copyright © 2005 pearson prentice hall, inc. chapter 18 systematics: seeking order amidst diversity

Copyright © 2005 Pearson Prentice Hall, Inc.

Chapter 18

• Systematics: Seeking Order Amidst Diversity


How Are Organisms Named and Classified?

• Classification of Selected Organisms, Reflecting Their Degree of Relatedness*

(T18.1 p. 346)


Three species of bluebird

(F18.1 p. 346)



• Classification Originated as a Hierarchy of Categories

• Systematists Identify Features That Reveal Evolutionary Relationships

• Anatomy Plays a Key Role in Systematics– Microscopic structures may

be used to classify organisms (F18.2 p. 347)



• Molecular Similarities Are Also Useful for Reconstructing Phylogeny– Human & chimp

chromosomes are similar (F18.3 p. 348)


What Are the Domains of Life?

• The Five-Kingdom System Improved Classification

• A Three-Domain System More Accurately Reflects Life’s History– Two domains of prokaryotic organisms (F 18.4 p.

349)

– The tree of life (F18.5 p. 349)


BACTERIAARCHAEA

EUKARYA

animalsfungi

plants

protists

The tree of life (F18.5 p. 349)


What Are the Domains of Life?

• Kingdom-Level Classification Remains Unsettled– Relatedness can be determined by

comparing DNA sequences (FE18.1 p. 350)

– A closer look at the eukaryotic tree of life (F18.6 p. 351)


PLANTAE ANIMALIAFUNGI“PROTISTS”

to Archaea

to Bacteria

Sar

com

astig

opho

ra(z

oofla

gella

tes,

sar

codi

nes)

Api

com

plex

a(s

poro

zoan

s)

Pyr

roph

yta

(din

ofla

gella

tes)

Cili

opho

ra(c

iliat

es)

Eug

leno

phyt

a(e

ugle

noid

s)

Pha

eoph

yta

(bro

wn

alga

e)

Oom

ycot

a(w

ater

mol

ds)

Rho

doph

yta

(red

alg

ae)

Chl

orop

hyta

(gre

en a

lgae

)

Bry

ophy

ta(li

verw

orts

, m

osse

s)

Pte

ridop

hyta

(fer

ns)

Con

ifero

phyt

a(c

onife

rs)

Ant

hoph

yta

(flo

wer

ing

plan

ts)

Zyg

omyc

ota

(zyg

ote

fung

i)

Asc

omyc

ota

(sac

fun

gi)

Bas

idio

myc

ota

(clu

b fu

ngi)

Por

ifera

(spo

nges

)

Cni

daria

(hyd

ras,

ane

mon

es,

jelly

fish)

Pla

tyhe

lmin

thes

(fla

twor

ms)

Mol

lusc

a(s

nails

, cl

ams,

squ

id)

Ann

elid

a(s

egm

ente

d w

orm

s)

Art

hrop

oda

(inse

cts,

ara

chni

ds,

crus

tace

ans)

Ech

inod

erm

ata

(sea

sta

rs,

sea

urch

ins,

sea

cuc

umbe

rs)

Cho

rdat

a(t

unic

ates

, la

ncel

ets,

ver

tebr

ates

)

Activity 18.2


Human ChimpPygmychimp Gorilla Orangutan

Common gibbon

Evolutionary

Relationships

by DNA Analysis


Why Do Classifications Change?

• Species Designations Change When New Information Is Discovered

• The Biological Species Definition Can Be Difficult or Impossible to Apply– The Phylogenetic Species Concept

Offers an Alternative Definition


How Many Species Exist?

• The black-faced lion tamarin (F18.7 p. 352)

• Reptiles are not a monophyletic group (F18.8 p. 353)

• Evolutionary analysis helps reveal the origin of HIV (F18.9 p. 354)


1 2 3 4

A

1 2 3 4

A

Crocodiles Birds Snakes Lizards Turtles

1-4 are monophyletic

on the left

(ALL the descendants of one

common ancestor)

But NOT on the right

Reptiles are not monophyletic!!


1 2 3 4

A

1 2 3 4

A


Crocodiles Birds Snakes Lizards Turtles


HIV-2 (strain 2)

SIV-pig-tailed macaque

SIV-sooty mangeby monkey

HIV-2 (strain 1)

SIV-mandrill

SIV-chimpanzee (strain 2)

HIV-1 (strain 2)

SIV-chimpanzee (strain 1)

HIV-1 (strain 1)Human HIVs

Do Not Cluster

2 Separate

Cross-

Species

Jumps:

One of

HIV-1

&

One of

HIV-2

copyright © 2005 pearson prentice hall, inc. chapter 18 systematics: seeking order amidst diversity

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