Changes in Species Over Time

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Changes in Species Over Time
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Age of Earth

• Scientist believe that the Earth is 4.6 Billion
  years old.
• Evidence
• Rock data, environmental changes

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Natural Selection

• Also know as survival of the fittest.
• Only certain members of the population will
  survive and reproduce.
• Ones that are most suited to the environment.

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If an organism reproduces, then the traits of
that organism are passed to the next
generation. Traits that are favorable for a
certain environment become more prevalent within
that population.
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What if the environment changes?

• The organisms must adapt to the environment.
  Those that dont adapt-die.
• This is a very slow process.does not occur over
  nightmany generations must past before any
  change in the population can be seen.

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Example Peppered Moth

• Two versions of the moth-
• Black and peppered
• During the industrial revolution on England
• Population of moths changed

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Decent with modifications
Overtime natural selection produces organisms
that have different structures, established
different niches, or occupy different habitats.
Organisms that were once the same have now grown
apart and have become different organisms.
These changes increase a species fitness in
their environment.
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History

• James Hutton -1785-Propsed that he Earth is
  millions of years old.
• Thomas Malthus -1798-proposed that populations
  outgrew their food supplies, causing competition
  between organisms and a struggle for one species
  to survive against another
• Jean-Baptiste Lamark -1809-believed that all life
  forms evolved and that the driving force of
  evolution was the inheritance of acquired
  characteristics. He believed that organisms
  changed due to the demands of their environment.

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• Lylle -1833-proposed that plant and animal
  species had arisen, developed variations, and
  then became extinct over time. He also believed
  that the Earths physical landscape changed over
  a long period of time.
• Alfred Russel Wallace -1858-emphasis was based on
  the idea of competition for resources as the main
  force in natural selection
• Charles Darwin -1859- Publishes On the Origin of
  Species

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Charles Darwin
British Naturalist 1809 -1882 I have called
this principle, by which each slight variation,
if useful, is preserved, by the term Natural
Selection. Charles Darwin from "The Origin of
Species"
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From 1831 to 1836 Darwin served as naturalist
aboard the H.M.S. Beagle on a British science
expedition around the world. In South America
Darwin found fossils of extinct animals that were
similar to modern species. On the Galapagos
Islands in the Pacific Ocean he noticed many
variations among plants and animals of the same
general type as those in South America.
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Artificial selection provides a model that helps
us understand natural selection.People have been
artificially selecting domesticated plants and
animals for thousands of years. These activities
have amounted to large, long-term, practical
experiments that clearly demonstrate that species
can change dramatically through selective
breeding. Broccoli and brussels sprouts bear
little superficial resemblance to their wild
mustard relatives (left).
Humans select and breed for certain
traits. Examples The largest hog, the cow that
gives the most milk, or fastest horse.
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Evidence for Change Over Time

• Fossil Record
• Fossils that show how the same organism looked
  millions of years ago.
• Paleontology
• Use rock layers
• Isotope dating

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Relative Dating
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Homologous structures Structures that have
different mature forms in different organisms but
have developed from the same type of tissue.
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Homologous structures
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• Embryology
• Early development of the organism

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Stages of developmentp385
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Vestigial organs

• Organs or structures that do not seem to be used
  by the organism any longer.
• They are usually reduced in size.

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Vestigial Organs
c
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• Genetics
• DNA sequences in organisms are close
• Sources of genetic variation in species
• Mutations
• Gene Shuffling
• Crossing over
• during meiosis

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• Speciation

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• is the evolution of a new species that occurs
  when interbreeding happens, or when the
  production of fertile offspring is prevented.

In the physical world, natural barriers form and
cause the breakup of populations to form smaller
populations.
Volcanoes, sea-level changes, and earthquakes are
a few examples of natural occurrences that affect
populations
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Speciation Mechanisms
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• Behavioral Isolation
• Populations are capable of interbreeding, but
  have different courtship rituals or other type of
  behavior.
• Geographic Isolation
• Separated by bodies of water or mountains.
• Temporal Isolation
• Reproduction takes place at different times of
  the year

• Overtime they can change so much that they become
  unable to breed as they adapt to their
  environment.

