Naturalist and the Balance of Nature

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Naturalist and the Balance of Nature
Phytosociology
Plant Community Ecologists and Succession
Animal Population Biologists and Theory
The Niche and the Rise of Competition
Anarchy and Experimental and Statistical Rigor
Spatial and Temporal Heterogeneity -
Metacommunities
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P. WERNER
MILLER
WINN
Sprugel, D. G. 1980. A "pedagogical genealogy" of
American plant ecologists. Bull. Ecol. Soc. Amer.
61197-200.
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• What is a community?
• A. Vague definition, at best
• 1. an assemblage of interacting populations
• living in a prescribed area or habitat.
• Note that they should be directly or indirectly
  interacting and that the limits are determined by
  some aspect of the habitat.
• 2. Make sure that it is defined, where
• necessary.

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Other terms similar to community Guild species
in the same community utilizing resources in the
same way, usually as competitors. Association
group of species living in the same
place. Ecosystem all the interacting parts of
the physical and biological worlds in a
prescribed area or habitat. Note that very few
studies actually follow anything close to an
entire community. Instead, they follow an
abstracted subset of the community, biased by the
question, convenience, and prior perception.
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• What is a community?
• A. Vague definition
• B. Scale and approaches
• 1. Spatial scale -- really a gradient
• Broad or large scale often used to describe
  the community within some physically defined
  area. Generally, observational approach.
• Individual or reductionist scale
  understanding the dynamics of a single population
  as influenced by its surroundings. Often
  experimental approach.
• 2. Currency
• a. Individuals or populations or species
• b. energy (Elton pyramids)

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Reading for this week Hubbell, S. P. 1979.
Tree dispersion, abundance, and diversity in a
tropical dry forest. Science 2031299-1309. Fukam
i, T., T. Martijn Bezemer, S. R. Mortimer, and W.
H. van der Putten. 2005. Species divergence and
trait convergence in experimental plant community
assembly. Ecology Letters 81283-1290.
References noted in lecture species number
stuff Abele, L. G. and K. Walters. 1979.
Marine benthic diversity a critique and
alternative explanation. Journal of Biogeography
6115-126. Gotelli, N., and R. Colwell. 2001.
Quantifying biodiversity procedures and
pitfalls in the measurement and comparison of
species richness. Ecology Letters
4379-391. Hill, M. O. Diversity and evenness
a unifying notation and its consequences.
Ecology 54427-432. James, F. C., and N. O.
Wamer. 1982. Relationships between temperate
forest bird communities and vegetation structure.
Ecology 63159-171. Sanders, H. L. 1968.
Marine benthic diversity a comparative study.
American Naturalist 102243-282. species
relative abundance stuff Fisher, R. A., A. S.
Corbet and C. B. Williams. 1943. The relation
between the number of species and the number of
individuals in a random sample of an animal
population. Journal of Animal Ecology
1242-58. MacArthur, R. H. 1957. On the
relative abundance of bird species. Proceedings
of the National Academy of Sciences USA.
43293-295. MacArthur, R. H. 1960. On the
relative abundance of species. American
Naturalist 4525-36. Preston, F. W. 1948. The
commonness and rarity of species. Ecology
29254-283. Simberloff, D., and E. O. Wilson.
1969. Experimental zoogeography of islands the
colonization of empty islands. Ecology 50278-296
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• Patterns in diversity and abundance
• A. Species number (richness)
• 1. Methodological concerns with counting
• a. what is a species?
• b. rarefaction and maximum species number
• c. species density
• 2. Application to Biogeographic patterns
• a. latitudinal gradients
• b. topographic relief
• c. Peninsulas
• d. Islands

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Ant data from Plots in Costa Rica
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• Patterns in diversity and abundance
• A. Species number (richness)
• 1. Methodological concerns with counting
• a. what is a species?
• b. rarefaction and maximum species number
• c. species density
• 2. Application to Biogeographic patterns
• a. latitudinal gradients
• b. topographic relief
• c. Peninsulas
• d. Islands

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If two equivalent areas of forests are sampled,
older growth forests with larger trees may have
fewer trees. If you looked at the number of
species per sample (e.g. hectare sampled), you
might find that second growth has a greater
number of species. However, if you look at
species per individual sampled, you wold likely
find a very different pattern. The first pattern
is deceptive because more trees were sampled in
the second growth forest. This second figure
would need to be rarified to compare the two
forests.
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Paxton, C.G.M. (1998) A cumulative species
description curve for large open water marine
animals. Journal of the Marine Biological
Association of the UK 78, 1389-1391.
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Paxton, C.G.M. (1998) A cumulative species
description curve for large open water marine
animals. Journal of the Marine Biological
Association of the UK 78, 1389-1391.
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Assumptions or Concerns with Rarefaction (1) sam
pling has to be sufficient to characterize the
actual distribution (2) the spatial distribution
of individuals within a species and among species
should be random --Michael Collins worked on this
problem for his Masters here a few years
back. (3) Samples to be compared must be
taxonomically similar (!) and drawn from the same
type of community. You can't compare insect
species numbers with African savanna
ungulates. (4) Standardized sampling techniques
must be used (problem with Sanders original
work) (5) Perhaps most important, rarefaction
should probably only be used for interpolation to
a smaller sample size, but nor for extrapolation
to a larger sample size.
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James, F. C. and N. O. Wamer. 1982. Ecology
63159-171.
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Data from a factorial experiment on aquatic
invertebrate communities, with two frequencies,
areas, and intensities of disturbance, resulting
in eight treatment combinations (n7 replicates),
along with an undisturbed control (c).
Macroinverts were collected on substrate surfaces
after 6 weeks. The first graph shows the
standard measure of response, species per sample.
The second shows rarified species
richness. Adapted from McCabe and Gotelli 2000.
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• Patterns in diversity and abundance
• A. Species number (richness)
• 1. Methodological concerns with counting
• a. what is a species?
• b. rarefaction and maximum species number
• c. species density
• 2. Application to biogeographic patterns
• a. latitudinal gradients
• b. topographic relief
• c. Peninsulas
• d. Islands

