5.3 Classification

Classification  For centuries, humans have been attempting to classify the various species on Earth in order to learn more about the species and their evolutionary history.  Classification attempts to group more related species together

Binomial system of Nomenclature  A “2 name” naming system that was designed by Carolus Linneaus in the 18 th century.

Binomial System of Nomenclature  Every species has a Latin name,  The first part of the name is the name of the genus, the second part is the species.  The name is printed in italics  If hand written, underline the name  The first letter of the genus is capitalized  The first letter of the species is not

Examples:  Humans: Homo sapiens GENUS SPECIES GENUS SPECIES  Dogs: Canis lupus familiaries SUBSPECIES SUBSPECIES

 Linnaeus’ system was largely based on morphology and is not the best way to classify organisms  (Modern methods use evolutionary relationships to classify organisms)  However, Linnaeus’ system is still the basis of how we name organisms today.

International Cooperation & Classification  Scientists all around the world use the binomial system as a universal naming system to identify a species rather than the many local names

Arum maculatum

Arum maculatum local names  England:  Lords-and-ladies  Cows and bulls  Devils and angels  France:  la chandelle  Le pied-de-veau  Spain:  Comida de culebra  Alcatrax  Dragontia menor  Vela del diablo

Hierarchy of Taxa  Taxonomists classify species using a hierarchy of taxa  TAXON = group of something  Taxon (singular), taxa (plural)  The taxa form a hierarchy, as each taxon includes taxa from the level bellow

Three Domains  Traditional classification systems have recognized 2 major categories of organisms based on cell types: eukaryotes and prokaryotes  Think back to Topic 1 in grade 11. Do you remember the difference?

Three Domains  Because prokaryotes are so diverse, most classifications systems recognize 3 major categories or domains  Eubacteria (bacteria) Types of  Archaea (archaeans) prokaryotes  Eukaryota (eukaryotes)

Comparing the 3 domains  See page 261 of text

Histones Associated with DNA BACTERIAARCHAEAEUKARYOTA absentProteins similar to histones bound to DNA Present

Presence of Introns BACTERIAARCHAEAEUKARYOTA Rare or absentPresent in some genesFrequent

Structure of Cell Walls BACTERIAARCHAEAEUKARYOTA Made of chemical peptidoglycan Not made of peptidoglycan Not made of peptidoglycan, not always present

Cell Membrane Difference BACTERIAARCHAEAEUKARYOTA Glycerol-ester lipids; Unbranched side chains; D-form of glycerol Glycerol-ether lipids; Unbranched side chains; L-form of glycerol Glycerol-ester lipids; Unbranched side chains; D-form of glycerol

Archaeans  Found in a broad range of habitats:  Ocean surface  deep ocean sediments  oil deposits below the Earth’s surface  High salt concentrations  High temperatures  Ex: methanogens which live in the intestines of cattle and produce methane as a waste product.

Hierarchy of Classification for Eukaryotes  Seven level hierarchy of taxa to classify organisms  Kingdom  Phylum  Class  Order  Family  Genus  Species

 King Phillip Coughs. Oh! Filthy Germs Spread!!!

Kingdoms  Kingdoms are the broadest category  Originally there were only 2 Kingdoms: Plants and Animals  Today, we have identified 5

Modern Kingdoms  Kingdom Plantae (plants)  Kingdom Animalia (animals)  Kingdom Fungi (fungi and moulds)  Kingdom Protoctista (protozoa and algae – includes paramicium and amoebas)  Kingdom Prokaryotae (bacteria)

Examples of Classification  You need to know an example of 1 plant and 1 animals species from domain to species level  See page 262 for an example of the grey wolf and the date palm

Ex: Humans KINGDOMAnamalia PHYLUMChordata CLASSMammalia ORDERPrima FAMILYHominidae GENUSHomo SPECIESsapiens

Ex: Garden Pea KINGDOMPlantae PHYLUMAngiospermae CLASSDicotyledoneae ORDERRosales FAMILYPapilionaceae GENUSPisum SPECIESsativum

Natural Classification  The genus and accompanying higher taxa consist of all the species that have evolved from one common ancestor  Because of the common ancestor we can expect the members of a natural group to share many characteristics

Natural vs Artificial Characteristics  Plants and fungi were one time classified together because they both have cell walls, but this is an artificial classification as their cell walls evolved separately and molecular research shows they are no more similar to each other than to animals.

