Mom, Dad…There’s something you need to know…

I’m a MAMMAL!

Origin of SpeciesOrigin of SpeciesChpt. 24Chpt. 24

“That mystery of mysteries…”Darwin never actually tackled

how new species arose…Darwin never actually tackled

how new species arose…

Both in space and time, we seem to be brought

somewhat near to that great fact—that mystery of mysteries—the first appearance of new beings on this Earth.

Macroevolution macroevoluti

macroevolu macroevo

speciation

speciati

specia

spec

speciationspeciation - - origin of a origin of a

new speciesnew species KEYKEY TOTO

MACROEVOLUTION!!MACROEVOLUTION!!

speciationspeciation = origin of a = origin of a new speciesnew species

AnagenesisAnagenesis = = one species one species transforming transforming into into oneone otherother species speciesNoNo biologicalbiological diversitydiversity createdcreated

speciationspeciation == origin of a origin of a new speciesnew species

CladogenesisCladogenesis = one species = one species transforming transforming into more into more speciesspeciesBiological Biological diversity diversity createdcreated

potential to interbreedproduce viable offspring

So…what is a species? Biological species concept

defined by Ernst Mayr population whose members can

interbreed & produce viable, fertile offspring

reproductively compatible

Western MeadowlarkEastern Meadowlark

Distinct species:songs & behaviors are different enough to prevent interbreeding

Distinct species:songs & behaviors are different enough to prevent interbreeding

QuestionHow many species of African Violets are

here?

What What factorsfactors/ / barrierbarriers can s can isolate isolate gene gene pools?pools?

mixing

What What factors factors isolate isolate gene gene pools?pools?

What What factors factors isolate isolate gene gene pools?pools?

What What factors factors isolate isolate gene gene pools?pools?Habitat Isolation

allopatricgeographic separation

What What factors factors isolate isolate gene gene pools?pools?Temporal Isolation

Temporal isolation Species that breed during different times of day, different

seasons, or different years cannot mix gametes

sympatricreproductive separation

Eastern spotted skunk (L) & western spotted skunk (R) overlap in range but eastern mates in late winter & western mates in late summer

Eastern spotted skunk (L) & western spotted skunk (R) overlap in range but eastern mates in late winter & western mates in late summer

What What factors factors isolate isolate gene gene pools?pools?Behavioral Isolation

Blue footed boobies mate only after a courtship display unique to their species

Blue footed boobies mate only after a courtship display unique to their species

reproductive isolation

What What factors factors isolate isolate gene gene pools?pools?Behavioral Isolation

reproductive isolation

QuickTime™ and a decompressor

are needed to see this picture.

What What factors factors isolate isolate gene gene pools?pools?Mechanical Isolation

sympatric speciation?

Plants

Even in closely related species of plants, the

flowers often have distinct appearances that attract

different pollinators. These 2 species of monkey

flower differ greatly in shape & color, therefore

cross-pollination does not happen.

Even in closely related species of plants, the

flowers often have distinct appearances that attract

different pollinators. These 2 species of monkey

flower differ greatly in shape & color, therefore

cross-pollination does not happen.

What What factors factors isolate isolate gene gene pools?pools?Mechanical Isolation

sympatric speciation?

For many insects, male & female sex organs of closely related species do not fit together, preventing sperm transfer

lack of “fit” between sexual organs: hard to imagine for us… but a big issue for insects with different shaped genitals!

Animals

QuickTime™ and a decompressor

are needed to see this picture.

What What factors factors isolate isolate gene gene pools?pools?Gametic Isolation

sympatric speciation

Gametic isolation Sperm of one species may not be able to fertilize eggs

of another species mechanisms

biochemical barrier so sperm cannot penetrate egg receptor recognition: lock & key between egg & sperm

chemical incompatibility sperm cannot survive in female reproductive tract

Sea urchins release sperm & eggs into surrounding waters where they fuse & form zygotes. Gametes of different species— red & purple —are unable to fuse.

