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Ecology Exam 3


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ecological diversity
same thing as species diversity

*NOT biodiversity!!*
The variety of life and its processes;
variety of living organisms,
genetic differences amoung them;
the communities & ecosystems in which they occur

-the variety of life and the patterns it forms

-the sum of organisms, their genetic variability, historical relationships, & symbiotic interactions

-a "progress report" on cosmic process of evolution

-not a state but a process

**Comprises all levels of integration (genes to proteins to geno/pheno to individuals & offspring to communities to landscapes to ecosystems to biosphere as whole)

demands appreciation for evolution & ecology over space & time

-a global inventory of species

*not simply richness & evenness (or ecological/species diversity)*
species diversity
includes species richness & evenness

=ecological diversity
species richness
number of species present in given area

*simple count*
species evenness
distribution of individuals in total species in given area

[relative abundance of species in community]

*calculated index*
communities are ________


(leads to pattern diversity)
of vegetation, soil, biota, systems, intertidal, etc.

(leads to pattern diversity)
regional-scale patterns


(leads to pattern diversity)
period in time

(leads to pattern diversity)
network organization of food webs

(leads to pattern diversity)
parent - offspring patterns

plant clones

(leads to pattern diversity)
flocks, herds, schools, etc

(leads to pattern diversity)
patterns from competition, mutualism, antibiosis, etc
increase in stability =
increase in diversity
increase in stability =
increase in diversity

*when less diverse food chain, one species dying off can result in extinction of many more species*

larger # of species ->
more redundancy in system
(species can be substituted) ->
resiliance (can recover from disturbance)
Diversity indexes:::


Shannon-Weiner index

-ecological time time (ecological succession)

-evolutionary time (community evolution)

-from poles to equator (latitudinal diversity gradiant)

-in warm / moist enviros

-rigorous (dry / cold enviros)

-with disturbances
alpha diversity

(diversity is SCALE / level dependent!)
WITHIN habitats
beta diversity

(diversity is SCALE / level dependent!)
BETWEEN habitats
gamma diveristy

(diversity is SCALE / level dependent!)
diversity of landcape scale areas
the living component of an ecosystem?
global sum of communities?
Communities are structured by:
SYMBIOSIS (+, -, 0)
Symbiosis leads to
exchanges of materials in an ecosystem
Competition leads to
NICHE structure of communities
over time _______ increases
diversity (richness / evenness)
interspecific competition w/i communities

leads to
divergence of species

*evolution of biodiversity*
community ecology is part of the PROCESSES and PRODUCTS of evolution
heritable variation
overpopulation (pop ecology)
competition (pop & comm ecology)
natural selection
smallest unit of ecology?

(individual organisms)
all the individuals of a species w/ potential to interbreed

(in a particular area at a specific time)
--time and space are implied
"population size"
number of individuals

(street term pop = # of ind as well)

of population
occurance of population in a space

*DESCRIBES SPATIAL LOCATION, based on presence, absence of ind*

(due to limits)

*biogeographic concept*

-often discontinuous

-area including all ind of pop = geographic range

-influenced by limits
--ind's have to be w/i range of tolerance
subpopulations (local populations) that can interact with eachother

metapopulation MUST have:
1)descrete habitat patches
2)substantial risk of extinction
3)migration & recolonization after local extinction
4)asynchronous dynamics

*balance between extinction & recolonization of empty habitat patches
population density
individuals / unit area


individuals / volume

*sessile - divide into quadrants
*mobile - mark-recapture method
population dispersion
spatial arrangment of individuals within a population

(how individuals are spaced out)

2)CLUMPED [contagious]
3)UNIFORM [hyperdispersed]
random dispersion
no intraspecific interaction

least common
clumped [contagious]dispersion
+ social interactions,
maternal care

most common
uniform [hyperdispersed] dispersion
age/sex structure

(age/sex distribution)
relative # of individuals of each age segregated by sex
population growth =
(birth + immigration)
(death + emmigration)

recruitment rate - loss rate
= pop growth rate

***rate = change / time
exponential growth
growth at a fixed RATE (%/yr)
(NOT a fixed amt)

*unregulated populations*
pop growth curves
change in pop size over time
"r" on pop curve
= rate of increase

