unit 8.1 ecology 1 megaset

Behavior

The way in which an animal acts in response to its environment or a particular stimulus

Stimulus

External or internal cue that triggers a change in behavior

4 questions to understand a behavior

1. causation

2. Development

3. Function/adaptive value

4. Phylogeny

Distinguish innate from learned behaviors

Only innate behaviors will be expressed by naive individuals

Learned vs Innate spectrum

many behaviors are not solely learned or innate but a combination of the two

Innate behaviors

genetically hardwired behaviors

1. reflexes (simple)

2. fixed action patterns (complex)

3. Kinesis

4. Taxis

reflexes

involuntary and rapid response to a stimuli

• some reflexes are so fast that they bypass the brain

fixed action pattern

• predictable, complex series of action triggered by a stimulus

Kinesis

non direction innate movement in response to a stimulus, such as speeding up or slowing down

Taxis

innate directional response to a stimulus, such as moving towards or away from a stimulus

1. Phototaxis

2. Chemotaxis

3. Geotaxis

Phototaxis

moving toward/away from light

Chemotaxis

moving toward/away from chemical stimulus

Geotaxis

moving with/away from force of gravity

learned behaviors

behaviors developed through experience

1. Classical Conditioning

2. Operant Conditioning

3. Cognition

Classical conditioning

associating a NEW stimulus to an already established stimulus and response

Operant conditioning

NO previous stimulus and response pair needed

NEW behavior (originally done at random) is reinforced by either reward or punishment

cognition

using knowledge and understanding to solve problems

behavior may be stimulated in the mind before acting

Plant responses to environment

1. Phototropism

2. Photoperiodism

3. Gravitropism

Phototropism

response to light in which a plant grows towards or away from light

Photoperiodism

plant response to the amount and type of light they are exposed to

Gravitropism

response to the direction of gravity

Exponential growth formula

dN/dT = r_maxN

r = per capita rate of increase, stays constant

unconstrained growth

r = r_max

Birth/Death Growth formula

dN/dT = B - D = rN

B = birth RATE

D = death RATE

Logistic growth

dN/dT = r_max((K-N)/K)*N

growth that slows as population reaches carrying capacity (K)

K = max pop size

r = rmax ( (K-N)/K ), gets smaller towards K

Density-Dependent Limiting Factors

• create logistic growth pattern and determines K

• factors are mostly biotic

1. Competition w/n population

2. Predation

3. Disease and parasites

4. Waste accumulation

Competition w/n population

• population grows but resources do not

  • food, water, shelter are limited

• Responses

  1. Slow down breeding

  2. Migrate

  3. Die

Predation

predators focus on HIGH density prey areas and avoid low density prey areas

Disease and parasites

• diseases and parasites spread easier in HIGH density populations

• have their own growth curves

Density-independent factors

• affect growth rates, not dependent on density

• mostly abiotic

• Natural disasters

Cyclic oscillations

populations that rise and fall over time

1. Seasonal changes

2. Overshooting carrying capacity

3. Predator-prey interactions

10% rule

each trophic level biomass is 10% of the level below

primary productivity

• biomass of the primary producers

• energy limitation of the entire ecosystem

types of ecological pyramids

1. Energy pyramid

2. Biomass pyramid

3. Numbers pyramid

Energy pyramid

each level represents amount of energy available to that trophic level

10% rule

Biomass pyramid

each level represents the amount of biomass consumed by the level above it

Number pyramid

each level represents the number of individual organisms consumed by the level above it

Trophic cascade

Indirect interaction between trophic levels that control an ecosystem

1. Bottom-up cascade — lower trophic levels limit upper ones

2. Top-down cascade — upper trophic levels affect lower ones

   • often creates keystone species

Metabolism

1. Endotherm

2. Ectotherm

Endotherm

use metabolism to keep a stable body temp

Baseline - Basal Metabolic Rate (BMR)

• Metabolism at rest

Ectotherm

does NOT use metabolism to keep a stable body temp

Baseline - Standard Metabolic Rate (SMR)

• minimum metabolism needed to sustain life at a given temperature

Smaller organisms

these organisms have higher metabolic rates per mass

• Applies to both ectotherms and endotherms

Torpor

state of decr activity and metabolism that allows animals to survive unfavorable conditions

1. Hibernation

2. Estivation

Hibernation

torpor during winter

Estivation

torpor during summer

types of Heat exchange

1. Radiation

2. Conduction

3. Evaporation

Radiation

exchange heat via infrared radiation

Conduction

exchange heat via direct contact

Evaporation

exchange heat via evaporation of water

Heat regulation methods

1. Behavioral changes

2. thermogenesis

3. vasoconstriction/vasodilation

4. countercurrent heat exchange

5. insulation and evaporation adaptations

Behavioral changes

changing behavior to increase or decrease body temperature

• very impt in ectotherms

Thermogenesis

• only in endotherms

  • thermogenesis uses metabolism to create heat

• deliberate movements

  • walking around, continuous motion, rubbing hands together

• Shivering

  • Nondeliberate muscle movements

• non-shivering thermogenesis

  • burning of special fat tissue - brown fat

  • brown fat is found in many hibernating mammals

Non-shivering thermogenesis

burn brown fat to generate heat

• found in many hibernating mammals

vasoconstriction

Increasing the amount and speed of blood flowing to and within the skin by widening the blood vessels (vasodilation) allows more heat to be lost thereby reducing body temperature.

Narrowing the blood vessels (vasoconstriction) means less heat will be lost this way thereby maintaining the core temperature of the body

Countercurrent heat exchange

Arterial blood heats up venous blood returning from extremities

→ arterial blood loses less heat as it goes to extremities

→ venous blood is warmed up before it returns to body’s core

insulation adaptations

hairs, feathers, fat insulate heat

evaporation adaptations

sweating helps regulate heat

Reproductive life histories (patterns)

1. Energy investment per offspring

2. fecundity

3. reproductive timing

4. semelparity vs iteroparity

Energy investment vs fecundity tradeoff 2 strategies

1. Low energy investment / high fecundity

2. high energy investment / low fecundity

reproductive timing

• breed earlier in life

• breed later in life — risk dying before you can breed

Semelparity

breed once in a lifetime

Iteroparity

Breeds multiple times in one lifetime