Community Ecology
This presentation is the property of its rightful owner.
Sponsored Links
1 / 47

Community Ecology PowerPoint PPT Presentation


  • 84 Views
  • Uploaded on
  • Presentation posted in: General

Community Ecology. Geography. Resources. Phylogeny. Community. Community – collection of species that occur at the same place & time, circumscribed by natural ( e.g ., serpentine soil), arbitrary, or artificial ( e.g ., 1-m 2 quadrat) boundaries. Many prefer a more

Download Presentation

Community Ecology

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Community ecology

Community Ecology


Community ecology

Geography

Resources

Phylogeny

Community

Community – collection of species that occur at the same place & time, circumscribed by natural (e.g., serpentine soil), arbitrary, or artificial (e.g.,

1-m2 quadrat) boundaries

Many prefer a more

restrictive definition

in which species must interact to be included, e.g., Whittaker (1975)

Redrawn from Fauth et al. (1996)


Community ecology

Geography

Resources

Phylogeny

Community

Taxon – phylogenetically related group of species; a clade

E.g., Mammalian Order Rodentia

Taxon

Redrawn from Fauth et al. (1996)


Community ecology

Geography

Resources

Phylogeny

Guild

Community

Guild – a group of species “without regard for taxonomic position” that “exploit the same class of environmental resources in a similar way” (Root 1967)

E.g., granivores

Taxon

Redrawn from Fauth et al. (1996)


Community ecology

Geography

Resources

Phylogeny

Local

guild

Guild

Community

Local guild – a group of species that share a common resource and occur in the same community (Root 1967)

E.g., Sonoran Desert granivores

Taxon

Redrawn from Fauth et al. (1996)


Community ecology

Geography

Resources

Phylogeny

Local

guild

Guild

Community

Assemblage

Assemblage – a group of phylogenetically related species within a community

Taxon

Redrawn from Fauth et al. (1996)


Community ecology

Geography

Resources

Phylogeny

Local

guild

Guild

Community

Assemblage

Assemblage – a group of phylogenetically related species within a community

a.k.a. “Taxocene” (Hutchinson 1967)

E.g., Sonoran Desert rodents

Taxon

Redrawn from Fauth et al. (1996)


Community ecology

Geography

Resources

Phylogeny

Local

guild

Guild

Community

Ensemble

Assemblage

Ensemble – a phylogenetically bounded group of species that use a similar set of resources within a community

E.g., Sonoran Desert granivorous rodents

Taxon

Redrawn from Fauth et al. (1996)


Community ecology

Geography

Resources

Phylogeny

Local

guild

Guild

Community

Ensemble

Assemblage

E.g.,

granivorous rodents,

pond-breeding salamanders…

Taxon

In this course any collection of two or

more species is

“fair game” for close

scrutiny

Redrawn from Fauth et al. (1996)


Community ecology

Robert H. MacArthur’s definition of Community

“Any set of organisms currently living near each other and

about which it is interesting to talk” (MacArthur 1971)

Painting by D. Kaspari for M. Kaspari (2008) – anniversary reflection on MacArthur (1958)


Community ecology

Community Ecology

Some historic landmarks

Community Ecology has matured from purely descriptive studies (i.e., description & analysis of patterns) to mechanistic studies (i.e., investigations into processes) that aim to improve our explanatory

& predictive abilities

In any case, the tradition of good Natural History

is not ignored by the best modern practitioners

“Though I do not believe that a plant will spring up where no seed has been, I have great faith in a seed. Convince me that you have a seed there, and I am prepared to expect wonders.”

