focus is on an individual
focus is on a single species
main question in population ecology
How does the environment affect the:
of a species?
Reasons for studying populations
-saving endangered and functionally important species
-controlling pest populations
-managing fish and game populations
-controlling disease epidemics and understanding their impacts
-human population growth
What does population ecology measure?
-Rate of growth
Characteristics of populations
The distribution of species: Why isn't every species found everywhere?
-Evolved physiological, anatomical, and behavioral characteristics to compensate for environmental variation.
-metabolically costly, limiting distribution.
describes a species SPATIAL LOCATION over the area that it occurs
-can change (i.e. seasonal)
-all the environmental factors that INFLUENCE GROWTH, SURVIVAL, and REPRODUCTION of a species.
-all the factors necessary for its existence.
-multidimensional (Predators v. Nutrients v. Temperature)
-fundamental and realized
the TOTAL RANGE of physical environmental conditions that are suitable for existence, in the ABSENCE of COMPETITION and PREDATION
describes the FRACTION of the fundamental niche that is ACTUALLY OCCUPIED by a species
-represents current distribution
difference between the fundamental niche and the realized niche is usually the result of:
What controls the distribution of organisms at SMALL SCALES (within populations)?
3 basic patterns of Dispersion
EQUAL CHANCE of being anywhere
-RESOURCES distributed UNIFORMLY
-frequent, random pattern of disturbance SOLITARY animals with LARGE HOME RANGES
-EXCLUSIVE use of areas
-individuals AVOID one another TERRITORIAL, NON-GROUP animals
UNEQUAL CHANCE of being anywhere
-MUTUAL ATTRACTION between individuals
-patchy resource distribution, HABITAT HETEROGENEITY
How are individuals distributed on a LARGER SCALE, across environmental variation?
most species show a CLUMPED DISTRIBUTION, whether they range over a large or small geographic area
Which factors influence species abundance and density?
conditions toward the EDGE of the RANGE may lead to PHYSIOLOGICAL STRESS, which could DECREASE reproductive FITNESS
Animals must ____ and this influences the distribution of the animal...
animals must EAT and whatever regulates the distribution of their FOOD will REGULATE the distribution of the ANIMAL
the TOTAL NUMBER of individual of a species PRESENT in a SPECIFIED AREA
measuring abundance and density
(#recaptured)/(#marked 1st visit)=(#captured 2nd visit)/(#population)
discovered body size and density correlation
John Damuth, 1981
negative linear relationship
v body mass= ^ density
# species of herbivorous mammals
Lincoln-Peterson Index (Mark-Recapture)
N: population size estimate
M: marked individuals resleased (new marked)
S: size of 2nd sample
R: marked animals recaptured
highly effected by recapture rates
Schnabel Index (Mark-Recapture)
Mi: total previously marked in population
Ci: captured sample
Ri: recaptured in current sample
More accurate due to more samples taken and higher recapture rates