exam 2 Flashcards
community
group of various species in a common location at the same time
what is the difference between species richness and species diversity?
species richness: # of species in a defined region
species diversity: measure of abundance (shannon’s h index)
what is community stability?
ability of a community to defy change or rebound to equilibrium from change
what does a community in community stability have?
1) equilibrium stable over time
2) return to equilibrium after a disturbance that alters community structure
succession
process of directional change in communities over time and includes:
1) regular change in community composition (have life introduced to a new area)
2) one set of species succeeds a previous set (one paves the way and gets replaced)
ecological succession
the process of change in the species structure of an ecological community over time
-gradual change in plant communities in an area following a disturbance
sere
each stage of change (chunk of time)
climax community
a late successional community that remains stable until disrupted
1) not prone to invasion by non-climax species and can “renew” themselves
2) determined by the interaction between plant species and abiotic factors
ex: Sonoval desert in AZ and CA
primary succession
-occurs only on newly exposed geological substrates not yet modified by organisms
-where bare rocks have not seen presence of primary producers
-ex: lava flow, new lake after glacial retreat
seconday succession
-following disturbance that doesn’t destroy soil
-life has already existed and something disturbed it
-ex: harvesting, deforestation, hurricanes, and forrest fires
pioneer community
made up of very first species to colonize an area in successional sequence
pioneer plants characteristics
-hardy
-short life cycle
-high rate of dispersal
-easy to germinate (seeds can land anywhere and grow)
-opened to wind pollination
what is the order of nitrogen fixation?
1) nitrogen fixation
2) NO2 (nitrogen dioxide)
3) NH3 (ammonia)
characteristics of succession
1) increase in species diversity
2) changes in species composition
3) change in ecosystem properties
4) soil changes
what are some soil changes in succession?
-soil depth gets deeper for large root systems
-nitrogen, moisture, and organic matter increase
-phosphorous, pH, and bulk decrease
why does nitrogen increase with succession?
more plants = more nitrogen fixation
why does phosphorous decrease with succession?
phosphorous is limiting and comes from weathered rocks
chronosequence
communities/ ecosystems with a range of times since disturbance
-once had hot spots but then started primary succession
When are nitrogen and phosphorous limiting?
N= early succession
P= late succession
what are the 3 mechanisms of succession?
facilitation (most well accepted)
tolerance (survivor like- those can handle the change)
inhibition- no one superior. just whoever gets there first
facilitation
-only certain species can colonize (pioneers) which modify environment
-makes environment less suitable for themselves but easier for new species
tolerance
-initial colonization can have pioneers and juveniles of climax community
-later succession species are the ones tolerance of environmental conditions during succession
inhibition
-initial colonization can have pioneers and juveniles of climax community
-no one is superior. Just whoever gets there first
stability
absence of change
-due to resistance
resistance
ability to maintain structure and function in face of potential disturbance
resilience
ability to recover from disturbance
population
a single species inhabiting same place at same time
what does p= ?
frequency of a trait (0-1.0)
necessary resources to survive and reproduce
-water
-food
-CO2/ oxygen
-solar radiation
competition
Caused by reduction in quantity resources by activity of organisms
habitat vs niche
habitat= home
niche= job
habitat
-where the organism lives (its home)
-biotic and abiotic habitat
-ex: conifer forests, marsh, desert
niche
-the sum total of organism’s tolerances, requirements, physical and biological conditions to survive and reproduce
-its job/role/lifestyle
-production of the organism. NOT environment
-defined by a species
n-dimensional hypervolume
n= # of factors important to the survival and reproduction of species
fundamental niche
full range of environmental conditions under which an organism cna exist
realized niche
conditions under which the organism actually survives, grows, and reproduces
-smaller part of the fundamental
-interactions with other organisms usually force a species to occupy a niche that is narrower than fundamental niche
what are some factors that affect the rate of decomposition
temp, burial depth, access by scavengers, clothing (or lack-thereof), trauma, humidity, rainfall, body size/ weight, etc
what is the driving force of decomposition?
bacteria
what is distribution and the 2 areas to consider?
the size, shape, and location of organisms in a population
consider
1) boundary: where does the population start and end
2) patterns within the boundary
patterns of distribution
1) random
2) regular
3) clumped
random pattern & process of distribution
-an individual has equal probability of occurring anywhere in an area
-no disadvantage anywhere within the boundary
-neutral interaction between
individuals
and
individuals and local environment
regular pattern & process of distribution
-individuals are uniformly spaced through the environment
-might try to inhibit growth of nearby individuals if they come to their space
-antagonist interactions:
between individuals
or
local depletion or resources
clumped pattern & process of distribution
-individuals live in areas of high local abundance, separated by areas of low abundance
-drop seeds straight to he ground right where thy are (positive feedback loop because favorable conditions)
-attraction:
between individuals
or
of individuals to a resource
biomass
the collective sum of mass in a population
what is the order of population densities?
