1 22 February 2017 EEOB 5310 Assignment 2 (parts a and b) Due: 24 March 2018 a) Speciation - A New Species of Salmon?
Please answer the following questions about phylogenetics 1. The following are nucleotide sequences from a homologous gene sequence in six different species of the slime mold genus, Dictyostelium, and an outgroup (Dermamoeba algensi):
a) Identify the synapomorphies in the table and recode them as binary characters (0, 1) in a table like that shown below. Al character states (traits) in the outgroup are ancestral so are coded by convention as 0 while derived character states are coded as 1. Omit synapomorphies that only support the ingroup as a monophyletic clade.
b) Consider the tree diagram below. Assuming that this phylogeny us accurate, map each of the six characters onto the branches of the tree to show where the characters are gained and/or lost. There are multiple ways of mapping the characters – show just one (correct) one here.
2. How many “evolutionary steps” are described by the phylogenetic hypothesis shown above? Using the same six characters propose an alternative phylogenetic hypothesis in the form of a branching diagram. You can do this by rearranging the taxa in the terminals of the diagram or by mapping the characters onto your diagram differently. How many steps does your alternative diagram have?
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122 February 2017EEOB 5310 Assignment 2 (parts a and b)Due: 24 March 2018a) Speciation – A New Species of Salmon?In a controversial paper, Hendry et al. (2000) claimed to have found an example of reproductiveisolation developing between two salmon populations in 13 generations. Various issues raised by criticsof the article include: 1) Whether the low level of genetic differentiation observed between populationsactually represented evidence for reproduction isolation or could be explained by other geneticmechanisms and 2) That population differentiation per se is not a sufficient condition the developmentof incipient speciation (Gustafson et al. 2001 and Howard et al 2001). In your response, briefly 1)Summarize the arguments for and against each of these two points using the literature provided and 2)If you had funding to study these fish populations what additional information would you collect toaddress both of these issues? Please limit your response to no more than 2 pages. All of these papershave been posted on the course website.b) PhylogeneticsPlease answer the following questions about phylogenetics1. The following are nucleotide sequences from a homologous gene sequence in six different species ofthe slime mold genus, Dictyostelium, and an outgroup (Dermamoeba algensi): a) Identify the synapomorphies in the table and recode them as binary characters (0, 1) in a table likethat shown below. Al character states (traits) in the outgroup are ancestral so are coded by conventionas 0 while derived character states are coded as 1. Omit synapomorphies that only support the ingroupas a monophyletic clade. 2 b) Consider the tree diagram below. Assuming that this phylogeny us accurate, map each of the sixcharacters onto the branches of the tree to show where the characters are gained and/or lost. There aremultiple ways of mapping the characters – show just one (correct) one here. 2. How many “evolutionary steps” are described by the phylogenetic hypothesis shown above? Usingthe same six characters propose an alternative phylogenetic hypothesis in the form of a branchingdiagram. You can do this by rearranging the taxa in the terminals of the diagram or by mapping thecharacters onto your diagram differently. How many steps does your alternative diagram have?
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