Ecosystems &Biodiversity When is it a species ? 1

Practical 2 When is it a Species? Taxonomy and Keeping

Track of Biological Diversity

Reading

Burgman M.A. & Lindenmayer D.B (1998) Conservation Biology for the Australian

Environment. Surrey Beatty & Sons. Chapter 2 What should be conserved ? sections 2.1-2.5.

Primack R.B. (2002) Essentials of Conservation Biology 3rd edition. Sinauer

Associates, Publishers. Chapter 2 What is biological diversity pp 27-33.

Introduction

The world’s "biological diversity" can be subdivided into three levels. The first and

most basic, includes all the species on earth. At a finer level it includes genetic

diversity, and at a wider scale it includes communities and ecosystems.

A species can be defined using two quite different approaches -- (1) a biological

species is where individuals which successfully breed together are considered to be of

the same species, or (2) a morphological species is where individuals which look

similar (similar morphology or biochemical make-up) are considered to be of the same

species.

This second method of assigning individuals to a species is frequently used when we do

not have any information about the breeding habits of the individuals – many plants and

invertebrates are in this category.

Scientists who specialize in the identification and grouping of species are called

taxonomists. Taxonomy is critically important for biodiversity conservation, as the

inability to distinguish between species, or confusion over species names, may slow

down or prevent our efforts at protection.

Ecosystems &Biodiversity When is it a species ? 2

Taxonomy is simply a convenience, so that we are able to give names to all the

different sorts of ‘things’, or taxa on earth. There is often enormous variation between

individuals of different species, and it may be difficult to decide exactly how to separate

groups of individuals into separate species. This is particularly true when we have only

morphological characteristics to help us. For example, how similar do individuals have

to be in order that they be considered the same species ?

However, the way that we group or order the organisms on earth (biodiversity) will

have a large influence on how we recognise the taxa we aim to conserve.

In this exercise we will investigate the difficulties we face when we try to define the

basic elements of biodiversity - the species - using a hypothetical example.

In Practical 4 we will look at an example, where we use “morphospecies” of moths [the

individual’s morphology looks the same therefore they are called the same species] to

compare diversity between three different locations, and then make some decisions

about conservation based on the comparison.

The task

An Hypothetical Example - MoonMorphs

A scientist arrived on the moon, and in the five minutes allocated to her, collected a

number of ‘animals’ from the moon's surface. These animals have been brought back to

earth and will be part of a book on the ‘Biodiversity of the Moon’. You have been

given the job of assigning these moon animals to different groups (or “species”).

Divide into groups of about four. Cut out one set of “animals”, and group them into

‘species’. Make a note of the number of “species”, which moonmorphs are in that

“species” and which characteristics you emphasized when grouping them.

Ecosystems &Biodiversity When is it a species ? 3

Assume thet they are all adult, and that there is no difference visible between

“female” or “male”. You have no information on habitat or behaviour, so you can

only use characteristics you can see (ie. their morphology).

Did you have 29 “species”, or did you group some individuals together into a

species?

Your Report

Your report should have a title, a brief introduction explaining what the prac is about,

and a brief discussion (about 300 words) of the following questions. This report can be

written as a “question and answer” style, but it must be correctly referenced.

What characteristics did your group emphasise when you first put the animals

together ? Why did you pick those characteristics ? Why not some other one(s) ?

Do all individuals in a species have to be identical ? How much variation should we

accept between individuals ‘within’ a species ?

What would happen to your “species” if you accepted a high level of individual

variation? What would happen if you accepted a very low level of variation?

Explain how it is possible for a taxonomist to split a species into two or more “new”

species”.

What factors cause variation in individuals of a species?

Why are these “MoonMorphs” species called “morphospecies”?

Explain why your “species” are not a reproductive/biological species.

Due Date

Check the Assessment Details File for the date. This report is worth 5% of your total

mark.

Ecosystems &Biodiversity When is it a species ? 4

MoonMorphs

Ecosystems &Biodiversity When is it a species ? 5

Ecosystems &Biodiversity When is it a species ? 6

Ecosystems &Biodiversity When is it a species ? 7

Ecosystems &Biodiversity When is it a species ? 8