EVIDENCE FOR EVOLUTION
Define the following terms:
Fossil: Any trace of an organism
Transitional fossil: Fossil species with traits
intermediate between those of older and younger spp
Vestigial trait: A trait that a no longer retains function
Mass extinction: The extinction of many species in a
short period of time
Biogeography: The study of the distribution of life
Endemic species: specie that occupies only one place on
Earth
Radiometric dating: The method that uses the half-life
of radioactive isotopes to calculate age rocks/minerals Dispersal: The movement of organisms from their place
of origin.
Continental drift/plate tectonics: Earth’s crust broken
into pieces and floats on semisolid mantle
Homology: the traits species share due to common
ancestor.
Artificial selection: The selective breeding of organisms
to attain desirable traits.
Convergent evolution: The evolution of similar traits in
distantly related organisms that occupy similar envt’s
Background extinction:
Describe, briefly, the general process of fossilization, including the conditions ideal for fossilization.
Fossils can be formed in a # of ways, but most commonly, mineralization of parts occur
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1) Rain and runoff eroded the land
2) Particles of rock and soil ran-off to a body of water
3) Particles settled to the bottom, forming layers over millions of years.
4) The newer sediments compress the older sediments into a solid matrix.
Ideal conditions include low oxygen and high acidity.
You require fast burial and slow decomposition.
Explain why the fossil record is incomplete, addressing at least two types of bias in the fossil record.
Habitat Bias
Location, Location, Location: Burial is crucial to fossilization, so those living in areas that allow fossilization are
more common
Type of Animals: Burrowing animals are more easily fossilized than terrestrial or air animals.
Temporal Bias
Date of fossilization: Organisms that were fossilized recently are more commonly found than ancient ones
o Why: This is due to subduction zones, when fossils enter the core of the earth.
o Extreme pressure and heat destroy fossils.
o Rocks become eroded and fossil is destroyed.
Taxonomic Bias
Structures: Harder structures fossilize better
Teeth of shark are more common than bones because bones are made of cartilage. (soft bones)
Describe, briefly, how continental drift could affect the evolutionary history of a species. [Comprehension]
The evolutionary history of a species is fossils.
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When the continents drift apart, species become separated and they end up isolated.
When organisms are separated, then they evolve in isolation, so you end up with new species that have
evolved to their new environments.
Describe, briefly, Darwin’s observations and explanation regarding the phenotype/morphology of
organisms on islands compared to those on the closest mainland. [Comprehension]
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Darwin saw that the finches were each their own species on each of the Islands
They all closely resembled a finch living on the mainland (Ecuador)
He explained it by saying, as species disperse from the mainland to a new island, they may give rise to new
species as populations spread out.
The beaks had a feature that were best fit for their environment (natural selection)
Compare and contrast homology and convergent evolution, noting how they can be distinguished.
Homologies are traits that have come from a common ancestry. They have a range of functions
Convergent evolutionary traits have come from an uncommon ancestry and have the same function.
You can distinguish between them by checking the structure. If the structure is similar, but function different then
it is a homologous traits. If the structure is different and function is similar, then it is a result of convergent evo.
Define and describe the three levels of homology and how they are related. [Comprehension, Analysis]
Homologies are traits that are similar as a result of common ancestry. They can be similar in THREE ways:
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Structural
o Anatomically similar
o Vestigial Traits
Developmental sequences
o All mammals look the same as embryos
Genetic
o DNA sequence of genes is similar for different species
THE BE ALL AND END ALL POINT!!!!
o STRUCTURES AND DEVELOPEMT CANNOT BE THE SAME UNLESS GENES ARE SIMILAR
Describe two ways that evolution can be observed today. [Comprehension]
Evolution can be observed today through 1) Fossil records and plotting the evolutionary history and 2) Running
experiments in laboratories (fruit fly starvation experiment)
Provide and explain two lines of evidence, each, for the ideas: 1) that species change over time and 2)
descent with modification. [Comprehension]
1) Species change over time
Continental Drift and extinction: When Pangaea formed, 96% of species were lost because shallow marine
habitats were gone.
Continental Drift and diversification: when Pangaea broke up, there was a blast of diversification due to
climate and isolation change.
2) Descent with modification
Transitional Fossils: If life evolved from a common ancestor then we should see transitional fossils and we
do.
Vestigial Traits: Reduced or non-functioning structures but similar to functioning structures in ancestor.
Shows that species are related and they are changing.
Artificial Selection
Biogeography
Homology
Explain, using examples, how each of the following provides evidence for the process of evolution
Biogeography: When species disperse from the mainland, they can give rise to new species as populations spread
to neighbouring islands.
Artificial Traits: artificial selection provides evidence for evolution because it shows the power of selection.
Populations can be altered based on their desired traits. Instead of humans selecting, the environment selects.
Define:
Evolutionary developmental biology: The study of comparing genes controlling the developmental processes
Genetic tool-kit: genes shared by all organisms
Explain, using a very general example, how changes in developmental regulatory genes can be a genetic
switch between different morphologies. [Comprehension]
Homoeotic genes are regulatory genes that code for transcription factors that bind regulatory sites on DNA. All life
shares these genes that control their development. It governs the basic design of the body plan by controlling
thousands of other genes.
Morphological differences among species arise when mutations alter the effects of developmental regulatory
genes. Changing the combinations of the toolkit genes may be expressed at different times and in different body
regions.
Define gene duplication and explain how it can lead to evolutionary change. [Knowledge, Comprehension]
Gene duplication is the act of duplicating any region of DNA that contains a gene. It can lead to evolutionary change.
When genes are mutated the organism diversifies, which could lead to an evolutionary advantage in which the trait
will be magnified and passed on whereas it also lead to detrimental effects and the organism could will go extinct.