Darwin - PowerPoint PPT Presentation

Loading...

PPT – Darwin PowerPoint presentation | free to download - id: 77f89a-MTVjY



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Darwin

Description:

Darwin & Evolution by Natural Selection Warbler finch Ground finches Tree finches Cactus eater Insect eaters Seed eaters Bud eater 2006-2007 – PowerPoint PPT presentation

Number of Views:99
Avg rating:3.0/5.0
Slides: 34
Provided by: Roxan93
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Darwin


1
Darwin Evolution by Natural Selection
2
Incorrect Theories of Evolution Lamarck
  • Lamarck proposed an incorrect mechanism for how
    organisms evolve.
  • Believed organisms could pass on aquired traits
    to offspring
  • Simple life forms continually came into existence
    from dead matter
  • Continually become more complex
  • More "perfect" -- as they transformed into new
    species.
  • He correctly pointed out that change in species
    is linked to an organisms environment.

3
Charles Darwin
  • Proposed a way how evolution works
  • How did creatures change over time?
  • by natural selection
  • Collected a lot of evidence to support his ideas
  • 1809-1882
  • British naturalist
  • -Wrote the Origin of Species

4
Voyage of the HMS Beagle
  • Invited to travel around the world
  • 1831-1836 (22 years old!)
  • makes many observations of nature
  • main mission of the Beagle was to chart South
    American coastline

Robert Fitzroy
5
Voyage of the HMS Beagle
  • Stopped in Galapagos Islands
  • 500 miles off coast of Ecuador

6
Galapagos
Recently formed volcanic islands. Most of animals
on the Galápagos live nowhere else in world, but
they look like species living on South American
mainland.
800 km west of Ecuador
7
Darwins Observations
  • Animals on the coast of S. America
  • Resembled those on the nearby islands
  • Evolved differences
  • Or
  • Descended w/ modification after separating from a
    common ancestor.

8
Darwin foundmany unique species
Many of Darwins observations made him wonder
Why?
Darwin asked Why were these creatures found only
on the Galapagos Islands?
9
Darwin foundclues in the fossils
Darwin found Evidence that creatures have
changed over time
Darwin asked Why should extinct armadillos
modern armadillos be found on same continent?
10
Darwin found more fossils
Darwin found Evidence that creatures have
changed over time
Darwin asked Why should extinct sloths modern
sloths be found on the same continent?
11
Darwin found Different shells on tortoises on
different islands
Darwin asked Is there a relationship between the
environment what an animal looks like?
12
But Darwin found a lot of finches
  • Darwin was amazed to find out
  • All 14 species of birds were finches

But there is only one species of finch on the
mainland!
Large ground finch
Small ground finch
Finch?
Sparrow?
Darwin asked If the Galapagos finches came from
the mainland, why are they so different now?
Warbler finch
Tree finch
Warbler?
Woodpecker?
13
The finches cinched it!
  • different beaks are inherited variations
  • serve as adaptationsthat help birds compete for
    food
  • these birds survive reproduce
  • pass on the genes for those more fit beaks
  • over time nature selected for different species
    with different beaks
  • Darwin found
  • The differences between species of finches were
    associated with the different food they ate.

Darwin said Ahaaaa! A flock of South American
finches were stranded on the Galapagos
Large ground finch
Small ground finch
Big seed eater
Small seed eater
Warbler finch
Tree finch
Insect eater
Leaf bud eater
14
Relationship between species (beaks) food
15
Darwins finches
  • Darwins conclusions
  • variations in beaks
  • differences in beaks in the original flock
  • adaptations to foods available on islands
  • natural selection for most fit
  • over many generations, the finches were selected
    for specific beaks behaviors
  • offspring inherit successful traits
  • accumulation of winning traitsboth beaks
    behaviors
  • separate into different species

16
From 1 species to 14 species
natural selection for best survival reproduction
variation
17
  • Growth of Populations
  • Darwin was influenced by Thomas Malthus
  • He wrote
  • Populations grow as much as the environment
    allows.

