BIOS 3010: Ecology
Lecture 1: Habitat: Conditions & constraints
•  Lecture summary:
– What is ecology?
•  Environment.
•  Scale.
– Conditions.
– Example:
•  The monarch
butterfly
Henri Rousseau, Femme se promenant dans une foret exotique 1905,
The Barnes Foundation Merion PA
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 1
2. What is Ecology?!
–  Some views of ecology:
Ecology is the scientific study of the
interactions between organisms and
their environment
(paraphrase of Ernst Haeckel, 1870).
Albrecht Dürer: The Large Turf 1503
•  The word is derived from the Greek 'Oikos' which means home.
–  Or, Ecology is the scientific study of the interactions that
determine the distribution and abundance of
organisms (C. Krebs, 1972).
•  This highlights the ultimate subject of ecology
–  where organisms occur
–  how many there are
–  what they do.
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 2
3. Environment:!
–  But Krebs' definition does not
include explicit reference to
environment.
Katsushika Hokusai The great wave off Kanagawa 1823-29.
–  However, environment is implicit in the reference to
interactions (either among organisms or between an
organism and its physical environment)
–  The environment of an organism is a description of the
factors outside the organism that influence it. These
factors are the sum of physical and chemical (abiotic)
influences plus the products of activities by other
organisms (biotic).
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 3
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4. Scale and organization:!
•  These interactions can be
understood at different scales
of organization:
William Blake The ancient of days 1794
–  Individual, population and community. Communities are
also organized into ecosystems, landscapes and biomes
–  At each level of organization we can examine the
components and the overall properties and structure. For
example for populations we can study both attributes of
individual organisms and direct characteristics of the
populations.
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 4
5. Habitat: Conditions and constraints:"
•  2 ways to consider ecology:
–  property = community - population - organism
–  component = organism - population - community
•  In both cases they are bounded by habitat
conditions - both abiotic and biotic
•  Today we will consider abiotic conditions and how
they can be constraints and cues.
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 5
6. Scale:"
•  Ecological organization from individuals through
populations, to communities and ecosystems should
immediately suggest that scale is very important.
•  On a coarse scale habitats are either terrestrial or aquatic (marine
and freshwater) but all are the product of interactions between
solar radiation and water.
•  At finer scales, habitats become microhabitats, e.g. from soil to the
spaces between soil particles or the particles themselves.
–  It is perhaps easiest to take a component view towards
understanding ecology and start with the ecology of
individuals and consider their abiotic habitat.
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 6
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7. Conditions and organism response:!
•  A condition is an abiotic environmental factor
which varies in space and time. Conditions are
not consumed or used up by organisms or made
less available to others.
•  Tolerance range for conditions
–  e.g. temperature, moisture or humidity, light, chemistry
(e.g. O2, pH, salinity), gravity, pressure, sound, fire, wind,
stream or current flow velocity, pollutants.
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 7
8. Organism response to conditions:
•  Figure 2.6: Ectothermic frog and heat exchange with its
environment
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 8
9. Variable performance across a range
of conditions:
•  Figure 2.1: (a) tolerance ranges & performance, (b) insect
temperature tolerance, (c) condition lethal at high concentration,
(d) condition lethal at both low & high concentrations
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 9
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10. Relative fitness:!
•  Performance of individuals within a population or
community is best measured by relative fitness.
–  This is the number of offspring that an individual
contributes to future generations relative to other
individuals.
–  Thus the fittest individuals are those that produce the
greatest number of descendants relative to the number of
descendants left by other individuals in the population.
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 10
11. Conditions influence the distribution &
abundance of organisms:
•  Occasional extreme
fluctuations in abiotic
conditions can be very
important and
determine the
abundance and
distribution of
individuals.
•  Fig. 2.13 of minimum
temperature and plant
family distribution
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 11
12. Temperature and plant distribution:
•  Fig. 2.14: (a) Jan 4.5°C isotherm & wild madder distribution,
(b) Regression of temperature range boundary for Tilia cordata
(solid circles),
(c) range of T. cordata defined in (b).
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 12
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13. Conditions and animal distribution:
Fig. 2.18 (3rd ed.): Amphipod
crustacean distribution and salt
concentration in British rivers
Dr. S. Malcolm
Fig. 2.13 (3rd ed.): Fish
distributions related to optimal
temperatures for growth
BIOS 3010: Ecology
Lecture 1: slide 13
14. Physiological time:
•  These distributions are the product of how
conditions influence the rates of physiological and
behavioral processes with time. This means that
conditions are integrated by individuals over time.
Perhaps the best known example of this is for daydegree accumulation as a more accurate measure
of how temperature affects organisms over time
between lower and upper temperature constraints.
–  E.g. monarch butterfly voltinism (generation distribution in
time) across its spatial distribution in North America
(slides).
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 14
15. The monarch butterfly:
•  Danaus plexippus
Dr. S. Malcolm
Photograph by Lincoln P. Brower
BIOS 3010: Ecology
Lecture 1: slide 15
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16. Monarchs
overwinter in Mexico:
•  Monarchs stay in
Mexico from October
to March in oyamel fir
forests at the tops of
mountains in the
Transvolcanic Range
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 16
17. Annual goal is to exploit
milkweeds across
North America:
–  Monarch larva
feeding on
Asclepias eriocarpa
in California.
Photograph by Lincoln P. Brower
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 17
18. Asclepias syriaca - the most
abundant milkweed in North America:
•  The common milkweed occurs throughout the Great Lakes region
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 18
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19. Continental-scale migration:
–  Spatial distribution of
primary larval host
plants in North
America (+5 locations
for temperature &
daylength constraints)
from Malcolm et al. (1993)
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 19
20. Abiotic constraint model of
monarch voltinism:
from Cockrell et al. (1993)
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 20
21. Field data from Wisconsin
& Florida verify model:
•  Censuses of larvae
on milkweeds in
Florida and
Wisconsin
corroborate abiotic
model.
from Malcolm et al. (1987)
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 21
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22. Day-degree field data show successive
brood migration:
•  Censuses of larvae
across North America
allow calculation of
dates of oviposition and
dates of adult
maturation in daydegrees.
from Cockrell et al. (1993)
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 22
23. Map of successive brood migration:
•  Field and laboratory
data allow us to reject a
hypothesis of single
sweep migration in
favor of a successive
brood migration
hypothesis.
from Malcolm et al. (1993)
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 23
24. Conditions as cues and constraints:
•  Reliable or predictable shifts in conditions can be
used as cues or constraints for various physiological
and behavioral responses by organisms, such as
migration.
•  Thus, rapidly changing abiotic conditions can be
used as cues for the predictable onset of optimum
conditions for reproduction.
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 24
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25. Large scale influences of conditions:
•  Conditions also
have profound
influences on the
distribution of
organisms at very
large scales such
as landscapes
and biomes.
Fig. 1.13. Distribution of major terrestrial biomes of the world
Dr. S. Malcolm
BIOS 3010: Ecology
Lecture 1: slide 25
26. Biomes vs rainfall & temperature:
Fig. 1.18. Global environment & 5 biomes
Dr. S. Malcolm
Fig. 1.15 (3rd ed.). Eight terrestrial biomes
BIOS 3010: Ecology
Lecture 1: slide 26
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