Chapter 14: Population Ecology
p. 648
14.1: Characteristics of Population
Organization of Life:
1
Cells
2
Compounds
Elements
Atoms
Organisms
3
Organs systems
Organs
Tissues
Cells
Biosphere
Ecosystem
Community
Populations
Organisms
Ecosystem: interactions between the biotic and abiotic factors
Biotic: Living other species
Abiotic: Non-living, H2O O2, soil
Habitat: the place where an organism or species normally lives (abiotic)
Niche: the role an organism plays within its habitat (biotic).
Classification:
Binomial Nomenclature
Human – Homo
↓
Genus
Sapiens
↓
Species
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Species:
Animalia
Chordata
Mammalian
Primates
Hominidae
Homo
Sapiens
Species: organisms that resemble one another in appearance, behaviour,
chemistry, and genetic make up, and that interbreed or have the ability to
interbreed, with each other under natural conditions to produce fertile
offspring.
Population Size: is the number of individuals in a given area.
Population Density: the number of given species per unit area.
Calculated:
Density = Number of individuals
Square area
D = 480 moose
600 ha
= 0.80 moose/ha
Population Dispersion
- the general pattern in which individuals are distributed through a
specific area.
3 Types….
1. Clump dispersion: the pattern in which individuals in a population are
more concentrated in certain parts of a habitat.
2. Uniform dispersion: the pattern in which individuals are equally spaced
throughout a habitat.
3. Random dispersion: the pattern in which individuals are spread
throughout a habitat in an unpredictable and pattern less manner.
Figure 3: a) A clumped pattern of dispersion is evident in fish that live is social groups. b)
A random pattern of dispersion, seen here in an Australian rainforest, is rare in nature.
This pattern serves as a yardstick for evaluating other dispersion patterns. C) A nearly
uniform pattern is demonstrated by creosote bushes near Death Valley, Cailfornia.
Measuring Population Characteristics
Populations are dynamic and their numbers and geographic locations change
over time, generally making a precise count impractical. To over come this
biologists sample the population. They count a sample population at a
particular time, than estimate a total size.
Biologists use a variety of sample techniques to estimate the size and density
of a population.
a) Quadrat is a common technique for calculating a population for small or
stationary organisms. Average estimates of population size and density for
the entire area can be extrapolated based on these calculations.
b) Mark – Recapture: sampling technique for estimating population size and
density by comparing the proportion of marked and unmarked animals
captured in a given area: sometimes called ‘captured – recaptured’.
Mark – Recapture is common technique for estimating the size and density
of mobile wildlife populations. The proportion of marked animals to
unmarked animals provides a basis for estimating the size of the entire
population.
Mark – recapture depends on the following assumptions:
- every organism in a population has an equal opportunity of being
captured
- during the time period between the initial marking and the
subsequent recapture, the proportion of marked to unmarked
animals remains constant.
- The population size does not increase or decrease during the
sampling study.
Estimating Population Size and Density
1. A biology students want to estimate the size of the slug population on a
gulf course, biology students randomly selected five 1.0 m2 quadrat in a 10
X 10 m site. The numbers of slugs in each quadrat were 4, 8, 9, 5, and 1.
Estimate the population density and size of slugs in this study site.
2. In a river in British Columbia, 430 sockeye salmon were captured and
marked on the fin with a uniquely numbered T-bar anchor tag. Two weeks
later, a total of 154 sockeye salmon were recaptured and 15 bore the tags on
their fins.
a) Estimate the sockeye salmon population in this river during this study.
b) Identify conditions that must be met in this study to obtain a valid
estimate.