= biotic potential

= slope of curve

= change N / change t (time)
if pop grows exponentially, doubling daily and is completely full on 30th day... on what day is it half full?
29th day... last day of doubling before full

*remember exponential growth means DOUBLING everytime!!!*
age specific death rate

(probability of an individuals death at a given age)

*shown as species specific survivorship curve [type I-human, type II-robin, type III-oyster]*

*curve derived from life table*

***REFLECTS species Reproductive Strategy***
limiting factors

(of population growth)
restrain exponential pop growth... slowing growth rate down

**may level off at carrying capacity**
carrying capacity
max population of species an enviro can sustain

*based on resources, NOT a feature of a pop*
*measured by individuals (a pop size)*
logistic growth curve
initial exponential growth, slowing, then stabilizing at carrying capacity (K)

*S curve*
logistic growth equation
dN / dt = rN (K - N/K)
environmental resistence (k)
the sum of factors that keep the observed pop increase below the theoretical max increase

k = r-max - r-observed
Density independent controls

(limiting populations)
not controlled in respect of initial densisty

[100 yr flood drowns all beavers, whether pop is 5 or 500]

*usually due to abiotic factors [flood, fire, frost]
Density dependent regulation

(limiting populations)
how intense the regulatory mechanism is proportional to pop size
(larger the pop the larger the regulatory effect)

*usually due to biotic factors:
-nesting sites / territoriality
populations limited by two types: (in addition to density dependent and density independent controls)

-pop regulates itself
[territoriality, competition for mates]

-pop controlled by outside forces
[food, nesting sites, predation]
portion of home-range defended against individuals of the SAME species

area through which individual moves during usual round of activities


(time frame may be needed to distinguish home range -- daily v monthly, etc)

-associated with
1)dispersal (ONE WAY movement from place of birth to place of reproduction. PERMANENT)
(movement, often seasonal, from one place to another AND BACK. a -> b -> a. often seasonal change in home range.)
distinction between


change in Home-Range
(ONE WAY movement from place of birth to place of reproduction. PERMANENT)

(movement, often seasonal, from one place to another AND BACK. a -> b -> a. often seasonal change in home range.)
all mechanisms that influence pop size::
1) density-dependent v density-independent factors

2) intrinsic v extrinsic factors

3) birth-rate v death-rate mechanisms [b - d = r]
"biotic potential"
potential growth rate (r)
of a particular species

(innate reproductive capacity)
(rate of natural increase)

**HIGH r = species producing a lot of young (insects/fish/plants)

**LOW r = mammals & birds (produce few young / time interval)
High v Low "r"
("r" = potential growth rate)
HIGH "r" = species that produce a lot of young (fish/insects/plants)

LOW "r" = few young / time interval (mammals/birds)

"life history"


"reproductive strategy"
a species general pattern of reproduction

*how many offspring does it take to acheive fitness?*

*ie success in becoming a grandparent...

**an ind. getting genes into the gene pool of the next generation
-many offspring
-little parental care
-small body size
-fast growth rate

(comes from logistic curve... pops can potentially grow fast, have high r)
-few offspring
-high parental care
-large body size
-slow growth rate

(comes from logistic curve... some pops reproduce so they tend to stabilize near K.)
human population ecology
human populations often distort ecosystems by amensalism
amensalism = when one species is harmed and the other is unaffected
distribution of human population?


-widest of any vertebrate
worldwide density of human pop?

highest of any megavertebrate

127 / sq. mile
dispersion of human pop?

highly contagious

(large human cities = largest known sums of any terrestrial vertebrate)
carrying capacity (k) for humans has to do with:
economics, ethics, peer pressure, cultures
Poverty is POSITIVELY correlated with pop. growth rates
(lower education, higher growth rates)
Human's survivorship curve?
Type III

Human growth rate curve is:
exponential as of now
why the pop boom?
advances in public health
(people began to live longer on average)
fertility rate is POSITIVELY correlated with pop density
higher density = higher reproductive output

*no apparent intrinsic, density-dependent regulator.... no reproductive strategy*

--Probably due to the fact that k has been expanded by cultural advances thru history
human age/sex diagram?

long post-reproductive life span
carrying capacity of humans?

no apparent k so far

(humans fit k-strategists description but culture keeps pushing k up)
times in human history that k has been raised:
1)Paleolithic Revolution
-taming of fire
-expanded geographic range

2)Neolithic Revolution

3)1st Industrial Revolution
-steam engine
-fossil fuels

4)Advanced Industrial Revolution
-electric power
-combustion engine

(technology, tool-making, agriculture, & industrialization expanded carrying capacity)
cultural influences affecting human pop growth?

education correlated with TFR

*more education = fewer children*

*family planning = fewer children*
human population growth rate has fallen since ___?