(H. D. Thoreau ~1860)


Community ecology

Community Ecology

Some historic landmarks

Charles Darwin (1809 - 1882)

Not the first “ecologist,” but clearly recognized the importance of organisms’ interactions(intraspecific, interspecific & with their abiotic environments) for evolution by natural selection

Ernst Haeckel (1834 - 1919) coined “oekologie”

for the study of Darwin’s multifaceted “struggle for existence”

Photo from WikiMedia Commons


Community ecology

Community Ecology

Some historic landmarks

Charles Darwin (1809 - 1882)

On biotic interactions:

“Hence it is quite credible that the presence of a feline animal in large numbers in a district might determine, through the intervention first of mice and then of bees, the frequency of certain flowers in that district!” (Darwin 1859)

Photo from WikiMedia Commons


Community ecology

Community Ecology

Some historic landmarks

Charles Darwin (1809 - 1882)

On abiotic processes, e.g., abiotic disturbance:

“If turf which has long been mown… be let to grow, the most vigorous plants gradually kill the less vigorous, though fully grown plants; thus out of 20 species growing on a little plot of mown turf (3 feet by 4 feet) nine species perished from the other species being allowed to grow up freely…” (Darwin 1859)

Photo from WikiMedia Commons


Community ecology

Community Ecology

Some historic landmarks

Ellen Swallow Richards (1842 - 1911)

Chemist who probably “created and taught the first ecology curriculum” in the U.S. and may have introduced the term “ecology” into the English language (from Ernst Haeckel’s “oekologie”)

Photo from WikiMedia Commons; for further details see Damschen et al. (2005)


Community ecology

Community Ecology

Some historic landmarks

Stephen Forbes (1844 - 1930)

One of the earliest ecologists to examine multiple, cross-trophic level interactions simultaneously within an explicitly evolutionary framework

Wondered how in spite of a constant “struggle for existence” some balance is nevertheless maintained in ecosystems (see: The lake as a microcosm, 1887)

Photo from http://home.grics.net...


Community ecology

Community Ecology

Some historic landmarks

Henry Cowles (1869 - 1939)

A pioneer of “dynamic ecology,” especially on the sand dunes of Lake Michigan

Photo of Cowles from http://oz.plymouth.edu...

Photo of Lake Michigan sand dune from http://ebeltz.net...


Community ecology

Community Ecology

Some historic landmarks

In the grand traditions of Alexander von Humboldt (1769 - 1859; the “father of biogeography”) &Alfred Russel Wallace (1823 - 1913)…

Clinton Hart Merriam (1855 - 1942)also noticed that geographic changes in physical conditions often coincide with changes in biota

Merriam devised Empirical Life Zones (similar biotic changes with increased elevation or latitude)


Community ecology

Community Ecology

Some historic landmarks

Leslie Holdridge (1907 - 1999) – devised

Theoretical Life Zones (1947)

Image from WikiMedia Commons


Community ecology

Community Ecology

Some historic landmarks

Clements vs. Gleason (1920s & 1930s)

Frederic Clements (1874 - 1945) – thought succession always reached a predictable climax community; viewed communities metaphorically as “superorganisms”

Henry Gleason (1882 - 1975) – proposed the “individualistic concept” of communities; discrete populations whose patterns of distribution and abundance give rise to communities as epiphenomena


Community ecology

Community Ecology

Some historic landmarks

Robert H. Whittaker (1869 - 1939) His gradient analyses helped end the

Clements-Gleason debate

Photo from WikiMedia Commons; figures from http://ecology.botany.ufl.edu...


Community ecology

Community Ecology

Some historic landmarks

We continue to need good descriptions of patterns, often supported by sound, quantitative techniques

E.g., Bray & Curtis (1957) introduced ordination methods to define plant communities in Wisconsin

See: The Ordination Web Page (http://ordination.okstate.edu)

E.g., the Ecological Society of America, The Nature Conservancy, the U.S. Geological Survey, the U.S. National Park Service & others collaborate to continue to refine the National Vegetation Classification Standard (NVCS)


Community ecology

Community Ecology

Some historic landmarks

Margaret Davis (b. 1931)Her paleo-ecological perspective hashelped increase awareness of historical contingencies

Photo of Davis from U. Minnesota; photo of pollen from http://www.gl.rhbnc.ac.uk...


