Chapter 26: Phylogeny and the Tree of Life Flashcards
What is taxonomy?
the discipline in which organisms are named and classified
What is a binomial?
2-part format of scientific names
What is a taxon (taxa = plural)
a taxonomic unit at any level
What are the hierarchical classifications from more specific to least specific
species genus family order class phylum kingdom domain
What is a phylogenetic tree
a branching diagram used to represent the evolutionary history of a group of organisms
what is a branch point?
a point on a phylogenetic tree that represent a common ancestor of the two evolutionary lineages diverging from it
What are sister taxa?
groups of organisms that share an immediate common ancestor that is not shared by any other group
What is polytomy?
a branch from which more than 2 descendant taxa emerge (often shows unclear evolutionary history)
What is the basal taxon?
the taxa that diverges from all other members of its group early in the the history of the group
What is the “rooted” branch point?
the most recent common ancestor of all taxa in the phylogenetic tree
What is phylogeny?
the evolutionary history of species or groups of species
what is homology? example?
genotype and phenotypic similarities due to shared ancestry
ex. forelimbs of whales, horses, bats, and humans
what is analogy/homoplasy? example?
phenotypic similarities but not shared ancestry
ex. sugar glider
what is convergent evolution? example?
similar adaptation evolving in organisms from different evolutionary lineages due to similar environmental pressures
ex. Australian mole and North American mole
marsupial vs. not (but they look the same!)
What are the 4 steps in creating a character table?
- label one side with taxa and the other with characteristics
- make sure that the characteristics have yes or no answers (mark 1 for yes, and 0 for no)
- assign an OUTGROUP
- Determine the symplesiomorphies and the synapomorphies
What is an OUTGROUP?
a taxa that is closely related to the group of organisms that one is studying but not part of the study group
What is a synapomorphy?
shared, derived characteristics that represent departure from a common ancestor
What is a symplesiomorphy?
shared ancestral characteristics that evolved PRIOR TO THE MOST RECENT COMMON ANCESTOR
What is the PRINCIPLE OF MAX. PARISMONY?
a method for deciding evolutionary “closeness” in which the hypothesis with the least possible assumptions is most probable
What is the PRINCIPLE OF MAX LIKLIHOOD?
a method for deciding evolutionary “closeness” in which given certain probability rules about how DNA sequences change over time, the hypothesis that reflects the most likely sequences (smaller percent differences between branches) should be supported
What is a MONOPHYLETIC group?
A group that includes the ancestral species and ALL of its descendants
What is a PARAPHYLETIC group?
a group that consists of the ancestral species and some but not all of the descendants
What is a POLYPHYLETIC group?
a group that does not include the common ancestor but does include all of the descendants
What are the assumptions we can make about dinosaurs due to the fact that we know they were related directly to crocodiles and birds?
that they sang, made nests, had four chambered hearts, and exhibited brooding behaviors
what is the study Systematics?
The analytical approach to understanding the diversity and relatedness of both extant and extinct organism
