BIOL 2060 Study Guide - Final Guide: Primary Succession, Natural Selection, Parental Investment

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Published on 15 Apr 2013
School
University of Guelph
Department
Biology
Course
BIOL 2060
Large/expanding ranges
Species vulnerable to extinction
Habitat tolerance (broad vs. narrow)
Geographic range (extensive vs. restricted)
Local population size (large vs. small)
Trajectory of population (increasing or decreasing)
Population dynamics populations change over time
Prob: how can we study whether populations are changing?
o Count all individuals of each age class in the population (=age distribution)
o Info on life expectancy survival to reproductive age
Life tables
Cohort Life table follow a cohort of indiv over time, recording deaths; difficult
(length, tracking moving)
Static Life Table based on age structure, record # indiv who died in each age
class; need good records
Survivorship curves summarizes pattern of survival in a population
Type I high juvenile survivorship high, most mortality at older age, high
parental care, few offspring (humans)
Type II constant, birds, die at equal rates, regardless of age
Type III die at high rate as juveniles, lower rates later, low parental care,
many offspring, perennial
Influences Life History describes how over a lifetime, efforts are allocated to
functions such as:
o Growth
o # offspring produced
o Parental investment in offspring
o Size at reproductive maturity
o Dispersal
o influences timing of reprod b/c available energy is limited
TRADEOFF (an exchange that occurs as a compromise)
Growth & reprod
# & size of offspring
# offspring & parental care
Parent life-span & # of offspring
Growth & defense
Dispersal
Permanent movement of indiv from their site of origin to a previously unoccupied location
Avoid competition, inbreeding, expand population
Lack of causes population growth to stop
Costs:
o Energy expense
minimize by utilizing other organisms/media to move; produce small offspring
small, abundant offspring > low parental care (type I)
o Risk of predation
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minimize by disperse when mature & can defend self, when in protected stage (seed)
more parental care > type II
o Risk finding a poorer habitat/variable environment
minimize by produce lots of cheap offspring
lots of offspring > small offspring > low parental care
Population growth
growth rate = r = b-d (births-deaths) per capita = net # new indiv/exisiting # indiv
         
r>0 increasing; r<0 decreasing; r=0 constant
When new indiv added as a function of population size, grows exponentially
   
Overlapping Generations plants/animals that die after reproducing once; Population growth w/
Multiple generations can contribute to births = per capita rate of increase ®
Convert Ro to r using info on the generation time (T = average amt of time from the birth of a female
until the birth of her daughters
R=ln (Ro) / T
Fecundity ability to reproduce
Net Reproductive Rate ()
=1 population is stable; >1 increases; <1 decreases
 
Resource limited environment
Carrying capacity (K) the # of indiv that can be supported in a given environment
Popn grows rapidly, slows, then stops: K reached theoretical maximum population
K=N, growth stops
Density dependence population depends on density influenced by disease, predation, competition, etc.
o Logistic growth model can predict future popn size and K
o Regulate pest popn using these factors limited food supply, adding disease, predators keeps K
at lowest point
o Allee effects
Only applies to species that req mates to reproduce
Effectiveness of density independent controis: must reduce popn to the pt where growth
is mate limited
Conservation: determines the min viable popn size
Density Independence if per capita birth and death rates are unrelated to popn density
o Examples: abiotic factors (temperature, rainfall) that exceed tolerance, rare extreme event (early
freeze, flood, etc.
o Manipulating would effect popn size allows popn to grow at the highest rate (exponential phase
of logistic growth) so must be applied multiple times
Table 1 Differences between species: r- versus K- selection
Rate of increase (r)
r High
K low
Development rate
Fast
Slow
Body size
Small
Large
Generation time
Short
Long
#offspring/size
Many/small
Few/large
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Type of habitat
Variable
Stable
Population growth & life history a conceptual framework
So Far: Distribution of indiv species based on:
Abiotic tolerance
Adaptation/developmental plasticity
Popn growth and regulation
Species Richness number of species in a given area
Birds, trees, mammals, insects, gastropods, etc.
Latitude gradient resource availability, ecological tolerance, seasonal temperature range
Competition
-
-
Predation/Paratsitism
+
-
Mutualism
+
+
Table 2Interactions among species
Competition
Occurs when organisms in the same community seek same limiting resource (prey, water etc.
INTRA-specific comp among indiv of SAME species
INTER-specific comp among indiv of DIFFERENT species
Exploitative competition (resource limitation)
o Occurs when indiv use same limiting resource(s)
o Depletes amt of resources avail to ea indiv (-/-)
o Strongly density-dependent
o Short-term ecological response reduced growth per indiv or fewer indiv
o Ex. Self-thinning plant popn size vs. density high density-dependent mortality allows
remaining indiv to grow to lrg size
Interference comp
o Occurs when indiv interfere w/ the foraging, survival or reprod of others
o Directly prevents the physical establishment of a competitor in a portion of habitat
o Ex: purple sage aromatic, volatile compounds leak from leaves
Competition coefficient = α
o Per capita effects on the growth of one species (1), of a second species (2)
o Displacement of species 1 by species 2
o =1, 1 indiv of species 1 is displaced by 1 indiv of species 2
Short-term response exclusion based on interference competition; reduced growth/popn size
(suppression)
Popn should evolve to reduce ve effects of competition minimize interaction
Character Displacement tolerance ranges differentiate to reduce interaction
Ex finches beak depth, determines size of seeds able to eat
Causes: drought in 1970 reduced small seed abundance
Larger beaks sized birds popn decreased
Phenotypic differences must be genetic (variation)
sympatry
Phenol diff related to diff in resource use
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Document Summary

Prob: how can we study whether populations are changing: count all individuals of each age class in the population (=age distribution) Info on life expectancy survival to reproductive age. Cohort life table follow a cohort of indiv over time, recording deaths; difficult (length, tracking moving) Static life table based on age structure, record # indiv who died in each age class; need good records. Survivorship curves summarizes pattern of survival in a population. Type i high juvenile survivorship high, most mortality at older age, high parental care, few offspring (humans) Type ii constant, birds, die at equal rates, regardless of age. Type iii die at high rate as juveniles, lower rates later, low parental care, many offspring, perennial. Influences life history describes how over a lifetime, efforts are allocated to functions such as: growth, # offspring produced. Parental investment in offspring: size at reproductive maturity, dispersal. Influences timing of reprod b/c available energy is limited .

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