Lecture 10 Flashcards
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
T/F if there is relatedness on a phenotypic phylogenetic tree is is inferred from homologous traits
true
what are 2 principal sources of macroevolution
- paleontology
- phylogenetics
what is paleontology
provides a direct record of past evolutionary change
good for groups that fossilized well
problem: a lot of species do not fossilize well
what is phylogenetics
provides an indirect record of past evolutionary change
inference is strongest for groups that have living representatives - to make better connection and observe
how can the fossil record relate to macroevolution
shows evidence for completely extinct clades
shows proof for long-term patterns of biodiversity
shows proof for catastrophic extinctions
what is a mass extinction
when more than 75% of the earths species in a short period of time disappear
what is the diversification rate
speciation rate - extinction rate
what are some ways that increase diversification
herbivory
wider selection for mating
animal pollination for plants
increases dispersal
increases range size
