topic 2 Flashcards
how can phylogenies ve developed
• Not only organisms have phylogenies
• Phylogeny can be developed using genetic info
• Gene tree or gene genealogy
○ A branching diagram portraying history of DNA sequences of a gene (= haplotypes)
• Ex. Mitochondrial cytochrome b gene in McGillivray's warbler ○ Haplotypes are more closely related within a region than between regions
example of parsimony analysis - new world vs old world monkeys, look at this in notes
ok
what is traditional evolutionary taxonomy
c Evolutionary taxonomy utilizes common descent and amount of adaptive evolutionary change to rank higher taxa.
Sometimes includes
paraphyletic groupings.
fate of pongidae
• No! it doesn’t
• It is a paraphyletic group, not a monophyletic group
Chimpanzee & human share a common ancestry
and must be classified together in a group
The most parsimonious tree we just saw has EIGHT
fewer evolutionary changes than the tree that separates
chimpanzee & human
Family pongidae is no longer recognized!
describe molecular clock. ex in notes
• Estimating time of divergence - molecular clock
• Does DNA evolve at a constant rate?
• More DNA similarities = more closely related, more recent divergence
• Much of a DNA molecule is non-coding, not
expressed in the phenotype, and therefore
not subject to selection
• Evolving in large part by drift, it may have an
approximately clock-like rate of change
• Molecular clock used to estimate time of divergence
why should rates of DNA change be constaNT?
• Why should rates be approx. constant?
• Most DNA consists of non-coding parts of the molecule
• Even within coding regions, changes at 3rd base positions
of each codon are mostly silent substitutions (they don’t
change the amino acid)
• If non-coding and silent changes predominate, then most
mutations are not expressed in the phenotype
• Not being expressed, they are not subject to selection
They, thus, may accumulate at a stochastic (=non-
deterministic) rate
why arent DNA change rates constant
They are known to differ from one taxonomic
group to another, on average
-Use of the molecular clock to date lineages is thus approximate at best
Many estimates of the ages of groups obtained by molecular clocks are absurdly wrong by paleontological
standards (estimates of group origins are usually far too
ancient). This situation is improving with new methods.
classification of organisms b4 and after darwin
- Before darwin
- Kinds, types, ideals
- Similarity, characteristic features
- After darwin
- Shared ancestry, phylogeny (genealogical relationships)
- Adaptations
darwins theory on common ancestor
tree of life with 3 domains (eucarya, bacteria, archaea) and root (CA)
modern studies based on DNA molecules say there is one ancestor
when did darwins phylogeny appear
- The first such diagram ever published, in 1859
* But darwin had been thinking along these lines since at least 1837, as his notebook sketch shows
5 building blocks of taxonomy
• Descries species • Identification • Classification • Collections • Conservation • The 5 building blocks of taxonomy `
describe linnean taxonomy
- First to give us this hierarchical system
- Find key features of groups (shared adaptations/ancestry under darwin’s tree concept)
- Discern God’s plan
linnean taxonomy rules
• Italicized or underlined: ○ Genus and species only • Capitalization: ○ All except specific epithet • Singular or plural names: ○ Family and up: plural ○ Genus and species: singular
what did wilsons editorial say (1st 5 points)
wilson, father of biology
1.
Systematics is the study of biological diversity
2. At present, we do not even know, to the nearest order of
magnitude, how many species there are in the world
3. Approx. 1.7 million have been described, but this number
is far below the actual biodiversity
4. approx10,000 new species across all groups described every
year
5. Recent studies in rainforests and other major habitats
indicate as many as 30 million kinds of insects alone
what did wilsons editorial say (last 3 points)
6
Because of largely unknown nature of biodiversity,
systematics remains a tremendous source of discoveries
& new ideas in biology
7 Much of the research in taxonomy & systematics has
economic & medical importance
8 world supply of trained taxonomists is no where near
the number required to research even a small part of
unknown/poorly-known aspects of biodiversity
who uses knowledge gathered from systematic research
All disciplines within biology Conservationists & resource managers Forestry, fisheries, wildlife, & agriculture researchers Biotechnology researchers Human & animal health & medical researchers
what is systematics
• Study of biological diversity
• Reconstruction of patterns of relationships
• Building classifications based on these patterns
• Working definition: field of biology that studies and tries to establish phylogenies (=evolutionary histories)
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