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Biol 1407 SPC > Lecture 2: Phylogeny & the Tree of Life > Flashcards

Lecture 2: Phylogeny & the Tree of Life Flashcards

1
Q

How do biologists distinguish and categorize the millions of species on Earth?

A
  • Genetic Sequences
  • Morphology
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2
Q

Phylogeny Def

A
  • Examine the evolutionary history of a species or group of species
  • serve as hypothesis
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3
Q

Systematics Def

A
  • Discipline focused on classifying organisms and determining evolutionary relationships
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4
Q

Common Ancestry def

A

Organisms share many characteristics

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5
Q

Taxonomy def

A

The study of naming & classifying organisms

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6
Q

Who developed the classification scheme we use today?

A

Carolus Linnaeus

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7
Q

How to properly format a scientific name?

A

First part= Genus (capitilized)
Second part= species (lowercase)

Written => underline
type =>italized

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8
Q

Levels of Hierarchical Classification

A

Dear => Domain Broadest
King => Kingdom
Philip => Phylum
Came => Class
Over => Order
For => Family
Grape => Genus
Soda => Species Most specific

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9
Q

Taxon def

A

named taxonomic unit at any level of the hierarchy

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10
Q

How did taxonomists determine how “different” organisms are from each other?

A

Genetics, evolution, biological species, etc.

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11
Q

Phylogenetic tree def

A

Branching pattern often matches how taxonomists have classified groups of organism nested within more inclusive groups

  • Represents a Hypothesis about evolutionary relationships
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12
Q

Sister Taxa def

A

Share immediate common ancestor

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13
Q

Basal Taxa def

A

Diverges early in history of group
- originate common ancestor of all groups

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14
Q

Polytomy def

A

More than 2 descendant groups emerge

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15
Q

What we learn from Phylogenetic Trees?

A
  • They show patterns of descent, NOT phenotypic similarity
  • Sequence of branching in a tree does not necessarily indicate actual AGES of the particular species

IF AGES => MOLECULAR CLOCK

  • We shouldn’t assume that a taxon on a phylogenetic tree evolved from the taxon next to it
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16
Q

What happens during long branch lengths?

A

more genetic differences/ changes

17
Q

Divergence dates/time

A

impose molecular clock

18
Q

Application of Phylogenetics

A
  • Examine evolutionary relationships
  • Medical applications
  • Forensics
  • Infer species identities
19
Q

What types of data can be used to infer/ build phylogenies?

A
  • Morphological characters
  • DNA sequences
  • Microsatellites (repeats)
  • Mobile elements
20
Q

Homologous Characters

A

Phenotypic & genetic similarities due to shared ancestry

21
Q

Result of Homologous Characters

A

Environmental Pressure

22
Q

Analogous Characters

A

Similarities due to Convergent evolution

convergent= not share common ancestor

23
Q

Result of Analogous Characters

A

Similar environmental pressure and natural selection produce similar adaptations in organisms from different evolutionary lineages

24
Q

Could different datasets result in different phylogenies?

A

Morphology- physical characteristics

25
Q

Homologous vs Analogous Characters

A

Corroborative similarities
- number and intensity of similarities increases the more closely related two species are

26
Q

Cladistics def

A

an approach in systematics in which organisms are placed into groups based primarily on common descent

27
Q

Clades def

A

Monophyletic Group
- Biologists attempt to place species into groups

28
Q

Monophyletic Group def

A

consists of an ancestral species and ALL of its descendants

29
Q

Paraphyletic Group def

A

consists of an ancestral species and SOME, but NOT all, of its descendants

30
Q

Polyphyletic Group def

A

includes distantly related species but DOES NOT include their most recent common ancestor

31
Q

Maximum Parsimony def

A

SIMPLEST explanation that is consistent w/ facts

32
Q

Maximum Likelihood def

A

Tree most likely to have produced a given set of data, based on PROBABILITY RULES

33
Q

Max Likelihood vs Max Parsimony

A

Max Parsimony-> Recovers the most parsimonious tree, require fewest evolutionary events BAYESIAN

Max Likelihood->
- Simple: all nucleotide substitutions are equally likely
- Complex: accounts for different rates of change

34
Q

Molecular Clock def

A

An approach based on observation that some genes and other regions of genomes appear to evolve at CONSTANT RATES

35
Q

What two Domains are closely related to each other?

A

Eukaryotes and Archaea

36
Q

Horizontal gene transfer def

A

process which genes are transferred from one genome to another

37
Q

What makes it difficult to resolve relationships at higher taxonomic levels in the tree of life?

A

Two factors
- Events are closely spaced in time, so phylogenetic species are often small which lead short internal tree branches to resolve

-If species are ancient, branches tend to be long with multiple substitutions occuring at a same position.

Biol 1407 SPC (9 decks)

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