8.1 - 8.4

Behavior & physiologcal mechanisms

Organisms respond to changes in their environment through…

Stimulus

External or internal signal or combination of signals that causes a response from an organism

Signaling Behaviors

Actions or traits, including structures, that have evolved to convey information to other individuals, often with the goal of benefiting the signaller. These signals can be used to communicate a variety of information, such as intentions, preferences, or social status. 

Differential reproductive success

Signaling behaviors produce changes in behaviors of other organisms →

Indicate dominance, find food, establish territory, ensure reproductive success

Communication mechanisms have multiple uses:

Visual, audible, tactible, electrical, & chemical signals

Animals use various communication mechanisms:

Natural Selection

_____ _______ favors innate & learned behaviors that increase survival & reproductive success.

Innate behaviors

Behaviors that are genetically controlled & can occur w/out prior experience or training

Learned behaviors

Behaviors developed as a result of experience

Cooperative behaviors

Behaviors that involve teamwork between organisms of the same species.

Increase

Cooperative behaviors _______ the fitness of the individual and survival of the population.

Endotherms

Use thermal energy generated by metabolism to maintain homeostatic body temperatures (ex: change in heart rate, fat storage, muscual contractions (shivering)).

Ectotherms

Lack efficent interal mechanisms to regulate & maintain body temperatures. Rely on behaviors to regulate temperature (ex: moving into or out of the sun).

Metabolic rate

Amount of energy expended by an animal over a specific amount of time.

Net Gain in Energy

Energy storage or growth

Net Loss in Energy

loss of mass & possibly death

higher

The smaller the organism, the ______ the metabolic rate.

Less energy-efficent, more common in unstable environments where resources aren’t readily available and the environment experiences frequent changes.

What effects does producing a lot of offspring at one time lead to?

More energy-efficent, more common in stable ecological environments

What effects does producing few offspring at one time lead to?

Changes in energy availiability

_________ can result in changes in population size and disruptions to an ecosystem.

Change in energy resources (ex: sunlight)

________ can affect the # and size of the trophic levels.

Change in producer level

________ can affect the # & size of other trophic levels.

Trophic level

Position an organism occupies in a food chain

Food Chain

Shows the direction of nutrient & energy transfer from one organism to another. Each organism occupies a different trophic level & reflects how many energy transfers seperate it from the producer.

Food Webs

Many interconnected food chains.

10%

What percentage of energy is actually transferred from one trophic level to another.

Energy inefficiency

Limits the length of food chains & the size of populations (decreases up trophic levels).

Autotrophs

Organisms that capture energy from physical or chemical sources in the environment.

Photosynthetic Organims

Organisms that capture enrgy present in sunlight.

Chemosynthetic Organisms

Organisms that capture energy from small inorganic molecules present in their environment with or without oxygen.

Heterotrophs

Organisms that capture energy present in carbon compounds (ex: glucose) produced by other organisms. Metabolize carbohydrates, lipids, & proteins as sources of energy by hydrolysis.

Seasonal Reproduction

Animals often reproduce in the spring or summer when food is more available to support offspring. Reproduction is triggered by a critical photoperiod (relative length of night & day). Ex: Grizzly bears.

Population

Organisms of the same species in a particular area.

More

Individuals with in a population usually interbreed with one another ____ than interbreeding with individuals from the other populations.

When food is less available

Less food to support individuals, reproduction rates decrease, offspring survivability decreases.

When food is more available

More food to support individuals, reproduction rates increase, offspring survivability increases.

Energy availabity changes

Different species have adaptations that aid in survival when…

Age at reproductive maturity, # of offspring produced, frequency of reproduction, survivorship of offspring to reproductive maturity

Factors affecting population growth

Exponential Growth

Sharp increase in the growth of a population. Occurs under ideal conditions, when resources are abundent. The # of organisms added in each generation increase as the population gets larger (more individuals are reproducing & how long it takes to produce an offspring stays the same). Represented by a J-shaped curve.

Population Density

How close individuals within a population live near 1 another

dense

When an abundunce of food is available → population can become ____ (higher reproductive rate & space is limited).

Density-dependent factors

Abiotic or biotic factors whose effect on population size relies on a population’s density (competition for resources, territoriality, disease, & predation).

Density-independent facotrs

Abiotic or biotic factors that affect population size regardless of population density (ex: Natural Disasters)

Logistic-Growth Model

Population growth that initally starts slowly, immediately followed by exponential growth and ends with a relatively stable maximum growth. Shown as an S-shaped curve.

Carrying Capacity

Max # of individuals an environment can sustain. Both density-independent & density-dependent limiting factors can cause a population to reach _______ ________.

exceed

Under certain condidtions, a population can temporarily ____ the carrying capacity → limiting factors will always bring population down & fluctuations in population size can naturally occur @ or near carrying capacity.