chapter 22 descent with modifications l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Chapter 22: Descent with Modifications PowerPoint Presentation
Download Presentation
Chapter 22: Descent with Modifications

Loading in 2 Seconds...

play fullscreen
1 / 28

Chapter 22: Descent with Modifications - PowerPoint PPT Presentation


  • 208 Views
  • Uploaded on

Chapter 22: Descent with Modifications. Barbara Musolf Clayton State University Administration Building A 16-C 678-466-4851. Objectives. Develop an historical understanding of the Darwinian Revolution

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Chapter 22: Descent with Modifications' - ayame


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
chapter 22 descent with modifications

Chapter 22: Descent with Modifications

Barbara Musolf

Clayton State University

Administration Building A 16-C

678-466-4851

objectives
Objectives
  • Develop an historical understanding of the Darwinian Revolution
  • Natural selection is one of the mechanisms that underlies evolutionary changes in populations.
  • Proof that natural selection is powerful mechanism is its ability to explain changes in populations.
  • Understand the difference between hypothesis and theory.
darwin s theory
Darwin’s Theory
  • The mechanism of natural selection lies behind the evolutionary process.
  • The adaptation of organisms to their environment leads to the accumulation of genetic traits.
  • Darwin presented evidence that modern organisms evolved from ancestral species.
the origin of species 11 22 1859
The Origin of Species 11/22/1859
  • Descent with modification (Evolution) explains the diversity of species from the past to the present.
  • Natural selection is the mechanism underlying adaptive evolution.
  • Evolution implies ancestral organisms that give rise to new organisms.
  • Organisms are unified by this descent from a common ancestor.
natural selection and adaptation
Natural Selection and Adaptation

Ernst Mayr presented Darwin’s logic

  • Observation #1: Population sizes would increase exponentially if all individuals successfully reproduced.
  • Observation #2: Populations remain stable in size with the exception of seasonal fluctuations.
natural selection and adaptation8
Natural Selection and Adaptation

Darwin’s logic

  • Observation #1: Members of a population vary in their characteristics
  • Observation #2: Traits are heritable from parents to offspring
natural selection and adaptation9
Natural Selection and Adaptation

Darwin’s logic

  • Observation #3: All species are capable of producing more offspring than their environment can support.
natural selection and adaptation10
Natural Selection and Adaptation

Darwin’s logic

  • Observation #4: Lack of food or other resources leads to survival of only a few offspring.
  • Inference #1: Individuals with inherited traits that allow them to survive and reproduce will leave behind more offspring that less fit individuals.
  • Inference #2: The unequal ability of individuals to survive can lead to gradual changes in the characteristics of a population.
the influence of malthus
The influence of Malthus
  • Malthus contended that the growth in human populations exceeds the available resources.
  • All organisms tend to overreproduce
  • Environmental factors favor some heritable traits over others.
  • Those with favorable traits tend to produce more offspring.
artificial selection
Artificial selection

Terminal

bud

Lateral

buds

Cabbage

Brussels sprouts

Leaves

Flower

clusters

Kale

Cauliflower

Stem

Flowers

and

stems

Broccoli

Kohlrabi

Wild mustard

summary of natural selection
Summary of Natural Selection
  • Natural selection is the reproductive success of an individual with particular heritable traits within a particular environment.
  • The population changes over time to adapt successfully to its environment.
  • Environmental changes can lead to selection of different heritable traits that can give rise to a new species.
    • Populations evolve NOT individuals
the explanatory power of darwin s theory of evolution
The explanatory power of Darwin’s theory of evolution

The study of wild guppy populations in the Aripo River system in Trinidad

Observation: Brightly colored males are more attractive to females, however they are also more conspicuous and can attract predators.

the explanatory power of darwin s theory of evolution16
The explanatory power of Darwin’s theory of evolution

The study of wild guppy populations in the Aripo River system in Trinidad, Endler

Hypothesis: Intense predation causes selection of male guppies with drab coloration.

Test: Transplanted 200 guppies from pike-cichlid ponds to killifish ponds that had no guppies.

the explanatory power of darwin s theory of evolution17
The explanatory power of Darwin’s theory of evolution
  • Results: After 22 months and 15 generations…
the explanatory power of darwin s theory of evolution18
The explanatory power of Darwin’s theory of evolution

Drug Resistant HIV: Evolution of HIV to the drug 3TC

the explanatory power of darwin s theory of evolution19
The explanatory power of Darwin’s theory of evolution
  • Natural selection is more an editing process than a creative process.
  • Natural selection depends on time and place, which in the end is a dependency on the conditions of the current environment.
fossil evidence
Fossil evidence
  • Change in location of and angle of spines on head
transition to sea life
Transition to sea life
  • Hypothesis: Cetaceans evolved from terrestrial species
  • Predictions can be tested using radioactive dating.
homology
Homology
  • Homologies are similarities found in different organisms that arise because of a common ancestry.
    • Anatomical homologies such as the arrangement of the forelimb in ALL mammals.
    • Homologous structures seen during development often have very different functions.
    • Explains the presence of vestigial limbs on snakes.
convergent evolution and analogous structures

LE 22-17

Convergent evolution and analogous structures

NORTH

AMERICA

Sugar

glider

AUSTRALIA

Flying

squirrel

biogeography
Biogeography
  • Biogeography is the geographic distribution of organisms.
  • Geography affects the dispersal ability of organisms.
    • Continental drift
  • Islands provide the best evidence for an environment’s influence on an organism.
    • Islands have numerous endemic species.
    • These species are closely related to species on nearby mainlands
theory
Theory
  • The theory of evolution explains results from many observations and experiments.
  • Theories stand up to thorough testing, explains many scientific results, and can be observed in nature.
  • Additions can be made to the theory. Natural selection is likely not the only mechanism operating as an organism evolves.