Mom, Dad… There’s something you need to know… I’m a MAMMAL! Origin of Species Chpt. 24

“That mystery of mysteries…” 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

speciation - origin of a new species KEY TO MACROEVOLUTION!!

speciation = origin of a new species Anagenesis = one species transforming into one other species No biological diversity created

speciation = origin of a new species Cladogenesis = one species transforming into more species Biological diversity created

potential to interbreed produce 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

Question How many species of African Violets are here?

What factors/ barriers can isolate gene pools? mixing

What factors isolate gene pools?

Habitat Isolation

 allopatric  geographic separation

What factors isolate gene pools? Temporal Isolation

Temporal isolation Species that breed during different times of day, different seasons, or different years cannot mix gametes  sympatric  reproductive separation Eastern spotted skunk (L) & western spotted skunk (R) overlap in range but eastern mates in late winter & western mates in late summer

What factors isolate gene pools? Behavioral Isolation Blue footed boobies mate only after a courtship display unique to their species  reproductive isolation

What factors isolate gene pools? Behavioral Isolation  reproductive isolation

What factors isolate gene 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.

What factors isolate gene 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

What factors isolate gene 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.

What factors isolate gene pools? Reduced Hybrid Viability

What factors isolate gene pools? ex. mules Reduced 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 factors isolate gene 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?

=Allopatric Speciation ex. Adaptive radiation ex. Adaptive radiation

Polyploidy Polyploidy 2N 4N =Sympatric Speciation TEMPO of evolutio n

Polyploidy Polyploidy 2N 4N =Sympatric Speciation BIG changes occur b/c of the accumulatio n of small changes GRADUALISM

Polyploidy Polyploidy 2N 4N =Sympatric Speciation TEMPO of evolutio n

Polyploidy Polyploidy 2N 4N =Sympatric Speciation Big changes as it “buds” from parent species, few changes after that Stephen J. Gould – 1972

how did we differentiate ???????? ???????? change in rate & timing of developmental events in various parts of the body

how did we differentiate ???????? change in rate & timing of developmental events in various parts of the body If these genes are altered, the timing of development and rate will be altered within the species

change in rate & timing of developmental events in various parts of the body how did we differentiate ???????? 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 Indiana University discovered Dr. Thomas Kaufman - Indiana University discovered

Evolved in the paleozoic era

If mutated… OOPS

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 we are connected, how did we different iate ??? Evolution is not the survival of the fittest. Rather it is the survival of the just good enough.

What drove Human Evolution?

Summary Be able to discuss the main theories of what is a “species”. Know various reproductive barriers and examples.

Summary Know allopatric and sympatric speciation. Be able to discuss gradualism and punctuated equilibrium theories.

Summary Recognize various ideas about the origin of evolutionary novelties.