• If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • You already know Dokkio is an AI-powered assistant to organize & manage your digital files & messages. Very soon, Dokkio will support Outlook as well as One Drive. Check it out today!



Page history last edited by gerryc 12 years, 6 months ago

E1. Populations are the units of the community.


Student Outcome: E1.1

Know that a community is made up of localised, interacting populations.


  • Populations:


Ecologists are interested in the interactions between organisms. Since it takes more than one organism to have an interaction, the basic unit of ecology is the population. A population is a group of individuals that interbreed and share the same gene pool. While every individual in a species has the capacity to interbreed with any other individual, a population is a group of organisms that exist in the same specific geographic locale and actually are interbreeding. All the killer whales in the ocean make up a species, but only the killer whales that actually live and migrate together—only the killer whales that actually interbreed—make up a specific population.


Aimed at primary school students but....what can you do.


  • Communities


Just as individuals live within a population, populations exist within communities. A community refers to all the populations that interact with each other in a given environment and geographical area. The specific role and way of life of each population is called a niche. When populations have overlapping niches, a variety of types of interaction may occur, including competition, symbiosis, predation, and other food relationships. Communities are shaped over time by ecological succession.


Communities of Bacteria on your body!

Do you know that although we have over a trillion body cells, we carry or have inside us ten times that amount of bacteria!

This video is about the incredible range of bacteria on your body - not many pictures but interesting.


Read here about the incredible diversity of life on your skin!


What about this! Pictures, I repeat pictures of what can grow in your 'belly-button biome'.


Wow. Even more information here about bacterial populations in your body! Who would have thunk it.


Sorry, this has become a reoccurring theme. The skin bacteria of six individuals have been studied and compared.  Read on!


Source: http://www.sparknotes.com/testprep/books/sat2/biology/chapter10section2.rhtml


Student Outcome: E1.2

Explain that populations in a community consist of different species, and know the characteristics that define a species.


Definition of a species

The most famous, and the one that most biologists use today, is the biological species concept, which states that species are groups of actually or potentially interbreeding populations, which are reproductively isolated from other such groups. In other words, speciation is the evolution of reproductive isolation between two groups. Operationally, this definition works well for most animals. However, it has limitations: it does not always work with plants, and it cannot be applied to extinct species (e.g. fossils) or asexually reproducing species (e.g. bacteria).


Source: http://www.evoled.org/lessons/speciation.htm



Student Outcome: E1.3

Give examples of mechanisms that maintain reproductive isolation of species in a community.


All species concepts that address populations in physical contact require mechanisms of isolation to prevent the fusion of gene pools. These mechanisms can occur at several stages during the process of interbreeding. Individuals from different populations can mate, but their hybrid offspring can have low fitness (postzygotic incompatibilities). Alternatively, mating could occur, but there could be incompatibilities, such as between sperm and eggs, that are expressed before hybrid zygotes are even produced (postmating, prezygotic incompatibilities). Both of these categories are forms of postmating isolation between species. Finally, individuals from the different populations can be prevented from mating in the first place (premating isolation). One of the most interesting ways that this can happen is through mate choice; females can evolve to choose not to mate with males of a different population.


Source: http://www.bio.unc.edu/faculty/servedio/Lab/index.htm


Not sure this is going to be useful to you, but it is an example of how new species are formed.

YouTube plugin error


Go here for some flashcards to help you with some key definitions. Particularly useful if ecology is a new area of study for you.


Comments (0)

You don't have permission to comment on this page.