Transcript What determines the abundance of individuals in a population?

How do we describe an Ecological Population?
Evolutionary Genetic Description of a Population
- gene frequencies, {PA, Pa}
- genotype frequencies, {GAA, GAa, Gaa}
Ecological Population Description has 3 parts:
- 1) Distribution: What is the Geographic area
where the species occurs?
- 2) Density: What is the Number of individuals
per unit area.
- 3) Dispersion: What is the Local Distribution of
individuals within a specific, small region.
Population: individuals of the same species
present in the same place at the same time.
Community: the assemblage of populations of
different species present in the same place at
the same time.
Ecosystem: the community of species present plus
the abiotic environment (climate) with which
they interact.
What is the Science of Ecology?
Ecology is the study of geographic distribution
and abundance of organisms that result from
interactions between organisms and their
environment. (Where and How Many are
affected by interactions.)
Environment: an organism’s surroundings
- abiotic environment – physical environment,
like temperature, moisture, or day length.
- biotic environment – other living species.
Ecology is a basic science, concerned with the
geographic distribution, number, and
interactions among organisms.
Environmental Science is an applied science,
based on applying ecological principles to
solve specific problems, like reforestation
or detoxification or recycling organic
waste.
Ecology is to Environmental Science much like
Physics is to Engineering.
Environmentalism is a political movement.
Other Applications of Ecology
Conservation
Natural
History
Environmental
Science
Public
Health
Science
Epidemiology
of Human
Disease
Agriculture,
Forestry &
Resource
Management
Ecology
Human
Demography
Food
Science
What Ecologists Do:
1.
2.
3.
4.
Make observations.
Formulate hypotheses.
Test hypotheses using laboratory and field
experiments and statistical tests of data.
Use theory to test hypotheses and make predictions.
Mathematical Models: simplified descriptions
of organisms, their properties, and their
populations, which are used to explore the
dynamics of populations.
Example of a Model in Ecology: Dynamics of HIV
Goal: understand the rate of transmission of the virus
Number of
Uninfected
People
Number of
Infected People
With virus
Number of
People
With virus
And AIDS
Simple models reveal that this blood borne virus would
go extinct, if there were fewer contacts between infected
and uninfected people.
Rate of spread depends upon: sexual contacts, injected or
intravenous drug use, blood transfusions, birth rate, etc.
Three Basic Questions in Population Ecology:
What determines the geographic distribution of
a species?
What determines the abundance of individuals in
a local population?
What maintains diversity of species within a
community?
Black-capped Chickadee
This seed-eating bird is
found in North
America in the Blue
Region.
What determines the
distribution of this
species?
What determines the distribution
of this species?
European
Starling
Introduced into US
from England by
Shakespeare
enthusiasts in 1890
1959
1890
1926 1908
What about our National Bird?
Nearly exterminated from
continental US.
Suffered from DDT poisoning.
DDT banned and the eagle was
saved by the
Endangered Species Act.
Reintroduced into Indiana in
1985: Indiana DNR released 73
young eagles between 1985 and
1989
Bald Eagles were driven extinct in Indiana due to habitat
loss and DDT poisoning.
DDT was the first chemical insecticide.
-- Developed during World War II.
-- Bio-accumulated in top predators and caused egg
shells of birds of prey to thin and eggs did not hatch.
-- Motivation for Endangered Species Act.
-- DDT was banned.
-- Saved the eagle and falcon in the continental US.
Bald Eagles were driven extinct in Indiana due to DDT
poisoning.
In 1985, they started reintroducing Eagles to Indiana.
Between 1985 and 1989, the Indiana DNR Released 73
eagles.
Locations of Bald Eagles in January of 2001
280 total counted from a helicopter
- 31 nests
- 13 nests at Lake Monroe!!
Table 1: Bald Eagle Nesting in Indiana
Nesting
Nest
Nest
Young
Territories Attempts Success Fledged
1989
2
1
0
0
1990
2
1
0
0
1991
5
3
2
3
1992
10
5
3
5
1993
12
9
4
7
1994
12
11
4
7
1995
15
13
11
17
1996
17
14
11
15
1997
18
15
9
13
1998
19
15
11
20
1999
21
20
12
19
2000
23
23
16
35
2001
27
27
20
27
2002
38
38
26
45
Clumped dispersion is when individuals aggregate in
patches.
Fig. 52.2a
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Uniform dispersion is when individuals are evenly
spaced.
Fig. 52.2b
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Random dispersion: the position of each
individual is independent of the others.
Fig. 52.2c
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Locations of Bald Eagles in January of 2001
Eagle sightings across Indiana are
a. clumped
b. uniform
c. random
Locations of Bald Eagles in January of 2001
Eagle sightings across Indiana are
a. clumped
b. uniform
c. random
Eagle nests at Lake Monroe are
a. clumped
b. uniform
c. random
Three Basic Questions in Population Ecology:
What determines the geographic distribution of a
species?
What determines the abundance of individuals
in a population?
What maintains diversity of species within a
community?
What determines the abundance of individuals in
populations? (whooping cranes)
Fig. 52.9
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Number of Nesting Pairs of
Eagles in Indiana
Number of Nesting Eagles
40
73 Eagles introduced
Between 1985-89
Number of Nests
35
30
25
20
15
10
5
0
1985
1990
1995
Year
2000
2005
Number of Caribou
Why did the reindeer population increase
quickly and then crash?
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Why do some
populations increase
smoothly and level off
and others fluctuate
in numbers?
overshoot
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Increase/decrease in Lynx numbers lags (follows)
increase/decrease in Snowshoe hare numbers.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
Bald eagle numbers on Indiana Midwinter Bald Eagle Surveys,
1979-2001.
John Castrale and Amy Ferchak, DNR Biologists
Three Basic Questions in Population Ecology:
What determines the distribution of species?
What determines the abundance of individuals in
populations?
What maintains diversity of species within a
community?