Brainstorm  Please list 3 Abiotic and 3 Biotic factors that affect population growth and decrease in size.

Old Bio Stuff Abiotic vs. Biotic Factors That limit population growth  Not living  Sunlight  Temperature  Climate  Chemical environment  Living factors  Reproduction rates  Food supply  Habitat  Resistance to disease  Ability to adapt to change Abiotic Biotic

POPULATION SIZE Growth factors (biotic potential) Favorable light Favorable temperature Favorable chemical environment (optimal level of critical nutrients) Abiotic Biotic High reproductive rate Generalized niche Adequate food supply Suitable habitat Ability to compete for resources Ability to hide from or defend against predators Ability to resist diseases and parasites Ability to migrate and live in other habitats Ability to adapt to environmental change Decrease factors (environmental resistance) Too much or too little light Temperature too high or too low Unfavorable chemical environment (too much or too little of critical nutrients) Abiotic Biotic Low reproductive rate Specialized niche Inadequate food supply Unsuitable or destroyed habitat Too many competitors Insufficient ability to hide from or defend against predators Inability to resist diseases and parasites Inability to migrate and live in other habitats Inability to adapt to environmental change Biotic potential = growth Environmental resistance = decrease

How come this doesn’t happen

Population Dynamics

Bus Analogy  What is the bus a symbol of?  As the # of people on the bus increases, what is the impact on…  The people trying to get on  The people already on  The bus itself

Population Dynamics  Studying the change in size, density, and distribution of a population.

Population Dynamics Size: number of individuals Density: how many individuals are in a certain area Distribution: How many individuals are in a certain group (gender, age, etc.) and where the population lives

Size  Increases in population: through birth or immigration  Decreases in population: through death or emigration. Change in Population Births + Immigration Deaths + Emigration Note: You should know difference between Immigration & Emigration!

Turkey Trending  NY State population = 300,000  500,000 births, 25,000 immigrate  450,000 deaths, 50,000 emigrate  = (B + I) – (D + E)

Two Types of Growth  No limiting factors  Shown in r-species  Boom, then bust  Limiting factors present  Shown in K-species  Stable populations Exponential (Bacteria)Logistic (Turkeys)

Exponential or Logistic Growth Curve? “Boom and Bust” “Boom then stable”

Logistic Growth  Will see exponential growth at first introduction to new environment.  Then, growth will be limited by environmental factors and will follow carrying capacity  S shaped Population size (N) Time (t) Carrying capacity (K) Environmental resistance Biotic potential Exponential growth

Clearer view of “J” and “S”

Going up…  Intrinsic rate of increase (r) is the rate the population would grow if it had unlimited resources.  Can be seen as the “boom” of the population.

Coming down…  Overshoot occurs when the population “booms” and is too great for the resources to support  Overshoot is followed by dieback, or the sudden decrease in population

What species are you? Number of individuals Time Carrying capacity K species; experience K selection r species; experience r selection

Species  Reproduce early in life  Reproduce frequently  Large numbers of offspring  Little to no parental care  Boom and bust populations  Examples:  Frogs  Cockroach  Dandelions  Mice  Most insects  Reproduce later in life  Reproduce less frequently  Have less offspring at one time  Lower infant mortality  Logistic graph (stable at top)  Examples:  Humans  Elephants  Whales  Long-living plants r-selected SpeciesK-selected Species