Phylogeny 2 Flashcards
What are synapomorphies in DNA sequence data?
shared characteristics used to determine evolutionary relationships among species.
What is the difference between parsimony and maximum likelihood in phylogenetics?
Parsimony seeks the tree with the fewest changes, while maximum likelihood estimates the tree that best fits the observed data.
Why is using multiple genes important in phylogenetic analysis?
Using multiple genes improves the accuracy of species tree construction.
What should characteristics be for reliable phylogenetic analysis?
independent, homologous, maximize variability, and minimize homoplasy.
Why are single base pairs considered poor synapomorphies?
Single base pairs have limited states (only 4) and can result in homoplasy, making them less reliable for phylogenetic analysis.
What is homoplasy, and what causes it?
Homoplasy is similarity not due to common descent. It can occur due to convergent evolution or evolutionary reversals.
How does Parsimony work with DNA data?
Parsimony aims to find the tree with the fewest evolutionary changes based on DNA data.
Why are outgroups used in phylogenetics?
Outgroups help identify ancestral character states, aiding in the construction of phylogenetic trees.
What is the difference between rooted and unrooted trees?
Rooted trees have a designated root, while unrooted trees do not.
What are Parsimony Informative Sites (PI)?
Parsimony Informative Sites are positions in DNA sequences where at least two different bases are present in at least two different species.
What are the steps in a Parsimony Analysis?
Parsimony Analysis involves reconstructing ancestral nodes and determining which topology requires the fewest mutational steps.
How does genetic data assist in building phylogenies?
Genetic data, with each nucleotide as a character, helps infer evolutionary relationships. Different genes evolve at different rates and are useful for various lineages.
What is the main goal of phylogenetic analysis?
to construct the shortest phylogeny to represent evolutionary relationships, often aided by computers.
How do researchers decide on the best tree in phylogenetics?
Researchers use methods like parsimony, maximum likelihood, and multiple genes to improve accuracy and identify the best tree.
Why is analyzing more than 4 species challenging in phylogenetics?
Analyzing more species results in a large number of possible tree topologies, making it more complex.
