Ecology Exam 1

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112 Terms

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Ecology
The study of the interactions of organisms with one another and with their environment

The study of the distribution and abundance of organsism
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Evolution
Change in population’s gene pool over time

\
science of the origins of biological diversity and its distribution
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Ecological systems
1) individual

2) population

3) community

4) ecosystem

5) biosphere
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Individual
most fundamental unit of ecology
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species
individuals that are capable of interbreeding or share genetic similarity
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Population
individuals of the same species living in a particular area and interbreeding.​
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characteristics of populations (not individuals)
*Geographic range (distribution)* ​

*Abundance* ​

*Density* ​

*Change in size*​

*Composition (demography)* ​
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Community
Populations of species living together in a particular area.​
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Ecosystem
one or more communities of living ​organisms interacting with their nonliving ​physical and chemical environments.​ ( community+ physical and chemical environment= ecosystem)
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Biosphere
all ecosystems on earth
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Individual approach
Understands how **adaptations**, or characteristics of an individual’s morphology, physiology, and  behavior enable it to survive in an environment.​
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Populations approach
Examines variation in the number, density, and composition of individuals over time and space.​
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community approach
Understands the diversity and interactions of organisms living together in the same place.​
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ecosystem approach
Describes the storage and transfer of energy and matter.​

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Biosphere approach
Examines movements of energy and chemicals over the Earth’s surface.​
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Darwin’s 4 postulates

1. Individuals vary in their traits.​
2. Traits are heritable.​

(More offspring are born than survive)​

3\.  Variation in traits causes some individuals to experience higher *fitness* (survival and reproduction).​
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Producers
or autotrophs—convert ​

chemical energy into resources.​
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consumers
or heterotrophs—obtain their energy from other organisms.​
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Mixotrophs
can switch between being producers and consumers.​
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Scavengers
consume dead animals
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Detritivores
break down dead organic ​ matter (i.e., detritus) into smaller particles.​
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Decomposers
break down detritus into simpler elements that can be recycled.​
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types of species interactions
* predation
* parasitism
* herbivory
* competition
* mutualism
* commensalism
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predation
when an organism kills or consumes an individual
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parasitism
when one organisms lives in or on another organism.​
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competition
when two organisms that depend on the same resource have a negative effect on each other.​
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mutualism
when two species benefit from each other
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commensalism
when two species live in close association and one receives a benefit, whereas the other is unaffected.​
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Habitat
the place, or physical setting, where an organism lives.​

Distinguished by physical features, such as dominant plant type.​
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Niche
the range of abiotic and biotic conditions an organism can tolerate.​
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Hypothesis
ideas that potentially explain a repeated observation.​
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predictions
statements that arise logically from hypothesis
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Nemoria experiment and results
butterfly experiment where different conditions were used to determine what causes different phenotypes.

Results: diet changes development
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Population approach
Examines variation in number, density, and composition of individuals over time and space​
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Spatial Structure
the pattern of density and spacing of individuals in a population.​
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Fundamental Niche
the range of abiotic conditions (e.g., temperature, humidity, salinity) under which a species can persist.​(all possible options)
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realized niche
the range of abiotic and biotic conditions under which a species does persist.​ (reality)
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Geographic range
a measure of the total area covered by a population (e.g., temperature and drought define the range of sugar maple).​
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endemic
geographic range where species live in a single often isolated location
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cosmopolitan
a measure of the total area covered by a population (e.g., temperature and drought define the range of sugar maple).​
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abundance
the total number of individuals in a population that exist within a defined area (e.g., total number of lizards on a mountain).
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Density
in a population, the number of individuals per unit area or volume; calculated by dividing abundance by area.​
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Dispersion
the spacing of individuals with respect to one another within the geographic range of a population.​
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Clustered dispersion
when individuals are aggregated in discrete groups (e.g., social groups or clustering around resources).​
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Evenly spaced dispersion
when each individual maintains a uniform distance between itself and its neighbors (e.g., defended territories, croplands).​
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Random dispersion
when the position of each individual is independent of other individuals; not common due to non-random environmental heterogeneity.​
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Dispersal
the movement of individuals from one area to another.​(verb of dispersion, actual movement)

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Population abundance and range
Populations with high abundance also have large geographic ranges.​ (example: birds)
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Population density and body size
The density of a population is negatively correlated to the body size of the species.​
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Dispersal limitation
the absence of a population from suitable habitat because of barriers to dispersal.​

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Habitat corridor
a strip of favorable habitat located between two large patches of habitat that facilitates dispersal (e.g., a narrow band of trees that connects forests).​
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Ideal free distribution
when individuals distribute themselves among different habitats in a way that allows them to have the same per capita benefit.​ (pizza example)
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subpopulations
when a large population is broken up into smaller groups that live in isolated patches.​
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**Basic metapopulation model**
a model that describes a scenario in which there are patches of suitable habitat embedded within a matrix of unsuitable habitat; all suitable patches are assumed to be of equal quality.​
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Spatial structure models
* Metapopulation​
* Source-Sink​
* Landscape​
* Metapopulation​
* Source-Sink​
* Landscape​
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metapopulation
a set of local populations linked by dispersal​ : least complex
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patches
suitable habitat
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Matrix
barrier to dispersal
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Source sink model
recognizes differences in quality of suitable habitat patches: intermediate complexity ​

