Scientists found that, over a period of 200 years, a mountain pond was transformed into a meadow. During that time, several communities of organisms were replaced by different communities. Which of these best explains why new communities were able to replace older communities? a. The original species became extinct. b. Species in the older community died from old age. c. The abiotic characteristics of the habitat changed. d. Diseases that killed the older organisms disappeared.

In order to maintain the biodiversity in an aquatic ecosystem the water must have plenty of dissolved oxygen. Which of the following would increase the amount of dissolved oxygen available? a. Use heaters to warm the water because warm water has more available oxygen than cool water. b. Remove obstructions within the water way so that the water can maintain a steady flow because flowing water has more oxygen than stagnant water. c. Remove trees along the water way that rob the water of oxygen. d. Increase the amount of fertilizer run off leading to eutrophication.

How does succession impact the biodiversity in an area. A How does succession impact the biodiversity in an area? A. Both primary and secondary succession increases the biodiversity after an environmental disturbance. B. Primary succession only, increase biodiversity since this occurs on brand new land while secondary succession maintains the biodiversity. C. Secondary succession only, increase biodiversity since this occurs on brand new land while primary succession maintains the biodiversity. D. Both primary and secondary succession decreases the biodiversity of an area because the disturbance wipes out life in the area.

Determining Population Size There are four basic Methods that ecologists use to determine population size? Direct observation Indirect observation Sampling Mark and recapture studies

Determining Population Size Determining the size of ant population by knowing the number of ants that inhabit one ant hill, and then observing how many ant hills are in one particular area. Indirect observation

Determining Population Size Ecologists estimate the size of the rainbow trout population in a lake by catching a small sample, tagging them and then releasing them. They come back three weeks later and catch another sample noting how many trout have tags, and how many do not. Mark and recapture studies

Determining Population Size Determining the number of frogs in a pond by counting all of them individually. Direct Observation

Determining Population Size Estimating the number of daisies in a 100 square meter meadow by counting the daisies in a 10 meter by 10 meter plot, and then multiplying by 100. Sampling

Putting it all together Direct observation of a population gives you the most accurate count of a population while indirect observation is more of an estimate. Why would an ecologist use indirect observation instead of direct observation. Because it is not always practical to count all the individuals in a population.

Changes in Population Size List 2 ways a population can change in size: _______________________________ _________________________________ When new members join the population When members leave the population

Changes in Population Size Birth Rate Number of births in a population over time. Death Rate Number of deaths in a population over time. Immigration New members move into a population. Emigration Members leave the population.

Changes in Population Size Which Two allow a population to increase? Birth Rate Immigration Which two allow a population to decrease? Death Rate Emigration

Changes in Population Size What does the population statement say? If birth rate > death rate, population size increases. If death rate > birth rate, population size decreases.

Population Density The number of individuals in a specific area. Unit Area

Limiting Factors An environmental factor that causes a population to decrease. Food and Water Space Weather

Limiting Factors Pick one of the limiting factors and describe how it limits population growth. Food and Water Space Weather

Carrying Capacity The largest population that an area can support. Determined by the limiting factors that are present.

Carrying Capacity

Types of population growth

Predator-Prey Relationships Without predators, certain species of prey would drive other species to extinction through competition. Without prey, there would be no predators

Predator-Prey Relationships

Competition When the population increases to a size so that resources such as food or space become limited, individuals in the ecosystem must compete for resources

R strategist vs K strategist Unstable environment, density independent Stable environment, density dependent interactions small size of organism large size of organism energy used to make each individual is low energy used to make each individual is high many offspring are produced few offspring are produced early maturity late maturity, often after a prolonged period of parental care short life expectancy long life expectancy each individual reproduces only once individuals can reproduce more than once in their lifetime Mouse, frog Whale, elephant