classification chapter 18 · –unicellular to multicellular –autotrophic to heterotrophic...
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ClassificationChapter 18
• The domain system
– Prokaryotic domains Bacteria and Archaea
– Eukaryotes
• Are in the domain Eukarya
Bacteria Archaea Eukarya
Earliest
organisms
Prokaryotes
Eukoryotes
Figure 15.10B
Two patterns of evolutionary change
(b) Cladogenesis(a) Anagenesis
Hierarchical classificationPanthera
pardus
Panthera
Felidae
Carnivora
Mammalia
Chordata
Animalia
EukaryaDomain
Kingdom
Phylum
Class
Order
Family
Genus
Species
The connection between classification and phylogeny
Panthera pardus
(leopard)
Mephitis mephitis
(striped skunk)
Lutra lutra (European
otter)
Canis familiaris
(domestic dog)
Canislupus (wolf)
Panthera Mephitis Lutra Canis
Felidae Mustelidae Canidae
Carnivora
Ord
er
Fa
mil
yG
en
us
Sp
ec
ies
Monophyletic, paraphyletic, and polyphyletic groupings
(b) Paraphyletic. Grouping 2 does not
meet the cladistic criterion: It is
paraphyletic, which means that it
consists of an ancestor (A in this case)
and some, but not all, of that ancestor’s
descendants. (Grouping 2 includes the
descendants I, J, and K, but excludes
B–H, which also descended from A.)
(c) Polyphyletic. Grouping 3 also fails the
cladistic test. It is polyphyletic, which
means that it lacks the common ancestor
of (A) the species in the group. Further-
more, a valid taxon that includes the
extant species G, H, J, and K would
necessarily also contain D and E, which
are also descended from A.
D E
C
G H
F
J K
I
D E
C
G H
F
J K
I
D E
C
G H
F
J K
I
B
A
B
A
B
A
Grouping 2 Grouping 3Grouping 1
(a) Monophyletic. In this tree, grouping 1,
consisting of the seven species B– H, is a
monophyletic group, or clade. A mono-
phyletic group is made up of an
ancestral species (species B in this case)
and all of its descendant species. Only
monophyletic groups qualify as
legitimate taxa derived from cladistics.
Constructing a cladogram
Sala
mander
TAXA
Turt
le
Leopard
Tuna
Lam
pre
y
Lancele
t(o
utg
roup)
0 0 0 0 0 1
0 0 0 0 1 1
0 0 0 1 1 1
0 0 1 1 1 1
0 1 1 1 1 1
Hair
Amniotic (shelled) egg
Four walking legs
Hinged jaws
Vertebral column (backbone)
Leopard
Hair
Amniotic egg
Four walking legs
Hinged jaws
Vertebral column
Turtle
Salamander
Tuna
Lamprey
Lancelet (outgroup)
(a) Character table. A 0 indicates that a character is absent; a 1
indicates that a character is present.
(b) Cladogram. Analyzing the distribution of these
derived characters can provide insight into vertebrate
phylogeny.
CH
AR
AC
TE
RS
Trees with different likelihoodsHuman
Tree 1: More likely
Mushroom Tulip
40%
40%
0
30%
0
0Human
Mushroom
Tulip
(a) Percentage differences between sequences
(b) Comparison of possible trees
Tree 2: Less likely
15%
5%
15% 20%
5%10%
15%
25%
Monera Protista Plantae Fungi Animalia
Earliest
organisms
Prokaryotes
Eukoryotes
Figure 15.10A
• Arranging life into kingdoms is a work in progress
– In the five-kingdom system
• Prokaryotes are in the kingdom Monera
• Eukaryotes (plants, animals, protists, and fungi) are grouped in separate kingdoms
Prokaryotes (Monera)Bacteria live EVERYWHERE!
• Bacteria live in all ecosystems
– on plants & animals
– in plants & animals
– in the soil
– In EXTREMES (hot, cold, acid, salt, deep)
– on the living
– on the dead
Microbes alwaysfind a way tomake a living!
Prokaryote Structure
• Unicellular
– bacilli, cocci, spirilli
• Size
– ~1/10 size of smallest eukaryotic cell
• 1 micron (1um)
• Internal structure
– no internal compartments
• no membrane-bound organelles
• only ribosomes
– circular chromosome, naked DNA
• not wrapped around proteins
prokaryotecell
eukaryote cell
Protista:General characteristics
• Classification criteria
– eukaryotes
– not animal, plant or fungi
That’s more ofwhat they’re not& notwhat they are!
Protist Diversity
• The full spectrum of modes of life
– unicellular to multicellular
– autotrophic to heterotrophic
– asexual to sexual reproduction
– pathogenic to beneficial
– sessile to mobile
Problems with Protist Classification
Something’snot right here!