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• Gene Pool
• Combined genetic information of a particular
  population.
• All the genes present with in a population
• Can change

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Changes in allele frequency with in a population

• Genetic drift
• Random changes in allele frequency that occurs in
  small populations
• Also know as the founder effect
• Populations may move into a new area and the
  alleles that carry with them will be passed on to
  their offspring.

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Divergent Evolution

• Divergent evolution is the process of two or more
  related species becoming more and more
  dissimilar.
• The red fox and the kit fox provide and example
  of two species that have undergone divergent
  evolution.
• As they adapted to different environments, the
  appearance of the two species diverged.

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Convergent Evolution

• Convergent evolution is the emergence of
  biological structures or species that exhibit
  similar function and appearance but that evolved
  through widely different evolutionary pathways.
• examples include the multiple origins of wings
  (bats, birds) and eyes.

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Coevolution

• Predators and their prey
• Parasites and their hosts
• Plant-eating animals and the plants upon which
  they feed
• One example of coevolution is between plants and
  the animals that pollinate them.

Coevolution is the joint change of two or more
species in close interaction.
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• Evolution at the species level is called
  microevolution.
• It results from genetic variation and natural
  selection within a population of organisms.
• Macroevolution is evolution that occurs between
  different species.

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• Evolution is the change in a species over time.

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Rates of Evolution
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Gradualism Punctuated Equilibrium

• Two ways in which the evolution of a species can
  occur.
• A species can evolve by only one of these, or by
  both.

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• Species with a shorter evolution evolved mostly
  by punctuated equilibrium, and those with a
  longer evolution evolved mostly by gradualism.

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• Gradualism
• Very gradually, over a long time... Over a short
  period of time it is hard to notice.
• Small variations that fit an organism slightly
  better to its environment are selected for a few
  more individuals with more of the helpful trait
  survive, and a few more with less of the helpful
  trait die.
• Change is slow, constant, and consistent.

• Punctuated equilibrium
• change comes in spurts. There is a period of very
  little change, and then one or a few huge changes
  occur, often through mutations in the genes of a
  few individuals.

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Resistance in Bacteria
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Read page p403.
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Two main sources of genetic variation

1. Mutations
2. Genetic Shuffling

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EOCT- It is important that you are able to
explain how the concepts of genetics provide the
basis for explaining natural selection and
evolution. This will help you answer questions
like this

• What is the end result of natural selection?
• A increased number of offspring of a given
  phenotype that survive
• B changes in the frequency of alleles in a
  population
• C fossil formation through extinction
• D environmental changes of a habitat

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Although the Arctic fox and the kit fox are
closely related, they look very different because
the individuals A acquired traits during their
lifetimes that contributed to survival B with
traits most suited to their environments
reproduced most successfully C migrated long
distances to environments that most suited their
traits D passed on to their offspring acquired
behaviors that were helpful
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Fossils of Archeopteryx show that this animal had
feathers, like a bird. It also had a bony tail,
teeth, and claws on its wings, like a reptile.
This fossil is evidence that supports the idea
that A birds and reptiles have a common
ancestor B birds have changed very little over
150 million years C reptile species are more
advanced than bird species D reptiles are
warm-blooded like birds
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Horses and tapirs have a common ancestor, but now
look very different. Horses now are grassland
animals adapted for grazing on grass and shrubs.
Tapirs are jungle animals that live in dense
forests and eat fruit, leaves and aquatic
vegetation. Which of the following led to the
development of such differences in the two
species? A selective breeding B convergent
evolution C DNA hybridization D natural selection
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Adaptation is the key concept in natural
selection.
Review CLIP
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• Adaptation is a key concept in natural selection.
  
• Natural selection can change the inherited
  characteristics in a population and possibly even
  result in a new species.

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The environment affects the evolution of living
things.
House sparrows arrived in North America from
Europe in the nineteenth century. Since then,
genetic variation within the population, and
selection in various habitats, have allowed them
to inhabit most of the continent. House sparrows
in the north are larger and darker colored than
those in the south. Darker colors absorb sunlight
better than light colors and larger size allows
less surface area per unit volume, thus reducing
heat lossboth advantages in a cold climate. This
is an example of natural selection acting upon a
population, producing micro-evolution on a
continental scale.
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• Proposed by Charles Darwin, natural selection is
  the process by which organisms that are best
  suited to their environment survive and pass
  their genetic traits on to their offspring.