Download Evolution

Evolution
Natural Selection
Genetic Basis of Evolution
Speciation
The History of the Earth
Biological Evolution
• Scientists look at the history of living things.
Fossils – the remains or impressions of an
organisms that lived in the past
• Evolution is the changes in a population over
time. Population – a group of organisms of
the same species that live in the same area
• Biological evolution – the change in the gene
pool of a population over time
• Gene pool – the genes found within a
population
Charles Darwin
• Darwin sailed around the world,
making observations on nature.
• Patterns of Diversity – organisms
well suited to their environment
• Common descent – a theory that
present organisms descended
from past organisms
• Descent with modification – the
theory that more recent species
of organisms are changed
descendants of earlier species
Ideas that shaped Darwin’s thinking
• Belief that many periods of
creation in which
catastrophic events killed
species.
• Lyell and Hutton – dynamic
earth process have shaped
the Earth over many periods
of years. The Earth does not
look the same as it did when
it was first created.
Ideas that shaped Darwin’s thinking
• Lamarck proposed that by selective use or
disuse of organs, organisms acquired or
lost certain traits during their lifetime.
These traits could be passed on to their
offspring. This lead to a change in
species.
Ideas that shaped Darwin’s thinking
• Malthus reasoned that if the human
population continued to grow unchecked,
sooner or later there would be insufficient
living space and food for everyone
Darwin’s Theory of Evolution
• Evolution – the process by which modern
organisms have descended from ancient
organisms (change over time).
• Heritable variation in organism is caused by
variations in the genes.
• Adapts – to change genetically over
generations to become more suited to the
environment
• Modern synthesis – a theory that states
evolution involves changes in a population’s
gene pool over time
Darwin’s Theory of Evolution
• Artificial selection – nature provided the
variation and humans selected those
variations that they found useful
Darwin’s Theory of Evolution
• Struggle for existence – high birth rates
and shortage of life’s basic needs forces
organisms into a competition for resources
• Survival of the fittest – ability of an
individual organism to survive and
reproduce successfully in it’s environment
• Adaptation – any inherited characteristic
that increases an organism’s chance of
survival
Darwin’s Theory of Evolution
• Natural selection – only certain individuals
of a population produce new individuals,
based on the traits and their suitability to
the environment. Man does not intervene
in natural selection
Darwin’s Theory of Evolution
• Organisms tend to produce more offspring
than can survive. Overproduction – when
organisms produce more offspring than can
survive
• Individuals in a population vary in many traits.
• Individuals with alleles best suited to the
environment are more likely to survive.
• Individuals that survive produce more
offspring. Differential reproduction –
individuals leave more offspring that other
individuals.
Evidence of Evolution
• Fossil record – Earth must
be very old.
• Fossils from older rocks
show less diversity that
fossils from younger rocks
• Fossils could show
organisms change from
one form to another,
however, they don’t exist
Evidence of Evolution
• Geologic time – all the time that has
passed since the Earth formed
• Paleontologist – a scientist who studies
fossils
• Radioactive elements – an element that
decays to form another element
• Since decay happens over a consistent
time, scientists can estimate how old a
rock is based on the rate of decay.
Evidence of Evolution
• Geologic time scale – a table that divides the
Earth’s history into time periods
• Precambrian period (4 billion years – 550
million years ago) – mostly bacteria and small
cellular organisms
• Paleozoic period (550 million years – 250
million years ago) – first fishes and land plants,
amphibians, and small reptiles
– Invertebrates: an animal that does not have a
backbone
– Vertebrates: an animal that has a backbone
Evidence of Evolution
• Mesozoic period (250 million years to 65
million years ago) – dinosaurs, first
flowering plants and birds, mammals
– Reptile – an egg-laying vertebrate that
breathes with lungs
• Cenozoic period (65 million years ago to
present) – mammal evolution and humans
Evidence of Evolution
• Plate tectonics – a theory that the Earth’s
surface is made of large sections of crust
that move
• Continental drift – a theory that the major
landmasses of the Earth move
• Magma – hot, liquid rock inside the Earth
• Plate – a large section of the Earth’s crust
that moves
• Crust – the outer layer of the Earth
Evidence of Evolution
• Geographic
distribution of living
things
• Members of the same
species look very
different because of
the environment
Members of different
species have similar
behaviors and physical
traits because of the
environment
Evidence of Evolution
• Homologous
structures –
different species
have similar
structures to
perform similar
functions
• Vestigial organs
– organs that
have little or no
use on certain
species
Evidence of Evolution
• Embryology –
different species
have similar early
life stages
Genetic Variation
