Transcript Species Concept - Londonderry School District

CLASSIFICATION OF ORGANISMS

Biologists have classified nearly 2 million
species
 Estimates range from 13 million to 40+
million
 The science of describing, naming,
classifying organisms is called taxonomy
 Any particular group within a taxonomic
system is called a taxon
Species Concept

Species can interbreed to produce fertile
offspring
 Variations in a population include
individual variations, geographic variations,
and variations in form (polymorphisms)
 Species: a population of individuals that
interbreed and produce fertile offspring
under natural conditions

Taxonomists use structure, function,
biochemistry, behavior, genetic systems,
evolutionary history to classify organisms
 Homologies are similarities and can either
be structural or chemical
HOMOLOGOUS
STRUCTURE

Similar features that originate in a shared
ancestor (derive from same embryonic
structure)
 Can result from modifications that change
an original feature to 2 extremely different
types (wing and arm)
Modern Version
 Domain
-3
– Kingdom - 6
 Phylum – 30 – 89 (??)
–Class
• Order
- Family
- Genus
- Species
Human Classification
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Kingdom: Animalia (common phyla)
Phylum: Chordata (common class)
Class: Mammalia (similar order, common
characteristics)
Order: Primates (similar family, distinctive
anatomy and way of life)
Family: Hominidae (similar genera)
Genus: Homo (sp w/ similar characteristics)
Species: sapiens
(Homo sapiens = wise man) (Greek homo = same;
Latin homo = man, from the Earth)
6 Kingdoms

Eubacteria
 Archaebacteria
 Protista
 Fungi
 Plantae
 Animalia
The 6 kingdoms

Prokaryotes (Used to be 1 kingdom,
Monera)
– Archaebacteria
– Eubacteria

Eukaryotes
–
–
–
–
Fungi
Protista
Animal
Plantae
Overview of the 6 kingdoms

Archaebacteria
– Unicellular
– Live in extreme environments
– Prokaryotic

Eubacteria
– Unicellular
– Prokaryotic
– “Common bacteria”
Overview of the 6 kingdoms

Protista
– Eukaryotic
– Unicellular or colonial
– Lots of different life styles

Fungi
–
–
–
–
Cell walls made of chitin
Eukaryotic
Multicellular
External heterotrophs
Overview of the 6 kingdoms

Plantae
– Eukaryotic & Multicellular
– Cell walls made of cellulose
– Autotrophic

Animalia
– Eukaryotic & Multicellular
– No cell walls
– Internal heterotrophs
Prokaryotes vs. Eukaryotes

Cell structure is extremely important in
categorizing
 Prokaryotes are single-celled organisms that
have no nucleus or other membrane-bound
organelle (found in Domain Bacteria and
Archaea)
 Eukaryotes are cells that have a nucleus and
other membrane-bound organelles
Taxonomy

Science of grouping organisms
 Aristotle grouped organisms into 2
categories: plants and animals
 In the 1730’s Carl Linne (Carolus Linnaeus)
developed a system of taxonomy called
binomial nomenclature
Carolus Linneaus (Carl Linne)

Devised taxonomic system using hierarchal
categories, and devised binomial
nomenclature to identify species;
 Physalis amno ramosissime ramis angulosis
glabris foliis dentoserratis was changed to
Physalis angulata (ground cherry)
 Homo sapiens, Chaos chaos,
Chaos chaos

The Pelomyxa or
Chaos chaos is a
very large
protozoan and
belongs to the
Phyllum
Sarcodina.
Binomial nomenclature

Names usually describe organism, location;
can be used to honor scientist or friend (or
in some cases to insult individuals)
Phylogeny

Phylogeny is the evolutionary history of a
species (or taxon)
 Morphology, embryonic development,
genetics, and fossil evidence all used to
build phylogenetic trees
 Use of dichotomous key (written set of
choices)
Cladistics

Phylogenetic analysis that uses shared characters
and derived characters
 Shared characters are features that all members of
a group have in common (all mammals have
mammary glands / all birds have feathers)
 Derived characters are those features that evolved
only within the group under consideration (only
animals (living/fossil) with feathers are birds)