Phyogenes Flashcards
Phylogeny
Evolutionary history of a species or group
Binomial naming conventions
Genus + specific epithet
Order of Linnean system
Family-> orders-> classes-> phyla -> kingdoms -> domans
Taxon
Named group at any level
Panthera- taxon at genus level
Mammilia- taxon at class level
Placement of species does not reflect evolutionary history
True
Snails dont exhibit the same morphological differences
Issues with Phylogenetic trees and Linnean systems
Linnean systems do not tell us anything about how the groups are related to eachother. If classes are assorted evolutionarily things change: Birds become a subspecies of reptiles
Phylogenetic Tree- branch point
Common ancestor
Evolutionary lineage
Sequence of ancestral organisms that lead to a particular descendant
Sister taxa
Groups of organisms that share an immediate common ancestor not shared by any other group
Ex. Chimps and Humans
Phylogenetic tree- root
Most recent common ancestor of all taxa in branches
Basal taxon
Lineage that divergent early on
Phylogenetic tree
Hypothesis of how organisms are related to one another
Issues with phylogenetic trees
-Intended to show patterns of decent and not phenotypic similarity
(Crocodiles related more to birds than lizards)
-Cant infer ages of taxa or branch points
-Cant assume taxon evolved from the taxon next to it:
Lineages of chimps and humans did not involve from each other they evolved from an ancestor that was not chimp or human
Homology
Phenotypic and genetic similarities die to shared ancestry
Analogy
Similarities between organisms due to convergent evolution
(Similar environmental pressures = similar adaptations)
Cladistics
Common ancestry is the criterion used to classify organisms (they are grouped into clades)
Monophyletic
Taxon = Clade
Ancestral species + all descendants
Paraphyletic
Ancestral species + some descendants
Includes common ancestor
Polyphyletic
Includes distantly related species but NOT common ancestor
Shared ancestral character
Originated in ancestor of taxon
Shared derived character
Shared by taxon but not in ancestor (could be the loss of something too)
Maximum parsimony
Simplest explanation thats consistent with facts
Phylogenetic bracketing
Predictions that unknown (past/present) organisms will have certain features based on organisms of the present
DNA & evolution
DNA –> rNA is slow
Good for investigating relationships between taxa from far past
Mitochondrial DNA & evolution
Chages quickly used to explore recent events
Orthologous genes
Honology between organisms occurs due to speciation
(Occurs in genes of different species)
Diverge only after speciation happens (diff gene pools)
Paralogous genes
Homology results from gene duplication, multiple copies diverge within a species
Can diverge within a species
Molecular clock
Measuring absolute time of evolutionary change
(Based on the length of time it takes for some genes to evolve)
Assumption:
Number of nucleotide subs in orthologous genes is prop to time elapsed since last common ancestor (or since ancestral gene was duplicated-paralogus)
Problems with molecular clocks
Natural selection putting pressure on genes
2 -> 3 domain shift
Bacteria-prokaryotes
Archea-diverse prokaryotic
Eukarya-organisms w true nucleic
Shows the overwhelming about of life that is single celled
No more monera or protista
New classification spread organisms of those allboverb
Horizontal gene transfer
Movements of genes between organisms of different domains
-through transposable elements, viral infection
(Why trees built using different genes five inconsistent results)
Prokaryote-Eukarypte not off the table
Reinforcement
Where natural selection increases reproductive isolation
Genetic in Speciation
Reproductive isolation
Flowers pollinated by bees
Flowers pollinated by hummingbirds
Cross
Hybrid! Pollinated by both
More than 1 gene