• Gene pool – consists of all the genes,
including the different alleles, present in a
population
• Relative frequency - number of times that
an allele occurs in a gene pool
• Evolution, in genetic terms is any change
in the relative frequency of alleles in a
population
• Two main sources of genetic variation:
mutations and genetic shuffling
Genetic Change
• Single-gene trait – a characteristic
controlled by a single gene
• Polygenic trait – a characteristic controlled
by many genes
• Natural selection on single gene traits can
lead to changes in allele frequencies and
then to evolution
• Recombination – the creation of new
combinations of alleles of an offspring
Genetic Change
• Gene flow – the movement of genes into
or out of a population
• Genetic drift – the random changes in the
gene pool of a small population
• Endangered – a condition in which there
are almost no organisms of a certain
species
• Extinction – the death of all members of a
species
• Habitat – place where an organism lives
Genetic Change
• Hardy-Weinberg Equilibrium – a principle
that states the frequencies of alleles in a
population do not change unless
evolutionary factors act on the population
• In order for the principle to work, changes
must occur within a population
• p2 + 2pq + q2 = 1
Evolutionary Principles
• Microevolution – the minor changes in a
population’s allele frequencies from
generation to generation
– Moths changes from light-colored to darkcolored
• Macroevolution – the large-scale changes
in a population over long periods of time
– Extinctions or may result in a new species
• Frequency – the rate of occurrence
Speciation
• Species – a group of living things that can
breed with each other and produce
offspring that are fertile, capable of
producing offspring
• Reproductively isolated – a division
between populations that once mated, but
can no longer mate and produce fertile
offspring
• Interbreed – to breed together
Speciation
• Biological species concept – principle that
defines a species as populations that can
interbreed and produce offspring
– Donkeys and horses mate, but produce mules
which are infertile.
– Fireflies look similar, but different species do not
mate
Speciation
• Ecological species concept – principle that
defines species as populations that can
interbreed and produce offspring based on
their niche, the way of life of a species
– Asexual reproduction – reproduction that involves
one parent and no egg or sperm
– Organisms that use asexual reproduction can still
be defined as a species even though the do not
have a mate
Speciation
• Allopatric speciation –
when similar
organisms do not
interbreed due to
physical barriers
• Physical barriers
could include
mountains, forests,
deserts, rivers, or
oceans
• Sympatric speciation
– when similar
organisms live
nearby, but do not
interbreed due to
differences in
behavior
• Plant species that are
grown for food,
different animal
mating rituals
Speciation
• Species become different because of
different environments. Occur at different
rates.
• Stasis – showing little change over time
• Punctuated equilibrium – a theory that
states species stay the same for a long
time, then new species evolve suddenly
due to global changes and mass
extinctions.
• Coordinated stasis – pattern where most
species appear at about the same time
Speciation
• Mass extinctions – the dying out of large
numbers of species in a short period of
time
– One mass extinction 250 million years ago,
Dinosaurs died in a mass extinction 65 million
years ago
– Volcanic eruptions, plate tectonics, asteroids
hitting the Earth
• Community – a group of different
populations that live in the same area
Speciation
• Co-adaptation – one species becoming
dependent on another species
– Species come into contact with another
species so much that they change with each
other
• Instantaneous speciation – a new species
formed in one to several generations
– Fruit flies breed on one plant, while another
breed on another plant; genes mutate or
combine in a short time
Theory of Intelligent Design
Age of the Universe/Solar System
DNA/Microbiology
Evolutionary Myths
Intelligent Design
• The watch and the
watchmaker
• Universe and life
not made from a
series of random
processes.
• Since non-living
and living things
show a great deal
of complexity,
there must be an
intelligent designer
that created it.
Age of the Universe
• Approximate age of
the universe is
between 17 billion and
22 billion years old
• Hubble space
telescope – furthest
electromagnetic
radiation detected
• What is beyond the
universe?
• If the universe has an
end, it must have a
beginning
Age of the Solar System
• Solar system –
approximately 4.6
billion years old
• For natural
selection and
speciation to
occur, this is too
short a time for
the processes to
be successful.
DNA/Microbiology
• “To be or not to be” Image dropping
scrabble letters to spell out this sentence!
• DNA language is the same, no matter
what species. If evolution is true, then
DNA should have evolved every time a
species evolved and it would not be the
same.
Blood Clotting Biochemistry
Evolutionary Myths
• Fossil record does not show intermediary
species that prove speciation.
• Adaptations do exist, but do not lead to
formation of new species (Darwin’s
Finches)
• Embryology chart
• Homologous structures