area) of the population and community. Effects of these factors depends upon the size and density (individuals per area) of the population and community.

Population Density Patterns These are species specific distributions

Density Independent Affects ALL populations regardless of size (mostly abiotic ) Affects ALL populations regardless of size (mostly abiotic ) Weather Weather Seasonal Cycles Seasonal Cycles Natural Disasters Natural Disasters

Density Dependent Factors limit size ONLY when the population reaches capacity for a certain area – mostly biotic. Factors limit size ONLY when the population reaches capacity for a certain area – mostly biotic. Disease Disease Competition for limited resources Competition for limited resources Parasitism Parasitism Predation Predation

Population Capacity Carrying Capacity = the number of individuals (of a species) that an environment can support indefinitely Carrying Capacity = the number of individuals (of a species) that an environment can support indefinitely This results in a leveling off of the growth curve This results in a leveling off of the growth curve S-shaped curve S-shaped curve

Overpopulation = Sharp Decline “Boom & bust” pattern follows climatic fluctuations.

Ecosystems & Populations Demography- the study of populations Demography- the study of populations There is an on-going tendency to find a balance within systems (both living and non- living). There is an on-going tendency to find a balance within systems (both living and non- living). This is not an intentional act. If organisms can’t maintain homeostasis their populations will decline and they may become extinct. This is not an intentional act. If organisms can’t maintain homeostasis their populations will decline and they may become extinct.