Studied by 160 people
Ecology
The study of the interactions of organisms with one another and with their environment
The study of the distribution and abundance of organsism
Evolution
Change in population’s gene pool over time
science of the origins of biological diversity and its distribution
Ecological systems
individual
population
community
ecosystem
biosphere
Individual
most fundamental unit of ecology
species
individuals that are capable of interbreeding or share genetic similarity
Population
individuals of the same species living in a particular area and interbreeding.
characteristics of populations (not individuals)
Geographic range (distribution)
Abundance
Density
Change in size
Composition (demography)
Community
Populations of species living together in a particular area.
Ecosystem
one or more communities of living organisms interacting with their nonliving physical and chemical environments. ( community+ physical and chemical environment= ecosystem)
Biosphere
all ecosystems on earth
Individual approach
Understands how adaptations, or characteristics of an individual’s morphology, physiology, and behavior enable it to survive in an environment.
Populations approach
Examines variation in the number, density, and composition of individuals over time and space.
community approach
Understands the diversity and interactions of organisms living together in the same place.
ecosystem approach
Describes the storage and transfer of energy and matter.
Biosphere approach
Examines movements of energy and chemicals over the Earth’s surface.
Darwin’s 4 postulates
Individuals vary in their traits.
Traits are heritable.
(More offspring are born than survive)
3. Variation in traits causes some individuals to experience higher fitness (survival and reproduction).
Producers
or autotrophs—convert
chemical energy into resources.
consumers
or heterotrophs—obtain their energy from other organisms.
Mixotrophs
can switch between being producers and consumers.
Scavengers
consume dead animals
Detritivores
break down dead organic matter (i.e., detritus) into smaller particles.
Decomposers
break down detritus into simpler elements that can be recycled.
types of species interactions
predation
parasitism
herbivory
competition
mutualism
commensalism
predation
when an organism kills or consumes an individual
parasitism
when one organisms lives in or on another organism.
competition
when two organisms that depend on the same resource have a negative effect on each other.
mutualism
when two species benefit from each other
commensalism
when two species live in close association and one receives a benefit, whereas the other is unaffected.
Habitat
the place, or physical setting, where an organism lives.
Distinguished by physical features, such as dominant plant type.
Niche
the range of abiotic and biotic conditions an organism can tolerate.
Hypothesis
ideas that potentially explain a repeated observation.
predictions
statements that arise logically from hypothesis
Nemoria experiment and results
butterfly experiment where different conditions were used to determine what causes different phenotypes.
Results: diet changes development
Population approach
Examines variation in number, density, and composition of individuals over time and space
Spatial Structure
the pattern of density and spacing of individuals in a population.
Fundamental Niche
the range of abiotic conditions (e.g., temperature, humidity, salinity) under which a species can persist.(all possible options)
realized niche
the range of abiotic and biotic conditions under which a species does persist. (reality)
Geographic range
a measure of the total area covered by a population (e.g., temperature and drought define the range of sugar maple).
endemic
geographic range where species live in a single often isolated location
cosmopolitan
a measure of the total area covered by a population (e.g., temperature and drought define the range of sugar maple).
abundance
the total number of individuals in a population that exist within a defined area (e.g., total number of lizards on a mountain).
Density
in a population, the number of individuals per unit area or volume; calculated by dividing abundance by area.
Dispersion
the spacing of individuals with respect to one another within the geographic range of a population.
Clustered dispersion
when individuals are aggregated in discrete groups (e.g., social groups or clustering around resources).
Evenly spaced dispersion
when each individual maintains a uniform distance between itself and its neighbors (e.g., defended territories, croplands).
Random dispersion
when the position of each individual is independent of other individuals; not common due to non-random environmental heterogeneity.
Dispersal
the movement of individuals from one area to another.(verb of dispersion, actual movement)
Population abundance and range
Populations with high abundance also have large geographic ranges. (example: birds)
Population density and body size
The density of a population is negatively correlated to the body size of the species.
Dispersal limitation
the absence of a population from suitable habitat because of barriers to dispersal.
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).
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)
subpopulations
when a large population is broken up into smaller groups that live in isolated patches.
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.
Spatial structure models
Metapopulation
Source-Sink
Landscape
metapopulation
a set of local populations linked by dispersal : least complex
patches
suitable habitat
Matrix
barrier to dispersal
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
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
demography
The study of (the structure and growth of) populations
What causes population increase?
birth and immigration
What causes population decrease
deaths and emigration
geometric growth
discrete time intervals (choppy points and lines)
exponential growth
time is treated as continuous (one smooth line no points). Continuous growth -- overlapping generations with year round reproduction
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
N(t+1)
number of individuals after 1 time unit
N(t)
population size at time t
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”:
Geometric Population Growth for Multiple time intervals
Exponential population growth equation
Pe^rt
when a population is decreasing
λ<1 and r<0
when population is constant
λ=1 and r=0
when a population is increasing
λ>1 and r>0
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).
Density dependent limitations
factors that affect population size in relation to the population’s density.
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)
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
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)
Logistic growth model
a growth model that describes slowing growth of populations at high densities; it is represented by:
Carrying capacity (k)
the maximum population size that can be supported by the environment.
S- shaped curve
The shape of the curve when a population is graphed over time using the logistic growth model.
Inflection point
the point on a sigmoidal growth curve at which the population has its highest growth rate.
logistic growth model low in population size
N is small so the slope is higher rising in growth
logistic growth model with higher population size
N is closer to one so slope is smaller slowing growth
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
Age structure pyramids with narrow base (v shaped)
Indicates that population is declining because less babies are being born than previous generations
Life tables
tables that contain class-specific survival and fecundity data.
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
Number surviving to next age class
(nx) x (sx)
number of new offspring produced
(nx) x (sx) x (bx)
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).
type 2 curve
curve depicts a population that experiences constant mortality throughout its life span (e.g., squirrels, corals).
type 3 curve
depicts a population with high mortality early in life and high survival later in life (e.g., weeds, fish, alligators).
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.
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
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).
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.
population cycles
regular oscillation of a population over a longer period of time.
delayed density dependence
when density dependence occurs based on a population density at some time in the past.
Note 
Flashcard (24)