Ecology links

 Biology by Campbell and Reese:  Unit 8

Topics listed in the International Biology Olympiad Guide
Individual Organisms :       Unitary and modular organisms
Population:  structure/dynamics: exponential and logistic growth and carrying capacity / regulation and metapopulation dynamics
Biotic Communities:  species reach and diversity/ niche, competition and exclusion principle / interspecific interaction/ community/ terrestrial and aquatic biomes
Ecosystems:  trophic structure and webs / energy flow / productivity / biosphere and man / pollution / in situ conservation / ex situ conservation
General references which point to many more specific links: on the first section  if you cannot access directly from the link above.
This is an international site with mirrors in other languages.  It is so huge as to be slightly overwhelming.  However, it is alphabetical, well indexed, and has a separate search engine.  Recommended for those questions with excellent keywords or research on a particular topic.
An Encyclopedia of links listed alphabetically.  While no link is required for USABO, it is a good starting place for any teacher or student seeking additional information on a specific ecology topic.  It has not been updated since 2003, so many links are no longer valid.  The USA professional organization links are still functional.
Unitary and Modular Organisms:
This terminology is not indexed by Campbell but it is used at the internationals. 
Modular organisms are, by definition, composed of repeated building blocks (modules, ramets, polyps, and others), which are derived asexually by vegetative (iterative) growth. In many cases, growth of the clone or colony is indeterminate, i.e., even the largest individuals continue to grow until they are injured or killed . However, longevities of modular animals and plants vary greatly, from a few months (e.g., many temperate hydroids, bryozoans, some tunicates and weedy plants) to several centuries (e.g., some corals and clonal trees).
The body of unitary organisms is a determinate structure consisting usually of a strictly defined number of parts (such as legs or wings) established only during embryogenesis. Mobile animals are examples of age-structured populations of mobile, unitary (solitary) animals.
Review papers available on the internet:  NO need to read beyond the introductions.
A few Specific References
Generally OK but the choice of a Purvis illustrations to show the relationship between carrying capacity (k) and population density over time was not a good choice by the author. The illustration would tend to give the student the impression that population density cannot exceed k, or if so by a very small amount. In fact population density over time will oscillate around the carrying capacity of the habitat. It can go above k but of course cannot be maintained at that level, thus crashes with the population typically falling well below k, Population density will gradually build back up to around k and may remain fairly stable for a time, but invariably it will again exceed k, and so the process repeats itself over and over.  In this interactive lesson, you’ll learn more about two widely used population growth models: exponential and logistic.   Outline from an undergraduate Ecology Course.  Basic review of Campbell.
Competitive Exclusion Principle  Read the Introduction ONLY.  You are not responsible for the math or equations. Basic Food chain and pyramid.  

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