18
Evolution by Natural Selection
  • The process of
  • Survival of the Fittest
  • Organisms that adapt to their environment survive
    while those that do not adapt disappear
  • N.S. leads to adaptations in a population.

19
ADAPTATIONS LEAD TO FITNESS
Living things that are well adapted to their
environment survive and reproduce. Those that are
not well adapted dont survive and reproduce.
?An adaptation is any characteristic that
increases fitness, which is defined as the
ability to survive and reproduce. ? YOU CANNOT
AQUIRE AN ADAPTATION, MUST BE AN INHERITED TRAIT.
20
Label Paper
  • Genetic Variation
  • a.
  • b.
  • Overproduction of Offspring a.
  • b.
  • Struggle for Existence a.
  • b.
  • Differential Survival Reproduction a.
  • b.

Natural Selection Video
http//www.pbs.org/wgbh/evolution/library/11/2/e_s
_4.html 6 min 39 sec
21
SUMMARY Individuals best suited to their
environment survive and reproduce most
successfully. The characteristic that make them
best suited to their environment are passed on to
offspring.
Individuals whose characteristics are not as well
suited to their environment die or leave fewer
offspring.
22
Species change over time. This is natural
selection.
Over long periods of time, natural selection
causes changes in the characteristics of a
species, such as in shape and form. New species
arise, and other species disappear.
23
Species alive today have descended with
modifications form species that lived in the past.
African wild dog
Jackal
Fox
Thousands tomillions of yearsof natural
selection
Fox
Wolf
Coyote
Ancestral canine
  • These five canine species evolved from a common
    ancestor through natural selection

24
Darwins Ideas Updated
  • 1) Change Within Populations
  • N.S. causes the frequency of certain alleles in a
    population to change over time.
  • 2) Species Formation
  • Under certain conditions, change within a species
    due to reproductive isolation can lead to new
    species.
  • 3) The Tempo of Evolution
  • Gradualism is a process of evolution in which
    speciation occurs gradually
  • Punctuated Equilibrium is a process in which
    speciation occurs rapidly between periods of
    little or no change.

25
(No Transcript)
26
Examples of Evolution--
Natural Selection at Work
  • 1) Factors in Natural Selection
  • Organisms w/traits helping them survivereproduce
    pass genes.
  • 2) Evolution of Antibiotic Resistance
  • Experiments show that evolution through N.S. has
    occurred within populations of antibiotic-resistan
    t bacteria
  • Tuberculosis bacteria
  • 3) Evolution in Darwins Finches
  • Experiments show that evolution through N.S. has
    occurred in beak size in Darwins Finches.

27
Formation of New Species
  • 1) Speciation
  • Speciation begins as a population adapts to its
    environment.
  • 2) Forming Subspecies
  • Populations of the same species that differ
    genetically b/c of adaptations to different
    living conditions are called subspecies.
  • Newly formed subspecies are on the road towards
    speciation.
  • 3) Maintaining New Species
  • Reproductive isolation through barriers keeps
    species from breeding with one another.

28
Speciation
  • Geographic isolation of populations
  • Can lead to
  • Reproductive isolation of population
  • Can lead to
  • New Species
  • (unable to breed when together)

29
Geographic Isolation
  • Members of a population may become isolated from
    one another by geographic boundaries like
    mountains, rivers or even oceans

30
Reproductive Isolation
31
Convergent Evolution
32
Divergent Evolution(Adaptive Radiation)
33
Dichotomous Keys
  • Tool used when new species is found
  • Used to categorize different species based on
    physical characteristics
  • Classification is a way of separating a large
    group of closely related organisms into smaller
    subgroups.
  • A Dichotomous Key is a listing of
    characteristics, such as structure and behavior,
    organized in such a way that an organism can be
    identified or classified.
About PowerShow.com