BIOS 3010: Ecology Lecture 1: Habitat: Conditions ...homepages.wmich.edu/~malcolm/BIOS3010-ecology/Lectures/L01-Bios3010.pdf · conditions - both abiotic and biotic • Today we will

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Dr. S. Malcolm BIOS 3010: Ecology Lecture 1: slide 1

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


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).

•  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.

Albrecht Dürer: The Large Turf 1503


3. Environment:!

–  But Krebs' definition does not include explicit reference to “environment.”

–  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).

Katsushika Hokusai “The great wave off Kanagawa” 1823-29.

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4. Scale and organization:!

•  These interactions can be understood at different scales of organization: –  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.

William Blake “The ancient of days” 1794


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.


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.

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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.


8. Organism response to conditions:

•  Figure 2.6: Ectothermic frog and heat exchange with its environment


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

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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.


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


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).

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13. Conditions and animal distribution:

Fig. 2.18 (3rd ed.): Amphipod crustacean distribution and salt

concentration in British rivers

Fig. 2.13 (3rd ed.): Fish distributions related to optimal

temperatures for growth


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 day-degree 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).


15. The monarch butterfly:

•  Danaus plexippus Photograph by Lincoln P. Brower

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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


17. Annual goal is to exploit milkweeds across North America:

– Monarch larva feeding on Asclepias eriocarpa in California.

Photograph by Lincoln P. Brower


18. Asclepias syriaca - the most abundant milkweed in North America:

•  The common milkweed occurs throughout the Great Lakes region

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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)


20. Abiotic constraint model of monarch voltinism: from Cockrell et al. (1993)


21. Field data from Wisconsin & Florida verify model:

•  Censuses of larvae on milkweeds in Florida and Wisconsin corroborate abiotic model.


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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 day-degrees.

from Cockrell et al. (1993)


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.



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.

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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


26. Biomes vs rainfall & temperature:

Fig. 1.15 (3rd ed.). Eight terrestrial biomes Fig. 1.18. Global environment & 5 biomes

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BIOS 3010: Ecology Lecture 1: Habitat: Conditions ...homepages.wmich.edu/~malcolm/BIOS3010-ecology/Lectures/L01-Bios3010.pdf · conditions - both abiotic and biotic • Today we will