AP Biology Unit 8

Ethology

The study of how evolutionary processes shape inherited behaviors and the ways that animals respond to specific stimuli

Behavior

An animal’s response to a stimulus (internal or external)

Example: nature vs. nurture (genetic and environmental factors) and allow for survival and reproduction (subject to natural selection)

Proximate cause

How a behavior occurs or how it is modified


1. What was the stimulus to cause the behavior
2. How does the “nurture” component affect behavior? (How do the experiences during growth and development influence the response)

Ultimate cause

Why a behavior occurs (in context of natural selection)


1. How does the behavior help the animal survive and reproduce?
2. How does the “nature” component affect behavior? (What is the evolutionary basis of the behavior)

Innate behaviors

Developmentally fixed

* hereditary, born behaviors, do not need to learn them; instinctive
* Experience during growth have no obvios effect

Learned behaviors

Depend on environmental influence

* experiences do affect these behaviors
* High variation in a population

Fixed action patterns (FAPs)

Sequence of unlearned acts directly linked to a stimulus

* actions are unchangeable
* Carried out to completion
* Triggered by a sign stimulus (external cue)

Migration

A regular, long distance change in location

* triggered by environmental cues (sun’s position, earth’s magnetic field and celestial cues)

Signal

A stimulus generated and transmitted from one animal to another; animal communication

* examples: visual, auditory, tactile, electrical, chemical

Pheromones

Chemicals emitted by members of a species that can affect other members of the same species

Stimulus response chains

When a response to a stimulus serves as the next stimulus for a behavior

* seen in animal courtships

Body movement

Example: waggle dance in bees

Directed movements

Movements towards or away from a stimulus

Kinesis

A change in the rate of movement or the frequency of turning movements in response to a stimulus; non directional

Taxis

Directional movement towards (positive) or away from (negative) a stimulus

Phototaxis

Movement in response to light

Chemotaxis

Movement in response to chemical signal

Geotaxis

Movement in response to gravity

Learning

The modification of behavior based on specific experiences

Imprinting

A long lasting behavior response to an individual

* happens during a sensitive period of development (usually very early in life)
* Imprinting occurs on the first individual they encounter

Spatial learning

Establishing memories based upon the spatial structure of the animal’s surroundings

* some animals form a cognitive map or use landmarks as environmental cues (example: birds finding their hidden nests)

Associative learning

The ability to associate one environmental feature with another

* example: associating monarch butterflies with foul taste

Social learning

Learning through observations and imitations of the observed behaviors

* example: chimps breaking open oil palm nuts

Foraging

Food obtaining behavior

* searching for, recognizing and capturing food items
* Animals better at foraging will be more successful in finding food

Mating behaviors

Animals can be monogamous or polygamous (polygyny or polyandry)

* sexual dimorphism can result from sexual selection

Altruism

Selfless behavior

* reduced the individual’s fitness, but increases the fitness of the rest of the population
* Example: naked mole rat colonies have only one reproducing female (queen), who will only mate with a few males (kings). The other reproductive members will sacrifice themselves to protect their queen and kings

Phototropism

A directional response that allows plats to grow towards (an in some cases away from) a source of light

Photoperiodism

Allows plants to develop in response to day length; plants flower only at certain times of the year

Response in plants

* Defend themselves against herbivory
* physical defenses: thorns, trichomes (small plant like hairs)
* Chemical defenses: production of toxic or distasteful compounds

Soil composition

* soil composition can affect plants
* The pH of soil can affect flower coloring in some plants
* Nutrients are more accessible at certain pH
* Example: hydrangea blooms turn different colors based on soil pH

Ecosystem

the sum of all the organisms living in a given area and the abiotic factors they interact with

Biotic factors

Living, or once living, components of an environments

Abiotic factors

Non living (physical and chemical properties of the environment)

1st law of thermodynamics

energy can neither be created nor destroyed, only transferred

2nd law of thermodynamics

Exchanges of energy increase the entropy of the universe

Net gain in energy

Net gain results in energy storage or growth of an organism

Net loss of energy

Results in loss of mass and eventual death of an organism

Metabolic rate

The total amount of energy an animals uses in a unit of time

* can be measured in calories, heat loss or by the amount of oxygen consumed (or CO2 produced)
* An animal’s metabolic rate is related to its body mass

Animal’s metabolic rate

* smaller organisms = higher metabolic rate
* Larger organism = lower metabolic rate

Endotherms

Use thermal energy from metabolism to maintain body temperature

Ectotherms

Use external sources (ie. sun/shade or other organisms) to regulate their body temperature

Tropic levels

Species can be grouped into tropic levels based upon their main source of nutrition and energy

* energy cannot be recycled
* The sun constantly supplied energy to ecosystems

primary producers

Use light energy to synthesize organic compound

* plants, algae, photosynthetic plankton

Chemosynthetic

they produce food using the energy created by chemical reactions

Heterotrophs

rely on autotrophs because they cannot make their out food

Primary consumers

Herbivore

Secondary consumers

Carnivores that eat other carnivores

Decomposers

Get energy from detritus (no living organic material; leaves, wood, dead organism)