Sea urchins release sperm & eggs into surrounding waters where they fuse & form zygotes. Gametes of different species— red & purple —are unable to fuse.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

What What factors factors isolate isolate gene gene pools?pools?Reduced Reduced Hybrid Hybrid ViabilityViability

What What factors factors isolate isolate gene gene pools?pools?

ex. mulesReduced Hybrid Fertility

Mules are vigorous, but sterile

Reduced hybrid fertility Even if hybrids are vigorous

they may be sterile

chromosomes of parents may differ in number or structure & meiosis in hybrids may fail to produce normal gametes

Donkeys have 62 chromosomes(31 pairs)

Horses have 64 chromosomes(32 pairs) Mules have 63 chromosomes!

What What factors factors isolate isolate gene gene pools?pools?Hybrid breakdown

F1 fine, subsequent… no good

Hybrid breakdown

Hybrids may be fertile & viable in first generation, but when they mate offspring are feeble or sterile

In strains of cultivated rice, hybrids are vigorous but plants in next generation are small & sterile.On path to separate species.

In strains of cultivated rice, hybrids are vigorous but plants in next generation are small & sterile.On path to separate species.

sympatric speciation?

==AllopatricAllopatric SpeciationSpeciation

ex. Adaptive ex. Adaptive radiationradiation

ex. Adaptive ex. Adaptive radiationradiation

ex. Adaptive ex. Adaptive radiationradiation

ex. Adaptive ex. Adaptive radiationradiation

ex. Adaptive ex. Adaptive radiationradiation

ex. Adaptive ex. Adaptive radiationradiation

ex. Adaptive ex. Adaptive radiationradiation

Polyploidy Polyploidy

2N2N 4N 4N

==SympatricSympatric SpeciationSpeciation

TEMPO of

evolution

Polyploidy Polyploidy

2N2N 4N 4N

==SympatricSympatric SpeciationSpeciation

BIG changes occur b/c of the accumulation of small changesGRADUALISM

Polyploidy Polyploidy

2N2N 4N 4N

==SympatricSympatric SpeciationSpeciation

TEMPO of

evolution

Polyploidy Polyploidy

2N2N 4N 4N

==SympatricSympatric SpeciationSpeciation

Big changes as it “buds” from parent species, few changes after that

Stephen J. Gould – 1972

how did how did we we differendifferentiatetiate

????????????????

change in rate change in rate & timing of & timing of

developmental developmental events in events in

various parts various parts of the bodyof the body

how did how did we we differendifferentiate???tiate?????????????

change in rate change in rate & timing of & timing of

developmental developmental events in events in

various parts various parts of the bodyof the body

If these genes are altered, the timing of development and rate will be altered within the species

change in rate change in rate & timing of & timing of

developmental developmental events in events in

various parts various parts of the bodyof the body

how did how did we we differendifferentiate???tiate?????????????

If these genes are altered, the timing of development and rate will be altered within the species

Clusters of genes,

involved in the

regulation of

development of animals,

plants, fungi

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

1983 -Dr. Thomas Kaufman - Indiana Indiana

University University discovereddiscovered

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Evolved in the

paleozoic era

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

If mutated… OOPS

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

antennapedia, a mutation of the Hox Gene that

turns the antenna of a fly

into a leg.

Clusters of genes, that determine where limbs and other

body segments

will grow in a developing fetus or larva

Clusters of genes, provide

positional info in the

embryo

When these genes are altered,

positioning varies

Clusters of genes, provide

positional info in the

embryo

When these genes are altered,

positioning varies

So, if So, if we are we are

connecteconnected, how d, how

diddid we we

differentdifferentiateiate ??????

Evolution is not the survival of the fittest.

Rather it is the survival of the just

good enough.

What drove Human Evolution?

QuickTime™ and a decompressor

are needed to see this picture.

http://www.npr.org/templates/story/story.php?storyId=124906102

SummaryBe able to discuss the main theories of what is a “species”.

Know various reproductive barriers and examples.

SummaryKnow allopatric and sympatric speciation.

Be able to discuss gradualism and punctuated equilibrium theories.

SummaryRecognize various ideas about the origin of evolutionary novelties.