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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

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
What kinds of organisms are more likely to be closely related?
Organisms with similar morphologies or DNA sequences are likely to be more closely related than organisms with different structures or sequences
26
Analogy
Similarity due to convergent evolution
27
Homoplasy
A character shared by a set of species but not present in their common ancestor
28
Can homology be distinguished from analogy?
Yes, by comparing fossil evidence and the degree of complexity
29
How can you tell if two organisms are likely homologous?
If the genes in two organisms share many portions of nucleotide sequence
30
What do mathematical tools help to identify on a molecular level?
They help to identify molecular homoplasies, or coincidental similarities
31
Cladistics
Groups of organisms by common ancestry
32
Clade
A group of species that includes an ancestral species and all its descendants
33
Monophyletic
A true clade, signifying that it consists of the ancestor species and all its descendants
34
Paraphyletic grouping
Consists of an ancestral species and some, but not all, of the descendants
35
Polyphyletic grouping
Includes distantly related species but does not include their most recent common ancestor
36
Shared ancestral character
A character that originated in an ancestor of the taxon
37
Shared derived character
An evolutionary novelty unique to a particular clade
38
What is useful to know when inferring evolutionary relationships?
It is useful to know in which clade a shared derived character first appeared
39
Out-group
A species or group of species that is closely related to the in-group - a group that has diverged before the in-group
40
In-group
The various species being studied
41
What can the length of a branch reflect in some trees?
- 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
What is it generally easier to draw a phylogenetic tree according to?
To ancestral characters and then later appearance of derived characters
43
What are the two principles systematists use to narrow down possibilities of the best tree in a large DNA sequence data set?
Distance analysis and/or maximum parsimony
44
Distance analysis
Calculates the pairwise distance between sequence (how similar or different they are)
45
Maximum parsimony
Assumes that the tree that requires the fewest evolutionary events (appearances of shared derived characters) is the most likely
46
What is a valuable approach for tracing organisms' evolutionary history?
Comparing nucleic acids or other molecules to infer relatedness
47
What do scientists trace changes in?
'Homologous' genes
48
What is DNA that codes for rRNA useful for investigating?
Branching points that diverged hundreds of millions of years - changes relatively slowly
49
What does LUCA stand for?
Last Universal Common Ancestor
50
What genome is used to document an organisms evolutionary history? (specifically humans)
Maternal DNA - evolves rapidly and can be used to explore recent evolutionary events, means that it is easier to track ancestry
51
Orthologous genes
Found in a single copy in the genome and are homologous between species - can diverge only after speciation occurs
52
What does gene duplication increase?
The number of genes in the genome, providing more opportunities for evolutionary changes
53
Paralogous genes
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
What does repeated gene duplications result in?
Gene families
55
Can duplicated genes be traced to a common ancestor?
Yes
56
Molecular clock
Uses constant rates of evolution in some genes to estimate the absolute time of evolutionary change
57
In orthologous genes, what are nucleotide substitutions assumed to be proportional to?
The time since they last shared a common ancestor
58
In paralogous genes, what are nucleotide substitutions proportional to?
The time since the genes became duplicated
59
What are molecular clocks calibrated against?
Branches whose dates are known from the fossil record
60
What did Motoo Kimura propose in the 1960's?
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
If most of the evolutionary change in gene and protein sequence has no effect on fitness, then what happens to molecular change?
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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