Download Basic characteristics of Populations - Powerpoint for Sept. 25.

The Niche
American oystercatcher prying limpet off a horseshoe crab
The Niche
• ecological niche - the way in which an
organism interacts with all of the biotic and
abiotic factors in its environment - often
described as how the organism makes its
living, its functional role, but includes the
habitat it occupies
Niches in European seed-eating birds
Common redpoll
Greenfinch
Linnet
Hawfinch
Precursors to theory of the niche:
Law of the Minimum
• The distribution of a species will be controlled
by that environmental factor for which the
organism has the narrowest range of
adaptability or control.
- Carl Sprengel 1828
Precursors to theory of the niche:
Shelford’s law of tolerance
• The distribution of a species is controlled by
the environmental factor for which the species
has the narrowest tolerance.
G. Evelyn Hutchinson age 18
Hutchinson’s Niche Definitions
• The fundamental niche - the set of resources and
conditions that permits the survival and reproduction
of an organism - many resources and conditions
interact to form the niche.
• The realized niche - the portion of the fundamental
niche actually occupied by the species when restricted
by other organisms - restricted by competition,
predation, parasites, disease.
- Hutchinson 1958
Fundamental vs. Realized Niche
N-dimensional niche
Key point – two species cannot have
identical niche
Populations
Populations
• Population - a group of organisms of the same
species which have the potential to interbreed
– or a population is a group of organisms of
the same species occupying a particular place
at a particular time
• Populations have a number of properties which
are not possessed by individual organisms this is because a population is the sum of many
organisms interacting
Starling Murmuration
http://vimeo.com/31158841
Density and Distribution
Prairie Dog Distributions
Properties dealing with changes
in population size
• Natality - may think of this as births, but includes more than
just birth - hatching, germination, fission
• Natality includes idea of fecundity - number of offspring
produced per unit time - we are most concerned with realized
fecundity - actual number of survivors
• Mortality - death rate - its converse is survivorship mortality looks at how many die per unit time, survivorship at
how many don't die per unit time
• Longevity examines life-span of individuals - again we are
most interested in realized longevity, not potential longevity
• Immigration - individuals moving into a population
• Emigration - individuals leaving a population
Changes in human longevity
- life expectancy at birth
Typical animal life spans
What is an individual?
• unitary organism - individuals are highly
determinate in form and while growing pass through
predictable (innately determined) sequences of life
history stages
• modular organisms - zygote develops into unit, or
module, which produces more modules thus
producing an organism with a variable number of
modules, whose development is unpredictable and
strongly influenced by environmental factors
A classic unitary organism
A classic modular organism
Bryozoan colony
More classic modular organisms
Genets and Ramets
• ramet - a module with
the potential for a
separate existence
• genet - the "genetic
individual"; the
collection of all
modules derived from a
single zygote
A single Aspen clone
Posidonia oceanica – Neptune grass
Sampling to collect population data
Census - most basic sampling - count and determine age
of all individuals in population, count again later
Several ways to subsample and estimate population size:
1. Determine total area in which population occurs,
count all individuals in small plots, multiply average
number in plots to get total, repeat at later dates works best for sessile organisms
2. Mark-recapture methods
3. Catch per unit effort
4. Miscellaneous methods – traps, counts of fecal
pellets, counts of vocalizations, feeding damage on
plants, radar counts, roadside sightings, fur or pelt
records, roadkill
Quadrat Sampling
Mark recapture of Cicadas
Catch per unit effort – Pacific
Threadfin
Beetles feeding on Viburnum
Beetle damage on Viburnum
Bird migration data – typical
altitude – from radar
Bird migration radar map
Skylark
Metapopulations
• A metapopulation is a series of small, separate
populations united together by dispersal
Metapopulation Dynamics
Metapopulations of Bay
Checkerspot Butterfly
Bay Checkerspot
Jasper Ridge
Aphids and Epilobium
Habitat fragmentation in Amazonia