population ecology chapter 53. turtles population groups of individual of the same species that live...
TRANSCRIPT
Population Ecology
Chapter 53
turtles
Population
Groups of individual of the same species that live in the same placeCharacteristics of populations1. Population range– Area where it occurs
2. Spacing patterns– Spacing of individuals
3. Size
Population range
No population is in all habitatsNo population is static1. Changing environment (receding glaciers)2. Expansion to new areas
Cattle egret
Current
1966
1970
1965 1960
1961
1958
1951
1943
1937
1956
1970
Population
DensityDispersionPattern of spacing
Spacing
1. Randomly spaced– Little interaction
2. Uniformly spaced– Competition for resources
3. Clumped spacing– Uneven distribution of resources– Social interactions (herd, flock, pride)
Dispersion (a) Clumped
(b) Uniform (c) Random
Demography
Statistical study of populationsGrows: births outweigh deathsShrinks: deaths outweigh birthsSex ratios (females > males)Generation time (birth to reproduce)ReproductionSurvivorship curves
Age structure
CohortGroup of individuals that are of the same ageFecundity: Birth rateMortality:Death rateAge structure# of individuals in a given cohort
Survivorship curve
1,000
100
10
10 50 100
II
III
Percentage of maximum life span
Nu
mb
er
of
su
rviv
ors
(lo
g s
ca
le)
I
Factors regulate populations
Cost of reproductionAge at first birthSemelparity:Single birth eventAnnuals/insectsIteroparity:Several births over several years
Factors regulate populations
Carrying capacity K:Maximum population an environment can sustainDensity-dependent effects Increase density decreased birth ratesLight, water, space, food, diseaseDensity-independent effects:Fire, volcano, cold
Carrying capacity
Snowshoe hare
Lynx
Nu
mb
er
of
lyn
x(t
ho
us
an
ds
)
Nu
mb
er
of
ha
res
(th
ou
sa
nd
s)
160
120
80
40
01850 1875 1900 1925
Year
9
6
3
0
Factors regulate populations
K-selection:Density dependent selectionr-selection: Density independent selection
Human growth
Density dependent factors
Competition for resources
Territoriality Intrinsic factors
Disease Predation
Toxic wastes 5 µm
Population pyramids
Fig. 53-26
Less indus-trialized
countries
Indus-trialized
countries
60
50
40
30
20
10
0 0
20
40
80
Lif
e ex
pec
tan
cy (
year
s)
Infa
nt
mo
rtal
ity
(dea
ths
per
1,0
00 b
irth
s)
Less indus-trialized
countries
Indus-trialized
countries
60
Ecological footprint
Log (g carbon/year)
13.49.85.8
Not analyzed
Energy use (GJ):
> 300 < 10150–300 50–150 10–50
Growth
Population growth rate N= change in population sizet = change in timeB=birth rateD=death rate
Growth
B=births during specified timeD= deaths during specified time b= annual per capita birth ratem (mortality)= per capita death rateN is population size
B bND mN
Growth
r = (per capita rate of increase)
r b – m
Nt
rN
Fig. 53-10
Number of generations
0 5 10 150
500
1,000
1,500
2,000
1.0N =dNdt
0.5N =dN
dt
Po
pu
lati
on
siz
e (N
)
Fig. 53-11
8,000
6,000
4,000
2,000
01920 1940 1960 1980
Year
Ele
ph
ant
po
pu
lati
on
1900
Table 53-3
Fig. 53-12
2,000
1,500
1,000
500
00 5 10 15
Number of generations
Po
pu
lati
on
siz
e (N
)
Exponentialgrowth
1.0N=dN
dt
1.0N=dN
dt
K = 1,500
Logistic growth1,500 – N
1,500
Fig. 53-13
1,000
800
600
400
200
00 5 10 15
Time (days)
Nu
mb
er o
f Paramecium
/mL
Nu
mb
er o
f Daphnia
/50
mL
0
30
60
90
180
150
120
0 20 40 60 80 100 120 140 160
Time (days)
(b) A Daphnia population in the lab(a) A Paramecium population in the lab