AP Lab: Molecular Phylogeny - Decoding Evolutionary Relationships

Taxonomy

The science of naming, describing, and classifying organisms - including plants, animals, and microorganisms x based on shared characteristics and evolutionary relationships

Divisions in taxonomy (taxa)

A formally named group of organisms at any level of the hierarchical classification system, ranging from species to kingdom

Mutation

A permanent, heritable change in an organism’s DNA sequence

Adaptation

The evolutionary process and result whereby an organism becomes better suited to its habitat, enhancing its survival and reproductive success

Outgroup

A group of organisms (taxon) used as a reference point in phylogenetic analysis to determine the evolutionary relationships among a target group, known as the ingroup

Rooted tree

A phylogenetic diagram with a designated node (the root) representing the most recent common ancestor of all organisms in the tree

Homologies

Traits shared between species due to descent from a common ancestor

Morphological vs molecular

Morphological: refers to physical structural similarities

Molecular: refers to similarities in DNA, RNA, or protein sequences indicating shared genetic ancestry

If a protein is nearly identical across mammals, birds, and fish, what does this imply about the importance of that protein’s structure to the survival of the cell?

Implies the protein is under extreme selection; structure is essential to cellular survival

What is a molecular clock? How is it used?

• A technique in evolutionary biology that uses the mutation rates of biomolecules to estimate the time in geological history when two or more species diverged from a common ancestor

• Used to compare the number of amino acid/nucleotide differences between two species and calibrating it against known fossil records to estimate the date of their last common ancestor