Lecture 7- reconstructing and using phylogenies 1 Flashcards
(101 cards)
What is phylogeny?
A description of the evolutionary history of relationships among organisms
What is a phylogentic tree?
A diagram that portrays a reconstruction of the history of the evolutionary relationships among organisms
What does a split or node on a phylogenetic tree represent?
The point at which lineages diverge
What is the name of the common ancestor of all the organisms in the tree?
The root
What is a taxon?
A group of species that are designated a name
What is a clade?
A taxon that consists of all of the evolutionary descendants of a common ancestor.
What are two species/clades that are each others closest relatives called?
Sister species/clades
What is systematics?
The study of biodiversity
Where are phylogentic trees used?
In all fields of biology
What do biologists use phylogenies to do?
Make comparisons and predictions about shared traits across genes populations and species.
How do comparisons among species require an evolutionary perspective?
Biologists determine traits that differ within a group of interest then try to determine when these traits evolved and how the trait was influenced by environmental conditions
What are features shared by two or more groups that were inherited from a common ancestor called?
Homogenous
Give an example of a homogenous trait.
The vertebral column is homologous among vertebrates.
What have phylogenetic analyses been used to discover?
Changes in the genome of HIV that confer resistance to particular drug treatments
What does the association of a particular genetic change in HIV with a particular treatment provide?
A hypothesis about resistance that can be tested experimentally.
What is a trait that differs from its ancestral form called?
A derived trait
What is a trait that was present in the ancestor of the group called?
An ancestral trait
What are derived traits that are shared among a group of organisms and are viewed as evidence of the common ancestry of the group called?
Synapomorphies
Why do similar traits evolve in unrelated groups of organisms?
- Convergent evolution
- Evolutionary reversal
What is convergent evolution?
Independently evolved traits subjected to similar selection pressures may become superficially similar
Give an example of convergent evolution.
Bones of wing and bats are homologous (inherited from common ancestor)
Wings are not homologous- evolved independently from forelimbs of different non-flying ancestors.
What is evolutionary reversal?
A character reverts back from a derived state to an ancestral state.
Give an example of an evolutionary reversal.
Frogs lack teeth in lower jaw- ancestor had teeth
Teeth have been regained in lower jaw of genus Amphignathodon
What is the genus of the frogs that have regained teeth in their lower jaw?
Amphignathodon