(but still a + growth rate, and resource demand still rising)
(increasing population) x (increasing resource demand / capita)
(increasing population) x (increasing resource demand / capita)
"IPAT" model
I = P x A x T

Impact = (Population)(Affluence)(Technology)
Total Human Population? (#)
Annual % growth rate of human pop:
1.2 %
Doubling Time of human pop?
58 Years
Doubling Time

70 / % rate of growth
Doubling Time

(bacteria doubling time growing at 5% per hour =
70 / 5 = 14 Hours)
ecological footprint
= population x resource demand
population density
ecological density
pop density :
individuals / unit area
individuals / volume

ecological density:
#s / area of suitable habitat
(expresses how many ppl per resource base... human impact on the ecosphere)
4 principle stress factors
for pop growth
1) youth bulge
2) rapid urban growth
3)competition for cropland / freshwater
4) HIV/ AIDS (death in prime of life)

*most in africa*
giga-people-bucks / area
pop x demand = people-bucks

people x bucks = giga-people-bucks

giga-people-bucks / area = demand density = ecological footprint
PATTERN implies
PROCESS (history)

we need the process to understand the pattern
humans are immense force in ecosphere bc we are:
(endotherms)...(endotherms are expensive
E. O. Wilson
Sociobiology includes
-evolutionary biology
-comparative psychology
-social psychology
-population ecology
opportunities for social evolution
-anti-predator defences
-increased competitive ability
-increase foraging ability
-cooperative predation
-increased reproductive efficiency
-increased survival at hatching
-modification of physical enviro

*schools of fish*
communication implies:

*channels of communication =
conservation ecology seeks to conserve
the sum of organisms, their genetic variability, historical relationships and symbiotic interactions =
most species that have ever been are extinct
but present day extinction rates seem unusually high
extinction caused by:
failure to adapt

-climate change
-mountain building
-extra-terrestrial influences)

3)exotic species
[failure to adapt to humans]
how many mass extinctions in history?

we could be in the midst of the 6th
conservation biology
applies principles of ecology, biogeography, pop. genetics, economics, sociology, anthropology, philosophy to MAINTAIN BIOLOGICAL DIVERSITY

study to maintain, protect, & restore life



*theory of island biogeography important*

(only ~ 20 years old)
mass extinctions


-involve broad range of organisms

people responsible for conservation biology
-victor shelford
-aldo leopold
-charles elton
-e. o. wilson (spokesman)

-macarther (founding giants of ecology)
# of species on an "island" represents
between immigration & extinction

-extinction varies w/island size
-immigration varies w/distance from mainland
island biography predicts
smaller islands farther from mainland = smaller biotas
single large or several small?
Goals of Conservation Biology

-protection, maintanence, restoration



-encouragement of sciences

-education at all levels

-promotion of all of the above
leading cause of extinction?

(then pollution, exotic species, exploitation, & last-disease)
if species are going extinct bc we're destroying their habitats THEN
we must focus on habitats and not just the species

*avoid human creation of islands
organisms can be


-through sexual reproduction
-genetically unique organism

-zygote develops into unit of construction (module)
-then produces further similar modules
-(most plants)
-new shoots or suckers can remain attached or break off & live independently
types of modules
-individual tree/plant produced by sexual reproduction
-arising from a zygote
-genetic individual

-can remain linked to parent genet or may seperate
-possess same genetic comp as parent
geographic range
area including entire pop of a species

-influenced by limits
defines size

*the number of individuals in a population*

1)density (#/unit area = crude density)
(spatial arrangement wi a pop)

-position of each is independent of others

-usually results from negative interaction

-results from suitable habitat in patches, social groups, plants that reproduce asexually (ramets extending from parent plant)
age structure
proportion of individuals in different age classes


*short lived organisms = short pre-reproductive period = high growth rate

*long lived organsisms = long pre-repro period = slow growth rate (longer time span between generations

**age pyramids are snapshots of age structure at pt in time --patterns of mortality & reproduction
sex ratio of sexually reproducing organisms

& primary sex ratio (ratio at conception)?

