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L. O. U. V. T. E. I. O. N. Fig. 16-4b, p.239. EVOLUTION = change over time which is inherited. Macroevolution: major changes of life on earth since its formation 4.6 billion years ago from fossils to present-day species 2. Microevolution:

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L

O

U

V

T

E

I

O

N

Fig. 16-4b, p.239


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EVOLUTION

= change over time

which is inherited

  • Macroevolution:

  • major changes of life on earth since its formation 4.6 billion years ago

  • from fossils to present-day species

  • 2. Microevolution:

  • small scale changes in allele frequencies in the gene pool of a population

  • from mutations to speciation events


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Speciation

Definition (Ernst Mayr): Species are groups of interbreeding natural populations (which produce fertile offspring) that are reproductively isolated from other such groups.

Many/large microevolutionary steps

 new species

Reproductive isolation

Gene flow between populations stops = gene pools stay separate

Genetic divergence (change)

of structural, function, or behavioral traits

Reproductive isolation: populations are not longer reproductively compatible = a new species has originated


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How is gene flow stopped?

  • Separation by a physical barrier (created by glaciation, earth quakes, volcanic activity, formation of mountains, land bridges = allopatric speciation

  • Ecological separation without physical barriers (different food, mating areas) = sympatric speciation


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How is gene flow stopped?

  • Separation by a physical barrier (created by glaciation, earth quakes, volcanic activity, formation of mountains, land bridges = allopatric speciation

North American Prairie

camelid ancestor

landbridges

camels

Asia, Africa

Ilama

South America

vicuna

South America


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Stepped Art

1

A few individuals of a species on the mainland reach isolated island 1. Speciation follows genetic divergence in a new habitat.

3

2

4

Later in time, a few individuals of the new species colonize nearby island 2. In this new habitat, speciation follows genetic divergence.

1

2

Speciation may also follow colonization of islands 3 and 4. And it may follow invasion of island by genetically different descendants

of the ancestral species.

1

3

2

4

How is gene flow stopped?

  • Separation by a physical barrier (created by glaciation, earth quakes, volcanic activity, formation of mountains, land bridges = allopatric speciation

New islands created by volcanic activity.

Fig. 17-20a, p.275



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How is gene flow stopped?

2. Ecological separation without physical barriers (different food, mating areas) = sympatric speciation

Cichlids in Africa live on different food sources  many species in one lake.

Fig. 17-21a, p.276


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Speciation

Definition (Ernst Mayr): Species are groups of interbreeding natural populations (which produce fertile offspring) that are reproductively isolated from other such groups.

Many/large microevolutionary steps

 new species

Reproductive isolation

Gene flow between populations stops = gene pools stay separate

Genetic divergence (change)

of structural, function, or behavioral traits

Reproductive isolation: populations are not longer reproductively compatible = a new species has originated



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Naming species - taxonomy

  • Scientific name:

  • Latin

  • Binomial (2 parts: generic name + species epithet

Ursus arctos – brown bear

Ursus americanus – black bear

common name

genus

species


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Ranking species - classification

Ursus arctos – brown bear

Ursus americanus – black bear

Fig. 17-27, p.280





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Evolutionary Tree of Life

The three domain system:

Webpage:

http://tolweb.org/tree/phylogeny.html

p.259c


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Evolutionary Tree of Life

ANIMALS

PLANTS

arthropods

chordates

FUNGI

flowering plants

conifers

annelids

roundworms

club

fungi

echinoderms

sac

fungi

ginkgos

mollusks

cycads

horsetails

rotifers

zygospore-

forming

fungi

ferns

flatworms

cnidarians

lycophytes

bryophytes

chytrids

charophytes

sponges

chlorophytes

amoeboid

protozoans

PROTISTS

choanoflagellates

(stramenopiles)

brown algae

alveolates

red algae

ciliates

chrysophytes

apicomplexans

oomycotes

dinoflagellates

“crown” of eukaryotes

(rapid divergences)

euglenoids

slime molds

kinetoplatids

Parabasalids

(e.g., Trichomonas)

ARCHAEA

BACTERIA

spirochetes

diplomonads

crenarchaeotes

euryarchaeotes

Gram-positive bacteria

chlamydias

cyanobacteria

korarchaeotes

Webpage:

http://tolweb.org/tree/phylogeny.html


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Phylogenetic trees illustrate the relationship between species.

  • What type of evidence/support is used to build a tree?

