Systematics
 Biological systematics is :
Nomenclature & The Tree of Life
Why Classify?
 In binomial nomenclature, each species is assigned a ___________-____________ scientific name.
 The goal of systematics is to:
Why Binomial Nomenclature?
 By using a scientific name, biologists can be sure that they are discussing the same _____________________.
Common names can be confusing because they vary among ____________________ and from place to place.
 For example, the names __________________, puma, panther, and mountain lion can all be used to
indicate the same animal— Felis Concolor.
Binomial Nomenclature
 The first part of the name—Ursus—is the _________________ to which the organism belongs.
 A genus:
 The genus Ursus contains five other species of bears, including Ursus arctos, the brown bear or grizzly
bear.
 The second part of a scientific name—maritimus for polar bears—is unique to each species and is
often a description of the organism’s _______________________ or of an important ________________.
 The Latin word maritimus refers to the _____________: polar bears often live on pack ice that
floats in the sea.
Linnaean Classification
 Linnaeus also developed a classification system that organized species into a _______________________, or
ranking.
 Kingdom, Phylum, Class, _________________, Family, Genus, Species
Our Classification
 Kingdoms
 The _____________-kingdom system of classification includes the kingdoms Eubacteria,
Archaebacteria, Protista, Fungi, Plantae, and Animalia
Three Domains
 A domain is a larger, more ___________________ category than a kingdom.
 Under this classification there are three domains –
 Bacteria, Archaea, Eukarya
Domain Bacteria
 Members of the domain Bacteria are unicellular and _______________________. This domain corresponds
to the kingdom Eubacteria.
 Their cells have thick, rigid ______________ that surround a cell membrane and contain a substance
known as peptidoglycan.
Domain Archaea
 Members of the domain Archaea are unicellular and prokaryotic, and they live in some extreme
________________________. Many of these bacteria can survive only in the absence of ____________________.
 Their cell walls lack peptidoglycan, and their cell membranes contain unusual ___________________ that
are not found in any other organism.
Domain Eukarya
 The domain Eukarya consists of all organisms that have a ___________________. It comprises the four
remaining kingdoms of the six-kingdom system: “Protista,” Fungi, Plantae, and Animalia.
“Protists” – Unicellular Eukaryotes
 Recent molecular studies and cladistic analyses have shown that “the eukaryotes formerly known as
“Protista” do not form a single clade. Current cladistic analysis divides these organisms into at least
five clades.
 Since these organisms cannot be properly placed into a single taxon, we refer to them as “protists.”
 Most “protists” are _______________________, but one group, the brown algae, is multicellular.
 Some “protists” are ______________________, while others are heterotrophic.
 Some display characters that resemble those of fungi, plants, or animals.
Fungi
 Members of the kingdom Fungi are ________________________ with cell walls containing chitin.
 Mushrooms and other recognizable fungi are ________________________, like the ghost fungus
shown. Some fungi—yeasts, for example—are unicellular.
 Most fungi feed on dead or ____________________ organic matter.
 They secrete digestive ____________________ into their food source, which break the food down
into smaller molecules.
 The fungi then __________________ these smaller molecules into their bodies.
Plantae
 Members of the kingdom Plantae:
 are _________________________,
 have cell walls that contain _________________________,
 are _______________________ (can make their own food).
Animalia
 Members of the kingdom Animalia are:
 Multicellular
 __________________________(get their food from external sources).
 Animal cells do not have cell ___________________.
Evolutionary Classification
 The goal of phylogenetic systematics, or evolutionary classification, is to group species into larger
categories that reflect lines of evolutionary __________________, rather than overall similarities and
differences.
Cladograms
 A cladogram links groups of organisms by showing how evolutionary lines, or lineages, branched off
from common _______________________.
Building Cladograms
 A _______________________ event, in which an ancestral lineage branches into two new lineages, is the
basis for each branch point, or node. Each node represents the last point at which the new lineages
shared a common _____________________.
 The bottom, or “root,” of the tree represents the common ____________________ shared by all organisms
on the cladogram.
 A cladogram’s branching patterns indicate degrees of ______________________ among organisms.
 Note that in terms of ancestry, _____________________ are more closely related to mammals than they are
to ray-finned fish!
Reading Cladograms
 This cladogram shows a simplified ____________________ of the cat family.
Derived Characters
 A derived character is:
 The positions of the derived characters on the cladogram reflect the ___________________ in which those
characteristics arose in a lineage.
 Retractable claws is a derived character shared only by members of the clade Felidae.