Speciation
Speciation
Speciation
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<strong>Speciation</strong><br />
Biology 2<br />
Thursday, January 24, 2013
Evolution<br />
• Change in the genetic composition<br />
of a group of organisms over time.<br />
• Descent with modification<br />
Thursday, January 24, 2013
Microevolution<br />
• Changes within species<br />
• Short Time Period<br />
• e.g. Tuskless Elephants<br />
• e.g. Peppered Moths/Coloration<br />
• e.g. Bacteria/Antibiotic Resistance<br />
Thursday, January 24, 2013
Macroevolution<br />
• Changes over longer time periods<br />
• <strong>Speciation</strong> - evolution of 2 or more<br />
species from a single species<br />
Species B<br />
Species C<br />
Thursday, January 24, 2013<br />
Species A
Adaptive Radiation<br />
• One species evolves into many.<br />
Multiple Descendent Species<br />
Time<br />
Extinction<br />
Ancestral Species<br />
Thursday, January 24, 2013
Activity 4<br />
<strong>Speciation</strong> of<br />
Caminalcules<br />
Thursday, January 24, 2013
<strong>Speciation</strong> of Caminalcules<br />
Gradualism<br />
Punctuated Equilibrium<br />
Time<br />
Morphology<br />
Morphology<br />
Thursday, January 24, 2013
Species<br />
• Biological Concept<br />
• Group of similarly constructed organisms<br />
that interbreed and produce fertile<br />
offspring<br />
Thursday, January 24, 2013
Reproductive Isolating<br />
Mechanisms<br />
• Prezygotic - prevents fertilization<br />
• Postzygotic - prevents development<br />
Good Summary<br />
Text Figure 17.4<br />
Thursday, January 24, 2013
Prezygotic Isolating Mechanisms<br />
1. Habitat Isolation - live different habitats<br />
Tree Canopy<br />
Ground<br />
Thursday, January 24, 2013
Prezygotic Isolating Mechanisms<br />
2. Temporal Isolation - breed different times<br />
Squirrel Corn<br />
Dutchman’s Britches<br />
Thursday, January 24, 2013
Prezygotic Isolating Mechanisms<br />
3. Behavioral Isolation - different courtships<br />
Blue-Footed Bobbies<br />
Dancing<br />
Bird<br />
Songs<br />
Fireflies<br />
Flashing<br />
Thursday, January 24, 2013
Prezygotic Isolating Mechanisms<br />
4. Mechanical isolation - incompatible<br />
reproductive parts<br />
birch and passion flower<br />
pollen on passion flower<br />
Thursday, January 24, 2013
Postzygotic Isolating Mechanisms<br />
• Zygote Mortality<br />
• Hybrid Sterility<br />
• Hybrid Fitness<br />
Horse<br />
Donkey<br />
Mule<br />
Thursday, January 24, 2013
Species<br />
• Evolutionary Concept<br />
• Members of same<br />
species have similar<br />
structure<br />
• Can be applied to sexual<br />
and asexual reproduction.<br />
• Can be applied to fossils<br />
Thursday, January 24, 2013
<strong>Speciation</strong><br />
• Evolution of 2 or more species from a<br />
single species<br />
Species B<br />
Species C<br />
Species A<br />
Thursday, January 24, 2013
Types of <strong>Speciation</strong><br />
• Allopatric <strong>Speciation</strong> - geographical<br />
separation<br />
• Sympatric <strong>Speciation</strong> - same<br />
geographical area<br />
Thursday, January 24, 2013
Allopatric<br />
<strong>Speciation</strong><br />
Textbook Figure 17.8<br />
California<br />
Salamanders<br />
separated by large<br />
central valley<br />
Thursday, January 24, 2013
Allopatric <strong>Speciation</strong><br />
Darwin’s Finches - Different Islands<br />
http://www.pbs.org/wgbh/evolution/library/01/6/<br />
image_pop/l_016_02.html<br />
http://people.rit.edu/rhrsbi/GalapagosPages/SlideShow/<br />
SlidePages/Darwin's%20Finches.html<br />
Thursday, January 24, 2013
Types of <strong>Speciation</strong><br />
• Allopatric <strong>Speciation</strong> - geographical<br />
separation<br />
• Sympatric <strong>Speciation</strong> - same<br />
geographical area<br />
• Hybridization<br />
• Polyploidy<br />
Thursday, January 24, 2013
Hybridization<br />
• Crossing 2 different strains or related species.<br />
• Result in new species<br />
Wheat<br />
Type<br />
1<br />
Wheat<br />
Type<br />
2<br />
hybrid<br />
wheat<br />
Thursday, January 24, 2013
Polyploidy<br />
• Having more than 2 pairs of chromosomes<br />
2N<br />
3N<br />
4N<br />
Diploid<br />
Polyploids<br />
Thursday, January 24, 2013
Normal Meiosis<br />
Fertilization<br />
+ Egg/Sperm<br />
Egg Sperm Zygote<br />
Thursday, January 24, 2013
Polyploidy<br />
• Chromosomes fail to separate in meiosis<br />
Egg<br />
Sperm<br />
+<br />
Zygote<br />
Thursday, January 24, 2013
Sympatric <strong>Speciation</strong><br />
Polyploidy<br />
• Chromosome doubling due to no meiosis after<br />
replication<br />
Thursday, January 24, 2013
Wheat Evolution<br />
Triticum<br />
momococcum<br />
2N = 14<br />
7<br />
gamete<br />
Hybrid (Infertile)<br />
21<br />
14<br />
gamete<br />
Triticum turgidum<br />
2N = 28<br />
Thursday, January 24, 2013<br />
Modern Wheat<br />
Triticum fauschi<br />
2N = 42<br />
chromosome<br />
doubling<br />
42
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