Download Trends in Evolution

April 19, 2018 | Author: Anonymous | Category: , Social Science, Anthropology, Human Evolution
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STARTER #48 AND OBJECTIVES Table of Content: Trends in Evolution Starter: Comparing homologous structures of lizzard’s and cat’s forelimb we saw similar set of bones. Why is that? Objectives:  Analyze and evaluate the evidence for evolution

HOMEWORK AND REMINDER

Homework: Evolution concept map

Reminder: Cell phone should be off and out of sight! ID and Dress code check

EVOLUTION- - HOW DID CHANGE OCCUR? Process by which modern organisms have descended from ancient organisms Long, slow process of change Any change in the frequency of genes affects the gene pool Variations exist within species Change in population over time

GENE DUPLICATION

New genes can evolve through duplication, followed by modification, of existing genes.

MOLECULAR CLOCKS

Molecular clocks use mutation rates to estimate the time that two species have been evolving.

MUTATIONS More differences between DNA sequences of two species indicates more time elapsed since they shared an ancestor.

HOX GENES AND EVOLUTION

Small changes in Hox gene activity during embryological development can produce large changes in adult animals.

SPECIATION DUE TO ISOLATION Speciation is the process of forming new species and can occur in several ways:

Abert’s Squirrel

1. Geographic barriers (mt. ranges, ocean) Kaibab Squirrel

SPECIATION DUE TO ISOLATION 2. Temporal changes = timing (flowers, honeybees)

SPECIATION DUE TO ISOLATION 3. BEHAVIORAL ISOLATION

SUMMARY Isolated gene pools diverge into separate species.

Reproductive isolation occurs.

Members of a species share a gene pool.

Patterns of evolution

ARTIFICIAL SELECTION  Artificial Selection is the process of when people (instead of nature) select which organisms get to reproduce, to get their favorable desire traits.

DIVERGENT EVOLUTION  On species give rise to many species which means organisms have a common ancestor  Changes in environment cause them to adapt  Overtime, they become less and less alike and behave differently, but they are still related!  Also known as: Adaptive Radiation

ADAPTIVE RADIATION

DIVERGENT EVOLUTION

CONVERGENT EVOLUTION Unrelated organisms develop similar characteristics due to environmental pressures May look or act the same, but not related at all! Don’t have common ancestor Shark - dolphin Bat – bird - butterfly

CONVERGENT EVOLUTION

COEVOLUTION

Two organisms evolve together in response to changes in each other over time Insects & flowers

Both species become dependent on each other for survival

TIMING OF EVOLUTION

GRADUALISM Change is SLOW, constant, and predictable due to environment EX: Leg changes in horse population

PUNCTUATED EQUILIBRIUM Descent punctuated by short period of stable follow by a rapid change associated with environmental changes Ice age, meteorite impact, volcanoes

HARDY-WEINBERG PRINCIPLE  If the following 5 conditions are not met, then evolution cannot occur because there won’t be any changes: 1. Immigration or migration 2. Large Populations 3. Random mating, no preference 4. Natural selection 5. Mutations occur  However, these conditions do exist and happen in nature, Therefore…populations do change or evolve over time!

NATURAL SELECTION CAUSES GENETIC DRIFT A random change in allele frequency in a population Greater effect on small populations Can cause an allele to become common in a population

GENETIC DRIFT IS THE CHANGE IN THE ALLELE FREQUENCY IN A P O P U L AT I O N D U E T O R A N D O M S A M P L I N G O F O R G A N I S M S T H E F O U N D E R E F F E C T I S L O S S O F G E N E T I C VA R I AT I O N W H E N N E W P O P U L AT I O N I S E S TA B L I S H E D F R O M L A R G E R O N E

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Shows how two small groups from a large diverse population could produce new populations that differ from the original group

TYPES OF GENETIC DRIFT 1. Directional Selection: Individuals at one end of the phenotypic spectrum have the highest fitness

TYPES OF GENETIC DRIFT 2. Disruptive selection: Cause a population to diverge May cause speciation

TYPES OF GENETIC DRIFT 3. Stabilizing Selection: Causes the population to become more average in phenotype

FOSSILS IN SEDIMENTARY ROCK

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Water carries small rock particles to lakes and seas.

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Dead organisms are buried by layers of sediment.

The preserved remains may later be discovered and studied.

WHAT CAN FOSSILS REVEAL?

RELATIVE DATING

RADIOMETRIC DATING

PLATE TECTONICS AND EVOLUTION

End of the Permian Period

End of the Cretaceous Period

Triassic Period

Present Day

MICROEVOLUTION

MICROEVOLUTION

MICROEVOLUTION

MACROEVOLUTION

PATTERNS OF EXTINCTION

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