Mom, Dad… There’s something you need to know… I’m a MAMMAL! Origin of Species Chpt. 24.
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Transcript of Mom, Dad… There’s something you need to know… I’m a MAMMAL! Origin of Species Chpt. 24.
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
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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
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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.
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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
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1983 -Dr. Thomas Kaufman - Indiana Indiana
University University discovereddiscovered
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Evolved in the
paleozoic era
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If mutated… OOPS
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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?
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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.