Source patches : more food reproduce more

Sink patches: less resources less reproduction
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Landscape model
* most complex
* considers effects of differences in the habitat matrix:​​


* the quality of a habitat patch can be affected by the nature of the surrounding matrix​​


* some matrix habitats are more easily traversed than others​
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demography
The study of (the structure and growth of) populations​
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What causes population increase?
birth and immigration
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What causes population decrease
deaths and emigration
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geometric growth
discrete time intervals (choppy points and lines)
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exponential growth
time is treated as continuous (one smooth line no points). Continuous growth -- overlapping generations with year round reproduction
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Geometric (discrete) growth
*N*(*t* + 1) = *N*(*t*) ​

where:*N*(*t* + 1)  = number of individuals after 1 time unit​

  *N*(*t*)        = population size at time *t*​
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N(t+1)
number of individuals after 1 time unit​
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N(t)
population size at time t
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Geometric Population growth
**** = ratio of population size at any time to the population size 1 time unit earlier ​

****  is the “per capita growth rate” ​ \n      or “finite rate of increase”:​
**** = ratio of population size at any time to the population size 1 time unit earlier ​

****  is the “per capita growth rate” ​ \n      or “finite rate of increase”:​
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Geometric Population Growth for Multiple time intervals
\
\
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Exponential population growth equation
Pe^rt
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when a population is decreasing
λ
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when population is constant
λ=1 and r=0
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when a population is increasing
λ>1 and r>0
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Density independent limitations
factors that limit population size regardless of the population’s density.​ Common factors include climatic events (e.g., tornadoes, floods, extreme temperatures, and droughts).​
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Density dependent limitations
factors that affect population size in relation to the population’s density.​
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negative density dependence
when the rate of population growth decreases as population density increases.​ The most common factors that cause negative density dependence are limiting resources (e.g., food, nesting sites, physical space).​ (think about splitting the pie, the more people the less pie each person gets)
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Shelf-thinning curve
a graphical relationship that shows how decreases in population density over time lead to increases in the size of each individual in the population; often has a slope of -3/2
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positive density dependence
when the rate of population growth increases as population density increases (also known as **inverse density dependence**, or **Allee effect**).​ (typically happens when pop is so small that it makes it hard to find mates and reproduce)
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Logistic growth model
a growth model that describes slowing growth of populations at high densities; it is represented by:​
a growth model that describes slowing growth of populations at high densities; it is represented by:​
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Carrying capacity (k)
the maximum population size that can be supported by the environment.​
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S- shaped curve
The shape of the curve when a population is graphed over time using the logistic growth model.​
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Inflection point
the point on a sigmoidal growth curve at which the population has its highest growth rate.​
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logistic growth model low in population size
N is small so the slope is higher rising in growth
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logistic growth model with higher population size
N is closer to one so slope is smaller slowing growth
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Age structure pyramids with broad base and narrow top (arrow shaped)
 indicates population is growing because more babies are being born than in previous generations
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Age structure pyramids with narrow base (v shaped)
Indicates that population is declining because less babies are being born than previous generations
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Life tables
tables that contain class-specific survival and fecundity data.​
tables that contain class-specific survival and fecundity data.​
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life table parts
*x* = age class​

*nx =* the number of individuals in each age class immediately after the population has produced offspring.​

*sx* = the survival rate from one age class to the next age class​

*bx* = the fecundity of each age class​
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Number surviving to next age class
(*nx*) x (*sx*)​
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number of new offspring produced
(*nx*) x (*sx*) x (*bx*)​
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Type one curve
Type one curve
survivorship curve depicts a population that experiences low mortality early in life and high mortality later in life (e.g. bears, humans, elephants, whales).​

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type 2 curve
type 2 curve
curve depicts a population that experiences constant mortality throughout its life span (e.g., squirrels, corals).​
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type 3 curve
type 3 curve
depicts a population with high mortality early in life and high survival later in life (e.g., weeds, fish, alligators).​
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Cohort life table
a life table that follows a group of individuals born at the same time from birth to the death of the last individual.​
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Static life table
a life table that quantifies the survival and fecundity of all individuals in a population during a single time interval.​

Does not take into account the effect of time ​

Works well with organisms with long lifespans ​
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overshoot
when a population grows beyond its carrying capacity; often occurs when the carrying capacity of a habitat decreases from one year to next (e.g., because less resources are produced).​
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Die- offs
a substantial decline in density that typically goes well below the carrying capacity.​ Die-offs often occur when a population overshoots its carrying capacity.
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population cycles
regular oscillation of a population over a longer period of time.​

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delayed density dependence
when density dependence occurs based on a population density at some time in the past.​