Pat Hamer

Period 5

2/2/04

Ch. 14 Outline

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I.                    Developing a Theory of Evolution

a.       An Early Explanation for Evolutionary

                                                               i.      A Desire to Change

1.      Lamarck thought that organisms changed because they have an inborn urge to better themselves and become more fit for their environment

2.      Supposedly ancestors of birds acquired the urge to fly so they learned to fly.

3.      Proved not to be true

                                                             ii.      Use and Disuse

1.      Believed that change occurred because organisms could alter their shape by using their bodies in new ways.

2.      if the organ was used a lot it would become stronger but if it was not used it would eventually diminish

                                                            iii.      Passing on Acquired Traits

1.      Also believed that if an animal acquired a body structure such as long arms or feathers during its lifetime, it could pass that change on to its offspring.

2.      Lamarck once again was proved wrong and his theories to be false. Only genes are passed onto children not altercations in body structure  

b.      Ideas that Shaped Darwin’s Theory of Evolution

                                                               i.      The Influence of Geology: Lyell’s Ideas

1.      Darwin believed that the world was much older than believed after reading Lyell’s ideas.

                                                             ii.      The Influence of Farmers: Artificial Selection

1.      farmers altered and improved their crops and lifestock through breeding programs

2.      domesticated animals and plants vary a great deal because these variations  were inheritable variations

3.       Artificial Selection – process which allowed only the individuals who suited the farmers needs to produce offspring.

4.      In artificial selection, the intervention of humans ensures that only individuals with the more desirable traits produce offspring. 

                                                            iii.      The Influence of Malthus: Population Controls

1.      Malthus observed that babies were being born at a faster rate than people were dying

a.       If continued there would not be enough food or water to survive with so many people

2.      Malthusian Doctrine applied even more to animals and plants than to humans

II.                 Evolution by Natural Selection

a.       Natural Selection – a process that operates in a manner similar to the way artificial selection worked in that the strongest and fittest will survive while the weaker less fit will die off

                                                               i.      Wild animals and plants showed variations just as domesticated animals and plants did.

                                                             ii.      Individuals whose characteristics are well-suited to their environment survive.  Individuals whose characteristics are not well-suited to their environment either die of leave fewer offspring.

1.      Also Known as Survival of the Fittest

b.      Peppered Moths: Natural Selection in Action

                                                               i.      England peppered moth provides an example of natural selection in action

1.      Before industrial revolution only the white moth’s survived because they camouflaged into white trees but with soot and smoke the trees became black and only the black moths survived

III.               Genetics and Evolutionary Theory

a.       Genes: Units of Variation

                                                               i.      Carriers of inheritable characteristics and the source of the random variation

                                                             ii.      No way for an organism to cause a particular change in its DNA.

b.      Raw Material for Natural Selection

                                                               i.      Entire organisms not individual genes either survive and reproduce or do not.

                                                             ii.      Genetic instructions and environmental influences, such as nutrition and exercise produce the phenotypic variation

c.       Evolution as Genetic Change

                                                               i.      Populations – collection of individuals of the same species in a given area whose members can breed with one another.

                                                             ii.      Gene pool – common group of genes

                                                            iii.      Relative frequency – The number of times an allele occurs in a gene pool compared with the number of times other alleles for the same gene occur

                                                           iv.      Evolution is any change in the relative frequencies of alleles in the gene pool of a population

d.      Genes, Fitness, and Adaptation

                                                               i.      Each time an organism reproduces it passes copies of its genes to its offspring

1.      thus we can define evolutionary fitness as the success an organism has in passing on its genes to the next generation

e.       A Genetic Definition for Species

                                                               i.      Species previously defined as organism that looked alike, but now defined as a group of similar looking organisms that breed with one another and produce fertile offspring in the natural environment.

                                                             ii.      Species share common gene pools since they breed together

IV.              The Development of New Species

a.       The Niche: How to Make a Living

                                                               i.      Niche – combination of organisms “profession” and the place in which it lives

                                                             ii.      No two species can occupy the same niche in the same location for a long period of time

1.      cause competition and fighting

b.      The Process of Speciation

                                                               i.      Scientists have learned that new species usually for only when populations are isolated or separated.

                                                             ii.      Reproductive isolation – the separation of populations so that they do not interbreed to produce fertile offspring

c.       Darwin’s Finches: An example of Speciation

                                                               i.      Step 1: Founding Fathers and Mothers

1.      descendants of a few ancestral finches that found their way to the Galapagos Islands

                                                             ii.      Step 2: Separation of Populations

1.      oceans and other physical features can form barriers to prevent species from blending their gene pools

                                                            iii.      Step 3: Changes in the Gene Pool:

1.      over time populations grow adaptations to help them survive in their new habitat.

                                                           iv.      Step 4: Reproductive Isolation

1.      if the species mixed together they would probably not breed with each other producing Reproductive Isolation

                                                             v.      Step 5: Sharing the Same Island

1.      there are 3 choices

a.       coexistence

b.      extinction

c.       further evolution

d.      Speciation and Adaptive Radiation

                                                               i.      Adaptive radiation – number of different species diverge, or move away, from a common ancestral form

                                                             ii.      Divergent evolution – is also known as Adaptive radiation and share the same meaning as above.

                                                            iii.      Convergent evolution – adaptive radiations among different organisms often produce species that are similar in appearanace and behavior

                                                           iv.      Analogous structures – similar in appearance and function, but they have different origins.

1.      similar exterior structure; very different internal structure

V.                 Evolutionary Theory Evolves

a.       Genetic Drift

                                                               i.      With the aid of theories  and genetic experiments, biologists have realized that gene pools can change – in other words, evolution can occur – in the absence of natural selection

                                                             ii.      Genetic drift – random change in the frequency of a gene

b.      Unchanging Gene Pools

                                                               i.      Its possible for the gene pool of a species to remain the same for a long time by the following

1.      sexual reproduction itself does not change the frequency of alleles in a population

2.      Natural selection and genetic drifts do not always occur.

c.       Gradual and Rapid Evolutionary Change

                                                               i.      Gradualism – theory that evolutionary change occurs slowly and gradually

                                                             ii.      Equilibrium – that organisms do not change very much

                                                            iii.      Mass Extinction – when a species has vanished in a phenomenon extinction.

1.      some are caused by global climates that altered many environments

                                                           iv.      punctuated equilibria -  used to describe the pattern of long stable periods interrupted by brief periods of change

d.      The Significance of Evolutionary Theory

                                                               i.      Foundation on which all science is built on.

                                                             ii.      Evolution has supposedly changed every aspect of life and culture in the world.