16-The Origin of Biological Diversity-H14

8/7/2019 16-The Origin of Biological Diversity-H14

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Origin of Biological Diversity

Formation of a Species

Evolution: A Remodeling Process

Lifes History

Modern Taxonomy

Life Begins

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Formation of a Species

A. Speciation

B. Causes of Speciation

C. Adaptive Radiation

D. Punctuated Equilibrium


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A. Speciation

1. Biological Species Concept:(Ernst Mayr) a group ofinterbreeding organismsthat can produce healthy,fertile offspring

2. Speciation, the origin of newspecies can arise by:

a. separation by a barrier

b. two groups live indifferent environments

for thousands of years_

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c. individuals with favorabletraits survive andreproduce

d. in time each group maybecome a different

species_


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1. Geographic isolation is thephysical separation of apopulation (allopatricspeciation)

a. mountain, ocean_


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2. Reproductive isolation is dueto the inability of twospecies to breed (sympatricspeciation)

a. Prezygotic isolation

before fertilization(temporal, behavioral,habitat)

b. Postzygotic isolation after fertilization (hybridinviability, hybrid sterility,

hybrid breakdown)_


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C.Adaptive Radiation

1. Adaptive radiation producesdiverse species adapted todiverse environments allfrom one common ancestor

(Darwins finches)_

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D. Punctuated Equilibrium

1. Darwin proposed thatevolution occurred at aconstant, gradual rate(gradualism)

2. Eldredge and Gould proposed

that evolution progresseswith little change,punctuated by rare, shorttimes with increaseddiversification (punctuatedequilibrium)_


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THE END


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Evolution: A Remodeling Process

A. Refine Existing Adaptations

B. Adapting Existing Structures

C. Types of Selection


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1. Complicated structures haveevolved from the gradualrefinement of simplerstructures (eyes)

2. Co-evolution one species can

influence the evolution ofanother species and viceversa (finches and beetles)_

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B.Adapting Existing Structures

1. Pre-existing structures thatevolved as adaptations forcertain functions can laterfulfill other functions

a. convergent evolution_

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C.Types of Selection

1. Directional Selection - onephenotype is favored overanother (giraffe neck)_


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2. Stabilizing Selection -extreme phenotypes areselected against (humanbirth weight)_


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3. Disruptive Selection(diversifying selection) favors individuals at eitherextreme phenotype

(seed size)_


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D. Other Notable Scientists

1. Alfred Wallace-

British Naturalist

Studied Flora and Fauna ofmany islands

Came up with a theory ofNatural Selectionindependent of CharlesDarwin_


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2. Charles Lyell-

Scottish Geologist

Uniformitarianism Thepresent is the key to thepast_


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3. Thomas Malthus

Population Growth Apopulation grows faster thanits food supply_


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4. Ernst Haeckel

Otogeny recapitulatesphylogeny

(embryonic developmentalstages look like adult

evolutionary ancestors)Better to say otogenyrecapitulates ancestralotogeny_


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D. Miscellaneous

Red-Queen Hypothesis aspecies must continue toevolve simply to maintaincurrent fitness

Non-evolutionist TheoryScala-naturae great chainof being

Definitions

Homology study of similarstructures (due to sharedancestry)

Morphology study of overallform or shape

Physiology study of function inliving organisms

Aggregate - collection

Fitness success of passingones genes to the next

generationAssortive mating selecting

similar mates

Selective mating choosing onebest trait_


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THE END


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1. Complicated structures haveevolved from the gradualrefinement of simplerstructures

a. eyes and flowers_

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C.Adaptive Radiation

1. Adaptive radiation producesdiverse species adapted todiverse environments allfrom one common ancestor

a. Darwins finches

b. genetic drift_

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16-The Origin of Biological Diversity-H14