Transcript Modern Classification

Topic 5.5 - Classification
What is Taxonomy?
•
Systematics is the study of the diversity of
life and its evolutionary history
• Systematics is combinaton of several
sciences:
1. Taxonomy is science of naming and
arranging living organisms into
groups
2. Phylogeny is the evolutionary history
of an organism or group
Goals of Taxonomy
Three important goals:
1. Sort out closely related organisms into
individual species
2. Assign a single universal name to all living
organisms
– Necessary to facilitate
communication between all scientists
worldwide
3. To place all living organisms into groups
with real biological meaning.
Benefits of Taxonomy
• Species Identification – a system allows us to
quickly identify organisms
• Predictive value – if several members of a
group have a common trait, another species will
probably have that trait too
• Evolutionary links – species in the same group
probably share a common ancestor – helps
indicate how they evolved
The Beginnings of
Classification
• The first
classification
scheme was
developed by
Aristotle about 2000
years ago
Aristotle’s System
• Artistotle grouped organisms into:
And
Plants
Animals
Changing the System
• Aristotle’s system was used until the 1400s
– At that point “modern,” science was
beginning to realize that system was
too simplistic
– Too often names for species varied
from location to location and did not
accurately describe the organism.
Carolus Linneaus
• Swedish Biologist who
developed the basis for the
classification system still in
use today (mid 1700s)
• Utilized morphology
(structure and function) to
classify all living organisms
Linneaus’s System
• Linneaus created a “filing,” system for grouping
organisms
• Hierarchy of increasingly more general
categories:
–
–
–
–
–
–
Species are grouped into genera ( sing. genus)
Genera into families
Families into orders
Orders into classes
Classes into phyla (sing. phylum)
5.5.2
Phyla into kingdoms
Linneaus’s System
• Each group is called
a taxon (plural taxa)
• Individual species
are classified into a
series of taxa –
each one larger
than the previous
one
5.5.2
An Example - Human
Classification
• Kingdom: Animalia
– Phylum: Chordata
• Class: Mammalia
Larger group
–Order: Primate
» Family: Hominidae
Genus: Homo
Species: sapien
Smaller group
5.5.2
Another Example - Corn
Classification
• Kingdom: Plantae
– Phylum: Magnoliophyta
• Class: Liliopsida
Larger group
–Order: Cyperales
» Family: Poaceae
Genus: Zea
Species: mays
Smaller group
5.5.2
Linneaus’s System
• Linneaus assigned each species a twopart scientific name – binomial
nomenclature
• Why mostly Latin or Greek?
• First name – Genus
• Second name – species
5.5.1
Binomial Nomenclature
Canis familiaris
5.5.1
Binomial Nomenclature
Rules for naming organisms:
1. The genus name is always uppercase.
2. The species name is always lowercase
3. Italics are used if the name is printed
(typed)
4. Handwritten names are underlined
with two separate lines.
5.5.1
Modern Classification
• Linneaus only created two kingdoms for
living organisms – plants and animals –
why?
• Modern taxonomists argue about the number
of kingdoms – five or six
– Prokaryote (monera) – archaebacteria and
eubacteria?
– Protoctista (protist)
– Fungi
– Plantae
– Animalia
Kingdom Plantae
• All organisms in Kingdom Plantae have the
following characteristics:
– Multicellular
– Eukaryotic
– Photosynthetic autotrophs
– Almost all terrestrial
• Plants are divided into divisions (instead of
phyla) based on evolutionary characteristics
5.5.3
Division Bryophyta
• Display evolutionary adaptations that helped
bryophytes move from water to land:
– Covered with a waxy cuticle – why?
• However, bryophytes are NOT totally independent of
water.
– Flagellated sperm must “swim,” to egg for
fertilzation to occur
– No vascular tissue – must absorb water from
surface instead of absorbing from roots
• Moss are commonly found in damp, shady
areas
5.5.3
Division Bryophyta
5.5.3
Division Filicinophyta
• First group of vascular plants:
– Evolved as a means to obtain all required
resources
– Xylem and phloem transport resources
between distant organs:
• Soil and roots provide minerals and water
• Above ground provides light for leaves and
photosynthesis
• Includes over 12,000 species of ferns
– Located in tropical and temperate forests
5.5.3
Division Filicinophyta
5.5.3
Division Coniferophyta
• Includes ~ 550 species of
large trees including pines,
firs, spruces, and redwoods
• All produce seeds in cones
• Most use wind pollination
for reproduction.
• Almost all conifers are
evergreens
• Most conifers have needles
– leaves modified to
prevent water loss
5.5.3
Division Angiospermophyta
• Angion means
“container,” – seeds
are enclosed in fruits
• Includes ~ 235,000
species of flowering
plants
• May rely on wind, birds,
insects, and even
mammals for pollination
and reproduction.
5.5.3
Kingdom Animalia
• All organisms in Kingdom Animalia
have the following characteristics:
– Eukaryotic
– Multicellular
– Heterotrophic
Phylum Porifera
• Includes sponges
• Characteristics: no body symmetry, no tissues, no
organs; hermaphrodites; filter feeders; sessile
5.5.4
Phylum Cnidaria
• Includes corals, jellyfish, and sea anemone
• Characteristics: stinging cells for food and protection;
two-way digestive tract; radial symmetry; drifters or
sessile
5.5.4
Phylum Platyhelminthes
• Includes flatworms like planaria, flukes, and
tapeworms.
• Characteristics: distinct head region (cephalization);
bilateral symmetry; most are parasites; two-way
digestive tract; no heart or lungs; flat shape - why?
5.5.4
Phylum Annelida
• Includes earthworms, marine worms, and
leeches.
• Characteristics: segmented; well developed nervous,
digestive, and circulatory systems; one-way digestive
system.
5.5.4
Phylum Mollusca
• Includes snails, clams, octopus and squids.
• Characteristics: bilateral symmetry; one or more shells;
soft bodies; most are aquatic
5.5.4
Phylum Arthropoda
• Includes insects, arachnids (spiders), and
crustaceans
• Characteristics of all arthropods:
exoskeleton made of chitin; jointed
appendages; segmented body; open
circulatory system
• Molting – process of shedding and
exoskeleton and growing a new one to grow
larger.
5.5.4
Insects
• The largest group of all animals (more than 1
million species)
• Characteristics: three body segments (head, thorax,
and abdomen); six legs; live in water and land.
5.5.4
Crustaceans
• Include lobsters, shrimp, crayfish, crabs, and
barnacles.
• Characteristics: aquatic; two body segments
(cephalothorax and abdomen); gills
5.5.4
Arachnids
• Include spiders, scorpions, mites, horseshoe
crabs, and ticks
• Characteristics: 2 body segments; eight legs; book
lungs
5.5.4