Community ecology

Community Ecology

Some historic landmarks

Joseph H. Connell (b. 1923)

Heralded as milestones in ecology, his studies demonstrated the utility of field experiments for answering ecological questions; empirically assessed multiple hypotheses for intertidal zonation

The concept of equifinality was formalized by Ludwig von Bertalanffy (1968; founder of General Systems Theory)– multiple hypotheses or mechanisms can equally explain or generate the same pattern

Photo from UCSB


Community ecology

Community Ecology

Some historic landmarks

Joseph H. Connell (b. 1923)

Observations:

Balanus balanoides – Larger barnacle, generally found lower in the intertidal

Chthamalus stellatus – Smaller barnacle, generally found higher in the intertidal

Photo from UCSB


Community ecology

Community Ecology

Some historic landmarks

Joseph H. Connell (b. 1923)

Photo from UCSB


Community ecology

Community Ecology

Some historic landmarks

Joseph H. Connell (b. 1923)

Observations:

Balanus balanoides – Larger barnacle, generally found lower in the intertidal

Chthamalus stellatus – Smaller barnacle, generally found higher in the intertidal

Why might these patterns exist?

Photo from UCSB


Community ecology

Community Ecology

Some historic landmarks

Joseph H. Connell (b. 1923)

Hypotheses:

Differentialphysiological tolerances to desiccation and submersion

Interspecific competition

Predation (e.g., Thais lapillus is a predator of Balanus balanoides)

Photo from UCSB


Community ecology

Community Ecology

Some historic landmarks

Joseph H. Connell (b. 1923)

Exclusion experiments, results & conclusions:

The absence of competitors & predators produced no change in upper level of distributions

For Chthamalus, removing Balanus increased downslope survivorship & distribution

For Balanus, removing Thais increased downslope survivorship & distribution

Photo from UCSB


Community ecology

Community Ecology

Some historic landmarks

Joseph H. Connell (b. 1923)

Photo from UCSB; figure from Connell (1961; one of Connell’s 5 Science Citation Classics)


Community ecology

Community Ecology

Some historic landmarks

Robert H. MacArthur (1930 - 1972)

More than most of his predecessors, MacArthur demonstrated the utility of simplifying assumptions combined with mathematical rigor for exploring ecological problems

Criticisms: oversimplification; over-emphasized competition & equilibria

Photo from Wikipedia


Community ecology

Community Ecology

Some historic landmarks

G. Evelyn Hutchinson (1903 - 1991)

Conceived of fundamental vs. realized

nichespaces or hyper-volumes

“Ecologists use the metaphor of the ‘ecological niche’ to express the idea that plant and animal species play certain roles in the ecological community” (Kingsland 2005, pg. 1)

Photo from Yale Peabody Archives


Community ecology

Community Ecology

Some historic landmarks

G. Evelyn Hutchinson

E.g., Hutchinsonian ratios

A ratio of ~ 1.3 in size

occurs between pairs of

coexisting species,

possibly owing to inter-

specific competition

The idea & disagreement over how to

test it helped motivate the development

of null models in ecology

Figure from Gotelli & Graves (1996, pg. x)


Community ecology

Community Ecology

Some historic landmarks

“Null hypotheses [models] entertain the possibility that nothing has happened…” (Strong 1980)

“A null model is a pattern-generating model that is based on randomization of ecological data or random sampling from a known or imagined distribution. The null model is designed with respect to some ecological or evolutionaryprocess of interest. Certain elements of the data are held constant, and others are allowed to vary stochastically to create new assemblage patterns. The randomization is designed to produce a pattern that would be expected in the absence of a particular ecological mechanism…” (Gotelli & Graves 1996)


Community ecology

Community Ecology

Some historic landmarks

Stephen P. Hubbell (b. 1942)

Neutral theory…

asks how well community-level patterns conform to predictions under the simplifying assumption that all individuals are equal (in terms of probability of recruiting, dying, and replacing themselves through reproduction)

“When we look at the plants and bushes clothing an entangled bank, we are tempted to attribute their proportional numbers and kinds to what we call chance. But how false a view is this!”