  • Biochemical evidence

  • Fossil evidence

  • Morphological evidence

  • Developmental evidence

Fig. 17-15, p.271


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1. Biochemical evidence: species.

DNA, protein, or metabolite analysis

DNA example

ATGCGCCTTAGCA polar bear

TTGCGCCTAAGCA brown bear

GTCGGCCTAATCT black bear

protein example (cytochrome c needed for respiration):

conserved areas between Yeast/wheat/primate

Fig. 17-14b, p.271


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1. Biochemical evidence: species.

DNA, protein, or metabolite analysis

Molecular clock:

Time scale of biochemical analysis: when have species diverged from each other?

Assumption: neutral mutations happen at a constant rate


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2. Fossil evidence: species.

  • Evidence of ancestral species

  • Evidence for a time scale:

  • the deepest layer in the ground contains the oldest fossils

  • radiometric dating

p.259b



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Radiometric Dating species.

Uranium (in rocks) → Lead: the earth is at least 4.6 billion years old

after one half-life

after two half-lives

a A simple way to think about the decay of a radioisotope to a

more stable form, as plotted against time.

Fig. 17-4a, p.262


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Radiometric Dating species.

b Long ago, trace amounts of 14C and a lot more 12C were incorporated into tissues of a living mollusk. The carbon was part of the organic compounds making up the tissues of its prey. As long as it lived, the proportion of 14C to 12C in its tissues remained the same.

Fig. 17-4b, p.262


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Radiometric Dating species.

c When the mollusk died, it stopped gaining carbon. Over time, proportion of 14C to 12C in its remains declined because of the radioactive decay of 14C. Half of the 14C had decayed in 5,370 years, half of what remained was gone in another 5,370 years, and so on.

Fig. 17-4c, p.262


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Radiometric Dating species.

dFossil hunters find the fossil. They measure its 14C/12C ratio to determine the half-life reductions since death. The ratio turns out to be one-eighth of the 14C/12C ratio in living organisms. Thus the mollusk lived about 16,000 years ago.

Fig. 17-4d, p.262


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Midnight, origin of life species.

11:59:40 PM, first humans

origin of prokaryotes

dinosuars, flowering plants

origin of eukaryotes

Fig. 17-6, p.263



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Location of fossil records needs to be interpreted in the context of the plate tectonic theory: continents are drifting

island arc

oceanic crust

oceanic ridge

trench

continental crust

lithosphere

(solid layer of mantle)

hot spot

athenosphere

(plastic layer of mantle)

subducting plate

Fig. 17-7b, p.264


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Location of fossil records needs to be interpreted in the context of the plate tectonic theory: continents are drifting

a 420 mya

b 260 mya

c 65 mya

d 10 mya

PANGEA supercontinent

Fig. 17-8a, p.265


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NORTH AMERICAN PLATE context of the plate tectonic theory:

EURASIAN PLATE

PACIFIC PLATE

PHILIPPINE PLATE

COCOS

PLATE

SOMALI PLATE

SOUTH AMERICAN PLATE

NAZCA

PLATE

INDO-

AUSTRALIAN PLATE

AFRICAN PLATE

ANTARCTIC PLATE

Fig. 17-7a, p.264


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3. Morphological evidence: context of the plate tectonic theory:

Fig. 17-30, p.281


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3. Morphological evidence: context of the plate tectonic theory:

HOMOLOGIES give useful information about relationship:

Homology = similar structure (bone, muscle, nerve, …) inherited from a common ancestor

ANALOGIES should not be used to infer relationship:

Analogy = structure that seems to be similar but has not been inherited from a common ancestor

Fig. 17-9a, p.266


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Homology context of the plate tectonic theory: = similar structure (bone, muscle, nerve, …) inherited from a common ancestor

Example: comparison of

forelimbs

Fig. 17-9, p.266


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Analogy context of the plate tectonic theory: = structure that seems to be similar but has not been inherited from a common ancestor

Example: comparison of

wings

skin

extension of exoskeleton (chitin)

feathers

Fig. 17-10a, p.267


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body wall (exoskeleton) context of the plate tectonic theory:

strong membrane (extension of wall)

wing veins

Fig. 17-10d, p.267


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4. Developmental evidence: context of the plate tectonic theory:

Similarities may be obvious only during the early stages of development, not in the adult individual:

chimpanzee skull

proportions in infant

adult

human skull

Fig. 17-12a, p.268


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Fig. 17-17b, p.272 context of the plate tectonic theory:


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