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The CONCEPT of the SPECIES
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we can look at biodiversity at many levels
mostlywe are looking at conserving all thedifferent 'kinds' of things
this usually means the SPECIES
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The composition and levels of biodiversity
Ecologicaldiversity Genetic diversity Organismaldiversity
biomes Populations kingdoms
bioregions Individuals phyla
landscapes Chromosomes families
ecosystems genes genera
habitats nucleotides species
niches subspecies
populations Populations
individuals
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1. reproductively
-individuals able to interbreed with each other(the traditional definition)
mostly relevant to animals(hybridization is relatively common inplants)
SPECIES can be defined in many ways
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there are many waysthat populations can
become reproductivelyisolated
eg Kangaroo Pawthere is variation inflower length whichcan result inreproductive
isolation
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flower length determinesthe type of pollinatorvisiting flowers results
in genetic isolationbetween adjacent plantsof different species
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2. morphologically
- individuals look alike and form a distinctive group
where do we draw the line ? traditionally flower (or reproductivestructures) have been emphasised to definespecies
these are relatively stable within plantgroups
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3. chemically
- individuals which can be consistently identifiedusing a range of compounds
volatile oils, flavonoids, proteins, enzymes useful in detecting hybrids
current emphasis is on DNA and proteins
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eg flavonoidpatterns detected by paperchromatography
Species 1 Species 2 Hybrid
flavonoids are chemicals extracted from leaves
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parent1 parent 2
hybrid
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or proteins detected bygel electrophoresis
Species 1 Species 2 Hybrid
electric
current
gel
proteins
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Sometimes differentiation of species gives differentviews:
eg chemical racesmorphologicallyidentical,
butchemically distinct
examples:
Eucalyptusoil typesHeath (Epacr is impressa) flower colourshemp (Cannabissp) psychoactive compounds
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some morphologically uniform species canbe genetically extremely variable
eg Sty l id iumin WA
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16 chromosomeraces which wereunable to interbreed
what is theirstatus ?are they all the samespecies ?
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are some characters intrinsically moreimportant than others ?
ie should we rely on morphology, orare chemical and genetic structure justas important
genetic make-up is generally acceptednow as the most important characteristic
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EXAMPLES
1. Eucalyptu s yarraensis(Yarra Gum)
now widely accepted as a well defined 'species'
has been recognised as rare andthreatened and listed underFlora and Fauna
Guaranteelegislation
once included as a rough-barked variant ofEucalyptus ovata(Swamp Gum)
which is very common, not needingprotection
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Eucalyptu s yarraens is
Eucalyptu s ovata
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SO . is it
common, and needing no protectionOR
rare, in danger of extinction and needingprotection
depending on the TAXONOMIC STATUS ofthis tree, legislative protection and resources
for conservation will vary
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2. Eucalyptu s X studleyensis
the Xindicates a hybrid
originally described as a species, but nowaccepted as a hybrid between E. ovata(Swamp
Gum) and E. camaldu lens is(River Red Gum)
as a hybrid it cannot breed true should we treat it as a 'once-off' oddity, or worthyof protection ?
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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 morphologicallyand chemically virtually identical
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it is easy to propagate - do we need to conserveboth populations ?
do we need anynatural populations ?? ($$$$)
consider as an umbrella or flagshipspecies to conserve the community (which
has some other interesting species such as
Sphagnummoss ) ?
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SHOULD WE EMPHASISE MORPHOLOGY OR
EVOLUTIONARY RELATIONSHIPS IN OURRECOGNITION OF SPECIES ?
(phenetics or phylogeny)
phenetics based on how species appearie morphological similarity
phylogeny based on inferred pastevolutionary relationships
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Eucalyptus - one genus o r nine ??
one recognisable group EucalyptusORninegroups which are virtuallyindistinguishable using adult morphology
base classification on the number ofopercula('caps') in buds which reflects pastevolution
Monocalyptus, Symphyomy rtus etc
groups are accepted generally, but givendifferent RANKS
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eucalypt flowers have a cap or operculum
(instead of separate sepals and petals)
some specieshave two caps(separate fusedsepals andpetals)
scar
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so either:
1. one genusand all groups = Eucalyptus
OR
2. several generasuch as
Corymbia
Symphyomyr tus
Blakella
Monocalyptus etc
(wh ich we can only separate on m icroscopic
characters)
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ARE SOME SPECIES WORTH CONSERVINGMORE THAN OTHERS ?
such asIsop hysis tasmanica
(Hewardia) in Tasmania
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only one species
in a genus(monospecificspecies)
are species with
a unique genepool moreimportant thanothers ?
Isophysis
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HOW MUCH OF EACH SPECIES SHOULD WECONSERVE ?
ALL ? probably not economically orpolitically possible
SOME ? use genetic analysis to decidehow to conserve a representative gene pool
use morphological and chemicalmarkers to indicate likely genetic variation
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in the end, it is our ideas about the nature
of species and the variation within them thatguides our attempts to conserve as muchas possible of the gene pool of species
how much we actually conserve dependson the resources we have available
$$$$$