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Exceptions abound, including for ants, bats, and
pitcher plant communities.
Latitude
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Diversity in Peninsulas
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• Patterns in diversity and abundance
• A. Species number (richness)
• 1. Methodological concerns with counting
• a. what is a species?
• b. rarefaction and maximum species number
• c. species density
• 2. Application to biogeographic patterns
• a. latitudinal gradients
• b. topographic relief
• c. Peninsulas
• d. Islands

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Island Biogeography Theory (MacArthur and
Wilson)
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• Patterns in diversity and abundance
• A. Species number (richness)
• B. Relative and absolute abundance patterns
• 1. Indices of diversity
• 2. Relative abundance figures
• 3. Rank-abundance figures

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Ant data from Plots in Costa Rica
Can species number adequately describe community
patterns?
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• Diversity indices
• H' Shannon Wiener diversity (sometimes
  mislabeled as Shannon-Weaver).

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• Diversity indices
• Simpsons Reciprocal Index (sometimes not given
  as a reciprocal)
• The lowest possible value would be 1 and the
  maximum value would be s.
• H' Shannon Wiener diversity (sometimes
  mislabeled as Shannon-Weaver).
• The Brillouin index is given by
• where ni is the individual in species i and N is
  total number of individuals.
• Others include Margalef index, McIntoshs measure
  of diversity, the Berger-Parker index, Evar
  Index, and Hurlbert's PIE (probability of an
  interspecific encounter). Perhaps Simpsons is
  safest.

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Examples of Diversity Measures Bats of the Black
Volta
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• Evenness

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Clark and Warwicks taxonomic distinctness
index -- describes the average taxonomic
distance between two randomly chosen organisms
through the phylogeny of all species in the
assemblage. Where s the number of species
in the study and wij is the taxonomic path length
between species i and j.
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Now, we are left with 3 different simple measures
of communities -- species richness -- species
diversity -- species evenness
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Ant data from Plots in Costa Rica
Can species number adequately describe community
patterns? Can a diversity index adequately
describe community patterns?
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• Patterns in diversity and abundance
• A. Species number (richness)
• B. Relative and absolute abundance patterns
• 1. Indices of diversity
• 2. Relative abundance figures
• 3. Rank-abundance figures

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Corbets original data on butterflies from
Malaysia
number of species
number of individuals/species
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A different way to present the same data is a
relative abundance graph
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Measures of stability might include Stability
the ability to return to an initial point
following a perturbation. Resilience the time
require for a system to return to an initial
point following a perturbation. Resistance the
degree to which a variable (e.g. species
abundance or diversity) is changed following a
perturbation. Variability the variability
(e.g., sd, variance, or CV) exhibited in some
community measure over time.
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• III. Broad patterns in diversity and abundance
• A. Overview how can we quantify a community?
• 1. no. of organisms (N)
• 2. no. of species (species richness, S)
• 3. Diversity index (richness abundance)
• 4. Evenness
• 5. Rank abundance figures
• 6. Trophic structure
• 7. Temporal patterns (e.g., stability)
• B. Patterns in Species Number
• a. Rarefaction

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probability of having S number of species in the
community
Expected abundance ri of the ith ranked species
Hubbell, S. J. 1997. Coral Reefs 16 S9-S21.
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Hubbell, S. J. 1997. Coral Reefs 16 S9-S21.
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Hubbell, S. J. 1997. Coral Reefs 16 S9-S21.
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Murtaugh and Kollath. 1997. Ecology 781382-1387
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Murtaugh and Kollath. 1997. Ecology 781382-1387
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Gary Polis research where he attempted to
construct the full food web for a simple real
community in a California desert. This is only
part of the food web.
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Orloci, L. 1966. J. Ecology 54193-215.
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connectedness webs emphasize the feeding
relationships among organisms
energy flow webs show energy flow between
resource and consumers
functional webs links that maintain the integrity
of the community
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• Top predators -- species that get eaten by
  nothing else in the food web
• Basal species -- species that feed on nothing
  within the web (usually plants)
• Omnivores -- species that feed at more than one
  trophic level
• Trophic species -- groups of species that have
  the same predator and prey
• Cannibalism -- a cycle in which a species feeds
  upon itself
• Connectance -- number of actual interactins
  divided by the number of possible interactions
• Compartments -- suites of species with strong
  linkages among group members but weak linkages to
  other species

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Hubbell, S. J. 1997. Coral Reefs 16 S9-S21.