Life Table
age-specific account of mortality

displayed in
1) mortality curve
2)survivorship curve [type I, II, & III]
group of ind born in same period of time
age-specific mortality rate
# ind died during given time interval / number alive at beginning of interval
dynamic life table
follows cohort from birth to death

[dynamic COMPOSIT life table follows ind born over several time periods not just one]
time-specific life table
obtain distribution of age classes during single time period

--less accurate

survivorship curve
humans / mammals

-survival rate high thru life span w/ heavy mortality rate toward end

-convex )

survivorship curve
birds / rodents / reptiles

-survival rates don't vary w age

-straight line

survivorship curve
oysters / fish

-mortality rates high early in life

-concave (
the study of social behavior
(sociality... the tendancy for interaction between members of the same species)

-branch of population ecology
group of individuals of same species organized in cooperative manner

[definition & advantages]
the tendasncy for interaction amoung/between members of same species

1)defense against predators:
(flock of birds w/100 eyes v 1 bird w/2eyes)
*flocks, herds, schools, etc*

2)modifies physical enviro:
-air conditioned nests
-heat generated from colony

3)foraging efficiency
-mixed species of birds can group

4)reproductive functions
-increasing genetic diversity

5)social protection of young
-increases survival of young

in sociality
an action by one ind that alters the probability of the behavior of another animal [not cause but alter]

-implies a SENDING ind (transmitter) and a RECEIVING ind (which may or may not respond)

-social behavior depends on communication

species communicate by making senders match their receptors
in complex organisms are transducers (converts input energy into output energy)

-once there's a receiver all thats needed is a sender (allowing a communicative link to be established)
agonistic behavior
involves contest between 2 ind of the same species

-is cooperative

*mothers aggresively protective over young*
when ind endangers or destroys itself to benefit another

*a deer may endanger herself but save a full nest of young, thus increasing fitness*
E O Wilson
brought together darwin and such to publish book on SOCIOLOGY
organic altruism
product of biological evolution

(NOT based on genetic self sacrifice)
cultural altruism
a human peculiarity

product of cultural evolution, NOT biological evolution
most recent geologic time interval
(present geological epoch)
time since latest glacial maximum

-an interval of increasing human predominance

("homogecene" due to increasing globalization
homogenization may be self limiting
global climate change
-->resource exhaustion
human population growth is not the issue...
the issue is

# of people x per capita demand for materials / energy

(the human ecological footprint)
human biomass
3.9% of global animal biomass
human's take __ annual production of entire biosphere
~ 25 - 40 %
unique about the holocene epoch?
-rates of cultural evolution

-degree of dominance of single species

-number of people x demand per person

-oxidation of fossil fuels
->release of C into atmosphere
->cultural climate change

-single species impacts ecosphere on geological scale
-biogeochemical cycles -> anthrobiogeochemical cycles
depletion curve for "stock limited" (non-renewable) resources
at peak (y sub p)
y sub 50 = year 50 % depleted

beyond y50 price rises, scarcity increases

(came very close to actual oil depletion estimate)
"population growth"
# of individuals increasing / decreasing with time

change in pop / change in time
open populations
immigation &/or emmigration occur
closed populations
movement in & out of populations does not occur

-no immigration or emmigration
crude birthrate
*birthrates expressed as births per 1000 population per unit time

(# of births over time period)
(estimated pop size at beginning of time period)
gross reproductive rate
sum of age-specific birth ratesof all age classes

-gives avg number of female offspring born to female over lifetime
age-specific birthrates
avg number of female births per female at age x
fercundity table
aka fertility table

-uses survivorship from life table together with age specific BR's
net reproductive rate
avg # of females that will be left during the lifetime of a newborn female

(on avg females replace themselves
--produce one daughter
demographic stochasticity
random (stochastic) variations in B & D rates occuring in a pop from year to year
environmental stochasticity
random variations in the enviro
(including annual variations in climate or natural disasters)
that can directly influence B & D rates
factors leading to pop extinction
1)D rate exceeding B rate

