Phylogeny Flashcards
application of phylogenetics
reconstruct evol history of organisms
understand evol of genes and proteins
framework to understand evol of traits
reconstruct evol of languages
Was Darwin aware of Linnaeus’ classification
yes
define phylogenetic tree
mathematical structure used to depict evol history of a group of organisms or genes
show historical relationship, not similarity
define systematics
infers phylogenetic relationships of organisms and creating classifications based on their evol histories
define bifurcation
resolved node- 1 ancestor gives rise to 2 descendents
define polytomy
unresolved node, hard to decipher relatinship
1 ancestral branch giving rise to at least 3 taxa
define resolution
when 1 ancestral lineage gives rise to 2 descendents
t/F: can twist any branch and rearrange order of taxa
T
define homology
ptypic and genetic similarities due to shared ancestry
significance of cladograms
no meaning, just shows relationship
signif of chronograms
show time
signif of phylograms
show amount of change; genetic muts or bp changes
T/F: the width of the horizonal axis is signif
F
define rooted trees
implies dirction from last common ancestor to present
define unrooted tree
don’t know where root is or direction of evol
define homologous characters
present in a group of species due to shared ancestry
2 kinds
what are the 2 types of homologous characters
shared derived
shared ancestral
define analogous/homoplastic characters
present in certain species that have evolved through convergent evol
define monophyletic
an ancestral species and all its descendants
define paraphyletic
an ancestral species and some but not all of its descendents
define polyphyletic
a group without a common ancestor
what are 2 important assumptions about phylogen characters
they are homologous and are evolving independently from each other
most phylogen analyses use…
moleculr data
why do most phylogen analyses use molecular data
genetic basis of characters known
larger amount of phylogen info
any groups of organisms can be compared
diff rates of evol in diff genes
math modeling
character delimitation is straightforward (when u have same genes from diff organisms and align seq, each character in seq alignment is easy to identify)
DNA is ultimate level of infodefine parsimonious
fewest base changes
what does parsimony use
only characters that are informative
define informative
have same character in at least 2 diff seq
challenges for phylogenetic inference
phylogencis are hypotheses about gene/organism relationship that are constantly updated w/ new data
genes can be transferred horizontally from 1 organism to an unrelated on leading to complications
genes undergoing selection can be repaidl evoloving and contain many convergently evolving sites
diff sires may be evolving at diff rates
rearrangements of geneitc mateiral can lead to false conclusions
ancient phylo relationships is hard
