Evolution

" Glow baby Glow !!! "

Evolution - A change in the gene frequency occurring in a population over time.

          Darwin - Descent with modification.

          Lamarck - Change came from an inner drive to improve. Recently acquired traits could be passed on.

          Wallace - Worked in Indonesia and developed a similar idea to Darwin's evolution hypothesis.

Evidence for Evolution:

         Fossil record - More aquatic than terrestrial and more hard parts than soft parts.

         Artificial selection - Man made animals and plants through selective breeding. We made 400 species of dogs.

         Vestigial structures - Remnants of structures found in our ancestors. Tail bone, muscles that move the ears, wisdom teeth, and our appendix.

         Similarities of cells - All living things are made of cells and all cells have the same organelles.

         Microbial evolution - Because the generation time for bacteria is about 20 minutes, we can see great changes in bacterial populations in just a few weeks.

         Embryology - Study of development to tell them how similar (how closely related) species are to each other.

         Genetics - Tells us how evolution occurs. It gives the mechanism for natural selection. Darwin did not know this.

                    GMO - genetically modified organism - a plant, animal, or microorganism whose genetic makeup has been modified in a laboratory using genetic engineering or transgenic technology.

         Biogeography - The study of the distribution of plants and animals. Where a species originated, what climate it started in, and how it has spread.

                    Continental drift - Continental plates shifted apart and now different regions have similar but unique species.

Microevolution - Change in an allele frequency of a population or species over time.

          Natural selection - Individuals with better abilities to survive, outcompete those that are less able, and produce a greater proportion of the next generation.

                   5 Assumptions for natural selection to work:     1) more young are born than survive to reproduce     2) there is variation among individuals     3) individuals with certain traits are more likely to survive     4) these particular traits can be inherited     5) long spans of time are often necessary to see changes

Gene pool - The sum total of all of the genes, with all of their alleles, in the population.

Fitness - An individuals contribution to the next generation.

          Survival of the fittest - Survival of genes into the next generation and fittest refers to individuals who contribute the most alleles into the next generation.

*Stabilizing selection - Will decrease the extreme phenotypes and favor the intermediate phenotypes. Decreases overall variation.

*Directional selection - Shifts a phenotype to one extreme or the other extreme.

*Disruptive selection - The 2 extreme phenotypes are favored over the intermediate phenotype.

Biological species - One whose members can potentially interbreed.

Species - Organisms that share a common gene pool and produce fertile offspring.

Reproductive barrier - Keep individuals from 2 different species from interbreeding and producing fertile offspring.

          Prezygotic barrier - Prevent mating and fertilization.

          Postzygotic barrier - Prevent the hybrid from developing into a fertile adult.

Macroevolution - So much genetic change builds up to give rise to a whole new species or even new genera.

          Speciation - 2 populations are isolated over time and changes at the microevolutionary level add up to enough differences so that the 2 populations become distinctly separate species.

          Adaptive radiation - A species has invaded new habitats, adapted, changed and speciated to fill all available niches.





Natural Selection Game with Peppered Moths:

Click on the bird with 2 moths.   Try eating the moths you see with your mouse and watch how the ratio of dark moths to light moths changes.

Earth Viewer - Continental drift




























Return to Greg Sievert's GB 100 Syllabus
Last updated on 25 March 2018