Ecology Pt. 1 Flashcards
ecology
scientific study of the disttibution and abundance of organisms and the interactions that determine distribution and abundance
demonstrates how adaptations that arose by natural selection explain the distribution and abundance of organisms
biotic
living interactions
ex: spruce trees, mosses, understory later, bacteria, fungi, animals
abiotic
nonliving (physical and chemical) interactions
ex: nutrients, sunlight, water
hierarchy of ecological systems
- individual
- population
- community
- ecosystem
- landscape
- biome
- biosphere
ramet
clone
ganet
genet
genetically disinct individual
population
a group of individuals of the same species that occupy a given area
community
populations of different species interacting within an ecosystem
ecosystem
biotic and abiotic components
landscape
patchwork of communities and ecosystems
biome
geographic region with similar geological and climatic conditions
biosphere
thin layer surrounding the earth and supports all of life
characteristics of populations
- abundance
- density
- dispersion
- proportion of individuals of avarious ages and stages
- birth death and movement of individuals
distribution of a species
described its spatial locations
there are different ways to describe this
influences of population distributions
occurence of suitable enviornmental conditions & interactions with other species
what is the broadest description of distribution?
geographic range
geographic range
area that encompasses all individuals of a species
crude density
number of individuals per unit area
dispersion
evenness of the population’s distribution through space
what are the three dispersion patterns?
random, uniform, aggregated (clumped)
random distribution
an individual’s position is independent of others
intermediate dispersion
uniform distribution
results from negative interaction among individuals
high dispersion
aggregated distribution
results from patchy resources, social groupings
low dispersion
abundance
number of individuals in the population and defines it size
can rarely be measured, use sampling instead
function of population density and the area over which the population is distributed
describe the geographic range of the whale shark
typically around the equator
describe the geographic range of orangutan
historically- SE Asia, southern China and Java
currently- Borneo and Sumatra
what can abundance estimates be skewed by
aggregated (clumped) distribution
different age classes
prereproductive
reproductive
postreproductive
what can cause range expansion
naturally through changes in climate or other enviornmental conditions
when humans introduce species to a region where they did not previously exist
examples-
shift in tree distributions after last ice age
humans bringing animals accidentally or intentionally
invasive species
non-native species that have been intentionally or accidentally introduced to a region
alter the balance of natural communities
aspects of demography
population growth
age structure
life tables
population growth
how the number of individuals in a population increases or decreases with time
individuals are added by birth and immigration
individuals removes by death and emigration
what kind of growth do all species have the potential for
exponential growth
the rate of increase is represented by “r”
when does arithmetical increase occur
when over a given interval of time, an unvarying number of new units are added to a population
when does exponential increase occur
when the number of new units added to a population is proportional to the number of units that exists
birthrate
number of individuals born as a PROPORTION of the TOTAL POPULATION
deathrate
number of individuals who die in a given time period of the total population
how is r calculated
r= birthrate- deathrate
what does it mean when r is less than 0
the population is shrinking
what does it mean if r is zero
zero population growth
what does the intrinsic rate of increase (r) measure
measure of a population’s potential for growth
equation for population growth
rate of change one
dN/dt=rN
this predicts the rate of population change through time
alternate equation for instanteous population growth
population growth equation
N(t)= N(0) e^rt
N(t)- population at time t
N(0) - population at time 0
e= 2.72
r - (b-d)
t= time
what is exponential growth rate characteristic of
population that inhabit favorable conditions at low population densities
what does population growth depend on (think population pyramids)
age structure - birth and death rates vary with the ages of individuals
life table
age specific account of mortality
cohort
group of individuals born in the same period of time
types of life tables
cohort/age-specific/dynamic
static/time-specific
cohort/age specific/dynamic life tables
data is collected by following a cohort throughout its life
static/time specific life tables
age distribution data is collected from a cross section of the population at one particular time
for life tables
x
age classes
for life tables
nx
number of individuals from the original cohorts that are alive at the specified age (x)
for life tables
lx
probability at birth of surrviving to any given age
n of whatever x/ n0
for life tables
dx
age specific mortality, the difference between the number of individuals alive for any age class (nx) and the next older age class (nx+1)
for example if x=1, dx would be calculated by
n1- n2= d1
for life tables
qx
age specific mortality rate, the number of individuals that died in a given time interval divided by the number alive at the beginning of that interval
