Outline
1. Review of scale and hierarchy in biological
organization (handout from Monday)
2. Introduction to autecology (ecology of individual)
3. Variation within species; subspecies (examples)
4. Tolerance and limiting factors
5. Niche
6. Introduction to physiological processes and
abiotic factors
Reading
1. Related to this lecture
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Kolb and Sperry 1999. Ecology 80(7):2373-2384
Shahba et al. 2003. Crop Science 43:2142-2147
Text Chapter 3
2. Related to next lectures
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Monday – Text Chapters 18 & 19
Wednesday – Text Chapters 14 & 15
3. Lab discussion (Tues Feb 3)
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Bestelmeyer et al. 2003. Ecological Applications
13(6):1750-1761.
Hull et al. 2002. Conservation Ecology 6(2):#12.
If interested: there are two responses to Hull et al. in
Conservation Ecology 7(1).
Organization
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Organisms influenced by 4 types of relationships (see
handout from Monday)
1. Physiological (grp 1 on diagram)
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Increasing complexity, emergent properties
2. Phylogenetic (grp 2 on diagram)
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Taxonomic/evolutionary
Partitioning of genetic descent
3. “Coevolutionary”(grp 3 on diagram)
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Deme, Population, Community (definitions)
Organisms affect each other’s reproductive success
Traditional “synecology”
4. Matter-energy (grp 4 on diagram)
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Ecosystems ecology
Hierarchy and scale
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With increasing spatial scale, temporal scale of
processes also tends to increase
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Ecologists study across spatial and temporal scales
Observation scale may affect both our interpretation of
ecosystem interactions and our management decisions
Organizational level: individual
or species
• Autecology = Physiological ecology. Ecology of
individual organisms
– Environment – rainfall, temperature, light, biotic
interactions
– Resource acquisition – nutrient uptake, photosynthesis
– Allocation of resources to growth and reproduction
– Effects of environmental changes, stresses
Variation in species (ch. 3)
• Substantial variation within taxonomic species:
heritable, adaptive characters (Turesson)
• e.g. hawkweed in Sweden (ecotypes):
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Three habitats (woodland, field, dune)
Differ in traits: habit, leave shape, dormancy
Traits maintained when grown in greenhouse
All groups interfertile
• Similar experiment in California (Clausen et al
1940).
Variation in species
• “common gardens” at Stanford, Mather (Midelevation Sierra Nevada), and Timberline (3000m
elevation)
• Grew 60 different species collected from a range
of sites from coast to eastern slopes
• Potentilla glandulosa ecotypes (subspecies) differ
in growth form, frost and disease and survival in
different gardens (see textbook Ch. 3)
Variation in species
• Other experiments show two ecotypic extremes
with gradient of variation between them (ecocline)
• Current usage of “ecotype” = population, not
group of populations. Populations have genetic
and phenotypic differences, but act as individuals.
Subspecies or different
species?
• What is a subspecies?
– Regional variants in a species; morphological
differentiation (not great enough to be
considered separate species) occurs in relation
to geographic, ecological or temporal
separation from other subspecies.
Subspecies or different
species?
• Pinus contorta – three subspecies. Contorta not fire
adapted (shore pine). Latifolia (rocky mountain lodgepole)
fire dependent; dominance in landscape and proportion
serotinous cones related to fire frequency. Murrayana
(sierra lodgepole) fire sensitive, but early after-fire
coloniser. Not serotinous.
• Pinus ponderosa and Pinus jeffreyi. Differ in resin
chemistry and habitat (elevation). Are sympatric at midelevation, and hybridize. Different enough to be species.
• Ord’s kangaroo rat in Alberta – hibernate. Don’t hibernate
anywhere else. Is this peripheral population worth saving
as a distinct taxon?
Physiological Differences
• Kolb & Sperry (1999) – drought adaptation between
subspecies of sagebrush.
• Three subspecies: wyomingensis (low elevation, arid)
tridentata (mid elevation, less arid)
vaseyana (high elevation, mesic)
• Subspecies differ in stature, inflorescence, and ploidy.
Differences maintained in common garden (genetic).
• Differ in physiology: pressures at which xylem cavitates
and leaves wilt differ among subspecies. Differences
maintained in common garden.
Variation in species
• Additional examples:
– Saltgrass frost tolerance: Crop Science 43:2142-2147
– Norway Spruce altitudinal ecotypes: Functional
Ecology 12:573-590
– Sagebrush subspecies: Ecology 80(7):2373-2384
• Liebig’s “Law of the Minimum”: crop yield
dependent on nutrient most limited in amount.
– More general: growth/distribution of species
depends on critical environmental factor.
– Limitations: upper limit to tolerance
factors interact
• Shelford’s “Law of Tolerance”: minimum,
maximum, and optimum values for all
environmental factors
Niche concept = law of tolerance
Expanded law of tolerance (Good, 1953):
• Plant species exist and reproduce in a definite range
of conditions (climatic, edaphic, biotic)
Niche concept = law of tolerance
Expanded law of tolerance (Good, 1953):
• Plant species exist and reproduce in a definite range
of conditions (climatic, edaphic, biotic)
• Tolerance ranges related to physiology
Niche concept = law of tolerance
Expanded law of tolerance (Good, 1953):
• Plant species exist and reproduce in a definite range
of conditions (climatic, edaphic, biotic)
• Tolerance ranges related to physiology
• Habitat is sum total of tolerance for all environmental
factors (fundamental niche – Hutchinson 1957)
Niche concept = law of tolerance
Expanded law of tolerance (Good, 1953):
• Plant species exist and reproduce in a definite range
of conditions (climatic, edaphic, biotic)
• Tolerance ranges related to physiology
• Habitat is sum total of tolerance for all environmental
factors (fundamental niche – Hutchinson 1957)
• May shift depending on levels of other factors (e.g.
N and water)
Niche concept = law of tolerance
Expanded law of tolerance (Good, 1953):
• Plant species exist and reproduce in a definite range
of conditions (climatic, edaphic, biotic)
• Tolerance ranges related to physiology
• Habitat is sum total of tolerance for all environmental
factors (fundamental niche – Hutchinson 1957)
• May shift depending on levels of other factors (e.g.
N and water)
• May vary as a function of life stage (e.g. seedlings
narrow range, adults broad)
Niche concept = law of tolerance
Expanded law of tolerance (Good, 1953):
• Plant species exist and reproduce in a definite range
of conditions (climatic, edaphic, biotic)
• Tolerance ranges related to physiology
• Habitat is sum total of tolerance for all environmental
factors (fundamental niche – Hutchinson 1957)
• May shift depending on levels of other factors (e.g.
N and water)
• May vary as a function of life stage (e.g. seedlings
narrow range, adults broad)
• Natural distribution not always equal to optimum
(biotic interactions affect – realized niche)