(C. Darwin 1859)

Photo from UCLA


Community ecology

Community Ecology

Patterns & Processes

Patterns – any observable properties of the natural world, often expressed as variable quantities

or distributions (since variation characterizes

every level of biological organization)

Processes – the causal mechanisms

that give rise to the patterns

See also Watt (1947) Pattern and process in the plant community – J. Ecology


Community ecology

Processes that determine local community composition

(most of which produce community structure that

wouldn’t be predicted by null models)

Redrawn from Morin (1999, pg. 27)


Community ecology

Processes that determine local community composition

(most of which produce community structure that

wouldn’t be predicted by null models)

Community A

Community B

What relative contributions do the various processes make (and have made) towards maintaining (and originally creating) differences between communities A and B?

Redrawn from Morin (1999, pg. 27)


Community ecology

Processes that determine local community composition

(most of which produce community structure that

wouldn’t be predicted by null models)

From HilleRisLambers et al. (2012, pg. 228)


Community ecology

Parallels between Community Ecology & Population Genetics

These affect biological variants, i.e., alleles or species

Processes

Drift

Migration

Selection

Abiotic environment

Biotic interactions

(e.g., competition, predation, etc.)

Speciation

… and extinction (owing to drift & selection)

Primary patterns(across space & time)

Emergent patterns

Productivity

Species diversity

Stability

Species composition

(identity & traits)

Food-web connectance

Etc.

Species abundances

Redrawn from Vellend & Orrock (2010)


Community ecology

Parallels between Community Ecology & Population Genetics

Global community

Drift

Selection

Speciation

Migration

Migration

Regional community

Drift

Selection

Speciation

Local

community

Migration

Migration

Drift

Selection

Speciation

Redrawn from Vellend & Orrock (2010)


Community ecology

Parallels between Community Ecology & Population Genetics

Global community

Drift

Selection

Speciation

Migration

Migration

Regional community

Drift

Selection

Speciation

Migration

Migration

Local

community A

Local

community B

Drift

Drift

Selection

Selection

Speciation

Speciation

Redrawn from Vellend & Orrock (2010)


Community ecology

Parallels between Community Ecology & Evolutionary Theory

Global community

“the central narrative of evolutionary theory is that

variation originates from random mutation and

then natural selection in a local setting acts upon this variation to produce organic diversity”

In a parallel fashion the “formational theory of communnity ecology” could be: “local interactions act upon the species arriving at the community’s boundary to produce a diversity of communities”

Supply-side

ecology

Supply-side

ecology

Local

community A

Local

community B

Local interactions

Local interactions

Roughgarden (2009)


Community ecology

+

-

0

A

B

A

B

A

B

-

-

-

Antagonism

(Predation/Parasitism)

Amensalism

Competition

-

+

0

A

B

A

B

A

B

0

0

0

Neutralism

(No interaction)

Amensalism

Commensalism

-

+

0

A

B

A

B

A

B

+

+

+

Antagonism

(Predation/Parasitism)

Mutualism

Commensalism

Pair-wise species interactions

(owing to acquisition or assimilation of resources, etc.)

Influence of species A

- (negative)

0 (neutral/null)

+ (positive)

-

Influence of Species B

0

+

Redrawn from Abrahamson (1989); Morin (1999, pg. 21)


Community ecology

Pair-wise species interactions

Interactions are often asymmetric, even when the sign of the interaction is the same in both directions (e.g., obligate for one organism, but facultative for the other)

Species B

+/+

_/+

Species A

_/_

+/_


Community ecology

Laws in Community Ecology

In any case, the laws of physics & chemistry apply (e.g., thermodynamics & stoichiometry)

Are there “laws” specific to Ecology,

and Community Ecology in particular?


Community ecology

To separate Ecology and Evolution into separate

disciplines is somewhat artificial

…just as is completely separating Community Ecology

from other related sub-disciplines

Nothing in biology makes sense except in the light of evolution (T. Dobzhansky 1973)

All organisms interact with other organisms, both conspecific and heterospecific, and their environments; i.e., the evolutionary play takes place within an ecological theater

(G. E. Hutchinson 1965)

Ecologists and evolutionary biologists must recognize and embrace the complexity of natural ecosystems to understand them, and their components, much as Zen masters recognize and embrace the interconnectedness of the universe

(D. P. Barash 1973)


  • Login