for example if x=1
d1/n1= q1
how is life table data generally presented
mortality or survivorship curve vs age
what scale is lx plotted on
log scale ( stating from 0.01 to 1.0)
types of surrvivorship curves
type 1
type 2
type 3
type i survivorship curve
found in populations where they have long life spans, survival rate is high with heavy mortality at the end
ex: humans, other mammals and some plants K-strategists
small amount of offspring at a time but have high parental care
type ii survivorship curve
survival rates do not vary with age
ex: adult birds, rodents, reptiles, perennial plants
type iii survivorship curve
mortality rates are extremely high in early life
ex: fish, many invertebrates, and plants
typically have lots of offspring
r strategists
little to no parental care
how can population size be estimated
N= (A/a) * n
N= estimated population size
A= total study are
a= the area of the quadrat
n= number of organisms per quadrat
k-selected species population size
flucuates within narrow range around carrying capacity
k selected species type of population growth
density dependent- larger the population, stronger the factors limiting growth such as food and disease
k selected species reproductive rates
lower, and there is parental investment in the offspring
k-strategists habitat
relatively stable
describe k strategist life history
delayed and repeated reproduction, larger body size, slower development, produce few young
may have parental care
r-selected species population size
limited by reproductive rate
r selected species type of population growth
density independent popualtion growth, physical forces (frost, temperature, rain) more important than biologicals forces
r selected species reproductive rates
high, little investment in care of offspring
r-strategists habitat
unstable/unpredictable environments that can cause catastrophic mortality
r-strategists life history
short lived, high reproductive rates, rapid development, small body size, large number of offspring, resources rarely limiting , may have long dispersal distances
what is c-s-r triangle theory used for
plants
csr triangle theory
R
ruderal: plants to rapidly colonize disturbed sites and reproduce quickly
wide seed dispersal, small and short lived
csr triangle theory
C
competitive: favored by predictable habitats with abundant resources - maximize resouirce acquisition and resource control
csr theory
S
stress tolerant: allocate resources to maintenance in resources
life history characteristics
- mode of reproduction
- age at reproduction
- allocation of resrouces to reproduction
- time of reproduction
- number and suze of offspring produced
- parental care
how would an organism maximize fitness
reproduce a soon as possible, continously, and large numbers of large offspring that it would nuture and protect
not actually possible, there are trade offs that need to be made
typical relationship between body size of an organism vs. the number of young produced
production of offspring incr. with size
reproductive effort
time and energy put towards reproduction
the more energy that is put towards reproduction less for other aspects such as growth, maintenace, foraging etc.
trade off
early reproduction
early maturity, less growth, reduced survivorship, reduced potential for later reproduction
trade off
late reproduction
incr. growth, later maturity, incr. survivorship, less time for reproduction
semelparity
mode of reproduction in which an organism uses all its energy in a suicidal act of reproduction
ex. most invertabrates, some fish (salmon) many annual and biennial plants, bamboo
iteroparity
mode of reproduction in which an organism produces fewer young at one time and repreats reproduction throughout its lifetime
ex: vertebrates, perennial plants, shrubs, and trees
relationship between number of offspring and parental investment?
inverse
altricial young
born or hatched in a helpless condition and require considerable parental care
mice
precocial young
emerge from egg or womb ready to move and forage
ungulate mammals
what happens to popuation size when resources are unlimited
growth will be exponential
what model is used to model the relaity of limited resources
logistic growth model
intraspecific competition
members of the same species compete fofr limited resources
density dependent effects
influence a population in proportion to its size
what happens when population density increases
mortality rate increases ( density dependent mortality)
the fecundity rate decreases ( density depended fecundity)
or both
equation for logistic model of population growth
dN/dt= rN (1-N/K)
K
carrying capacity
logistic model
when is the rate of population growth the greatest
inflection point: N=K/2
scramble competition
when growth and reproduction are depressed equally across individuals
what can scramble competition cause
local extinction
contest competition
when some individuals claim enough resources while denying others a share
what happens to a population during contest competition
fraction of the population may suffer, sustained by those who access resources
exploitation competition
when individuals indirectly interact with one another but affect the availability of shared resources
depletion of shared resource
ex: herbivores on african savannas
interference competition
results when individuals directly interact and precent others from occupying a habitat or accessing resources
bird nesting sites
self thinning
progressive decline in density and increasein growth of remaining individuals
what is self thinning caused by
