Population Distribution and Abundance Flashcards
population
a group of individuals of a single species inhibiting a specific area
Reasons why ecologists study populations
population holds key information to:
1) saving endangered species
2) controlling pest populations
3) managing fish and game population
4) understanding and controlling disease epidemics
Distribution
the size, shape, and location of an area a population occupies
Density
the number of individuals per unit area
abundance
total number of individuals, or biomass, of a species in a specific area
Characteristics of a population
Distribution, Abundance, and density
define fundamental and realized niche
fundamental: the physical conditions under which a species might live, in the absence of interactions such as competition.
realized: the actual niche whose distribution is limited by biotic factors such as competition, abundance, growth, survival, reproduction, and distribution of a species.
what is tagging used for?
Migration patterns, growth rates, identifying individuals for behavior studies, etc.
Examples of methods to assess relative density
Insect pit traps
Pugmark traps
Camera traps
Scented moth traps
Insect light traps
Bait traps
Fecal pellet counts
Frequency of vocalizations
Survey questionnaires of people hunting, fishing or
living in an area.
Records of catches from professional harvestersQuadrants vs transects
Quadrats/ photoquadrats: random points or simple visual estimation.
Transects: random points along the transect or measuring under the transect.
3 types of distribution patterns
random, regular, clumped
Random; pattern
Individuals are distributed independently of other organisms of the same species within the environment. equal probability of occurring anywhere in an area
Regular; pattern
Individuals are more regularly spaced in the environment than would be expected by chance (more orderly than random). uniformly spaced in an environment.
clumped; pattern
Individuals are closer together in groups, with larger gaps separating groups, than would be expected by chance. individuals live in an area of high local abundance, separated by areas of low abundance
Random; process
neutral interaction between individuals, and between individuals and the local environment
Regular; process
antagonistic interactions between individuals or local depletion of resources
Clump; process
the attraction between individuals or attraction of individuals to common resources
Pheromones
are chemical substances secreted by some animals for communication with other members of their species.
as desert shrubs grow, the population goes from clumped to random to regular, this is because___?
1) seeds germinate at limited numbers of “safe sites”
2) seeds are not dispersed far from the parent plant
3) asexually produced offsprings are necessarily close to the parent plant
reasons for changing in the distribution of Creosote bush
Creosote bushes grow in a way to reduce overlapping. Competitive interactions with neighboring shrubs influence the distribution of Creosote bush roots.
on large scales, individuals within a population are____?
clumped
population density declines with _____ organism size
increasing
Habitat tolerance
range of conditions in which a species can live in
a classification of commonness and rarity is based on three factors:
1) geographical range
2) habitat tolerance
3) local population size
the inverse relationship between size and density is because
of the metabolic requirement of species of larger size.
Describe how the age of a population influences its distribution
ll distributions vary with age
example:
*young and small shrubs establish in high densities and produce a clumped distribution
*mortality, as the shrubs grow, reduces clumping and produce a random distribution among medium shrubs
*competition enforces a regular distribution among large shrubs
