AP Biology Unit 2 : Ecology and Animal Behavior

Behavior

1) What an animal does and how it does it
2) Subject to natural selection

What is behavior affected by?

Genetic and Environmental Factors

Ethology

The study of behavior

Proximate Cause

"How" a behavior occurs or is modified

Ultimate Cause

"Why" a behavior in context of natural selection

Innate Behavior

1) Developmentally Fixed (instinctual)
2) Automatic (Built in)
3) All Individuals do them

Learned Behaviors

1) Behaviors modified based on experiences
2) Flexible with environment
3) Complex

Types of Innate Behaviors

1) Fixed Action Patterns
2) Movement
3) Communication

Fixed Action Patterns

1) Sequence of unlearned acts that are unchangeable and usually carried to completion
2) Triggered by sign stimulus

Movement Types

1) Kinesis
2) Taxis
3) Communication

Kinesis

Random movement in response to a stimulus

Taxis

Oriented movement toward or away from a stimulus

Types of Taxis

1) Phototaxis (light)
2) Geotaxis (earth)
3) Rheotaxis (current)
4) Chemotaxis (chemicals)

Migration

Regular, long-distance change in location

How Animals know where to migrate

Environmental Cues

Types of Communication

1) Auditory (sound)
2) Visual (sight)
3) Tactile (touch)
4) Pheromones (chemicals, smell)
5) Dancing

Types of Learned Behaviors

1) Imprinting
2) Associative Learning
3) Social Learning

Imprinting

1) Long-lasting behavioral response to an individual/object
2) Both learned and innate components
3) Formed during sensitive period in life
4) Results in newborn animals bonding with their parent(s).

Associative Learning

1) Associate one stimulus w/ another
2) Classical and operant conditioning

Classical conditioning

Arbitrary stimulus associated with a particular outcome

Operant conditioning

Associates own behavior with a reward or punishment

Social Learning

Learning by observing others

Foraging Behavior

1) Food obtaining behavior
2) Includes searching for, recognizing, and capturing food items

Optimal Foraging Model

1) A "cost benefit" analysis
2) Natural selection should favor a foraging strategy that maximizes benefits and minimizes costs
2a) Costs of foraging (risk of predation/injury, energy spent)
2b) Benefits of foraging (food for energy, survival)

Mating Systems

1) Monogamy
2) Polygamy

Monogamy

Male-Female pair

Polygamy

1) Individual of one sex mating with several of the other
2) Polygyny
3) Polyandry

Polygyny

One males; many females

Polyandry

One female; many males

Factors that influence Mating Systems

1) If offspring need large, continuous food supply
2) If both partners can contribute
3) Certainty of paternity
4) Maximizing reproductive success

Parental Care

Young born to or eggs laid by female definitely share 50% of her genes

Internal fertilization

1) Mating and egg laying/birth separated by time
2) Paternity unknown

External fertilization

1) Mating and egg laying occurs at the same time
2) Paternity more clear
3) More male parental care

Selfishness and Fitness

1) Natural selection favors an individuals survival and reproduction
2) Behavior is often selfish (ie blood parasitism)

Altruism

A behavior that reduces an individuals fitness but increases the fitness of other individuals in the population

Inclusive fitness (altruism)

Genes passed on by producing own offspring AND helping close relatives to produce offspring

Kin Selection

Enhancing reproductive success of relatives

Hamilton's Rule of Altruism

Altruism will be selected for if r*B > C
r = coefficient of relatedness (% of shared genes)
B = benefit to relative
C = Cost to helper
"I would lay down my life for 2 of my siblings or eight of my cousins"

Reciprocal Altruism

Altruism/cooperation between unrelated individuals
"I help you now, you help me later"

Biological Organization

Organized by Small to Big or Big to Small

BECPO

biosphere, ecosystem, community, population, organism

Biosphere

The part of the earth that contains all ecosystems

Ecosystem

A biological community of interacting organisms and their abiotic (non-living) factors with which they interact.

Community

populations that live together in a defined area

Population

a group of organisms of the same species that live in the same area

Organism

Individual living thing

Abiotic Components of an Environment

Non-living things (water, gasses, minerals, temp, etc)

Biotic Components of an Environment

Living things (plants, animals, bacteria, fungi, dead things, etc)

Ecology

Study of ecosystems

Biome

1) A major ecosystem type
2) Classified by predominant vegetation or physical environment

Ecosystem vs. Biome

Biome is a general term; Ecosystem is specific
(Desert vs. Mojave Desert)

Habitats and Niches

Habitat - Where an organism lives
Niche - The role a species plays; its job (includes its habitat, activity patterns, resources it uses)

Trophic Levels

1) Autotroph
2) Heterotroph

Autotroph

Self-feeder/Primary Producer - Energy from sun/light

Heterotroph

Other-feeder/Consumers (eat other auto/heterotrophs)

Heterotroph Types

1) Primary consumers (herbivores)
2) Secondary consumers (carnivores) - eat herbivores
3) Tertiary Consumers (carnivores)
4) Decomposers (eat dead stuff)/Heterotrophs

Food Chain vs. Food web

Food Chain: Pathway along which food energy is transferred between trophic levels
Food Web: Interconnected feeding relationships of various organisms in an ecosystem
Both: Arrows pt. towards direction biomass is moving

Trophic Pyramid Energy Transfer

Only 10% of biomass & energy transfers up each trophic level

Measure of efficiency of animals as energy transforms

Production Efficiency =
(net secondary production * 100%) /
(Assimilation of primary production)

Factors that Influence Population Growth

1) Birth Rate
2) Death Rate
3) Immigration
4) Emigration

What would zero population growth look like?

