Classification

What we need to learn How and why organisms are hierarchically classified

and based on evolutionary relationships

Learn the reasons for changes in how organisms are classified

Learn the distinguishing characteristics of the domains and kingdoms of living organisms

Classifying Organisms One branch of biology investigates biodiversity

The variety of organisms considered at all levels from populations to ecosystems

Every year scientists find new species and try to classify them in a meaningful way

This species has scales and a stinky tongue to catch ants

What species would you group this with?

Taxonomy The science of describing, naming, and classifying

organisms is called Taxonomy

Any particular group within a taxonomic system is called a

Taxon

Taxonomy Early work to classify organisms only looked at their

life on land or in water

As more species were named, this system became inadequate

Common names were widely used but ran into issues Some common names don’t truly identify the species

The Linnaean System Carolus Linnaeus developed a

system to categorize according to form and structure

Levels of Classification The modern version of Linnaeu’s system

Binomial Nomenclature Scientific name Latin Starts with with genus name Followed by species identifier

Homo sapiens Homo-genus Sapiens-species

Levels of classification Name of species is often very descriptive

Always capitalize first name, lower case second. ALWAYS italicize the names

Subspecies names are often needed When the same species lives in different geographic areas

Terrapene carolina triunui is a subspecies of Terrapene carolina

Systematics

Phylogenetics We have already learned this

Phylogenetic trees? Remember?

Phylogenetics The analysis of the evolutionary or ancestral

relationships among taxa

Evidence of Shared Ancestry

Remember homologous and analogous structures? YOU BETTER!

Systematics use homologous structures

Analogous structures and misidentify species

Pangolins and dogs have similar jaw structures We therefore classify them with dogs

If we classified them based on their scales, what would we classify them with?

Cladistics Cladistics-a system of phylogenetic analysis that

uses shared and derived characteristics as the only criteria for grouping taxa

Shared characteristic- a feature that all members of a group have in common Hair in mammals Feathers in birds

Derived characteristics- features that evolved only within the group under consideration

Cladistics Clade- the group of organisms that includes an

ancestor plus all its descendants

Cladograms-diagrams that show clades and characteristics

Modern Classification

Three Domains of Life Domain Bacteria

Small single celled prokaryotic organisms

Have a cell wall, plasma membrane, cytoplasm that lacks complex organelles

Reproduce by cellular fission

No membrane bound DNA, therefore no nucleus

Three Domains of Life Domain Archea

Consists of prokaryotes Distinctive cell membranes Some are autotrophic, and produce food by

chemosynthesis Some produce flammable gases, such as methane Many inhabit harsh environments Scientists think archea were among the earliest

organisms on Earth Archaea and bacteria have possible coevolved

Three Domains of Life Domain Eukarya

Most familiar group Consists of eukaryotic

organisms Large cells that have

true nucleus and complex cellular organelles

Plants Animals

The Six Kingdoms Eubacteria

True bacteria

The Six Kingdoms Archaebacteria

Literally means “ancient bacteria” So different from bacteria now, scientists only use

“archaea” to name them

The Six Kingdoms Protista

First of 4 eukaryotes Called protists Defined as those eukaryotes

that are not plants, animals, or fungi

Most are unicellular Scientists actually think the

kingdom “Protista” is no longer useful. Most protista are not related to each other

Amoebas and paramecia Some seaweed and molds

The Six Kingdoms Fungi

Eukaryotic Heterotrophic Unicellular, multicellular Fungi absorb nutrients rather than ingest them 70,000 species of fungi

The Six Kingdoms Plantae

Eukaryotic Multicellular Besides some parasitic

plants, most are autotrophic Use photosynthesis as a

source of energy Develop from embryos Most live on land Mosses, ferns, flowering

plants

The Six Kingdoms Animalia

Eukaryotic Multicellular Heterotrophic Develop from embryos Symmetrical body

organization Move around their

environment to find and capture food