How populations are described and how they grow. Discuss here the fact that we often compartmentalize our world—focusing on one thing as though it existed in a vacuum. Ecology is about broadening your focus and realizing the interconnectedness of everything! Mr. Roes Living Environment

How do we define a population? A population has four important characteristics: it’s geographic distribution, population density, growth rate, and age structure. Introduce abiotic and biotic factors

1. Geographic Distribution: The distribution of a population is often also referred to as the range of that population. Geographic Distribution: The distribution of a population is also called the __________ of a population. The geographic distribution of a population could be as small as a few __________________ or as big as __________________________________. Ex. A single bacterial colony vs. The migration area of a humpback whale. Giraffe African Elephant

1. Geographic Distribution: The range of an organism is variable. It could be as small as a few centimeters, or as big as millions of square miles. How might the range of a population affect it? Geographic Distribution: The distribution of a population is also called the __________ of a population. The geographic distribution of a population could be as small as a few __________________ or as big as __________________________________. Ex. A single bacterial colony vs. The migration area of a humpback whale.

2. Population density: The number of individuals per unit area. The population density of a species will vary greatly depending on the biotic and abiotic factors of that specific ecosystem. Population Density: the density of a population is also thought of as the ___________ of individuals per _____________. (Ex. 20 ducks per square acre of a pond.) The population density of a species will vary greatly depending on the species and the specific ecosystem.

3. Growth Rate: The growth rate of a population will be affected by many different factors. 3. Growth Rate: In nature, a population may remain approximately the same size from year to year, or it may show bursts of rapid growth or sudden plummeting. The growth rate of a population is determined by ____________ different factors: the __________________________, the _________________, and the number of individuals that __________________________ the population.

3. Growth Rate: The growth rate of a population is determined by three different factors; the number of births, the number of deaths, and the number of individuals that enter or leave the population. In essence, a population will change in size depending on how many individuals are added to it or removed from it. 3. Growth Rate: In nature, a population may remain approximately the same size from year to year, or it may show bursts of rapid growth or sudden plummeting. The growth rate of a population is determined by ____________ different factors: the __________________________, the _________________, and the number of individuals that __________________________ the population.

3. Growth Rate: Add this in your notes: Immigration—Individuals moving into a population. Emigration—Individuals moving out of a population. 3. Growth Rate: In nature, a population may remain approximately the same size from year to year, or it may show bursts of rapid growth or sudden plummeting. The growth rate of a population is determined by ____________ different factors: the __________________________, the _________________, and the number of individuals that __________________________ the population. End of per 4

Exponential growth: Under ‘perfect conditions’ and with unlimited resource, a population will grow exponentially.

Exponential growth: The length of time required for an organism to grow and mature before reproducing impacts the rate of population growth. One day of E Coli reproduction could lead to 4,720,000,000,000,000,000,000 bacteria. 750 years of Elephant reproduction could lead to 20 million elephants. 4 sextillion, 720 quintillion

Logistic Growth: In nature, populations cannot simply grow to unlimited numbers. Eventually, a population’s growth rate begins to decrease and will eventually reach zero due to various factors.

Logistic Growth: Logistic growth rate occurs when an organism goes through a period of exponential growth, and then enters a period of little or no growth. The point at which a population’s growth rate levels out is called the carrying capacity of the ecosystem for that population. Mnemonic device for logistic growth; The population growth rate graph for a population undergoing logistic growth is “S ” shaped because the population shows a slowing or stopping of growth.

Carrying Capacity: During periods of logistic growth, the population’s rate of growth slows down because of the competition for resources. The carrying capacity is the number of organisms of one population that an environment can support.

Limiting factors: An ecosystem has many different factors. Some factors will encourage a population to grow and flourish. Other factors will cause a population to shrink. Liming factors are any of those factors that cause the rate of a population’s growth to decrease. Limiting factors can be divided into two groups; Density-Dependent Factors, and Density-Independent Factors. Any factor that causes the________ of a population’s growth to _________. Limiting factors can be divided into two groups: _______________________________, and ____________________________.

