Age of EarthAge 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 What if the environment changes?changes?
The organisms must adapt to the environment. Those that
don’t adapt-die.This is a very slow process….does
not occur over night…many generations must past before
any change in the population can be seen.
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Example: Peppered MothExample: Peppered Moth
Two
versions of
the moth-
Black
and
peppere
dDuring
the
industrial
revolution
on England
Populatio
n of moths
changed66
Decent with modificationsOvertime
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.88
These changes increase a species’
fitness in their environment.
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. 1111
•Lylle -1833-proposed that plant and animal species had arisen, developed variations, and then became extinct over time. He also believed that the Earth’s 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. 1144
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Humans select and breed for certain traits.
Examples: The largest hog, the cow that gives the most milk, or fastest horse.
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).
Evidence for Change Over TimeFossil Record
–Fossils that show how the same organism looked millions of years ago.
–Paleontology –Use rock layers– Isotope 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.1199
Vestigial organsVestigial organs–Organs or structures Organs or structures that do not seem to be that do not seem to be used by the organism used by the organism any longer. any longer.
–They are usually They are usually reduced in size.reduced in size.
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GeneticsGenetics
DNA sequences in
organisms are close
Sources of genetic
variation in species:
1.Mutations
2.Gene Shuffling
3.Crossing over
during meiosis
•Speciation •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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•Overtime they can change so much that they become unable to breed as they adapt to their environment.
Speciation Mechanisms• 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
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Gene Pool•Combined
genetic
information
of a particular
population.
•All the
genes present with
in a population
•Can change
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 Convergent EvolutionEvolution
•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.
Coevoluti
on is the
joint
change of
two or
more
species in
close
interactio
n.
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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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Gradualism Gradualism && Punctuated Equilibrium 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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GradualismGradualism•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 equilibriumPunctuated 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.
Two main sources of Two main sources of genetic variationgenetic variation
1.1.MutationsMutations
2.2.Genetic ShufflingGenetic 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 extinctionD 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 individualsA acquired traits during their lifetimes that contributed to survivalB with traits most suited to their environments reproduced most successfullyC migrated long distances to environments that most suited their traitsD 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 thatA birds and reptiles have a common ancestorB birds have changed very little over 150 million yearsC reptile species are more advanced than bird speciesD reptiles are warm-blooded like birds
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Horses and tapirs have a common ancestor, but Horses and tapirs have a common ancestor, but now look very different. Horses now are grassland now look very different. Horses now are grassland animals adapted for grazing on grass and shrubs. animals adapted for grazing on grass and shrubs. Tapirs are jungle animals that live in dense forests Tapirs are jungle animals that live in dense forests and eat fruit, leaves and aquatic vegetation. Which and eat fruit, leaves and aquatic vegetation. Which of the following led to the development of such of the following led to the development of such differences in the two species?differences in the two species?
A selective breedingA selective breedingB convergent evolutionB convergent evolutionC DNA hybridizationC DNA hybridizationD natural selectionD natural selection
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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.
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 loss—both advantages in a cold climate. This is an example of natural selection acting upon a population, producing micro-evolution on a continental scale.