1= highest
1) terrestrial invertebrates
2) aquatic invertebrates
3) vertebrae poikilotherms
4) mammals
5) birds
N future =
Nnow + B + I - D - E
equilibrium
a point at which there is no net change in the system
what are life tables?
tools for keeping track of births, deaths, and reproductive output in a population interest
cohort
-horizontal life table
-follows a group of same-aged individuals from birth throughout their lives
-assumes all cohorts have the same pattern
static
-vertical life table
-from data collected from all ages at 1 particular time
-less accurate than other 2 assumptions
-proportion of individuals in each age class doesn’t change from gen to gen (stable generation distribution)
-population is (nearly) stationary
mortality records
-static life table but based on age of dead organisms
-ex: skulls of moose
fecundity
organism’s potential reproductive capacity over a certain period of time
-aka how many babies an individual can have in x time
what is annual plant?
seed to seed
-nonoverlaping generation
what does lx represent?
proportion of original cohort surviving stage x
what does mx represent?
average number of offspring/individual of stage x
what does R0 represent?
net reproductive rate
-average number of offspring produced by an individual in a population in its lifetime
Type I survivorship curve
-juvenile survival is high
-mortality in older generations
-ex: humans
Type II survivor curve
die at equal rates regardless of age
-ex: many birds, turtles
Type III Survivor Curve
-high juvenile mortality rate
-low mortality rate later in life
what are the 2 aspects of a life table?
survivorship and fecundity
-form a foundation for natural selection
what do fecundity schedules tell us?
which ages/stages individuals make the greatest contribution to the next generation
what 3 measurements do life tables and fecundity schedules require?
1) age (or stage)
2) fate (alive/dead)
3) number of springs
what can life tables and fecundity schedules together provide an estimate for?
-R0, lambda, T, r
-predict and manage population growth
what do growth models enable us to predict?
*rates and patterns of population growth
*what factors limit population sizes
geometric growth model
*for organisms with discrete breeding seasons (pulse breeding)
*reproductive event in unknown time (ex: annual plants)
LAMBDA = R
*species with a single annual season and a life span of 1 year
exponential growth
*continuously reproducing organisms with overlapping generations
*instantaneous rate of increase
*geometric growth with no interval because growth increments
when may exponential growth be important?
CONDITIONS DURING WHICH RESOURCES / SPACE ARE NOT LIMITING
*establishment of new environments
*exploitation of transient (short lasting) favorable conditions
*during the recovery after a major decline
what are some factors that limit population growth?
*limited food supply/ space
*buildup of toxic wastes
*increased disease (because so packed together)
*predation
*competition
what happens when there is crowding?
*increased competition: reduces access to food and other resources
*promotes spread of disease
*attracts attention of predators
AS A RESULT, POPULATION GROWTH SLOWS AND EVENTUALLY HALTS
density dependence
decreasing growth rate with increasing population size
logistic population growth
as resources as depleted, rate of population increase slows down and eventually stops
what are the 2 components to density dependence?
1) logistic population growth
2) populations tend to level off at the carrying capacity
what happens when R=N?
IROC=0
population size remains constant
what are assumptions of logistic population growth?
no migration, constant K, and all individuals use resources equally
why do humans tend to live where weather is nicer?
*more access to resources
*highest pop. densities are in coastal regions
what is adaptation?
a heritable trait/ behavior that aids the organism in survival and reproduction in its current environment
what is adaptive response?
how someone reacts to change
what is life history?
*the series of changes related to survival and reproduction undergone by an organism during its lifetime
what is allocation?
*how we use our time, money, and resources
*if organisms use energy for function (like growth), amount of energy available for other function is reduced
what does allocation lead to?
trade-offs between functions (like number of offsprings and size of them)
asexual reproduction style
1) produces identical clones of parent
2) generation of offspring from a single individual
3) budding, binary fission, cloning, vegetative propagation, parthenogenesis
PRO: pop. can increase rapidly, more time and energy efficient
CONS: dangerous to have all identical in a changing environment. NO variation
sexual reproduction style
1) produces variable offspring
2) produces new species -> diversity
3) organisms combine genes -> next gen does more than parents -> upping chance of survival
4) shuffling and recombining genes creates complexity but also more was to survive a changing world
DIVERSITY STEMING FROM MIXING GENES
