BIOL 1111 Chapter Notes - Chapter 29: Ecosystem Ecology, Population Ecology, Allelopathy

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Saturday, April 2, 2016
Chapter 29 Population Ecology
Ecology
-Ecology: Study of relationships among species and between species and the
environment in which they occur
The Science of Ecology
-workers in applied ecology develop conservation plans and amelioration programs to
limit repair and migrate ecological damage caused by human activities
-organismal ecology: study organism to determine genetic, biochemical, physiological,
morphological, and behavioural adaptions to the abiotic environment
-population ecology: focus on groups of individuals of the same species that live
together
-community ecology: examines populations of different species that occur together in
one area (sympatric)
-ecosystem ecology: explore how nutrients cycle and energy flow between biotic
components of an ecological community and the abiotic environment
Population Characteristics
Geographic Range is
Determined by the
Boundaries of
Distribution
-population have characteristics that transcend those of individuals making
up the pop. at specified time (Nt)
-population density: # of individuals per unit area/volume of habitat
-large body size-lower pop. density
-mark/release/capture, head count, etc
Population Dispersion Is
the Distribution of
Individuals in Space
-dispersion— spatial distribution of individuals within the geographic range
clumped/uniform/random
-Clumped Dispersion (occurs in 3 structures)
Suitable conditions are patchy distributed (pasture, plants)
Population of some social animals are clumped bc mates are easily to
locate within groups
when species reproduce by asexual clones remaining attached to
parents (aspen trees/sea anemones)
-Uniform
when individuals, repel one another bc resources are in short supply
(creostate bushes)
chemical warfare between bushes — allelopathy
-dispersion of population often rainforest trees time in response to natural environmental ryhtms
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Life Tables Show the Number of Individuals in Each Age Group
-few individuals survive to maximum age possible
-life table: summarizes demographic characteristics of a population
-cohort: group of individuals of soppier age at birth and monitor their survival until all
members of the cohort die
-life spans of organism are divided into age intervals of appropriate length
-age specific mortality: proportion of individuals alive at start of an ange interval that
died during age interval
-Age specific survivorship:proportion of individuals alive at the start of age interval that
survived until start of next age interval
-for any age interval, sum of age specific mortality and age specific survivorship must
equal 1
-Age specific fecundity: average 3 of offspring produced by surviving females during
each age interval
Age Structure Is the
Numbers of Individuals
of Different Ages
-age structures statistical description of the relative #s of individuals in each
age class
-pre reproductive, reproductive or post reproduction
-reflects growth history, predicts future growth
Generation Time Is the
Average Time Between
Birth and Death
-generation time-average time between the birth of its offspring
short in species that reach sexual maturity at small size
Sex Ratio: Females:
Males
-sex ratio: relative proportions of males to females
-in northern elephant seals—mature bulls fight for dominance on beaches
were they mate
presence of other males in the group may have little effect on size of
future generations
The Proportion
Reproducing Is the
Incidence of
Reproducing Individuals
In a Population
-population ecologists try to determine the proportion of individuals in a
population that are reproducing
Demography
-statistical study of the process that change a populations size and density
through time
-used to predict growth
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Survivorship Curves Graph the Timing of Deaths of Individuals In A
Population
survivorship curve: displays rate of survival for individuals over the species’ average life
span
The Evolution of Life Histories
-life history: includes the lifetime patterns of growth, maturation, and reproduction
-every organism is constrained by a finite energy budget—total amount of energy it
can accumulate and use to fuel its activities
-organisms that enter states of inactivity or dormancy can maximize time over which
they use stored energy
animals/plants that survive freezing (hibernation)
-estivation: inactivity during prolonged periods of high temperatures
-organisms use energy they can harvest for 3 functions: maintenance, growth, and
reproduction
Fecundity Vs. Parental Care: Cutting Your Losses
-The amount of energy invested in each offspring before its born is passive parental
care provided by the female
-Active Parental Care to offspring after birth
-A lot of offspring = little active parental care
Type I curve
-reflect high survivorship until late in life
-large animals with few young
Type II curve
-relatively constant rate of mortality in all age classes, pattern makes steady
declining survivorship
Type III curve
-high juvenile mortality followed by period of low mortality once offspring
reach critical age and seize
-cleome droserifolia
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Document Summary

Ecology: study of relationships among species and between species and the environment in which they occur. Workers in applied ecology develop conservation plans and amelioration programs to limit repair and migrate ecological damage caused by human activities. Organismal ecology: study organism to determine genetic, biochemical, physiological, morphological, and behavioural adaptions to the abiotic environment. Population ecology: focus on groups of individuals of the same species that live together. Community ecology: examines populations of different species that occur together in one area (sympatric) Ecosystem ecology: explore how nutrients cycle and energy ow between biotic components of an ecological community and the abiotic environment. Population have characteristics that transcend those of individuals making up the pop. at speci ed time (nt) Population density: # of individuals per unit area/volume of habitat. Dispersion spatial distribution of individuals within the geographic range clumped/uniform/random. Uniform: when individuals, repel one another bc resources are in short supply (creostate bushes, chemical warfare between bushes allelopathy.

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