Limiting factors: Density-Dependent Factors—any limiting factor that depends on the density of a population. These are factors only when the population is of a certain density. Competition Predation Parasitism Disease Predator-Prey Relationships—Populations in nature are often controlled by predation. In fact, one of the best-known mechanisms of population control is within a predator-prey relationship. In predator-prey relationships, the periodic increase in the population of the prey is followed by the ____________ in population of the predators. The increased amount of predators eventually leads the prey population to ____________, which, after a period of time, causes the predator population to ___________ as well. This cycle of predator-prey relationships can be repeated indefinitely.

Limiting factors: Density-Independent Factors—any limiting factor that doesn’t depend on the density of a population. These are factors regardless of whether or not the population density is large. Unusual weather Natural disasters Seasonal cycles Predator-Prey Relationships—Populations in nature are often controlled by predation. In fact, one of the best-known mechanisms of population control is within a predator-prey relationship. In predator-prey relationships, the periodic increase in the population of the prey is followed by the ____________ in population of the predators. The increased amount of predators eventually leads the prey population to ____________, which, after a period of time, causes the predator population to ___________ as well. This cycle of predator-prey relationships can be repeated indefinitely.

Limiting factors: Predator-Prey Relationships—Populations in nature are often controlled through levels of predation. Think about your food chains! In predator-Prey relationships, a population of prey species will temporarily increase. In time, the increase in the population of prey is followed by the increase in population of the predators. The increased amount of predators eventually leads the prey population to decrease. After a period of time, the predator population will then decrease. This opens the door for the prey species to increase in population once again. Predator-Prey Relationships—Populations in nature are often controlled by predation. In fact, one of the best-known mechanisms of population control is within a predator-prey relationship. In predator-prey relationships, the periodic increase in the population of the prey is followed by the ____________ in population of the predators. The increased amount of predators eventually leads the prey population to ____________, which, after a period of time, causes the predator population to ___________ as well. This cycle of predator-prey relationships can be repeated indefinitely.

Limiting factors: A Predator-Prey Relationship. Predator-Prey Relationships—Populations in nature are often controlled by predation. In fact, one of the best-known mechanisms of population control is within a predator-prey relationship. In predator-prey relationships, the periodic increase in the population of the prey is followed by the ____________ in population of the predators. The increased amount of predators eventually leads the prey population to ____________, which, after a period of time, causes the predator population to ___________ as well. This cycle of predator-prey relationships can be repeated indefinitely.

Limiting factors: A Predator-Prey Relationship. Predator-Prey Relationships—Populations in nature are often controlled by predation. In fact, one of the best-known mechanisms of population control is within a predator-prey relationship. In predator-prey relationships, the periodic increase in the population of the prey is followed by the ____________ in population of the predators. The increased amount of predators eventually leads the prey population to ____________, which, after a period of time, causes the predator population to ___________ as well. This cycle of predator-prey relationships can be repeated indefinitely.

Limiting factors: A Predator-Prey Relationship. Predator-Prey Relationships—Populations in nature are often controlled by predation. In fact, one of the best-known mechanisms of population control is within a predator-prey relationship. In predator-prey relationships, the periodic increase in the population of the prey is followed by the ____________ in population of the predators. The increased amount of predators eventually leads the prey population to ____________, which, after a period of time, causes the predator population to ___________ as well. This cycle of predator-prey relationships can be repeated indefinitely.

Age Structures: The age structure of a population will affect its growth rate and its ability to withstand limiting factors. Age structure diagrams visualize the age structures of a certain population. The growth potential of a population depends, in part, on the percent of individuals of different ages that make up a given population. _______________________ visualize the age structures of a certain population. Age structure diagrams are commonly created with data from human populations in different countries. A population that has a large percentage of young individuals shows a large potential for a burst of growth in the future. Compare the two age structures below. Which population shows the most potential for growth?