The CONCEPT of the SPECIES

we can look at biodiversity at many levels

population

species

community

mostly we are looking at conserving all the different 'kinds' of things

this usually means the SPECIES

1. reproductively

-individuals able to interbreed with each other- this is the traditional definition of a species

mostly relevant to animals as hybridization is relatively common in plants

SPECIES can be defined in many ways

there are many ways that populations can become reproductively isolatedeg Kangaroo Paw – there is variation in flower length which can result in reproductive isolation

flower length determines the type of pollinator visiting flowers – results in genetic isolation between adjacent plants of different “species”

2. morphologically

- individuals look alike and form a distinctive group

where do we draw the line ?

traditionally flower (or reproductive structures) have been emphasised to define species

these are relatively stable within plant groups

ie less 'plastic' than some other characters

3. chemically

- individuals which can be consistently identified using a range of compounds

volatile oils, flavonoids, proteins, enzymes

useful in detecting hybrids

current emphasis is on DNA and proteins

eg flavonoid patterns detected by paper chromatography

Species 1 Species 2 Hybrid

flavonoids are chemicals extracted from leaves

parent1

parent 2

hybrid

or proteins detected by gel electrophoresis

Species 1 Species 2 Hybrid

electric current

gel

proteins

sometimes differentiation of species by morphological and chemical characters gives different views

eg chemical races

morphologically identical, but

chemically distinct

examples:

Eucalyptus oil typesHeath (Epacris impressa) flower colourshemp (Cannabis sp) psychoactive compounds

some morphologically uniform species can be genetically extremely variable

eg Stylidium in WA

16 chromosome races which were unable to interbreed

what is their status ?are they all the same species ?

are some characters intrinsically more important than others ?

ie should we rely on morphology, or are chemical and genetic structure just as important

genetic make-up is generally accepted now as the most important characteristic

EXAMPLES

1. Eucalyptus yarraensis (Yarra Gum)

now widely accepted as a well defined 'species'

has been recognised as rare and threatened and listed under Flora and Fauna Guarantee legislation

once included as a rough-barked variant of Eucalyptus ovata (Swamp Gum)

which is very common, not needing protection

SO… . is it

common, and needing no protection

OR

rare, in danger of extinction and needing protection

depending on the TAXONOMIC STATUS of this tree, legislative protection and resources for conservation will vary

2. Eucalyptus X studleyensis

the X indicates a hybrid

originally described as a species, but now accepted as a hybrid between E. ovata (Swamp Gum) and E. camaldulensis (River Red Gum)

as a hybrid it cannot “breed true”

should we treat it as a 'once-off' oddity, or worthy of protection ?

3. Eucalyptus crenulata (Buxton Gum)

only known from two sites at Yering (with only a few trees) and Buxton (with a few hundred trees)

populations are morphologically and chemically virtually identical

it is easy to propagate - do we need to conserve both populations ?

do we need any natural populations ?? ($$$$)

consider as an umbrella or flagship species to conserve the community

(which has some other interesting species such as Sphagnum moss ) ?

SHOULD WE EMPHASISE MORPHOLOGY OR EVOLUTIONARY RELATIONSHIPS IN

OUR RECOGNITION OF SPECIES ?

(phenetics or phylogeny)

phenetics – based on how species appear

ie morphological similarity

phylogeny – based on inferred past evolutionary relationships

Eucalyptus - one genus or nine ??

one recognisable group EucalyptusOR nine groups which are virtually indistinguishable using adult morphology

base classification on the number of opercula ('caps') in buds which reflects past evolution

Monocalyptus, Symphyomyrtus etc

groups are accepted generally, but given different RANKS

eucalypt flowers have a “cap” or operculum (instead of separate sepals and petals)

some species have two caps (separate fused sepals and petals)

scar

so either:

1. one genus and all groups = EucalyptusOR2. several genera such as

CorymbiaSymphyomyrtusBlakellaMonocalyptus etc

(which we can only separate on microscopic characters)

ARE SOME SPECIES WORTH CONSERVING MORE THAN OTHERS ?

such as Isophysis tasmanica (Hewardia) in Tasmania

only one species in a genus (monospecific species)

are species with a unique gene pool more important than others ?

Isophysis

HOW MUCH OF EACH SPECIES SHOULD WE CONSERVE ?

ALL ? probably not economically or politically possible

SOME ? use genetic analysis to decide how to conserve a representative gene pool

use morphological and chemical markers to indicate likely genetic variation

in the end, it is our ideas about the nature of species and the variation within them that guides our attempts to conserve as much as possible of the gene pool of species

how much we actually conserve depends on the resources we have available

$$$$$