density dependent mortality and individual growth
home range
area that an animal normally uses during a year
home range size varies with
- food resource availability
- mode of food gathering
- metabolic needs
- body size
- sex
- age
density independent factors
factors that influence population growth but are unrelated to population density
examples of density independent factors
- temperature
- precipitation
- natural disasters
similarity and difference of density dependent and density independent
both can change the number of individuals in a population but only density dependent factors will regulate population size
neutral species interaction response
0/0
mutualism species response
+/+
commensalism species response
+/0
competition species response
-/-
amensalism species response
-/0
predation species response
+/-
parasitism species response
+/-
parasatoidism species response
+/-
interspecific competition
competition between difference speciies due to overlapping distributions and ecological niches
affects the populations of two or more species adversely
ecological niche
range of physical and chemical conditions under a species can persist
fundamental niche
the ecological niche of a species in the absence of ineractions with other species
realized niche
ecological niche as modified by its interactions with other species in the community
competitive exclusion principle
if two competitors try to occupy the same realized niche, one species will eliminate the other
niche partitioning / resource partitioning
two species divide a limiting resource suchas light food supply or habitat
what does it do
lotka-voleterra competition model
modified logistic growth by adding a term to account for the competitive effect of one species on the population growth of the other
lotka-volterra competition model equation
there are two, one for each species
species 1: dN1/dt= r1N1(K1-N1-aN2/K1)
species 1: dN2/dt=r1N1(K1-N1-bN1/K2)
in the absence of interspecific competition, a and b and N1, N2 being 0 the population grows logisitcally
lotka-volterra competition model
describe the four situations that can result
1 and 2: the winner species inhibits the growth of the loser (goes extinct) more than it inhibits it own growth
3: both species inhibit the growth of the other species more than its own growth, winner species is the one with the higher population
4: each species inhibits its own population growth more than the other species: populations coexist
lotka-volterra compeition model
what happens when the isoclines of the species are parallel
one species is always the superior competitor
lotka-volterra model
what happens if the isocline of species 1 falls outside the isocline of species 2
species 1 always wins
character displacement
shift in feeding niche that affects morrphology, behavior or physiology
ex: birds
predation
consumption of one living organism by another
simple categories of heterotrophic organism
carnivore, omnivore, herbivore
function classifications of predators
- true predator
- grazer/browse
- seed predator/plantivore
- parasite
- parasitoid
true predator
kills it prey immediately upon capture, consumes multiple prey organisms and functions as a agent of mortality on prey populations
grazers/browsers (herbivores)
most of them
consume only part of the plant and typically don’t kill it
parasites
feed on the prey organism while it is still alive and is generally not lethal in the short term
parasitoids
lay eggs onthe host and when the eggs hatch the larvae feed on the host slowly killing it
lotka-volterra model predator equation
dNpred/dt= b(cNpreyNpred)-dNpred
dNpred/dt = population growth of predators
b(cNpreyNpred)= birth rate which is a function of the amount of prey that is captured
dNpred= mortallity rate
lotka-voleterra model prey equation
dNprey/dt= rNprey - cNpreyNpred
dNprey/dt= population growth of prey
rNprey = expoenential growth rate of prey
cNpreyNpred= mortality term, predation rate x the number of predators
how are the lotka-volterra predator prey populations a density dependent regulator of the other
predators act as a source of regulation of the mortality of the prey population
prey acts as a soruce of regulation on the birthrate of the predator population
what are additional factors that influence predator-prey interactions
- cover or refuges for the prey
- difficulty of locating prey as it lessens
- choice among multiple prey species
- coevolution
predator’s
functional response
the relationship between the per capita rate of consumption and the number of prey
the greater the numeber of prey the more the predator eat
type i functional response
- as # of prey incr. predators eat more of them
- characteristic of passive predators (spides filter feeders)
- linear relationship between number of prey and the per capita rate of predation
type ii functional response
- predation apporaches as an asymptote
- prey mortality rate clines with increasing prey density
- the per capita rate of predation incr. in a decelerating fashion up to a max rate that is attained at some high prey density
type iii functional response
- the rate at which prey are consumed is initally low, increasing as the rate of predation reaches a max.
- predator may prefer more abundant prey
- inital rate of prey portality incr. with prey density of declines as a rate of predation reaches max
- can potentially regulate a prey pop.
availabillity of cover
suscpetibility of prey individuals will incr. as the population grows and hiding places become filled
search image
abillity of a predator to recognize a prey species will incr. as the prey pop. incr.
