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Evolution
Chapter 15
Two schools of thought Creationism – The belief that the universe and
living organisms originate from divine creation Evolution – A gradual process in which something
changes into a more complex form
Creationism vs. Evolution
Creationism Evolution
Definition God created everything in the universe
Change of organisms over a long period of time
Time of Earth’s existence
More than 4,000 years
4.5 billion years
Life started with God made animals, plants, and people
A single cell organism
Creationism vs. Evolution
Issue # 1: The origin of the earth Creation – God (or an intelligent designer) created
the heavens and earth Evolution – several ideas (have not decided on
one theory) Solar nebular theory – Hydrogen and helium came
together to form stars. When stars die, they explode releasing clouds of gas and dust. The dust started to stick together. Over millions of years, they formed planets.
Creationism vs. Evolution
Creationism vs. Evolution
Issue # 2: People believed the earth was flat Columbus “proved” that the earth is round in the
15th century
Isaiah 40: 21-22 states that the earth has a circular shape
Evolution
Evolution – a change in an organism over a long period of time
Charles Darwin – the father of evolution Darwin had some proof to support his theory
The shape of fossils Darwin’s time on the HMS Beagle Darwin’s trip to the Galapagos Islands
Located off of South America
Evolution
Endemic species – a species which is only found in a given region or location and nowhere else in the world Two examples
Galapagos tortoises and Galapagos finches
Evolution
Galapagos tortoises
Evolution
Galapagos finches
Artificial Selection
Artificial selection – breeding organisms with specific traits in order to produce offspring with identical traits Man chooses which traits
organisms should have Example – dogs and
cows
Artificial Selection
Example – beef cows vs. dairy cows
Natural Selection
Natural selection –Organisms with favorable variations survive, reproduce, and pass their variations to the next generation Selection occurs on its
own or “naturally” Example – birds with
long tail feathers
Natural Selection
Darwin called natural selection “survival of the fittest” Stronger organisms with
preferred traits lived and made fertile offspring
Example – Two populations of fish One population is faster
than the other
Natural selection would favor which population?
“X” indicates faster swimmer
Natural Selection
Natural selection would favor polar bears in the arctic and grizzly bears in the taiga. Why?
Adaptations: Evidence for Evolution Adaptation – any
variation that aids an organism’s chances of survival in its environment
Adaptations in species develop over many generations
Adaptations of a frog
Adaptations: Evidence for Evolution Several forms of
adaptations: Mimicry – a structural
adaptation that enables one species to resemble another species
Adaptations: Evidence for Evolution
Aggressive mimicry – a technique used by some animals to lure prey to them by mimicking something else Angler fish
Adaptations: Evidence for Evolution
Aggressive mimicry Golden orb weaver will
weave heavy zig-zag lines of web to attract insects Found in Australia
Adaptations: Evidence for Evolution
Aggressive mimicry Snapping turtle’s tongue
resembles a worm
Adaptations: Evidence for Evolution
Camouflage – an adaptation that enables species to blend with their surroundings
Adaptations: Evidence for Evolution
Warning coloration – A protection adaptation used by some animals that uses color to alert other animals to keep away Yellow jacket Poison dart frog
Other Evidence for Evolution
Anatomy Homologous structures – structures with common
evolutionary origins Provides evidence of evolution from a common ancestor Examples: forelimbs of lizards, whales, humans, and
birds
Other Evidence for Evolution
Analogous structures – structures that do not have a common evolutionary origin but are similar in function
Other Evidence for EvolutionInsect
PterodactylBat
Bird
Analogous structures
Other Evidence for Evolution
Vestigial structure – a structure in a present-day organism that no longer serves its natural purpose, but was probably useful to an ancestor Example: appendix
Other Evidence for Evolution
Embryology – the earliest stage of growth and development of both plants and animals
Population Genetics and Evolution Evolution occurs on populations, not
individuals Variation coupled with natural selection fuels
evolution Gene pool – all of the alleles in a population’s
genes
Population Genetics and Evolution Natural selection acts on variations
Stabilizing selection –favors average individuals in a population
Directional selection – favors one of the extreme variations of a trait
Disruptive selection – individuals with either extreme of a trait’s variation are selected for Tends to eliminate intermediate phenotypes
The Evolution of Species
Speciation – the evolution of a new species Several ways for speciation to occur:
Geographical isolation – a physical barrier divides a population
The Evolution of Species
Reproductive isolation – formerly interbreeding organisms can no longer mate and produce fertile offspring
Patterns of Evolution
Divergent evolution - (adaptive radiation) an ancestral species evolves into an array of species to fit a number of diverse habitats
Laysan finches from the Hawaiian islands
Patterns of Evolution
Convergent evolution – Unrelated species evolve similar traits