* include fungi and many prokaryotes
* Important for recycling chemical elements

Tropic structures

Structures of a community are determined by the feeding relationships between organisms

Food chain

The transfer of food energy up the trophies levels

Food ebs

Linked food chains

Disrupted ecosystems

* if energy resources change so can the number and size of trophies levels (increase energy = increase tropic levels or decrease energy = decrease tropic levels)
* A change at the producer level can affect the number and size of the remaining trophies levels

Primary production

The amount of light energy that is converted to chemical energy

* set a spending limit for the entire ecosystems energy budget

Gross primary production (GPP)

Total primary production in an ecosystem

Net primary production (NPP)

the GPP minus the energy used by the primary producers for respiration (Ra)

Secondary production

the amount of chemical energy in a consumer’s food that is converted to new biomass

* the transfer of energy between tropic levels is at 10% efficiency

Biogeochemical cycles

Nutrient cycles that contain both biotic and abiotic factors

* water, carbon, nitrogen and phosphorus cycle

Water cycle

Water is essential for all life and influences the rate of ecosystem processes

Carbon cycle

Carbon is essential for life and required in the formation of organic compounds

Nitrogen cycle

Nitrogen is important for the formation of amino acids, proteins and nucleic acids

Phosphorus cycle

Phosphorus is important for the formation of nucleic acids, phospholipids and ATP (energy)

Population

A group of individuals of the same species living in an area

Population ecology

Analyzes the factors that affect population size and how and why it changes over time

Density

The number of individuals per unit area

Can be determined by:

* counting number of indizaos in the population
* Sampling techniques (count small areas, average the areas and then use the averages to estimate total population size)

Dispersion

The pattern of spacing among individuals within a population

Clumped

Indícelas gather in patches

Uniform

Evenly spaced India urls in a population

* can be due to territoriality

Random

Unpredictable spacing; not common

Size of a population

Affected by:

* births/deaths
* Immigration/emigration
* Demography

Demography

The study of the vital statistics of populations and how they change over time

Life table

Age specific summary of the survival pattern of a population

* represented by a survivorship curve

Type 1 curve

Low death rate during early/middle life and high death rate later in life

Type II curve

Constant death rate over the lifespan of the organism

Type III curve

High death rate early in life and lower death rate for those that survive early life

Exponential growth model

A population living under ideal condition (ie easy access to food, abundant food, free to reproduce, ect)

* population grows rapidly
* J shaped curve

Logistic growth model

The per capita rate of increase approaches zero as the population size nears its carrying capacity

* the density of individual exceeds the system’s resource availability

Life history

The traits that affect an organism’s schedule of reproduction and survival

Can be affect by:

* when reproduction begins
* How often the organism can reproduce
* The number of offspring produced per reproductive episode

K-selection

* density dependent selection
* Selection for life history traits that are se site to population density
* Seen in high density populations that are close to carrying capacity (K)

R-selection

* density independent selection
* Selection for life history traits that maximize reproduction success
* Seen in low density populations with little competition

Density dependent regulation

As a population increases, factors can slow or stop growth by decreasing birth rate and increasing death rate

* competition, predation, toxic wastes, territoriality, disease, intrinsic factors

Density-independent regulation

Factors that excerpt their influence on population size, but the birth/death rate of a population does not change

* weather, climate, natural disasters

Community

A group of population of different species living closely and capable of interacting

Habitat

A place or part of an ecosystem occupied by an organism

Ecological niche

The role and position a species has in its environment

Fundamental niche

The niche potentially occupied by the species if there were no limiting factors (predators, competitors, ect.)

Realized niche

The portion of the fundamental niche the species actually occupies

Interspecific interactions

Interactions of individuals from one species with individual of another species

* competition, predation, herbivore, symbiosis, facilitation

Competition

\-/- relationship where individuals of different species compete for limited resources

Competitive exclusion principle

Two species completing for the same resource cannot coexist permanently

* the competitor with even a slightly better advantage will eliminate the inferior competitor

Niche partitioning

Natural selection drive competing species into different patterns of resource use, or different niches

Predation

\+/- relationship where one species (predator) kills and eats the other species (prey)

* adaption of both predators and prey have been refined by natural selection

Cryptic coloration

Camouflage

Batesian mimicry

Harmless species mimics a harmful one

Mullirian mimicry

Two or more bad-tasting species resemble each other

Herbivory

\+/- relationship where one organism eats part of a plant or alga

Symbiosis

When 2 or more species live in direct contact with one another

Parasitism

* +/-
* When one organism (parasite) derives nourishment from another (host)

Mutualism

* +/+
* When both organisms benefit rom the relationship

Commensalism

* +/0
* When one organism benefits and the other is neither harmed nor benefited