Birth Rate = Death Rate

Experimental Population Growth Ideal Conditions

1) Few/No predators
2) Lots of Food/shelter
3) Population grows rapidly

Experimental Population Growth Equation

dN/dt = rmax(N)
dN/dt : Population size during time interval
rmax : Maximum per capita growth rate of population (birth rate - death rate)
N : population size

Logistical Population Growth

Population growth that levels off as population size approaches carrying capacity
K : Carrying Capacity - max stable population which can be sustained by environment

Logistical Population Growth Equation

dN/dt = rmax(N) * ((K-N)/K)

Factors Influencing Carrying Capacity

Abiotic Factors
1) Rainfall, Temperature, Sunlight, Currents
Biotic Factors
1) Food sources, predators, diseases, competition

What happens if a population size goes over K?

The Population size will return to K

Human Carrying Capacity

Varies; depends on standard of living

Survivorship Curve

Shows the proportion of individuals likely to survive to each age

Type 1 survivorship curve

Low death rate; many individuals live to old ages

Type 2 survivorship curve

Moderate death rate; individuals die at all ages

Type 3 survivorship curve

High death rate; many individuals die young and few live to old age

Life History

Things that affect an organism's schedule of reproduction and survival

Life History Traits

1) Age of sexual maturation
2) How often an organisms reproduces
3) Number of offspring each time
*Remember these traits are evolutionary outcomes, not conscious decisions

r/K Selection theory

1) Reproduction is a trade off between "quality" and quantity of offspring
2) Not enough energy for tons of offspring, multiple times, provide lot of care to all babies for super high fitness

Evolutionary Strategies

1) r-selection
2) k-selection

r-selection

Have MANY babies, provide little/no care

K-selection

Have FEW babies, provide care to help with survival

Semelparity (Semelparous)

"Big bang reproduction"
-Many offspring produced at once
-Individual often dies afterward
-Less stable environments

Iteroparity (Iteroparous)

Repeated reproductive events
-Few offspring multiple times during life
-Usually larger
-More stable environments

Density Independent Factors

Population size DOESN'T matter
- Natural disasters, fire, flood, drought

Density Dependent Factors

Population size DOES matter
- Competition, territoriality, parasitism, disease, predation, waste build up, stress

competitive exclusion principle

1) Two species cannot coexist in a community in identical niches
2) one will eventually "win"

Resource Partitioning (niche competition)

differences in niches that enable similar species to coexist

Fundamental Niche

The niche potentially occupied by the species

Realized niche

Portion of fundamental niche actually occupied by the species

Predation defenses

1) Camouflage/Cryptic coloration
2) Aposematic/warning coloration (poison)
3) Toxins/thorns/spikes

Batesian mimicry

A harmless species mimics color of harmful species

Mullerian mimicry

Bad tasting species resemble each other; both to be avoided

Dominant species

Species with the highest biomass or most abundant species in the community

Keystone species

1) Species that play a critical role in their community
2) impact is greater than expected based on their abundance

Community Regulation

Top Down: Top predator in the trophic pyramid controls biomass
Bottom Up: The autotrophs control the biomass of the trophic levels above it

Trophic Cascade (Top Down)

1) Predators suppress the abundance or alter the behavior of prey
2) Releases the next lower trophic level from predation

Primary succession

Species invade where soil has not yet formed

Secondary succession

1) Disturbances: Fire, flood, storm, human activity
2) Soil still intact

Succession sequence

1) Pioneer species - 1st to colonize
2) Climax community - no longer changing

Biogeochemical (nutrient) Cycles

1) Life depends on recycling chemical elements
2) Nutrient cycles in ecosystems involve biotic and abiotic compounds

Four nutrient cycles

1) Water
2) Carbon
3) Nitrogen
4) Phosphorous

Water (hydrologic) cycle

1) Essential to all organisms
2) Nearly all chemical reactions in our body occur in water found in/around cells
3) Water carries nutrients, gas, and waste
4) Influences rate of primary production/decomposition in terrestrial ecosystems
5) Liquid water is the primary physical phase in which water is used

Water Cycle Key Processes

1) Evaporation by solar energy
2) Condensation of water vapor into clouds
3) Precipitation (rain, snow, fog, hail)
4) Transpiration (water loss from plants)
4) Surface/ground water flow to ocean