2)if enviro events exceed bounds of tolerance for species
(droughts floods)

3)shortage of resources by enviro extremes or overexploitation

4)new species introduced

5)loss of habitat
a small population's susceptability to extinction
1)small populations
-only a few ind
-widely dispersed = hard to find mate
-breakdown of social structures that species cooperate to mate, forage, defend
-reduced genetic diversity
(rare recessive deleted genes can become widely expressed)
allee effect
decline in either reproduction or survival under conditions of low pop density
intrasexual selection
male to male or
female to female
competition for opportunity to mate

--leads to exaggerated secondary sexual characteristics (large size, aggressiveness)
intersexual selection
differential attractiveness of individuals of one sex to another

**bright colors
reproductive success depends on habitat selction
reinforces fact that we need to focus on habitats to preserve diversity
assigning species to either
-critically endangered -endanered -vulnerable
REQUIRES one of the following:
1)decline in ind #s of species
2)geographic area occupied & the # of pop
3)total # alive & # breeding
4)expected decline if current trends continue or habitat destruction continues
5)probability of species going extinct in certain # of yrs
___ known species
1.4 million known species

--many beleive the actual # could be 10x that amt
gradient of increasing species richness
from poles to equator
tropical rain forest contribution to species diversity
only cover 7% of land surface

more than 1/2 of all known species in these ecosystems
topographic variation of species diversity
topographic variation (ridges, valleys)
support higher amt of diveristy than flatter areas in same region
endemic species
restricted to certain habitat
norman myers

-regions exhibiting high species richness and endemism

-unusually high diversity

1)overall diversity of region
2)significance of impact from human activities

-25 regions designated as hotspots by IUCN
-contain 44% of all plant species
-35% of all terrestrial vertebrate species
-ONLY 1.4% of planets land area
International Union for conservation of Nature

developed quantitative classification based on probability extinction

(demographic stochasticity & probability of extinction)
Minimum Viable Population

defined # of ind necessary to ensure long-term survival of species

-the smallest isolated pop having 99% chance of remaining for 1000 yrs despite variations (below)

-large enough to cope with chance variations in demographic processes (B&D), enviro changes, genetic drift, & catastophes

-MVP dependent on life history of species & ability of ind to disperse amoung habitat patches
Minimum Dynamic Area
area required to support the MVP

-classification begins w/home range requirement
"capture, relocation, release"
sometimes avoiding extinction requires establishing new pops thru transplants & reintroductions
larger areas contian greater # of species than small
-more heterogenous
--encompasses greater variety of habitats
-provides greater probability that species can find another area of suitable habitat if something happens

-some species require larger areas for basic needs
--larger organisms have greater home ranges
advantages to several small
rather than single large
-once an area is larger than certain size the number of new species added w/each successive increase in area declines

-network of smaller areas positioned over larger region can include greater variety of habitat types and less suceptible to single catastophic eents
restoration ecology
human intervention

restoring natural communities affected by human activities

restoring ecosystem closest to original conditions prior to disturbance thru application of ecologic principles
economic argument to preserve biodiversity
products come from orgnaisms



rubber, solvents paper, cotton, leather
evolutionary argument to preserve biodiversity
processes of mutation, mixing of genetic info, & natural selection
give rise to new species

all species eventually go extinct
(some fade into extinction after giving rise to new species]

--the mass extinction of modern day species limits the potential evolution of species diversity in the future
etical argument to preserve biodiversity
humans are only one of millions of species inhabiting earth

to what degree will we allow human activities to continue to result in such a high rate of extinction? decrease in biodiversity?
a species w/ geographically widespread distribution
a species' susceptability to extinction
-loss of habitat in that one geographic region = complete loss of habitat

2)small metapopulations
(one or few local pops)
-more vulnerable to chance factors or habitat destruction

3)seasonal migration
-depend on 2+ habitats
-any one destroyed = extinction

4)specialized habitat requirements
-specialized habitats often scattered and rare

5)species requiring large home range
-habitat fragmentation

6)hunting / collecting
or species that "threaten" human activity / human lives
"critically endangered species"
50+% probability of extinction

within 10 yrs

or 3 generations
"endangered species"
20% probability of extinction

within 20 yrs

or 5 generations
"vulnerable species"
10+% probability of extinction

within 100 yrs
ex. flocking, schools

can confuse a predator
natural limits to pop growth
-enviro not constant
-resources limited

