7.4 Human Genetics and Pedigrees Bell Work. 7.4 Human Genetics and Pedigrees Bell Work.
Bell Work
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Transcript of Bell Work
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Bell Work
• Dogs of a certain breed can have black fur or white fur. Black fur is dominant, but the breeder only wants puppies with white fur. Cross two heterozygous dogs until that happens.
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Biology – Lecture 59
Phylogeny
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Taxonomy
• The classification, identification, and naming of organisms
• Connected to phylogenetics
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Phylogenetics
• The study of evolutionary relationships among groups of organisms which are discovered through molecular sequencing data and morphological data matrices.
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Phylogeny
• The evolutionary history of taxonomic groups• Made from the results of phylogenetic studies
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Example of Phylogeny
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Phylogeny Branches
• Evolution is a branching process.• Populations are altered over time and may
split into separate branches, hybridize together, or terminate by extinction.
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Phylogenetic Tree
• A hypothesis of the order in which evolutionary events are assumed to have occurred.
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Tracing Relationships
• Biologists estimate that there are about 5 to 100 million species of organisms living on Earth today.
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Tracing Relationships
• Evidence suggests that all organisms on Earth are genetically related, and the genealogical relationships of living things can be represented by a vast evolutionary tree, the Tree of Life.
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The Tree of Life
• Phylogenetic analyses have become essential in researching the evolutionary tree of life.
• The tree of life is a large project to trace the evolutionary relationships of large groups of organisms.
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Example - Tree of Life
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The Tree of Life
• Implies that different species arise from previous species and that all organisms are connected via descent to one another.
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How is a Phylogeny Created?
• Matrix-based methods are used to construct trees based on overall similarity, which is often assumed to approximate phylogenetic relationships.
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Flaws of Hypothesis
• There is no way to measure whether a particular phylogenetic hypothesis is accurate or not, unless the true relationships among the taxa being examined are already known.
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Phylogeny Vocabulary
• Monophyletic clade – all the members in a group with the same characteristics
• Synapomorphy – a particular trait within the phylogeny
• Autapomorphic trait – only one organism has this trait
• Outgroup - The simplest form of a common ancestor• Sister Groups – Two groups that can be traced back
to a single split.
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Example - Phylogeny of Beasties
• Reconstruct the evolutionary history of a group of imaginary organisms known as Beasties.
• The Beasties are a morphologically diverse group, and your analysis will take advantage of this diversity.
• You will infer the simplest phylogenetic tree for the group of Beasties.
• The outgroup taxon is indicated, as are six other Beastie taxa (A-F).
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The Beasties
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Step 1
• Conduct a character analysis by examining the similarities and differences.
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Example ChartCharacteristic
ABCDEF
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The Beasties
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Step 2
• Figure out those that are most similar to one another.
• Start by comparing to the Outgroup (if given).• If no outgroup is given, start with the one with
the most “no” responses.
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Step 3
• Draw the initial branch and then make branches off of that branch based on the similarities and differences of the organisms.
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Drawing Our Phylogeny
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Answer Phylogenyoutgroup E D B F A C
Tongue
Spots
BeardPointed Feet
Brushy Tail
Branched Antenna
Fin
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• Based on your tree, find all the groups in the list that are sister to each other.