Please have out: Population Notes (from Monday and Tuesday) Lion Population Carrying Capacity

Population Dynamics Opener: What is the population density of this room if the room measures 7m x 9m (approximately)?

Today’s Goals: I will be able to differentiate between exponential and logistical growth I will be able to identify factors that affect population growth

All populations are dynamic, meaning that they: Population Dynamics All populations are dynamic, meaning that they: change in size and composition over time. To understand the changes that are taking place in a population, the following must be considered: Birth rate: the number of births occurring in a given period of time. Death rate or mortality rate: the number of deaths in a given period of time. Migration: the movement of individuals into and out of a population. Life expectancy: the length of time an individual is expected to live.

Birth and Death Rates Births Growth rate is the amount by which a population’s size changes over time. If more individuals are being born than die in a given period of time, the population size will . If birth rate is equal to death rate the population will remain in size. If death rate is greater than birth rate, the population will . Total Population increase Deaths stable decrease

…the movement of individuals into and out of a population. Migration is… …the movement of individuals into and out of a population. Immigration: The movement of individuals into an area. Total Population Emigration Immigration Immigration would _________ the size of the population while emigration would cause the population to __________ in size. increase Emigration: The movement of individuals out of an area. decrease

Patterns of Mortality The mortality rate of the individuals in the population generally follows one of the following patterns. These are called __________________________ because they show the likelihood of ___________ at different _____ throughout the lifetime of the organism. Number of survivors survivorship curves Age (years) survival ages

It drops steeply near the end indicating: Type I Survivorship Curve: This curve is: flat at the start, indicating a low death rate in the early and middle stages of life. It drops steeply near the end indicating: a high death rate as the organisms become older. An example is large mammals that produce very _____ offspring, but provide them with _______________. few good care

Type III Survivorship Curve: This curve drops sharply at the start, indicating a high death rate among the young. It flattens out as death rates decline for the few that do survive the early die-off. This would include organisms that produce large numbers of offspring, but provide them with little or no care. d) Examples include: fishes, many plants, and most marine invertebrates.

Type II Survivorship Curve: a) This curve is: intermediate (midway) to the above 2 curves. b) There is a constant death rate over the organism’s life span. c) This may occur in rodents and lizards.

Life Histories The life history of an organism is the _______ that affect an organism’s schedule of: reproduction and survival. traits The reproduction of most organisms can be described as: 1. Big-bang reproduction 2. Repeated reproduction

Big-bang Reproduction This is reproduction in which: an organism produces all of its offspring in a single event. Big-bang Reproduction Example: Pacific salmon spend several years __________________________. Near the end of their life they _________, producing millions and millions of eggs, followed by ________.   growing and maturing spawn death

Repeated Reproduction In this type of reproduction, the organism: produces a few offspring each year for several years. Repeated Reproduction

With a partner next to you quietly work on the packet to the stop sign after question 8.

Under what conditions would rapid growth occur in a population? abundance of food and space no predators or disease If all factors for reproduction and growth are ideal, the population might grow ______________. Exponential Growth exponentially

For example: A single bacterium can reproduce by dividing into two cells every 20 minutes. At the end of the first 20 minutes, there would be two bacterial cells. At the end of 40 minutes, four cells will have been produced, and by the end of the first hour, there would be eight cells. This growth doesn’t seem too impressive at first. But, if the number of cells doubles every 20 minutes, then at the end of one day the colony would contain 4.72 x 1021 cells (4,720,000,000,000,000,000,000 cells!)

At first, the population seems to be growing _______, but over time, the power of exponential growth can produce a population of extremely ______ size. This produces a curve on the graph. Exponential Growth: This occurs when the members of the population are reproducing at a constant rate. slowly large J-shaped Under conditions, with resources a population will grow exponentially. In reality, populations continue to grow exponentially for very long. ideal unlimited do not

How will resources be limited during the growth of the population? Carrying Capacity At first a population may appear to be experiencing exponential growth, but as resources become ______________, the growth of the population will ____________. less available slow or stop How will resources be limited during the growth of the population? becomes more and more scarce. Water may occur. may be introduced to the population. The population runs out of . Additional may be attracted to the growing population. will increase among members of the group. Accumulation of could lead to disease and poor health. Food shortages Disease space predators prey Competition waste

Eventually a growing population will reach the carrying capacity of the environment. The carrying capacity is: the number of individuals the environment can support over a long period of time.

The ___________ in the graph to the right indicates that the population has exceeded the _________________ of the environment. Many members of the population will ______________, causing the population size to ____________ the carrying capacity. overshoot carrying capacity die or starve The size of the population will fluctuate _________________ the carrying capacity of the environment. drop below above and below

Logistic Growth Logistic Growth: letter “S” A model of population growth in which growth slows or stops following a period of exponential growth. A graph of logistic growth looks like a stretched out __________. letter “S”

Logistic Growth When the population size is ______, birth rates are ______ and death rates are _____, causing the population to grow nearly _______________. small high low When the population is at the carrying capacity: the birth rate equals the death rate, and growth stops. exponentially As the population reaches the carrying capacity, the growth rate _______. slows

Assumptions of the Exponential Model and the Logistic Mode One assumption made by both models is that the carrying capacity is constant and does not fluctuate. In reality, the carrying capacity changes with the _____________. environment

A population of prairie dogs inhabits an area from 1990 to the present A population of prairie dogs inhabits an area from 1990 to the present. From 1990 to 1995 the population experiences growth. The prairie dog population reaches a carrying capacity of approximately individuals. On the graph draw a prediction for what would occur during a drought between 2010 to the present were the carrying capacity is reduced to ~50 individuals. exponential 110