Ecology Exam 3
Terms
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- ecological diversity
-
same thing as species diversity
*NOT biodiversity!!* - 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 ________
-
ARBITRARY
(changing) -
stratification
(leads to pattern diversity) -
local-scale VERTICAL LAYERING
of vegetation, soil, biota, systems, intertidal, etc. -
zonation
(leads to pattern diversity) -
regional-scale patterns
**LIFE ZONES** -
temporal
(leads to pattern diversity) - period in time
-
trophic
(leads to pattern diversity) - network organization of food webs
-
reproductive
(leads to pattern diversity) -
parent - offspring patterns
plant clones -
social
(leads to pattern diversity) - flocks, herds, schools, etc
-
co-active
(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:::
-
Simpsons
&
Shannon-Weiner index -
Richness
&
Evenness
INCREASE WITH -
-ecological time time (ecological succession)
-evolutionary time (community evolution)
-from poles to equator (latitudinal diversity gradiant)
-in warm / moist enviros -
Richness
&
Evenness
DECREASE WITH -
-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?
- COMMUNITY
- global sum of communities?
- THE BIOSPHERE
- 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?
-
individuals
(individual organisms) - population
-
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) -
DISTRIBUTION
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 - metapopulation
-
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
or
individuals / volume
*sessile - divide into quadrants
*mobile - mark-recapture method - population dispersion
-
spatial arrangment of individuals within a population
(how individuals are spaced out)
1)RANDOM
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
- territoriality
-
age/sex structure
(age/sex distribution) - relative # of individuals of each age segregated by sex
- population growth =
-
(birth + immigration)
-
(death + emmigration)
AKA
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
-
show
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!!!* - "Survivorship"
-
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)
*NEGATIVE FEEDBACK LOOP*
*usually due to biotic factors:
-food
-nesting sites / territoriality
-competition
-predation -
populations limited by two types: (in addition to density dependent and density independent controls)
1)INTRINSIC
2)EXTRINSIC -
1)INTRINSIC
-pop regulates itself
[territoriality, competition for mates]
2)EXTRINSIC:
-pop controlled by outside forces
[food, nesting sites, predation] - "territory"
-
portion of home-range defended against individuals of the SAME species
*DO NOT OVERLAP* - "home-range"
-
area through which individual moves during usual round of activities
*OVERLAP*
(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)
2)migration
(movement, often seasonal, from one place to another AND BACK. a -> b -> a. often seasonal change in home range.) -
distinction between
"home-range"
and
"territory"
MADE BY - W. H. BURT
-
DISPERSAL v MIGRATION
change in Home-Range -
1)dispersal
(ONE WAY movement from place of birth to place of reproduction. PERMANENT)
2)migration
(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)
****DIFFERENT STRATEGIES***** -
"life history"
AKA
"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 - r-strategists
-
-many offspring
-little parental care
-small body size
-fast growth rate
(comes from logistic curve... pops can potentially grow fast, have high r) - K-strategists
-
-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.) - "demography"
- 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?
(peculiarity) -
GLOBAL
-widest of any vertebrate -
worldwide density of human pop?
(peculiarity) -
highest of any megavertebrate
127 / sq. mile -
dispersion of human pop?
(peculiarity) -
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
(CONVEX) - 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?
(peculiarity) - long post-reproductive life span
-
carrying capacity of humans?
(peculiarity) -
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
-agriculture
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?
(peculiarity) -
education correlated with TFR
*more education = fewer children*
*family planning = fewer children* - human population growth rate has fallen since ___?
-
1960s
(but still a + growth rate, and resource demand still rising) -
(increasing population) x (increasing resource demand / capita)
====================== -
(increasing population) x (increasing resource demand / capita)
======================
INCREASING IMPACT ON THE ECOSPHERE - "IPAT" model
-
I = P x A x T
Impact = (Population)(Affluence)(Technology) - Total Human Population? (#)
- 6.555 BILLION
- Annual % growth rate of human pop:
- 1.2 %
- Doubling Time of human pop?
- 58 Years
-
Doubling Time
EQUATION -
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
v
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:
-
HUGE
NUMEROUS
WARM
(endotherms)...(endotherms are expensive - E. O. Wilson
- SOCIOBIOLOGY
- Sociobiology includes
-
-evolutionary biology
-anthropology
-ethology
-comparative psychology
-sociology
-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:
-
transmitter
-->signal
---->receptor
*channels of communication =
visual
mechanical
chemical
electrical
heat - conservation ecology seeks to conserve
- BIODIVERSITY
- the sum of organisms, their genetic variability, historical relationships and symbiotic interactions =
- BIODIVERSITY
- most species that have ever been are extinct
- but present day extinction rates seem unusually high
- extinction caused by:
-
failure to adapt
(to: PREVIOUSLY:
-climate change
-volcanism
-mountain building
-disease
-extra-terrestrial influences)
(to: CURRENT:
1)HABITAT LOSS
2)pollution
3)exotic species
4)exploitation
5)disease)
[failure to adapt to humans] - how many mass extinctions in history?
