IB 362Marine BiologyBiodiversity and Conservation

What is BIODIVERSITY?

Why is it important?

Biodiversity – term coined in 1980’s to refer to

Biological diversity, a concept already developed in the 1950’s

Lots of definitions, but perhaps simplest one is

“Species richness and relative species abundance in space and time”

Hubbell (2001)

Note that this definition is NOT limited to species richness,

or simply the number of species in an area or sample.

It also incorporates the notion of the relative EVENNESS of

distribution of the abundance of organisms

The idea here is this: If you go out into a corn field and see nothing

but corn and a few blackbirds, and very many of them, you will

conclude that this environment is not very diverse, even if there are

a number of rare and less obvious animals and plants there. On the

other hand, if you go into a tropical forest and see that

almost every other tree or insect you look at is different, you will

conclude that this environment IS diverse. IT is NOT just that there are

more species there, but also that you keep seeing new ones each time

you sample the forest.

Species richness

Species accumulation curve

Relative abundance of species:

RARITY and COMMONNESS

If one takes a sample of individuals (or encounters them in the field)

How often does one encounter species A versus species B?

Potential problems:

Biases in sampling methods

Variation in space and time

OK, so far we have been talking about describing diversity in one area

This is what we refer to as alpha diversity

How much does the composition of species differ between areas?

This we refer to as beta diversity or faunal turnover

And how does this add up to the global diversity of organisms?

This we refer to as gamma diversity

There are other ways to categorize diversity too, that could be useful.

For instance, ecological diversity (diversity of different ecological roles)

Phylogenetic diversity (diversity of major organismal lineages)

Interaction diversity (diversity of interconnected interactions

in food webs)

How do these different types of diversity relate to conservation?

Well, just think about these questions:

Chris mentioned earlier that tropical rain forests contain more

different species than coral reefs, but that coral reefs contain

more MAJOR KINDS of organisms. Does that add to the value

of coral reefs?

What if the only representative of a major group happens to be

found in an area you are considering preserving…?

Another question:

Let’s say you have four Caribbean coral reefs already set side as preserves,

and two mangrove forests and 3 rocky temperate shorelines. You have the

opportunity to purchase and set aside two more areas, but what you have available

are:

3 more Caribbean coral reefs

2 mangrove forests

2 rocky temperate shorelines

2 deep-sea vents

2 seagrass estuaries

2 South Pacific lagoons

What do you choose?