Classification The arrangement of organisms into orderly groups based on their

similarities The branch of biology that involves classifying is called taxonomy Taxonomists are scientists that identify & name organisms

Benefits of Classifying Accurately & uniformly names organisms Uses same language, Latin or some Greek, for all names

Basis for Classification Structural similarities, likely evolved from common ancestor Ex: lynxes

and bobcats If number & structure of chromosomes are similar, may have common

ancestor Ex: cabbage, cauliflower and kale -> almost identical chromosome structure

Similar organisms have similar DNA sequence Ex: giant panda is more closely related to a bear than the red panda

Classification Groups Taxon (taxa-plural) is a category into which related organisms are

placed There is a hierarchy of groups (taxa) from broadest to most specific Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

(Dapper King Phillip Came Over From Germany Singing)

Domains Broadest & most inclusive taxon 3 domains Archae & Eubacteria are unicellular prokaryotes (no nucleus or

membrane bound-organelles) Eukarya are more complex (have a nucleus & are membrane-bound

organelles)

Archaea 1st cells to evolve live in harsh environments found in sewage treatment plants, thermal or volcanic vents, hot

springs or geysers that are acid or very salty H2O such as the Dead Sea or the Great Salt Lake

Eubacteria some cause disease found in ALL habitats EXCEPT harsh ones important decomposers for the environment commercially important in making yogurt, cottage cheese, and

buttermilk

Domain Eukarya is divided into Kingdoms Protista – Ex: paramecium, slime mold

o Most are unicellular, some multicellularo Some are autotrophic, while others are heterotrophico Aquatic

Fungi - Ex: mushrooms, yeastso Multicellular, except yeasto Absorptive heterotrophs (digest food outside their body & then

absorb it)o Cell walls made of chitin

Plantae (multicellular plants) – Ex: mosses, fernso Autotrophico Absorb sunlight to make glucose – photosynthesiso Cell walls made of cellulose

Animalia (multicellular animals) Ex: fish, reptileso Ingestive heterotrophs (consume food & digest it inside their

bodies)o Feed on plants or animals

Taxons Most genera contain a number of similar species The species homo is an exception (only contains modern humans) Classification is based on evolutionary relationships

Cladogram – diagram showing how organisms are related based on shared, derived, characteristics such as feathers, hair, or scales

Dichotomous Keying Used to identify organisms Characteristics given in pairs Read both characteristics and either go to another set of

characteristics OR identify the organism

Early Taxonomists Aristotle was the 1st taxonomist He divided organisms into plants and animals Further subdivided them by their habitat – land, air, or sea dwellers

Linnaeus classified organisms by their similar structure Developed naming system still used today, uses Latin Called “the Father of Taxonomy” Developed the modern system of naming known as binomial

nomenclature, genus & species

Standardized Naming System Italicized in print Capitalize genus, but NOT species Underline when writing

Convergent Evolution – different organisms that live in similar environments become more alike in appearance & behavior Ex: bird wings/insect wings

Coevolution – when 2 species evolve together. There is a mutual evolutionary influence between 2 species. The species have a symbiotic relationship. Ex: birds & flowers

Divergent evolution – ancestral species gives rise to a number of new species that are adapted to different environmental conditions and are less alike. Ex: Darwin’s finches

Punctuated Equilibrium – some populations don’t change much over time, but have rapid periods of change in between long stable periods Ex: horseshoe crab haven’t evolved much but fossil records show short periods of speciation.