Unit 8 Ecology

Interactions between complex living organisms can lead to changes in communities and ecosystems

Ethology

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

Behavior

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

Proximate Cause

how a behavior occurs or how it is modified

what was the stimulus to cause the behavior and how does the “nurture” component affect behavior?

Ultimate Cause

why a behavior occurs (in context of natural selection)

how does the behavior help the animal survive and reproduce and how does the “nature” component affect behavior?

Innate Behavior

developmentally fixed

Learned Behavior

depend on environmental influence

Fixed Action Patterns (FAPs)

a sequence of unlearned acts directly linked to a stimulus

Migration

a regular, long-distance change in location triggered by environmental cues

Signal

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

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

Directed Movements

movements towards or away from a stimulus

Kinesis

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

Taxis

a directional movement towards (+) or away from (-) a stimulus

Phototaxis

movement in response to light

Chemotaxis

movement in response to chem signals

Geotaxis

movement in response to gravity

Learning

modification of behavior based on specific experince

Imprinting

a long-lasting behavioral response to an individual during a sensitive period of development

Spacial Learning

establishing memories based upon the spacial structure of the animal’s surrounding

Associative Learning

ability to associate one environmental feature with another

Social Learning

learning though observations and imitations of the observed behaviors

Natural Selection Favors

behaviors (innate or learned) that increase survival and reproduction

Foraging

food obtaining behavior

Mating Behavior

animals can be monogamous or polygamous

sexual dimorphism can result from sexual selection

Altruism

selfless behavior

Phototropism

a directional response that allows plants to grow towards (and 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

Ecosystem

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

Biotic Factors

living, or once living, components of an enviorment

Abiotic Factors

nonliving (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

Metabolic Rate

total remount of energy an animal uses in a unit of time

Endotherms

use thermal energy from metabolism to maintain body temperatures

Ectotherms

use external sources to regulate their body temperature

Chemosynthetic

produce food using the energy created by chemical reactions

Heterotrophs

rely on autotrophs because they cannot make their own food

Primary Consumers

herbivores

Secondary Consumers

carnivores that eat other carnivores that eat herbivores

Tertiary Consumers

carnivores that eat other carnivores

Decomposers

get energy from detritus (nonliving organic material)

Food Chain

transfer of food energy up the trophic levels

Food Webs

linked food chains

Primary Production

amount of light energy that is converted to chemical energy and set’s a “spending limit” for the entire ecosystem energy budget

Net Primary Production (NPP)

the GPP minus energy used by the primary producers for respiration

Gross Primary Production

total primary production in an ecosytem

Secondary Production

amount of chemical energy in a consumer’s food that is converted to new biomass but the transfer of energy is at around 10% efficency

Biogeochemical Cycles

nutrient cycles that contain both biotic and abiotic factors

Water Cycle’s Biological Importance

essential for all life and influences that rate of ecosystem processes

Carbon Cycle’s Biological Importance

essential for all life and required in the formation of organic compounds

Nitrogen Cycle’s Biological Importance

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

Phosphorous Cycle’s Biological Importance

important for the formation of nucleic acids, phospolips, and ATP

Population

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

Population Ecology

analyze the factors that affect population size and how and why it changes overtime

Density

number of individuals per unit area

Dispersion

Pattern of spacing among individuals within a population

Clumped Pattern

individuals gather in patches

Uniform Pattern

evenly spread individuals in a population that can be due to territoriality

Random Pattern

unpredictable spacing and not as common

Demography

study of the uital statistic of populations and how they change overtime

Life Table

an age-specific summary of the survival pattern of a population

Survivorship Type I Curve

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

Survivorship Type II Curve

constant death rate over the lifespan of the organism

Survivorship 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 conditions so the population grows rapidly

dN/dt = rmax * N

Logistic Growth Model

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

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

Life History

traits affect an organism’s schedule of reproduction and survival; affected by reduction beginning, how often they can reproduce, and the number of offspring produced

K-Selection

selection for life history populations that are sensitive to the population density; seen in high density populations close to carry capacity and in density-dependent selection

R-Selection

selection for life history traits that maximize reproductive success; seen in low density populations with little competition and in density-independent selection

Density-Dependent Regulation

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

Density-Independent Regulation

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

Community

a group of populations 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 enviornment

Fundamental Niche

the niche potentially occupied by the species if there were no limiting factors

Realized Niche

the portion of the fundamental niche the species actually occupies

Interspecific Interactions

interactions of individuals from one species with individuals of another species

Competition

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

Competitive Exclusion Principle

two species competing for the same resources cannot coexist permanently

Niche Partitioning

+/- realtionship where one species kills and eats the other species

Cryptic Coloration

Camouflage

Batesian Mimicry

harmless species mimics a harmful one

Mullerian Mimicry

two or more bad-tasting species resemble each other

Herbivory

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

Symbiosis

where two or more species live in direct contact with one another

Parasitism

+/- where one organism (parasite) derives nourishment from another

Mutualism

+/+ where both organisms benefit from the realtionship

Commensalism

+/0 where on organism benefits and the other is neither harmed or helped

Facilitation

+/+ 0/+ when one species has a positive effect on the survival and reproduction of another without intimate associations of symbiosis; common in plant species

Species Diversity

the variety of different organisms within a community

Species Richness

Number of different species

Relative Abundance

proportion each species represents of all the individuals in the community

Simpson’s Diversity Index

calculate diversity based on species richness and relative abundance

1 - sum of (n/N)^²

Keystone Species

not usually abundant, but other species in an ecosystem rely on because of their important ecological niches

Disturbance

an event that changes a communit by removing organisms from it or altering resource availability

Ecological Succession

the gradual process by which the species composition of a community changes and develops over time after a disturbance

Primary Succession

A series of changes on an entirely new (previously lifeless) habitat that has not been colonized

Secondary Sucession

a series of changes that clears an existing community, but leaves the soil intact