BIO205H5 Study Guide - Final Guide: Plasmodium, Understory, Heterosis

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Published on 6 Jan 2011
School
UTM
Department
Biology
Course
BIO205H5
Professor
Properties of Population
Population – group of organisms of the same species occupying a particular space at a
certain time
-same species: suggests potential for interbreeding
-is a spatial concept which talks about boundaries in space
-has structure (density, spacing, various ages), exhibits dynamics (birth, death,
immigration, emigration) which make it difficult to study
Organisms may be Unitary or Modular
Unitary: organism that are an individual unit such as a zygote that grows into a
genetically unique organism
Modular: organisms that have indefinite growth form such as plants and corals; a
genetically unique organism such as a zygote develops into a module and makes similar
modules (ex. Root extensions in plants)
9.1
Modular: 2 levels of population structure
Genet: genetic individual, an organism that has arisen from a zygote (sexual
reproduction) like a flower
Ramet: an individual produced asexually, remain attached or grow independently of
parents, is a clone of the parents like grass
9.2
Distribution: describes spatial location of population and is based on the presence and
absence of individuals
Geographic range: area that encompasses ALL individuals of a species
Geographic barriers limit the distribution of a population and restrict its ability to
colonize areas that are otherwise suitable (ex. mountains, oceans, lakes)
The red maple is a wide spread deciduous trees in North America which has a
Northern limit: -40deg C
Southern limit: gulf coast
Western limit: dry conditions
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Individuals are not distributed evenly throughout the geographic range of a population;
some individuals can occupy areas that can meet their requirements like for moss
(Tetraphis) moisture is important in areas where moisture is lacking moss cannot grow.
Due to local heterogeneity, populations are divided into local (main population) or sub
population (dispersed population).
9.3
Abundance: number of individuals in the population
-defines its size
Abundance is a function of population density (number of individuals per unit area per
unit volume)
An individuals spatial position relative to another influences population density
Three population distribution patterns (pictures in lec are useful in understanding)
Random: individuals position is independent of one another usually when there is no
limit or competition for resources
Uniform: negative interaction among individuals usually they are trying to repel each
other
Clumped: due to patchy resources or social behaviours when organisms gather due to a
water hole or wolves traveling in a pack
The spatial distribution of individuals within the population can be described at multiple
spatial scales. For example the shrub Euclea in the savannah ecosystems of South Africa
are clumped under Acacia trees for canopy cover, but clumps are uniformly spaced
2 approaches on estimating population density
1) Absolute density: number of individuals/area
2) Indices of relative density: area 1 has more organisms than area 2
Measurement of Absolute Density
1) Total counts: counting all organisms in a particular area
2) Sampling Methods: count a small portion of the population and use the sample to
estimate the total
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a)quadrats (subsample)
b) capture-recapture
9.4
Population size = density x area
In most cases, population density must be estimated by sampling a portion of the
population
Sampling methods for plants and sessile animals
Counting the organisms in a subsample (quadrats)
Abundance estimates may be skewed by a clumped spatial distribution
Quadrats
- Choose quadrats of known size
- Count all individuals on these quadrats
- extrapolate the average count to the whole area
- used a lot in plant ecology
Obtaining reliable estimates:
1) the population of each quadrat must be determined accurately and must be able to
identify the species by definition
2) The area of each quadrat must be known
3) The quadrats must be representative of the whole area
a.you must pick one that has similar distribution with the rest of the area
Sampling methods for mobile animals
-capture-recapture or mark-recapture methods are used based on trapping,
marking, and releasing a known number of marked animals(M) into the
population (N)
-Some time later, the same population is sampled and the ratio of recaptured (R) to
sample (n) individuals in the second sample represents the ratio for the entire
population
-N/M = n/R N=nM/R
-Lincon index or Petersen index of relative population size
Capture-Recapture
-allows for estimate of density and estimate of birth rate and death rate
-technique: capture, mark, release, recapture
Assumptions:
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Document Summary

Unitary: organism that are an individual unit such as a zygote that grows into a genetically unique organism. Modular: organisms that have indefinite growth form such as plants and corals; a genetically unique organism such as a zygote develops into a module and makes similar modules (ex. Genet: genetic individual, an organism that has arisen from a zygote (sexual reproduction) like a flower. Ramet: an individual produced asexually, remain attached or grow independently of parents, is a clone of the parents like grass. Distribution: describes spatial location of population and is based on the presence and absence of individuals. Geographic range: area that encompasses all individuals of a species. Geographic barriers limit the distribution of a population and restrict its ability to colonize areas that are otherwise suitable (ex. mountains, oceans, lakes) The red maple is a wide spread deciduous trees in north america which has a.