-as density increases, demand for resources increases
-shrinking resources can increase mortality &/or decrease fecundity
logistic model of pop growth
pop growth including B & D rate, & carrying capacity (K)
carrying capacity suggests
negative feedback between pop increase & resource availability

*density dependence*
density dependence
influence pop in proportion to size
-regulates growth
-function by slowing rate of increase
density independent
influences w/o regard to number of individuals
(flood wiping out entire pop, whether 5 or 500
intraspecific competition
competition amoung individuals of the same species

(as long as availability doesn't impede survival, growth & reproduction.. no competition exists)

**function as density-dependent**
2 kinds of competition
when resources are limited
1)scramble competition

2)contest competition

*normally only one type exhibited for a species (or at least during a given time of species life)
scramble competition
-when growth and reproduction are depressed equally accross individuals in a pop
as intensity of competition increases

-can lead to all individuals receiving insufficient resources = local extinction
contest competition
-when some individuals claim enough resources while denying others a share

-can lead to only fraction of pop suffering (the unsuccessful ones)
--successful ind sustain pop
ind respond to level of resource availability that is depressed by presence & consumption of other ind in the pop

*tree taking up water decreases remaining water in soil for other trees
ind interact directly preventing others from occupying habitat or accessing resources w/i it

*birds actively defend nest
the progressive decline in density & increase in biomass of remaining ind's
self regulating
-reduced fecundity
(when don't gain weight bc of high density -- not fertile)

-high density = stressful
(stress can supress growth & reproductive functions)

(to avoid stress some animals disperse)

-social behavior

(defense of terriotory)
(total area avail / size of territory = how many terr owners it can support
increasing CO2 in the atmosphere
*greenhouse gas*

-due to fossil fuel combustion & clearing land for agriculture

-plants respond w/ higher photosynthesis & partial closure of stomata
--increase h2o use efficiency
global climate change
could raise global mean temp by 1.4*C - 5.8*C by 2100

-not uniform

-distribution/abundance will shift

-rise in sea level

-decrease in crop production somewhat offset by increase photsynthesis rates

-mortality rates of humans raise due to heat related deaths

***to understand we must look at earth as a single, complex system***
amt of resource (ie tree biomass) harvested per unit time
rotation period
after harvest the period of time required for new (trees) to grow the amt of resource to same level again
sustained yeild

to have a similar yield at each harvest
swidden agriculture
shifting cultivation

trees cut down and burned to clear land for planting

**results in decline in productivity with each successive crop**`
sustainable agriculture
maintaining agriculture production while minimizing enviro impacts

*reduce soil erosion, reduce use of fertilizers, pesticides*
clear cutting
remmoval of forest and reversion to early stage of succession
seed tree /
shelterwood system
method of regenerating new stand by removing all trees except for a number of seed bearing trees
selection cutting
mature single trees or scattered groups are removed

--problem-- trails / roads needed

*econ concept*
when actions of one ind affect another ind's well being but the releveant costs are not reflected anywhere in the market price
rescue effect
immigration maintining a local population that would otherwise go extinct

*as long as some migration occurs no extinction*
asynchronous dynamics
factor in persisting metapopulation
-chance of extinction completely independent in each local pop

--decreased probability of metapop extinction
decreased ability of dispersal can be due to
isolated habitats

low fecundity

-asexual plants produce thru ramets and reduce dispersal ability

-smaller organisms
4 levels of hierarchle spatial groups
defining a population

*by garton*
-ideally distributed continuously

-collection of local pops close in proximity
--dispersing ind can colonize empty patches that resulted from local pop extinction

-collection of metapop's in geographic region
-metapops can be physically isolated by unsuitable habitats over large areas
-rare dispersal --some gene flow

4)COLLECTION OF SUBSPECIES encompassing entire distribution / geographic range of species
patterns of dispersion can be sociobiological
3 forms of peck order

linear *most efficient*

warning calls of prairie dogs

ex of?

**altruism is increasing fitness by taking care of relatives (who have your genes!)
biodiversity comes from
organic evolution

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