Classification(Taxonomy)

-naming and classification of species

Topics:• History of

classification• Current Scheme• Five/six kingdom

system• Kingdoms

overview

• To trace phylogeny (the evolutionary history of life) biologists use evidence from paleontology, molecular data, comparative anatomy, etc.

• Tracing phylogeny is one of the main goals of systematics, (the study of biological diversity in an evolutionary context.)

• Systematics includes taxonomy, which is the naming and classsification of species and groups of species.

As Darwin correctly predicted, “our classifications will come to be, as far as they can be so made, genealogies.”

Introduction

AristotleAristotle

Ancient Greece— Aristotle was the first to

use a classification

system. classified living things

into two categories: plants

and animals.

PlantsPlants -shrubs, herbs, or

trees.AnimalsAnimals -according to

where they lived.His classification system was based on structural

differences that were seen.

(384 BC to 322 BC)

Carolus Linnaeus (1707-1778) Carolus Linnaeus (1707-1778)

Considered to be the Father of modern

Taxonomy

Swedish Botantist

based hisbased hisclassification on classification on characteristics characteristics of of organisms that organisms that were similar.were similar.

Developed the two word system used to identify species: binomial nomenclature.

• First formally proposed system.

• Systema naturae in the 18th century, has two main characteristics.• Each species has a two-part

name.

• Species are organized hierarchically into broader and broader groups of organisms.

Taxonomy employs a hierarchical system of classification

Carolus Linnaeus(1707-1778)

• Each species is assigned a two-part latinized name, a binomial.

• The first part, the genusgenus, is the closest group to which a species belongs.

• The second part, the specific epithet, refers to one speciesspecies within each genus.

• The first letter of the genus is capitalizedcapitalized and both names are italicized & latinized.• Homo sapiens, which means “wise man”

Binomial Nomenclature.

• Groups species into broader taxonomic categories.

• Species that appear to be closely related are grouped into the same genus.

• For example, the leopard, Panthera pardus, belongs to a genus that includes the African lion (Panthera leo) and the tiger (Panthera tigris).

• Biology’s taxonomic scheme formalizes our tendency to group related objects.

Taxons

Hierarchical Classification

From Kingdom to From Kingdom to SpeciesSpecies

Timeline of ClassificationTimeline of Classification1. 1. 384 – 322 B.C. Aristotle384 – 322 B.C. Aristotle

2 Kingdom Broad Classification2 Kingdom Broad Classification2. 2. 1735 - Carl Linnaeus 1735 - Carl Linnaeus

2 Kingdom Multi-divisional Classification2 Kingdom Multi-divisional Classification Kingdom, Phylum, Class, Order, Family Kingdom, Phylum, Class, Order, Family

Genus, SpeciesGenus, Species3. Evolutionary Classification – (3. Evolutionary Classification – (After After

DarwinDarwin)) Group By lines of Evolutionary DescentGroup By lines of Evolutionary Descent

4. 5 Kingdom System – 1950s4. 5 Kingdom System – 1950s5. 6 Kingdom System – 1990s5. 6 Kingdom System – 1990s6. 3 Domain System – 1990s6. 3 Domain System – 1990s

Phylogenetic Trees reflect the hierarchical classification of many taxonomic groups.

Phylogeny is

determined by a

variety of evidence including fossils,

molecular data,

anatomy, and other features.

• Most systematists use cladistic analysis, developed by a German entomologist Willi Hennig to analyze the data

• A phylogenetic diagram or cladogramcladogram is constructed from a series of dichotomiesdichotomies.

Modern phylogenetic systematics is based on cladistic analysis

Systematics-the study of biological diversity in an evolutionary context.

• These dichotomous branching diagrams can include more taxa.

• The sequence of branching symbolizes historical chronology.

• The last ancestor common to both the cat and dog families lived longer ago than the last commonancestor shared by leopards and domestic cats.

branch or clade

Can not always base clade on appearance.Can not always base clade on appearance.

• It is especially important to distinguish similarities that are based on shared ancestry or homology from those that are based on convergent evolution or analogy.

• These two desert plants are not closely related but owe their resemblance to analogous adaptations (convergent evolution).

• The presence of hair is a good character to distinguish the clade of mammals from other tetrapods.

Analyzing the taxonomic distribution of homologies enables us to identify the sequence in which derived characters evolved during vertebrate phylogeny.

A cladogram presents the chronological sequence of branching during the evolutionary history of a set of organisms.

Systematics Systematics is the study of the diversity of organisms using information from cellular to population levels.

1. Classification reflects phylogeny; one goal of systematics is to create phylogenetic trees.

2. Phylogeny is the evolutionary history of a group of organisms.

3. A phylogenetic tree indicates common ancestors and lines of descent.

4. A primitive characterprimitive character is a trait that is present in a common ancestor and all members of a group.

5. A derived characterderived character is present only in a specific line of descent.

6. Different lineages diverging from a common ancestor may have different derived characters.

• The timing of evolutionary events has rested primarily on the fossil record.

• Recently, molecular clocks have been applied to place the origin of taxonomic groups in time.

• Molecular clocks are based on the observation that some regions of genomes evolve at constant rates.

• For these regions, the number of nucleotide and amino acid substitutions between two lineages is proportional to the time that has elapsed since they branched.

Molecular clocks may keep track of evolutionary time

• For example, the homologous proteins of bats and dolphins are much more alike than are those of sharks and tuna.

• This is consistent with the fossil evidence that sharks and tuna have been on separate evolutionary paths much longer than bats and dolphins.

• In this case, molecular divergence has kept better track of time than have changes in morphology.

Archae-bacteria

Eu-Bacteria

Protista

Fungi

Plantae

Animalia

Six Kingdoms of LifeArchaea

Bacteria

Eukarya

•Archaebacteria

Six Kingdoms of Life

•All Single celled prokaryotes•Anaerobes and aerobes•One circular chromosome•Heterotrophic and autotrophic

•Eubacteria

Six Kingdoms of Life

•Widest variety of organisms•All eukaryotes•Single and multicellular•Heterotrophic and autotrophic

Protista

Six Kingdoms of Life

•All Heterotrophic•Eukaryotic•Single and multicellular•Important as decomposers•Cell walls made of chitin•4 divisions

Fungi

Six Kingdoms of Life

•All Autotrophic•Eukaryotic•All multicellular•Cell walls made of cellulose•10 divisions

Plantae

Six Kingdoms of Life

•All heterotrophic•All Eukaryotic•All multicellular•35 phyla

Animalia

Mrs. Payne