1. As an aid to memory: Organisms are classifed in groups based upon similarities. It's easier to remember the characteristics of an entire group of organisms than to recall the individual characters of individual organisms over and over!
2. As an aid to prediction: If one knows that all members of a particular group have a particular set of characteristics, then there's a good bet that a *new* member of that group may have some of those (useful?) characteristics, too. (such as antibiotic production, edibility, etc.)
3. As an aid to explaining evolutionary relationships
4. To provide a stable, relatively unchanging system
of INTERNATIONALLY RECOGNIZABLE NAMES.
Common names are confusing!
(Helpful booklet: Greek and Latin Word Roots by Donald Borror)
Taxonomy - the science of naming and classifying organisms
Biosystematics - the science of determining evolutionary relationships among organisms.
In the very earliest studies of biodiversity...
1758 - Carl Linne (Swedish botanist) published
Systema naturae, which outlined a NEW system of binomial
nomenclature. We still use this system today. It's a nested hierarchy
that you've no doubt seen before. From largest (most inclusive) to
smallest (least inclusive) group, the order is...
Any living organism that has been DESCRIBED by a scientist (a taxonomist/biosystematist) has a scientific name which consists of the organism's Genus and species:
Oryctolagus cunniculus
remember our old motto:
"King Philip came over from Germany stoned."
Eleutherodactylus planirostris
(Greenhouse Frog)
eleutheros = "free"
dactyl - "digit"
plani - "flat"
rostris - "nose"
Proper names are okay to use as part of a scientific name (if you'd like to name a new species after your best pal, for example), but they, too, must be Latinized:
Chilomeniscus savagei
chilo = "lip"
meniscus - "crescent"
TAXON - generic term used to describe any group of
organisms that have been classified together at any given taxonomic
level (Kingdom, order, family, etc.)
1901 - formation of the International Commission of Zoological Nomenclature (ICZN)
1930 - ICBN (...Botanical...) formed
1947 - ICBacterial Nomenclature formed
In any one system, no two species can have the same scientific name.
(However, sometimes there is overlap between systems, with animal and plant sharing the same genus name.)
e.g. : Heliconius butterfly
Heliconia plant
Rules of nomenclature:
1. the three codes are independent of one another.
2. a taxon bears only one correct name
3. no two species (within one code) or gneral may have the same name
4. name must be latin or latinized
5. correct name is based upon publication priority (whoever described something first gets to give it the name!)
6. For plant families and animal superfamilies, the name of the family or superfamily must be based on that of a type genus.
Type genus: the first genus ever described in a given
family (plants) or superfamily (animals)
Old name Leguminosae (Pea family)
New name: Fabaceae (because the very first genus
of leguminous plants ever described was given the name Faba
by Linnaeus.)
Old name Compositae (Daisy family)
New name: Asteraceae (first genus described was Aster)
Classification is more than just naming things. There is a functionality to this!
Biosystematics alone among the sciences tends to
stress diversity, rather than commonality. It is not as REDUCTIONIST
as other sciences.
Early 1900's - sporadic, localized outbreaks of malaria (caused by
Plasmodium, a protozoan blood parasite, and transmitted by the
vector species, female mosquitoes of the genus Anopheles) were
believed to be caused by Anopheles maculipennis. Puzzling: this
was a widespread species. Why were outbreaks so localized?
Work by two systematists (Hackett in 1937 and Bates in 1940) revealed that
"A. maculipennis" was actually several *sibling* species, each of which had
a distinct ecology, diurnal periodicity and habitat.
Knowing this, those in charge of eradication efforts were able to
specifically target the responsible species and wipe out the problem.
1920's - Hawaiian forest preserves' fern populations were severely threatened by the invasion of an exotic fern weevil (Syagrius fulvitarsis). No one knew where it was native.
1921 systematist Pemberton identified a single museum specimen, labeled with locality, as Australian.
The beetle's natural predators from Australia could then be determined and (after careful study!) used as biological control.
EXOTIC SPECIES - imported to an area from its native habitat;
non-native.
Florida examples:
Side note on
KEYSTONE SPECIES - species on which many others in an ecosystem depend for
survival. (e.g. - Alligator in the Everglades creates temporary ponds in
the dry season that act as refugia for all sorts of water-dependent
animals. Without the gators, they might dry out and die!)
INDICATOR SPECIES - species by whose population densities one can gauge
the health of an ecosystem. (e.g. - Northern Spotted Owl indicates
population levels of Red-backed Vole, the most important disperser of
mycorrhizal fungus spores!)
ENDEMIC SPECIES - Species that lives only in a particular area, and no where else on earth. (e.g., Lemurs are endemic to Madagascar.)
Monophyletic taxon: derived from a single common ancestor.
Polyphyletic taxon: derived from more than one most recent common ancestor.
Paraphyletic taxon: includes only some of the descendants of a common ancestor, but not all of them.
RECALL:
derived character = apomorphy
shared, derived character = synapomorphy
primitive character = plesiomorphy
shared, primitive character = symplesiomorphy