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General Biology: OrganismL Biology and Evolution - Set 1 > Phylogeny and the Tree of Life > Flashcards

Phylogeny and the Tree of Life Flashcards

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1
Q

Phylogenetic tree

A

Represents a hypothesis about evolutionary relationships between taxa

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2
Q

Phylogeny

A

The evolutionary history of a species or group of related species

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3
Q

Systematics

A

Classifies organisms and determines their evolutionary relationships

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4
Q

What do systematists gather information about to infer phylogenies?

A

Morphologies, genes, and biochemistry of living organisms

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5
Q

What do phylogenetic trees allow us to predict?

A

Phylogenetic trees allow us to predict features of an ancestor from features of its descendants

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6
Q

Carl Linnaeus

A

Systema Naturae
- botanist who sought to classify life’s diversity “for the greater glory of God”
- developed a nested classification system, grouping similar species into increasingly general categories
- Did not ascribe relationships among species to evolution
- Interpreted the often remarkable match of organisms to their environment as evidence that the Creator has designed each species for a particular purpose

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7
Q

Binomial

A

What the two-part scientific name of a species is called

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8
Q

Genus

A

The first part of the two-part scientific name

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9
Q

Specific epithet

A

The second part of the two-part scientific name, is unique for each species within the genus

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10
Q

What is the correct format of a two-part scientific name?

A

The first letter of the genus is capitalized, and the entire species name is italicized

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11
Q

What part of the two-part scientific name names the species?

A

Both parts together name the species

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12
Q

Taxon

A

A taxonomic unit at any level of hierarchy

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13
Q

What can the evolutionary history of a group of organisms be represented by?

A

A branching phylogenetic tree

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14
Q

What do phylogenetic trees represent?

A

A hypothesis about evolutionary relationships

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15
Q

Branching point

A

Represents the divergence of two evolutionary lineages from a common ancestor

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16
Q

Sister taxa

A

Groups that share an immediate common ancestor that is not shared by any other group

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17
Q

How can phylogenetic trees be drawn?

A

They can be drawn horizontally, vertically, or diagonally without changing the relationships between groups

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18
Q

Rooted tree

A

Includes a branch to represent the most recent common ancestor of all taxa in the tree

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19
Q

Basal taxon

A

Diverges early in the history of a group and originates near the common ancestor of the group

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20
Q

Do phylogenetic trees show phenotypic similarities?

A

No. they show patterns of descent not phenotypic similarities

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21
Q

Do phylogenetic trees indicate when species evolved or how much change occurred in a lineage?

A

No, it should not be assumed that a taxon evolved from the taxon next to it

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22
Q

What important information can phylogenies provide?

A

Information about similar characteristics in closely related species

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23
Q

When constructing a phylogeny, what do systematists need to distinguish?

A

Whether a similarity is the result of homology or analogy

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24
Q

Homologies

A

Phenotypic and genetic similarities due to shared ancestry are called homologies

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25
Q

What kinds of organisms are more likely to be closely related?

A

Organisms with similar morphologies or DNA sequences are likely to be more closely related than organisms with different structures or sequences

26
Q

Analogy

A

Similarity due to convergent evolution

27
Q

Homoplasy

A

A character shared by a set of species but not present in their common ancestor

28
Q

Can homology be distinguished from analogy?

A

Yes, by comparing fossil evidence and the degree of complexity

29
Q

How can you tell if two organisms are likely homologous?

A

If the genes in two organisms share many portions of nucleotide sequence

30
Q

What do mathematical tools help to identify on a molecular level?

A

They help to identify molecular homoplasies, or coincidental similarities

31
Q

Cladistics

A

Groups of organisms by common ancestry

32
Q

Clade

A

A group of species that includes an ancestral species and all its descendants

33
Q

Monophyletic

A

A true clade, signifying that it consists of the ancestor species and all its descendants

34
Q

Paraphyletic grouping

A

Consists of an ancestral species and some, but not all, of the descendants

35
Q

Polyphyletic grouping

A

Includes distantly related species but does not include their most recent common ancestor

36
Q

Shared ancestral character

A

A character that originated in an ancestor of the taxon

37
Q

Shared derived character

A

An evolutionary novelty unique to a particular clade

38
Q

What is useful to know when inferring evolutionary relationships?

A

It is useful to know in which clade a shared derived character first appeared

39
Q

Out-group

A

A species or group of species that is closely related to the in-group - a group that has diverged before the in-group

40
Q

In-group

A

The various species being studied

41
Q

What can the length of a branch reflect in some trees?

A
  • The number of genetic changes that have taken place in a particular DNA sequence in that lineage
  • Time, can be determined from the fossil record
42
Q

What is it generally easier to draw a phylogenetic tree according to?

A

To ancestral characters and then later appearance of derived characters

43
Q

What are the two principles systematists use to narrow down possibilities of the best tree in a large DNA sequence data set?

A

Distance analysis and/or maximum parsimony

44
Q

Distance analysis

A

Calculates the pairwise distance between sequence (how similar or different they are)

45
Q

Maximum parsimony

A

Assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely

46
Q

What is a valuable approach for tracing organisms’ evolutionary history?

A

Comparing nucleic acids or other molecules to infer relatedness

47
Q

What do scientists trace changes in?

A

‘Homologous’ genes

48
Q

What is DNA that codes for rRNA useful for investigating?

A

Branching points that diverged hundreds of millions of years - changes relatively slowly

49
Q

What does LUCA stand for?

A

Last Universal Common Ancestor

50
Q

What genome is used to document an organisms evolutionary history? (specifically humans)

A

Maternal DNA - evolves rapidly and can be used to explore recent evolutionary events, means that it is easier to track ancestry

51
Q

Orthologous genes

A

Found in a single copy in the genome and are homologous between species - can diverge only after speciation occurs

52
Q

What does gene duplication increase?

A

The number of genes in the genome, providing more opportunities for evolutionary changes

53
Q

Paralogous genes

A

Result from gene duplication, are found in more than one copy in the genome - can diverge within the species that carries them and often evolve new functions

54
Q

What does repeated gene duplications result in?

A

Gene families

55
Q

Can duplicated genes be traced to a common ancestor?

A

Yes

56
Q

Molecular clock

A

Uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change

57
Q

In orthologous genes, what are nucleotide substitutions assumed to be proportional to?

A

The time since they last shared a common ancestor

58
Q

In paralogous genes, what are nucleotide substitutions proportional to?

A

The time since the genes became duplicated

59
Q

What are molecular clocks calibrated against?

A

Branches whose dates are known from the fossil record

60
Q

What did Motoo Kimura propose in the 1960’s?

A

That the majority of mutations are neutral (i.e., neither advantageous nor deleterious) - much evolutionary change at the genetic level has no effect on fitness and is therefore not influenced by natural selection - many regions of the genome appear to evolve at a constant rate

61
Q

If most of the evolutionary change in gene and protein sequence has no effect on fitness, then what happens to molecular change?

A

Then the rate of molecular change should be regular, like a clock

General Biology: OrganismL Biology and Evolution - Set 1 (23 decks)

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