-
5
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
CONSERVATION GENETICS + CONSERVATION ECOLOGY = CONSERVATION BIOLOGY
*APPLIED EVOLUTIONARY BIOLOGY*
*theory of island biogeography important*
(only ~ 20 years old) -
mass extinctions
(qualities) -
-global
-involve broad range of organisms
-rapid - 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
-
EQUILIBRIUM
between immigration & extinction
-extinction varies w/island size
-immigration varies w/distance from mainland - island biography predicts
- smaller islands farther from mainland = smaller biotas
- SLOSS
- single large or several small?
-
Goals of Conservation Biology
[by SOCIETY OF CONSERVATION BIOLOGY (SCB)] -
-protection, maintanence, restoration
-promotion
-management
-encouragement of sciences
-education at all levels
-promotion of all of the above - leading cause of extinction?
-
HABITAT LoSS
(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
1)unitary
2)modular -
1)unitary
-zygote
-through sexual reproduction
-genetically unique organism
2)modular
-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
-
1)genet
-individual tree/plant produced by sexual reproduction
-arising from a zygote
-genetic individual
2)ramet
-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 - abundance
-
defines size
*the number of individuals in a population*
FUNCTION OF:
1)density (#/unit area = crude density)
2)Distribution -
DISPERSION
(spatial arrangement wi a pop)
1)random
2)uniform
3)clumped -
1)RANDOM
-position of each is independent of others
2)UNIFORM
-usually results from negative interaction
[competition]
3)CLUMPED
-MOST COMMON
-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
1)pre-reproductive
2)reproductive
3)post-reproductive
*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)? -
1:1
1:1 - Life Table
-
age-specific account of mortality
displayed in
1) mortality curve
2)survivorship curve [type I, II, & III] - cohort
- 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 -
TYPE I
survivorship curve -
humans / mammals
-survival rate high thru life span w/ heavy mortality rate toward end
-convex ) -
TYPE II
survivorship curve -
birds / rodents / reptiles
-survival rates don't vary w age
-straight line -
TYPE III
survivorship curve -
oysters / fish
-mortality rates high early in life
-concave ( - Sociobiology
-
the study of social behavior
(sociality... the tendancy for interaction between members of the same species)
-branch of population ecology - "society"
- group of individuals of same species organized in cooperative manner
-
sociality
[definition & advantages] -
the tendasncy for interaction amoung/between members of same species
HAS EVOLVED IN RESPONSE TO ENVIRO PRESSURES:
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 -
"communication"
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 - Receivers
-
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*
*status*
*spacing* - altruism
-
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 - holocene
-
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
*by HUBBERT*
(came very close to actual oil depletion estimate) - "population growth"
-
# of individuals increasing / decreasing with time
change in pop / change in time
=
(b-d)(pop)(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)
*
1000 - 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
-inbreeding
(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
- hotspots
-
norman myers
-regions exhibiting high species richness and endemism
-unusually high diversity
BASED ON:
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
(IUCN) -
developed quantitative classification based on probability extinction
(demographic stochasticity & probability of extinction) -
Minimum Viable Population
(MVP) -
Shaffer
defined # of ind necessary to ensure long-term survival of species
DEFINED AS:
-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
(MDA) -
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
food
drugs
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? - ubiquitous
- a species w/ geographically widespread distribution
- a species' susceptability to extinction
-
1)endemic
-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 - allelomimetic
-
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
occur
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 - exploitation
-
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 - interference
-
ind interact directly preventing others from occupying habitat or accessing resources w/i it
*birds actively defend nest - "self-thinning"
- the progressive decline in density & increase in biomass of remaining ind's
-
desity-dependent
self regulating
factors -
-reduced fecundity
(when don't gain weight bc of high density -- not fertile)
-high density = stressful
(stress can supress growth & reproductive functions)
-dispersal
(to avoid stress some animals disperse)
-social behavior
-territoriality
(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*** - yield
- 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
-
*goal*
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 -
externalities
*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* -
1)LOCAL POPULATION
-smallest
-ideally distributed continuously
2)METAPOPULATION
-collection of local pops close in proximity
--dispersing ind can colonize empty patches that resulted from local pop extinction
3)SUBSPECIES
-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
- territory
- 3 forms of peck order
-
hierarchical
linear *most efficient*
circular -
warning calls of prairie dogs
ex of? -
altruism
**altruism is increasing fitness by taking care of relatives (who have your genes!) - biodiversity comes from
- organic evolution