chapter 16: evolution of populations

27
Chapter 16: Evolution of Populations 16.1 Genes and Variation 16.2 Evolution as Genetic Change 16.3 The Process of Speciation

Upload: lieu

Post on 20-Jan-2016

67 views

Category:

Documents


0 download

DESCRIPTION

Chapter 16: Evolution of Populations. 16.1 Genes and Variation 16.2 Evolution as Genetic Change 16.3 The Process of Speciation. Population Genetics. Evolutionary thought today is tightly linked to genetics. Remember, populations, not individuals evolve . - PowerPoint PPT Presentation

TRANSCRIPT

Page 1: Chapter 16: Evolution of Populations

Chapter 16: Evolution of Populations

16.1 Genes and Variation16.2 Evolution as Genetic Change16.3 The Process of Speciation

Page 2: Chapter 16: Evolution of Populations

4

Chapter 16 Concept MapGene Pool

Different Types of Natural Selection

Stabilizing Selection

Directional Selection

Disruptive Selection

example

example

example

Relative Frequency

Genetic Equilibrium

Genetic Drift

Hardy-Weinberg Principle

founder effect

single gene trait

polygenic trait

Pg. 398-399

Pg. 395-401

Pg. 393-394

Page 3: Chapter 16: Evolution of Populations

4

Chapter 16 Concept MapSpeciation

Geographic Isolation

example

Reproduction Isolation

example example example

17.4…. Macroevolution

extinctionadaptive radiation

example

example

convergent evolution

coevolutionpunctuated equilibriumgradualism

example

BehavorialIsolation

Temporal Isolation

Divergent

Pg. 404-409

Pg. 435-440

Page 4: Chapter 16: Evolution of Populations

Evolutionary thought today is tightly linked to genetics.

Remember, populations, not individuals evolve.

All the alleles in a pop. added together are called the gene pool.

Population Genetics

Page 5: Chapter 16: Evolution of Populations

Blue People of Kentucky

Page 6: Chapter 16: Evolution of Populations

Population Genetics The frequency that any one allele is seen

in the population is called the allele frequency (relative frequency). Is the frequency of the dominant

Huntington’s allele high? Is the frequency of the dominant allele causing 6 fingers high?

Page 7: Chapter 16: Evolution of Populations

If the frequency of the alleles doesn’t change over time, the population is at genetic equilibrium.

Hardy-Weinberg Principle see page 401

Population Genetics

Page 8: Chapter 16: Evolution of Populations

Population GeneticsWhen alleles are brought in and out

of a population due to migration of individuals, it is called gene flow.

Page 9: Chapter 16: Evolution of Populations

Population Genetics When isolated chance events

can alter gene frequencies in a population (therefore disrupting gene equilibrium) you have what is called genetic drift. Common in small isolated

populations such as the Amish of Lancaster, PA

Darwin’s finches (perhaps) founder effect: change as a

result of migration

Page 10: Chapter 16: Evolution of Populations

Population Genetics

Sources of Genetic Variation: Mutations Gene Shuffling Single gene trait Polygenic trait

Page 11: Chapter 16: Evolution of Populations

Population GeneticsTypes of selection:

When natural selection of a trait favors the average individuals in the pop. it is called stabilizing selection.

Page 12: Chapter 16: Evolution of Populations

Population Genetics

Types of selection: When natural selection favors both extreme phenotypes of a trait in a pop., it is called disruptive selection.

Page 13: Chapter 16: Evolution of Populations

Population Genetics

Types of selection: When natural selection favors one extreme phenotype of a trait, it is called directional selection.

Page 14: Chapter 16: Evolution of Populations

Population Genetics Type of Selection??

Grey mice are preyed upon but black and white mice are left alone?

The longer a giraffe’s neck gets the more food is available, while short necked giraffes die of starvation before they can reproduce?

A slow gazelle is easily caught by a cheetah, but one too fast breaks its legs easily and is eaten by hyenas??

Disruptive

Directional

Stabilizng

Page 15: Chapter 16: Evolution of Populations

Population Genetics

Artificial Selection: Selection for traits that are determined and monitored by man.

Ex. Breeding animals such as dogs or cats.

Sexual Selection: Selection by one gender for another gender.

Ex. Peacock feathers, body hair disappearance in humans, walrus tusks.

Page 16: Chapter 16: Evolution of Populations

Speciation

Speciation is when a new species is formed. This means that the individuals in the new species can no longer produce successful offspring with the population from which they came.

Page 17: Chapter 16: Evolution of Populations

Speciation

Geographic Isolation can cause speciation over long periods of time. The seperated organisms are

adapting to different environments and responding differently.

Eventually if a mating is attempted, they can no longer produce successful offspring with one another.

Page 18: Chapter 16: Evolution of Populations

Speciation Reproductive Isolation is when a

population can no longer successfully interbreed with its parent population (the pop. it came from). Reproduction if attempted will fail. Ex. One group breeds in the fall, one in the spring and over time the populations become new species incapable of interbreeding. Mating Calls Courtship rituals differ

Page 19: Chapter 16: Evolution of Populations

Speciation

Temporal Isolation: Two or more species reproduce at

different times Example: orchid in the rainforest

Page 20: Chapter 16: Evolution of Populations

Speciation

Changes in chromosome number can cause speciation.

Some cases of polyploidy (more common in plants) produce individuals that can only mate with other polyploids in a pop.

Page 21: Chapter 16: Evolution of Populations

17.4 Speciation

Can occur rapidly Punctuated Equilibrium Gould

Can occur very slowly Gradualism Darwin see page 439

Page 22: Chapter 16: Evolution of Populations

17.4 Patterns of EvolutionAdaptive Radiation: When an

ancestral species evolves into several different species, each filling a specific niche. Darwin’s finches Hawaiian Honeycreepers (p. 406 &436).

Page 23: Chapter 16: Evolution of Populations
Page 24: Chapter 16: Evolution of Populations

17.4 Patterns of Evolution

Divergent Evolution: Species that once were similar or closely related become very different. New Species are very different from

each other. Ex. Adaptive Radiation

Page 25: Chapter 16: Evolution of Populations

17.4 Patterns of Evolution Convergent

Evolution: Unrelated species that live in similar environments evolve the same adaptations in order to survive. Ex. Tasmanian Wolf and

North American Wolf. P. 437

Page 26: Chapter 16: Evolution of Populations

Patterns of Evolution

Coevolution: the process by which two species evolve in response to changes in each other over time. Example: flowering plants

and their pollinator Page 437

http://biology.clc.uc.edu/courses/bio303/coevolution.htm

Page 27: Chapter 16: Evolution of Populations

17.4 Note

Common genetic occurrences we have studied such as polyploidy, crossing over, and point mutations can provide the genetic basis for evolution. Although these genetic changes are not evolution themselves, they can begin the long process of evolution by affecting one individual in a population in a positive way. But only if the trait is passed on, and on, and on…