Life Ecology



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The coverage of the Ecology section is currently shallow. Most of the subsections are one-page summaries, which is frequently cited in course materials which use this site.

The section is organized along lines which reflect our interest in ecology as one aspect of evolutionary change. It is not intended to cover the much broader implications of the science of ecology as a whole.


Ecology: this introductory page

Biomes: major terrestrial assemblages

Biota: ecological communities as assemblages of organisms

Trophic Levels & Groups: biota as groups of organisms with similar food sources

Guilds: trophic groups as organisms with similar life styles

Radiations: sudden increases in range or diversity

Extinction: disappearance of a phylogenetic group


The study of the relationship of organisms with one another and with their environment.

This also means the distribution and abundance of organisms, and their co-evolution and even past history (paleoecology). Ecology is a multidisciplinary study, incorporating all the biological disciplines: botany, zoology, microbiology, marine biology, physiology, genetics, morphology, etc, and even non-biological fields like meteorology, geology, chemistry, and physics

Because life's interaction is like a series of boxes one within the other, ecological studies are organized in hierarchical levels.

organismal ecology, the organism's interaction with it's environmental

population ecology, factors which affect size an composition of a population of organisms.

community ecology, interactions of populations of different organisms (different species) within a particular area

ecosystem ecology, includes the community and all abiotic factors. An ecosystem regulates the flow of energy, derived ultimately from the sun, and the cycling of essential nutrients on which the lives of its constituent plants, animals, and microorganisms depend. The ecosystem is the largest unit in the study of ecology. Any selected part of the physical environment, together with the animals and plants in it, constitutes an ecosystem. An ecosystem therefore may be as large as the Earth or as small as a garden pond.

One important factor in the evolution of species is the relative ability of different individuals to survive and reproduce within a common ecosystem. An important component of the ecosystem is, of course, the other species that inhabit it. Thus, to some extent, groups of organisms co-evolve as a result of the selective pressures generated by one species on another. A faster predator may confers a selective advantage on faster members of the prey species. Tougher seeds may select for birds with stronger beaks. Accordingly, in an evolutionary context we may wish to look -- not just at species -- but at the whole evolutionary biota which characterizes a particular era or location.


Ecology - Ken's Bio-web references

Ecology: Distribution and Adaptation of Organisms - short but useful list of headings (lecture notes) - gives bare summary definition

Environmental Biology - Ecosystems - really excellent page, includes
Roles of Organisms
Energy Flow Through Ecosystems
Food Chains and Webs - Pyramids - Biological Magnification
Human vs. Natural Food Chains
BioGeoChemical Cycles - The Water Cycle - Carbon Cycle - Oxygen Cycle - Nitrogen Cycle -Phosphorous Cycle

BIODIVERSITY and CONSERVATION - A Hypertext Book by Peter J. Bryant - covers the origin, nature and value of biological diversity,  the threats to its continued existence, and approaches to preserving what is left

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photo of tree frog (top of page) from Columbia University Department of Earth and Environmental Sciences front page
checked ATW040220
original text content by M. Alan Kazlev, 14 May 2002, last modified MAK110414
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