• Too Diverse!– doesn’t reflect any evolutionary relationship amongst
all kingdom members
– paraphyletic
Plantae:
Bryophytes
non-vascular
land plants
Pteridophytes
seedless
vascular plants
Gymnosperm
pollen &
“naked” seeds
Angiosperm
flowers & fruit
pollen & seeds
vascular system = water conduction
mosses ferns
conifersflowering plants
colonization of land
Tracheophytes
xylem cells = tracheidsAncestral Protist
flowers
Fungi:General characteristics
• Classification criteria
– eukaryotes
– heterotrophs
• Absorb nutrients
– mostly multicellular
• EXCEPT unicellular yeasts
– cell wall
• chitin
– rigid polysaccharide
– sexual & asexual reproduction
Fungal Structure
• Fungal body
– mycelium
• thread-like cells
• hyphae
• Cells
– multiple nuclei
• Cell wall
– chitin
• just like crab shells
Ecological Roles
• Decomposers– recycle nutrients
• Symbiotic Relationships– lichen
• fungi + algae– cyanobacteria or green algae
• pioneer species in ecosystems
• makes soil from bare rock
– mycorrhizae• fungi + plants
• enables plants to absorb more water
Lichens are fungi that have discovered agriculture!
Fungal Diversity
Fungi
Animal Characteristics
• Heterotrophs
– must ingest orgnaisms (“food”) for nutrients
• Multicellular
– complex
• No cell walls
– Allows quickmovement
• Sexual reproduction
– no alternation of generations
– no haploid gametophyte
Porifera
Cnidaria
Platyhelminthes
sponges jellyfish flatworms roundworms
Nematoda
Mollusca Arthropoda Chordata
Annelida Echinodermata
mollusks
multicellularity
Ancestral Protist
tissues
bilateral symmetry
body cavity
segmentation
Animal Evolution
coelom
starfish vertebrates
endoskeleton
segmentedworms
insectsspiders
backbone
specialization & body complexity
specialized structure & function,
muscle & nerve tissue
distinct body plan; cephalization
body complexity
digestive & repro sys
digestive sys
body size
redundancy,
specialization, mobility
body & brain
size, mobility
radial
bilateral
Review Questions
1. The temperature at which hybrid DNA melts is indicative of the degree of homology between the DNA sequences. The more extensive the pairing, the higher the temperature required to separate the strands. You are trying to determine the phylogenetic relationships among species A, B, and C. You mix single-stranded DNA from all three species (in test groups of two) and measure the temperatures at which the hybrid DNA melts (separates). You find that hybrid BC has the highest melting temperature, AC the next highest, and AB the lowest.
(cont.) From these data you conclude that *A. species A and B are most closely related, whereas B and
C are least closely related.
B. B and C must be the same species, and A is more closely related to C than to B.
C. species B and C must have diverged most recently, and A is more closely related to C than to B.
D. A hybridizes most easily with B, and they must have a more recent common ancestor than do A and C.
E. these tests are inconclusive and you had better go back and check the fossil record.
2. According to this dichotomous phylogenetic tree created using cladistic analysis, C and D are most closely related because they
A. do not share a common ancestor with O, A, or B.
B. are monophyletic.C. evolved from a common
ancestor a long time ago.D. have the most shared
derived characters in common.
E. have the greatest number of anatomical similarities as shown by statistical analysis.
3. A biologist discovers two new species of organisms, one in Africa and one in South America. The organisms resemble one another closely. Which type of evidence would probably be least useful in determining whether these organisms are closely related or are the products of convergent evolution?
A. the history and timing of continental drift
B. a comparison of DNA from the two species
C. the fossil record of the two species
D. analysis of the behavior of the two species
E. comparative embryology
Use Figure 25.1 to answer the following questions.
4. A common ancestor for species C and E could be at position numberA. 1.
B. 2.
C. 3.
D. 4.
E. 5.
E. The two extant species that are most closely related to each other are
1. A and B.
2. B and D.
3. C and B.
4. D and E.
5. E and A.
5. If this evolutionary tree is an accurate depiction of relatedness, then which of the following should be correct?
A. The entire tree depicts anagenesis.
B. If all species depicted here make up a taxon, this taxon is monophyletic.
C. The last common ancestor of species B and C occurred more recently than the last common ancestor of species D and E.
D. Species A is the ancestor of both species B and C.
E. The species present at position number three is ancestral to three extant species.
1. B only
2. A and C
3. C and D
4. B, C, and D
5. B, C, and E
A researcher compared the nucleotide sequences of a homologous gene from five different species of mammals. The sequence homology between each species' version of the gene and the human gene are presented as a percentage of similarity.
Species Percentage
Chimpanzee 99.7
Orangutan 98.6
Baboon 97.2
Rhesus Monkey 96.9
Rabbit 93.7
6. What conclusion can be validly drawn from these data?
A. Humans and other primates evolved from rabbits.
B. All organisms have similar DNA.
C. Among the organisms listed, humans shared a common ancestor most recently with chimpanzees.
D. Humans evolved from chimpanzees.
E. Both A and D are correct.
7. Which statement represents the best explanation for the observation that the nuclear DNA of wolves and domestic dogs has a very high degree of homology?
A. Dogs and wolves have very similar morphologies.
B. Dogs and wolves belong to the same genus.
C. Dogs and wolves are both members of the family Canidae.
D. Dogs and wolves shared a common ancestor relatively recently.
E. Convergent evolution has occurred.