Biodiversity...biological diversity

[jack]

Originally Posted by Gloria

Thank you!

Things are getting very STRANGE around here, speaking of biodiversity! I saw your avatar and was about to comment when, all of a sudden, mine changed! I've heard of computer viruses before, but this one beats all!!!!!!!!!!!!!!!!!


The reason I came to this thread was to thank you, Gloria, for creating this very, very precious string of knowledge. There's a course contained in this thread, and much of it is not only highly informative, but also very readable and fascinating.

Ahhh, I feel I'm growing hair on my palms and I've suddenly a stiff neck...

[Gloria]

Canadian Biodiversity: Introduction

What is biodiversity?
Biological diversity, or biodiversity, is a term that is becoming more and more heard, yet few people really know what it is. There are many definitions for it (see the first chapter of Gaston (1996) for a long list), but there are two that will be given here. The first is from the Convention on Biological Diversity, also known as the Rio Summit: "'Biological diversity' means the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems." The Canadian Biodiversity Strategy defines it as "…the variety of species and ecosystems on Earth and the ecological processes of which they are a part". It is often simply used as a catch-all term for nature. No definition is perfect; as with life itself, it's a bit nebulous and there are always exceptions.

Canadian Biodiversity: Theory

This section consists of four parts. The first introduces the three levels of biodiversity that are studied, the second looks at how diversity can be gained or lost, the third examines the composition of diversity in more depth, and the fourth looks at how biodiversity affects the functioning of ecosystems. Each of these only scrapes the surface of the research available; the References section of this site lists more detailed resources.

[Gloria]

A bit more from Biological Theory

Canadian Biodiversity: Theory

Does Diversity lead to Stability?
Although it is a key question, the relationship between diversity and stability is still being resolved. As with many topics in biodiversity, there are different ways of expressing stability. One way is to define it as the ability of a system to return to its original state after being disturbed, so how quickly it can return and how large a disturbance it can return from are key variables. Another definition is how resistant to change the system is in the first place. No matter what the definition used, however, there are definite trends that appear.
If either the redundancy or rivet theories (see above) are correct, then more species means more stability. Current consensus is that greater diversity does lead to greater stability, for three general reasons:

Insurance Effect:
Different species do better under different conditions. As the number of species increases, the range of conditions that at least some species do well in also increases. When perturbations do occur, it's more likely that some of the species present will be able to do well, and these species will protect the community as a whole.

Averaging Effect:
Stability is measured as variability relative to community abundance. As diversity increases, the value of the variability will naturally decrease. One problem with this is that the impact of additional species can be confused with the effect of larger numbers of individuals (see Doak et al. 1998 and Tilman et al. 1998 for examples of this debate).

Negative Covariance Effect:
Since species are competing for resources such as space and food, any gains that one species makes will be to some extent at the expense of the other. This means that as a species does more poorly its competitors will do better. The result is that disturbances aren't as detrimental to the entire system as they could be, as the losses in one species are offset by the gains of another.

[Gloria]

Here is a link with a video and text on biodiversity that you will find interesting.

The Habitable Planet
www.learner.com
Harvard Smithsonian

video- 28.25 minutes...
The Habitable Planet Unit 9 - Biodiversity Decline // Online Textbook

http://www.learner.org/courses/envsci/support/guide_unit9.pdf

The Habitable Planet Unit 9 - Biodiversity Decline - Glossary


Unit Overview
The Habitable Planet Unit 9 - Biodiversity Decline // Online Textbook

"Just as scientists have discovered through ever more powerful telescopes that stars number in the billions, we are learning through DNA technologies that the number of marine organisms invisible to the eye exceeds all expectations and their diversity is much greater than we could have imagined."
Mitchell L. Sogin, Marine Biological Laboratory (Woods Hole, MA)

To determine whether a species is endangered or might become so, scientists collect data to answer questions including:
•Is the population growing, shrinking, or at a steady state, and why? How completely does it occupy its habitat? How is it being affected by competitors, parasites, harvesting, and hybridization with other species?
•Is the species' geographic range expanding or contracting? Is it fragmented into small areas? How many mature (breeding) individuals exist, and where are they located? How are external impacts on its habitat, such as pollution and development, expected to affect the species' range? How much habitat is needed to support a target population level?
•If the population is very small, is it expected to grow or contract? Will the number of mature individuals remain steady or fluctuate? Can they reach each other to breed?
•How biologically distinct is the species from other closely related organisms? Does the target group consist of one single species, or should it be reclassified as several distinct species?
•If a species is recovering from endangered status, what population size and distribution indicate that it no longer needs special protection?

Recently scientists have successfully cloned several endangered varieties of cows and sheep, and some biologists advocate creating DNA libraries of genetic material from other endangered species. Others counter that cloning fails to address the root causes of the problem, including habitat loss and over-harvesting.

[Gloria]

http://www.icternodisola.it/public/uploaded/manuale%20della%20qual/lim%20Scuola%20Secondaria/percorso%20economico-soc/letter/The%20closing%20circle%20Commoner.pdf

Life is a very powerful form of chemistry,
which, once on the earth, rapidly changed its surface.
Every living thing is intimately dependent on its physical and chemical surroundings, so that as these changed, new forms of life suited to new surroundings could emerge. Life begets life, so that once new forms appeared in a favorable environment, they could proliferate and spread until they occupied every suitable environmental niche within physical reach.

Every living thing is dependent on many others, either indirectly through the
physical and chemical features of the environment or directly for food or a sheltering place.

Within every living thing on the earth, indeed within each of its individual cells, is contained another network-on its own scale, as complex as the environmental system-made up of numerous, intricate molecules, elaborately interconnected by chemical reactions, on which the life-properties of the whole organism depend.

[Gloria]

Originally Posted by Gloria

I can not seem to embed this video but the link will take you to a site where it can be watched.
This lecture starts with a brief discussion of human population and biodiversity. Then it covers much of interest about biodiversity and why it is important.


Why So Many Species? The Factors Affecting Biodiversity | Yale Biology Lecture


Yale / Biology
Why So Many Species? The Factors Affecting Biodiversity
Taught By Stephen C Stearns | Evolution, Ecology and Behavior Lecture 31 of 36

Lecture 31 - Why So Many Species? The Factors Affecting Biodiversity - VideoLectures.NET

The link on post #5 is no longer working. That lecture seems important enough to keep within this thread so I took the time to relocate. Luckily the name of the professor and the lecture was included in the post making it easy to find. I do not have access to edit but maybe curiosity will bring viewers to this.