Natural vs Artificial Characteristics  Ex: wings of insects, birds, and bats  We will come back to this when we talk about convergent evolution and analogous traits.

Reviewing Classification  Sometimes taxonomists reclassify species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species  The new evidence is usually DNA sequencing

Advantages of Natural Classification  Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group

Plants  All plants are found in a single kingdom  During the life cycle of a plant, male and female gametes develop and fuse to form a zygote, which will develop into an embryo and then the particular plant

Expectation, page 266  Distinguish between the following phyla of plants using simple external recognition features  Phyla: bryophyte,filicinophyta, coniferophyta, angiospermophyta

Bryophyta  Mosses and liverworts  Small terrestrial plants that do not have true roots, stems or leaves (but may have similar structures)  Leaf-like structures arranged in a spiral  Usually live in clusters

Filicinophyta  Ferns  Have true leaves  New leaves unroll  Have an underground creeping stem (called a rhizome)

Coniferophyta  Conifers  Woody plants, with a single wooden trunk and side branches  Leaves are long thin needles and dark green  Produce seeds in cones

Angiospermophyta  Angiosperms/ Flowering Plants  Have flowers  Seeds are in ovaries with become the fruit  Leaves usually as a leaf blade and a leaf stalk, with veins visible on the lower surface

Animal Phyla  Animals are divided into over 30 phyla  Distinguish between the following phyla of animals, using simple external recognition features. (see page 267)

Porifera  Sponges  Most primitive animals with a simple body  Live in water  Do not move around  No mouth, but have small holes through which water is pumped into body and have be filtered for food before pumping out

Cnidaria  Jellyfish and sea anemones  Have stinging cells  Radially symmetrical  Have a gastro-vascular cavity (a hollow space in the centre of the body) with only one opening to the cavity  Often have tentacles around the opening

Plathyelminthes  Flatworms  Soft flattened body with a definite head region  Bilateral symmetry  Gastro-vascular cavity  Usually one opening to cavity  Live in water or damp environments  Can be free-living or parasitic

Arthropoda  Animals with jointed legs  Ex: insects, arachnids, crustaceans  Exoskeleton made of chitin (a polysaccharide)  Segmented body  Appendages to each segment  At least 3 pairs of legs  May be free living or parasitic

Annelida  Worms and leeches  Bodies of ring-like segments  Have a mouth and an anus  Live in water or moist soil  May be free living or parasitic  No legs  Bristles from body which help them move

Mollusca  Snails, squids, clams, slugs  Soft unsegmented bodies  May have a shell

Chordates - Vertebrates  All are vertebrates because they have a backbone composed of vertebrae  There are 5 major classes of chordates  You need to recognise the features of birds, mammals, amphibians, reptiles, and fish (page 268)

Birds  Skin with feathers made of keratin  2 legs, 2 wings  Females lays eggs with shells  Maintain constant body temp

Birds

Mammals  Skin with follicles with hair made of keratin  Lungs with alveoli, ventilated used ribs and diaphragm  Give birth to live young and all feed young with milk from mammary glands  Maintain constant body temperature

Mammals

Amphibians  Soft moist skins permeable to water and gases  Simple lungs with small folds and moist skin for gas exchange  4 legs as an adult  Larval stages lives in water and as an adult usually lives on land  Do not maintain constant body temp

Amphibians

Reptiles  Impermeable skin covered in scales of keratin  Lungs with extensive folding to increase the surface area  Female lays eggs with soft shells  Do not maintain constant body temp

Reptiles

Fish  Scales with are bony plates in the skin  Gills  No limbs  Remain in water throughout their life cycle  Do not maintain constant body temp

Fish

Dichotomous Keys  Apply and design a key for a group of up to eight organisms.  Keys are most commonly used to identify plants, insects, and birds.  You need to be able to construct a dichotomous key page 265