Lecture 2 intro to systematics

IntroductioIntroduction ton to

SystematicSystematicss

The Science of The Science of SystematicsSystematics

Definition◦from the latinized Greek word

“systema” (organized whole) as applied to systems of classification developed by early naturalists, notably Carolus Linnaeus (1735, Systema naturae)

◦according to G. G. Simpson (1961)-- it is the scientific study of the kinds & diversity of organisms & of any & all relationships (all biological interactions) among them

*simply, it is the science of the diversity of organisms

 Broad overlap in the terms systematics & taxonomy in dealing w/ the diversity & uniqueness of life; but there is also subtle difference.Taxonomy ---derived from Greek word “taxis” (arrangement) & “nomos” (law)- first proposed in its French form by de Candolle (1813) for the Theory of Plant Classification

Taxonomy- simply, the theory & practice of classifying organisms-has 2 divisions:1. classification ---arrangement of the kinds of organisms from smaller to larger groups2. nomenclature --- procedure of assigning names to the kinds & groups of organisms to be classified

Scope of SystematicsScope of Systematics1. Deals w/ populations, species, &

higher taxa- supplies needed information about these levels- cultivates:-- a way of thinking-- a way of approaching biological problems important for the balance & well-being of biology as a whole

2. Using comparative method, it determines:

a. what the unique properties of each species & higher taxon areb. what properties certain taxa have in common, andc. what the biological causes of the differences or shared characters are

3. Concerned w/ variation within taxa

 *classification makes organic

diversity accessible to the other biological disciplines

*that is why systematics holds a unique & indispensable position among biological sciences

Aims of SystematicsAims of Systematics1. To inventory the world’s kinds of

organisms (flora & fauna)2. To provide a method for

identification & communication3. To produce a coherent &

universal system of classification, &

4. To demonstrate the evolutionary implications of biodiversity

7 Component Fields of 7 Component Fields of Systematics Systematics 1. Biodiversity 2. Taxonomy3. Classification4. Nomenclature5. Biogeography6. Evolutionary Biology7. Phylogenetics

Biodiversity- number & kinds of organisms

Taxonomy- art & science of describing organismsClassification- methods of grouping organisms- could be artificial, natural, or evolutionary ----- based on homology Nomenclature- science of naming organisms

Biogeography- studies the distribution of organisms- aims to reveal where organisms live, at what abundance, and why they are (or are not) found in a certain geographical area.

Evolutionary Systematics- seeks to classify organisms using a combination of phylogenetic relationship and overall similarity- considers taxa rather than single species, so that groups of species give rise to new groups

Phylogenetics- study of evolutionary

relatedness among groups of organisms(e.g. species, populations), which is discovered through molecular sequencing data and morphological data matrices

Contributions of Contributions of Systematics to BiologySystematics to Biology

Applied Biology

◦epidemiology of malaria in Europe

- Anopheles maculipennis found throughout the continent - but, malaria was restricted to local districts & money were wasted because no one understood the connection between distribution of the mosquito & that of malaria

-careful taxonomic studies provided the key to the problem:* A. maculipennis consist of several sibling species w/ different habitats; only some species are vectors of malaria in a given area-thus, the control of the species was directed to specific areas where the organisms that causes malaria occurs

◦fern weevil, Syagrius fulvitarsis was destructive to Sadleria ferns in Hawaii (1920)

- C. E. Pemberton in 1921 ---examined an old private

insect collection in Sydney, Australia ---one of the specimen was S. fulvitarsis; date coll.:1857, with locality *a braconid (parasitoid wasps) parasite on the larvae of the weevil was used to control the weevils

Other fields◦correct identification & classification of species in agriculture, public health, ecology, conservation, genetics, and behavioral biology

Tools of SystematicsTools of SystematicsCurrently, systematists use

◦Morphological, biochemical, and molecular comparisons to infer evolutionary relationships

In evaluating molecular homologies, systematists use computer programs and mathematical tools◦When analyzing comparable DNA

segments from different organismsC C A T C A G A G T C C

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C C A T C A G A G T C C

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1 Ancestral homologous DNA segments are identical as species 1 and species 2 begin to diverge from their common ancestor.

2 Deletion and insertion mutations shift what had been matching sequences in the two species.

3 Homologous regions (yellow) do not all align because of these mutations.

4 Homologous regions realign after a computer program adds gaps in sequence 1.

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Roles of TaxonomyRoles of Taxonomy1. The only science that provides vivid

picture of organic diversity (eukaryotes/prokaryotes; sexual/asexual; producer/consumer)

 2. Provides much of the information for

the reconstruction of phylogeny (shows genealogical relationships among species)

3. Reveals evolutionary phenomena making them available for causal study

4. Supplies classifications which have heuristic (leads to discovery) & explanatory value in fields of evolution, biochemistry, ecology, genetics

5. Supplies almost all info for entire branches of biology, and

6. Makes important conceptual contributions that would not otherwise be easily accessible to experimental biologists