Phylogeny Flashcards
What is phylogenetic classification?
Classifying organisms on the basis of descent from a common ancestor
What is phylogeny?
Evolutionary relationships between organims
What is phylogeny used for?
To conform which group a particular organism belongs to through their evolutionary relationships
How are evolutionary relationships worked out?
Using differences in DNA, RNA and protein structures
What are the ways of deciding phylogenetic groups?
Morphology (structures), DNA and RNA structures, computer analysis and similarities grouped together which may challenge or reinforce classifications
What does phylogenetic classification focus on?
Evolution, using both physical similarities/difficulties and DNA/RNA and protein data to work out relationships
What does phylogeny not distinguish between?
Extinct and extant species
What is a monophyletic group?
The smallest group or organism that share a common ancestor
What do phylogenetic trees show?
How different species have evolved from a common ancestor
What can phylogenetic trees indicate?
How long ago taxa diverged from a common ancestor
What can you not use phylogenetic trees for?
Exactly how far back an individual species evolved, unless a timeline is present
How are extinct species represented?
The line doesn’t extend to the top where the present day species lie
What are the tips of branches in phylogenetic trees?
Represents groups of descendent organisms usually at species level
What do the nodes of phylogenetic trees represent?
A common ancestor
What do sister groups of phylogenetic trees show?
Two descendants that branch from the same node
What is the biological species concept?
Group or organism with similar physical characteristic that can successfully interbreed and are reproductively isolated from other groups
How does the biological species concept classified spies?
Species as a group of actually or potentially interbreeding individuals so any 2 individuals within the group could breed and produce fertile offspring
What are common issues with the biological species concept?
Not all species can sexually reproduce, cannot be applied to fossil record and closely related species may interbreed
What is the phylogenetic approach?
Compares DNA sequence so can find common ancestor as closely and this monophyletic group can be classed as a species
What are advantages of the phylogenetic approach?
Applicable to asexual organism, used for extinct species if DNA is available, no need to test if population can interbreed, not forcing organisms into a group and some species may originally have been wrongly classified based of looks
What are disadvantages of phylogeny?
It is subjective and the most common ancestor that can be distinguished is used
Why is phylogeny subjective?
Scientist had to decide how recent a common ancestor to use
