Presentation on theme: "Population Growth Fish Sharks"— Presentation transcript:
1Population Growth Fish Sharks Objective 5.01: Investigate and analyze the interrelationships among organisms, populations, communities and ecosystems
2Population size refers to the number of individuals in the population. A Population is a group of organisms that belong to the same species and live in a particular place at the same timePopulation size refers to the number of individuals in the population.
3Populations are usually too large and widespread to count directly, so sampling techniques are usually used.Sampling is when a small sample is counted and used to estimate the larger population (100 plants x 1,000)
4Population density measures how crowded a population is and is always expressed as the number of individuals per unit of areaPopulation DensitiesJapan337 people per square kmUnited Kingdom254 people per square kmKenya69 people per square kmMexico55 people per square kmUnited States32 people per square kmRussia8.3 people per square km
5Over time, all populations change in size and composition due to changes in birth rates, mortality rates, and life expectancy.
6Age structure refers to the distribution of individuals among different ages. Populations with more young people tend to increase more rapidly.
7Survivorship Curves show the life expectancy rate at different ages of a population. Type IMortality increases later in lifeType IIMortality probability doesn’t changeType IIIMortality probability is high early but low later in life
8Population Growth = Birth Rate - Mortality Rate Population growth refers to an increase in the size of a population over timePopulation Growth = Birth Rate - Mortality RateAn increase in birth rate or a decrease in mortality rate will cause an increase in population growth
9Population growth can also be affected by immigration, individuals moving in, or emigration, individuals moving out
10Immigration and emigration affect a local population’s size but not the world population
11Number of Churches in Ramseur Graphs are used to analyze population growthNumber of Churches in RamseurY axisNumberofChurchesX axis - Years
12Number of Churches in Ramseur Linear Growth is when the numbers increase steadily by the same amount (2, 4, 6…)Number of Churches in RamseurY axisNumberofChurchesX axis - Years
13Number of Churches in Raleigh Exponential Growth is when the numbers increase by a larger amount each time (2, 4, 16, 256…)Number of Churches in RaleighY axisNumberofChurchesX axis - Years
14Populations tend to increase exponentially in that as they grow larger they begin increasing faster Slow IncreaseRapid Increase
15The J – Curve Shows Exponential Population Growth
16All ecosystems have a limited amount of resources to support populations All organisms need water, food, space for habitats, and sanitary conditions
17Populations begin to die out due to disease, starvation, or thirst As populations increase, there is more competition for the same resourcesPopulations begin to die out due to disease, starvation, or thirst
18Therefore, any ecosystem can only support a certain amount of individuals Carrying Capacity refers to the maximum number of individuals an ecosystem can support
19The S – Curve shows logistic growth where a population begins to stabilize as it reaches its carrying capacityThe carrying capacity is determined by limiting factors such as amount of available resources or ability to fight off diseases
20Limiting factors that restrain population growth and do not depend upon the initial size of the population are called Density-Independent FactorsFloodsFiresEarthquakesCold SpellsHot SpellsDrought
21Limiting factors that restrain population growth and do depend upon the initial size of a population are called Density-Dependent FactorsFood ShortagesWater ShortagesDiseasesHabitat Space
22Competition between species that compete for the same resources can also affect population growth Sabel IslandGray SealHarbor SealLance Fish
23One population will out compete the other causing a decline in the other population Grey Seal in mixedHarbor Seal inMonths
24Predator – Prey Relationships also affect Population Growth Increase in predators cause a decrease in preyDecrease in prey causes a decrease in predatorsDecrease in predators cause an increase in preyIncrease in prey causes an increase in predators
25There is always a delayed relationship in growth and decline between the two populations
26The Lesson of the Kaibab Kaibab National Forest in Arizona
281905, there was about 4,000 deer on almost 300,000 hectares of land. 1906, President Teddy Roosevelt created the Grand Canyon National Game Preserve to protect the “finest deer herd in America”1905, there was about 4,000 deer on almost 300,000 hectares of land.The carrying capacity was estimated to be about 30,000 deer
29By this time though, over grazing by cattle, sheep, and horses had eliminated most of the tall perennial grassesThe first step to protect the deer was to ban all hunting of deer as well as extermination of the predators of the deer1907 – 1939816 mountain lions, 20 wolves, 7,388 coyotes, and 50 bobcats were killed
30The Kaibab Deer Investigating Committee recommended that all livestock not owned by local residents be removed immediately from the range and that the number of deer be cut in half as quickly as possible. Hunting was reopened, and during the fall of 1924, 675 deer were killed by hunters. However, these deer represented only one-tenth the number of deer that had been born that spring. Over the next two winters, it is estimated that 60,000 deer starved to death.
31Today, the Arizona Game Commission carefully manages the Kaibab area with regulations geared to specific local needs. Hunting permits are issued to keep the deer in balance with their range. Predators are protected to help keep herds in balance with food supplies. Tragic winter losses can be checked by keeping the number of deer near the carrying capacity of the range.
40Developing nations are those nations that are not fully industrialized and still use primitive means to farm and live. The average income is far below poverty level.Developing nations include India, those in the Mid-East, Africa, South America, and Asia
41The developing nations are growing faster in populations than the developed nations. Their faster growth places a much larger strain on their natural resources.