What are biological species?
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Easy question?
Homo sapiens = Canis familaris ?
Easily distinguished, but technical literature
less clear
Biologists have dozens of definitions
Not fringe accounts, but prominent with
current biological literature
Play NB role in/out Biology
In – fundamental units of classification
Out – debates over environmental laws etc.
Systematics
 The
study of the diversity of organism
characteristics,
 how they relate evolutionarily,
 establishing their phylogeny
 regardless of there phenetics.
Phylogeny
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Origin and evolution of a set of organisms
A major task of systematics is to determine the ancestral
relationships among known species.
Phylogenetics - study of evolutionary relatedness among
various groups of organisms (e.g., species, populations).
treats a species as a group of lineage-connected individuals
over time.
classifying groups of organisms according to degree of
evolutionary relatedness.
characters - nucleotide or amino acid sequences.
Phenetics
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Attempt to classify organisms based on
overall similarity, usually in morphology or
other observable traits, regardless of their
phylogeny or evolutionary relation.
Biological Classification
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Biologists group and categorize species of
organisms
NB extinct and living !
Modern classification has its root in the work of
Carolus Linnaeus, who grouped species
according to shared physical characteristics.
Improve - Common descent, Molecular
systematics.
Scientific classification belongs to the science of
taxonomy or biological systematics.
Common Descent
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A theory of universal common descent based on
evolutionary principles was proposed by Charles
Darwin
This theory is now generally accepted by
biologists, and the last universal common ancestor
is believed to have appeared about 3.5 billion
years ago.
The theory of universal common descent proposes
that all organisms on Earth are descended from a
common ancestor or ancestral gene pool.
Molecular Systematics
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The evolutionary relationships of organisms are
studied using their DNA, RNA and protein
sequences
These techniques help in objectively determining
the importance of characters or markers and in
evaluating evolutionary hypotheses.
Molecular systematics has introduced major
revisions in many groups of organisms.
Taxon
Grouping of organisms (named or
unnamed).
 Once named, a taxon will usually have a
rank and can be placed at a particular level
in a hierarchy.
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Carl Linnaeus
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Swedish botanist,
physician and zoologist
laid foundations for the
modern scheme of
nomenclature.
He is also considered one
of the fathers of modern
ecology.
He is known as the "father
of modern taxonomy."
The Linnaean system
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The Linnaean system classified nature within a
hierarchy, starting with three kingdoms. Kingdoms
were divided into Classes and they, in turn, into
Orders, which were divided into Genera (singular:
genus), which were divided into Species (singular:
species). Below the rank of species he sometimes
recognised taxa of a lower (unnamed) rank (for
plants these are now called "varieties").
Nomenclature
Refers to a method of assigning (unique)
names.
 In biology:
 Scientific nomenclature
 Bacterial nomenclature
 Botanical nomenclature
 Zoological nomenclature
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Binomial Nomenclature
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Formal method of naming species.
Each organism is given a name consisting of two parts
A GENERIC name – states genus – common to a group of closely related
organisms
A specific name – states species – unique to particular organism
- often descriptive of characteristics
Primula vulgaris
GENUS
specific
Basics!!
There are certain aspects which are universally
adopted:
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Printed - italics, such as Homo sapiens.
Handwritten - underlined.
The first term (genus) is always capitalized, while the
specific descriptor will not be for example, Canis
lupus or Anthus hodgsoni.
When used with a common name, the scientific name
usually follows in parentheses, for example, "the house
sparrow (Passer domesticus) is endangered."
Kingdom
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The top-level, or nearly the top-level.
Two kingdoms of living things:
Animalia for animals AND Vegetabilia for plants
(Linnaeus also treated minerals, placing them in a third
kingdom, Mineralia).
When single-celled organisms were first discovered, they were
split between the two kingdoms:
mobile forms - animal phylum Protozoa, and colored algae and
bacteria - plant division Thallophyta or Protophyta.
However, a number of forms were hard to place, or were placed
in different kingdoms by different authors: for example, the
mobile alga Euglena and the amoeba-like slime moulds. As a
result, Ernst Haeckel suggested creating a third kingdom
Protista for them
Five kingdoms
Phylum
Between Kingdom and Class.
 Defined - most basic body-parts shared by
that group.
 e.g. Chordata (animals with a notochord)
 Arthropoda (animals with a jointed
exoskeleton)
 Mollusca (animals with a shell-secreting
mantle)
 Angiosperma (flowering plants) etc.
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Genus
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In biology, a genus (pl. genera) is a taxonomic
grouping.
In the classification of living organisms, a genus is
considered to be distinct from other such genera.
A genus has one or more species
If more than one species - morphologically more
similar than species belonging to different genera.
Remembering The Order
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A mnemonic :
King Phillip Came Over From Germany Stoned
(and numerous variants thereof)
 = Kingdom, Phylum, Class, Order, Family,
Genus, Species.
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LEARN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Dichotomous Keys
Diagram or a table.
 It is important to note that dichotmous keys
have NOTHING to do with biology alone.
They are simply a tool. You can make a
dichotmous key to describe ANYTHING.
 fairly simple
 step by step
 each splitting of a branch with new
info/charactersitic.
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