Population Fluctuation Notes QQ#1: what is a population?

Populations Some important definitions. Species: a group of organisms that can breed with one another Population: within a species, a population is a group of individuals that mate with one another and live in the same place at the same time Individual: one member/organism of a population

What causes populations to fluctuate? QQ#2: what factors cause populations to grow? To shrink? Populations grow when: birth rate + immigration rate > death rate + emigration rate Populations shrink when: death rate + emigration rate > birth rate + immigration rate Immigration: individuals moving IN Emigration: individuals EXITING

QQ#3: What are two ways in which a population can grow?

QQ#4: What causes Exponential Growth? Under ideal conditions, with unlimited resources, a population will grow exponentially. Exponential growth occurs when the individuals in a population reproduce at a constant rate The population become larger and larger until it approaches an infinitely large size Make sure to draw all the graphs in your notes!!!

QQ#5: What is logistic growth? Logistic growth occurs when resources are not unlimited Population grows exponentially until slowing as it reaches the carrying capacity

Carrying capacity The largest number of individuals of a population that a given environment can support is called its carrying capacity When a population reaches the carrying capacity of its environment, its growth level hovers around the carrying capacity until it levels off. At this time, the average growth level is zero

QQ#6: What do you think would happen to a population if they somehow way exceed the carrying capacity? W If a population exceeds its carry capacity: The population size will drop rapidly and a new carrying capacity is established

Check For Understanding (you don’t need to write these) When the birthrate of a population exceeds its death rate, the population decreases. increases. stays the same. increases then decreases.

Check for Understanding An S-shaped curve on a graph of population growth is characteristic of exponential growth. logistic growth. carrying capacity. delayed growth.

Check for understanding Exponential growth in a population slows down or stops as resources become limited. rate of immigration increases. rate of emigration decreases. birth rate increases.