AP Bio Review (3.31)

Visual, chemical, tactile, and auditory

Visual: one individual of a species sees another individual of the same species.

Chemical: animals use chemicals or pheromones to detect or to communicate with each other.

Tactile: involves touching

Auditory: communication based on sound

Organisms respond to changes in their environment through behavioral and physiological mechanisms.

Example: phototropism in plants, nocturnal activity

Organisms exchange information with one another in response to internal changes and external cues, which can change behavior.

Example: Fight-or-flight response

Organisms learn to behave a specific way and improve their fitness.

Example: crows learn that a scarecrow is not a human and poses no real risk, so the crows will not avoid a garden anymore.

Learned

Instinctive behaviors performed without any previous experience.

Example: web-making in spiders

Innate

• Individuals can act on information and communicate it to others (ex: signaling behaviors that produce changes in the behavior of other organisms). They use the different forms of communication to establish dominance, find food, establish territory, and ensure their reproductive success.

• Natural selection favors innate and learned behaviors that increase survival and reproductive success

• Cooperative behavior tends to increase the fitness of an individual and survival of the population

Type of interaction Species 1 Species 2

Predation + -

Parasitism + -

Herbivory + -

Competition - -

Mutualism + +

Commensalism + 0

Population growth is limited by the ecosystem's carrying capacity (K) - the maximum amount of organisms an ecosystem can support with its resources

• Population grows exponentially until the cap is reached

• More realistic.

Logistic (S-shaped curve)

Population growth under ideal conditions - basically how a population would grow with unlimited resources

• Not a realistic model in most cases

Exponential (J-shaped curve)

Survivorship Curves

• Type I: High survival throughout most of their life, low survival late in life

• Type II: Experience steadily declining survival throughout their life

• Type III: Low survival early in life and then slower decline throughout the rest of their life.

Population growth is reduced regardless of the current population size.

• These are typically abiotic factors

  • Natural disasters

    • Both small and large populations are equally likely to experience declines

Density Independent

The growth of the population is increasingly limited as its size increases

• These are typically biotic factors

  • Competition, disease, etc.

Density Dependent

Population Size & Energy

As the population size changes, so does its energy consumption and requirements

• As a population grows, they will consume more energy

Heterotrophs capture energy present in carbon compounds from other organisms and continue the flow of energy up the food chain

Heterotrophs

Autotrophs capture energy from physical or chemical sources in the environment.

Essentially, this initiates the movement of energy throughout the ecosystem

Autotrophs

Producer

The primary producer is the grass/shrubs

Net primary production accounts for metabolism and maintenance, so it is the total amount of useful energy for an ecosystem

NPP = GPP - rate of energy loss to maintenance and metabolism

NPP

The gross primary production is the rate at which primary producers save and collect biomass for energy conservation

GPP