prey switching
act of a predator turning to a more abundant (but less prefered) alternate prey
what does the prey zero isocline show
prey numbers dont grow when the number of predators is equal to the ration of the preys intrinsic rate of incr. and the x the ffiency of predation
predator numbers don’t grown the when number of prey is equal to the ratio of the predator’s death rate
aggregative response
movement of predators into an area of high prey density
predator defenses
wide range of characteristics to avoid being detects, selected, and captured by predators
ex: chemical, cryptic coloration, warning coloration, protective armor, behavioral defense
chemical defense
- widespread
- odorous secretion repel predators ( arthopods and amphibians)
- storage or synthesis of toxins and poisons ( arthopods and snakes)
cryptic coloration
colors and patterns that allow prey to blend into the background
batesian mimicry
occurs when an edible species mimics the inedible species
mullerian mimicry
very similar color pattern shared by many unpalatable or venomous species
protecive armor
-shells quills
microparasites
characterized by small size and a short generation time
viruses, bacteria, protozoans
macroparasites
relatively large with a longer generation time and usually involve intermediate hosts and carriers
inverabrates(flatworms, licks lice) anf fungi- rusts
hemiparasitic plants
take nourishment from the host plant but also photsynthesizes itself
holoparasitic plants
nonphotosynthestic, completely dependent on host
ectoparasites
live on the host’s skin within feathers and hair
endoparasites
live within the host ( bloodstream, gills, mouth)
direct transmission of a parasite
can occur by direct contact with a carrier
can be dispersed through air, water, or other substrate
definitive host
organism that hosts adult parasite
intermediate host
hosts a juvenile parasite
hosts response to invasions
- behavioral defense mechanisms ( grooming or preening)
- inflammatory response
commensalism
relation between two species in which one species benefits without signifigantly affecting the other
mutualism
relationship that is beneficial to both species
lotka-volterra model of mutualism equations
species 1: dN1/dt= r1n1(k1-N1 + a21N2/K1)
species 2: dN2/dt= r2N2(K2-N2+a12N1/K2)
a21 - per capita effect of an individual of species 2 on species 1
a12- per capita effect of an individual speces 1 on species 2
attributes of a community
- number of species
- relative abundance of species
- nature of species interactions
- physical structure
species richeness (S)
count of number of species occuring within the community
relative abundance
represents the percentage each species contributes to the total number of individuals of all species
rank abundance diagram
plotting the relative abundance of each species against rank
species eveness
indicates the distribution of species eveness
simpson’s index (D)
sum of alll squared relative abundances for all species
Take sum of these ((ni/N)^2)
emphasizes eveness
ni = number of individuals for species i
N= tot. number of individuals of all species
what does D range between and what does that mean
ranges between 0 and 1
approaches 0 as both species richness and evenness incr.
Shannon (Shannon-Weiner) index
H= sum (pi)(lnpi)
emphasizes richness
pi = proportion of species i
in absence of diversity H=0
hmax= when all species are present in equal numbers
ecological zonation
change in the physical and biological structure of the community as one moves across the landscape
ecological succession
changes in community structre in one position as time passes
ecological dominants
few species that are abundant in a given area
often plants
keystone species
a species whose absence from a community would bring about signifigant change in that community
top predators or ecosystem engineers
sea otters
- keystone predator
- eat sea urchins which helps to maintain kelp beds
piaster
- sea stars
- top predator
- when removed from the intertidal zone the number of other species was reduced
gray wolves
- when removed from the yellowston population, elk populations exploded, leading to overgrazing
- this lead to bank instabillity
obligate mutualism
one organism cannot surrvive without the other
**relationship betweeen reef forming corals and zooanthellae algae:coral cannot make enough energy and algae provides that and gains protection **
facultative mutualism
each organism can survive independently but it benefits both to remain together
goby fish and shrimp: shrimp warns fish of danger
hollow curve
most species are rare and relatively few are abundant
food web
link
arrows from one species to another and indicate flow of energy
food web
basal species
feed on no other species but are fed upon others
food web
inermediate species
feed on other species and they themselves are prey
food web
top predator
prey on intermediate and basal species
trophic levels
broader categories that represent the general feedign groups
autotrophs
primary producers
heterotrophs
secondary producers
what happens to the amount of energy flowing into a trophic level with each next level
decreases, only ~ 10 % of biomass in a given trophic level is is converted to biomass at the necxt level
keystone predation
predator enhance one or more inferior competitors by reducing the abundance of superior compeitors
indirect effects
occur when one species doesn’t interact with a second species direcrly but instead influences a third species that does directly interact with the second
apparent compeition
occurs when a single species of predators feeds on two prey species
bottom up control
structure of food chains and food webs is controlled by the productivity and abundance of populations in the trophic level belwo
top down control
the predator populations control the abundance of prey species and the prey of the prey etc.
trophic cascade
triggered by the addition of remevol of a top predator and lots of changes happening in food web
mycorrhizal fungi
has a mutualistic relationship with plant roots, but can turn parasitic if the enviornment is nutrient rich
maccarthur’s warblers
display resource partitioning on tree
colorado bumblbees
different species canbe best adapted to specfic forms of a resource, different bumblebees adapted to specifc species of plant with different corolla size
monarch butterflies and milkweed
population trends of monarch butterflies may reflect availabillity of milkweed plants
wild cat species of the middle east
general relatioship between size of canine teeth and prey species selected
tadpoles at high densities
- slower growth
- required longer time to complete metamorphosis
- smaller at transformation
- less successful
density dependent growth
