Theme 5AB Flashcards

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1
Q

What is a phylogeny

A

History of descent with branching
Shown as phylogenetic trees/phylogenies

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2
Q

What does a branching diagram tell us

A

Shows relationships between species often according to time since a common ancestor

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3
Q

What do the tips, branches, node and root tell us on a phylogenetic tree

A

Tips: terminal node
Branches: new species
Node: point where a branch splits, represents a common ancestor from which the descendant species emerge
Root: common ancestor population

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4
Q

What are sister groups

A

Two species that share a common ancestor not shared with any other species or groups

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5
Q

What hypothesis do phylogenies provide

A

Hypothesis of evolutionary relationships

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6
Q

What is a phylogram

A

Tree where the branch lengths represent evolutionary change/time

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7
Q

What is a cladogram

A

Tree where the branch lengths are all the same (no time)

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8
Q

How can you use morphological data to infer phylogenies

A

Use “characters” shared among organisms (vary among, but not within species)and have a genetic basis

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9
Q

What is considered to be the “best” phylogenetic tree

A

The one with the fewest number of changes required

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10
Q

How can DNA data be used to infer phylogenies

A

Each nucleotide in a sequence can act as a trait underlying logic of phylogenetic inference is identical for morphological and molecular characters
DNA sequence differences represent time since common ancestor

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11
Q

What is a monophyletic group

A

Includes a common ancestor and all of its descendants

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12
Q

What is a paraphyletic group

A

Included a common ancestor and some but not all of its descendants

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13
Q

What is a polyphyletic group

A

Does not include common ancestor

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14
Q

What is adaptive radiation

A

The rapid evolution of new species occupying new niches

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15
Q

What is anagenesis

A

Speciation where the ancestor species is wholly replaced by a new species (evolution within lineage)

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16
Q

What is cladogenesis

A

Parent species splits into two species

17
Q

What is graduated evolution

A

Slow and steady gradual evolution (results in anagenesis)

18
Q

What is punctuated evolution

A

Rare and rapid events of branching speciation (results in cladogenesis)

19
Q

What is the difference between morphological, chromosomal and molecular characters

A

Morphological: observable traits (wing patterns)
Chromosomal (number of chromosomes)
Molecular: DNA sequences

20
Q

Homologous verses analogous characters

A

Homologous: shares a common ancestor
Analogous: similarity in appearance but not origin

21
Q

What is the outgroup

A

Belonging to similar class of animals

22
Q

What is the principle of parsimony

A

Not willing to spend resources unnecessarily

23
Q

What does it mean if all the animals on a phylogenetic tree have tips at the same length

A

All the species still exist (not extinct)

24
Q

How does phylogeny relate to taxonomy

A

Member of these groups (like genus) are assumed to share a more recent common ancestor with each other then members of other groups

25
Q

What is macro evolution

A

Evolution above the species level, assess the diversity of an entire Claude and its position on the tree

26
Q

What is a clade

A

A group of organisms believed to have evolved from a common ancestor

27
Q

What is convergent evolution

A

Evolution of similar adaptations in distantly related organisms that occupy similar environments

28
Q

What are the drawbacks to using molecular characters for phylogenetic trees

A

There are only 4 alternate character states that exist at each position in a DNA or RNA sequence
Only 20 alternate character states at each position in a protein
This makes it difficult to asses the homology of a nucleotide base substitution that appears at the same position in the DNA of 2+ species

29
Q

What are the 2 character states

A

1) ancestral character states: original state
2) derived character state: newer state

30
Q

What is the difference between apomorphy and synapomorphy

A

Anapomorphy: derived character state
Synapomorphy: derived character state found in 2+ organisms