Lecture 10 Flashcards
(32 cards)
what is taxonomy
the theory and practise of classification and naming
what is systematics
the study of biodiversity and the evolutionary relationships among organisms
what is a taxon
a single named taxonomic unit at any level
who is the father of taxonomy
Carolus Linnaeus
- created binomial nomenclature and the hierarchical system of classification
Kingdoms, phyla, class, order, family, genus, species (KPCOFGS)
what is the purpose of biological classification
- showing the shared information of an organism
- enables interpretation of origins and evolutionary history
- systematic research requires a robust and stable system for classifying organisms
T/F phylogenetic trees show the history of species
true
explain the node, tips, root and taxa components of a tree
nodes: when one lineage splits into 2
tips/leaves/terminals/OTU: do not have descendants - they can be individuals, species or clades
root: earliest time in the tree - showed by unlabeled branch
taxa: (sister groups): come from the same common ancestor = immediate descendants (sister clades, sister species, sister branches)
explain all the types of branches on a phylogenetic tree
branches: the edges - all branches are connected by nodes - correspond to single ancestor-descendant lineages (its common ancestor)
external branches: connect a tip to a node
internal branches: connect 2 nodes
parent branches: the big branches that connect the smaller daughter branches together
explain the ingroup of a tree
consists of the focal species in a phylogenetic study
- the more closely related species
what is the outgroup in a tree
the more distantly related species of the ingroup taxa
- can help root the phylogeny and help determine what species is ancestral
what is MRCA
- most recent common ancestor
different MRCA for different taxa - it is the youngest node that is ancestral to all lineages in a given group of taxa
- there can be many MCRA for one tree (connecting the small taxa and bigger taxa)
what is a clade
any piece of phylogeny that includes an MRCA and ALL of its descendants (one triangle)
- one tree = many clades
how to determine the exact number of clades
n-1
n = the number of species
10 species = 9 clades
what is a monophyly
describes a group made up of an ancestor and all of its descendants
- monophyletic group or clade
- scissor test –> if one cut separates the clade = monophyletic clade
what is a paraphyly
a group made up of an ancestor and some (but not all) of its descendants
- fails the scissor test - cuts between a large clade
what is a polyphyly
describes a group that does not contain the most recent common ancestor of all members
- multiple cuts in the phylogenetic tree
what does it mean for a clade of species to be ancestral
the inheritance of traits for a given group of species
- it is ancestral if it was inherited in its present form from the MCRA of the clade
what does it mean for a clade of species to be derived
a trait is derived if it originated within the clade
- all the descendants of the clades MRCA
T/F the same trait can be ancestral for a clade but derived within a larger clade
true
- the ancestral group of species was cut and did not include the entire clade only a small MRCA of the bigger MRCA
what is a synapomorphy
a shared, derived trait for a clade and it evolved on the branch leading to the clade
- a trait that all species in the clade share
how does homology relate to phylogenetic trees
when structures observed in different taxa can be traced to a single structure present in a shared evolutionary ancestor
- homologous = common ancestor
what is homoplasy
when a trait of a trait state arises more than once on a phylogenetic tree indicating convergent evolutionw
why are phylogenetic analyses important
understand the history of life
understand large scale patterns
understand how traits evolve, how fast
where/when did a parasite spread
tracking flu strains
T/F the data in the phylogenetic trees cannot be genetic
false
it can be genetic or phenotypic
