A3.2 Classification and Cladistics Flashcards

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1
Q

Reasons for classification system

A

Information storage and retrieval, identification of an organism or species’ name, predictive value/ (characteristics of a species can be predicted from its group), Researching evolutionary origins (grouping species that share traits that evolved from a common ancestor)

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2
Q

Taxa

A

Groups used to classify organisms (phyla, classes, and orders)

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3
Q

Taxonomy

A

Assigning organism to taxonomic groups

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4
Q

King Philip came over for good soup.

A

Kingdom, Phylum, Class, Order, family, genus, species

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5
Q

Disadvantages for Hierarchy of taxa

A
  • can be unclear how populations should be grouped due to the speciation of one species into two.
  • There can be disagreement about how species should be grouped into genera or larger groups.
  • There can be disagreement about what taxonomic rank a group should have.
  • Gradual divergence of species over time makes it hard to objectively determine at what time a species split so taxonomic rankings from domain to genus are inevitably arbitrary.
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6
Q

Ideal Classification

A

Should follow evolutionary relationships, all members of a taxonomic group have evolved from a common ancestor.

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7
Q

Criteria for ideal classification

A
  • Every organism that has evolved from the same common ancestor is included the same taxonomic group.
  • In each taxonomic group, all species have evolved from the same common ancestor.
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8
Q

Importance of Classification criteria

A

All members if a taxonomic group will have traits inherited from their common ancestor, which allows biologists to create predictions based on classification.

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9
Q

Paradigm

A

Ideal for demonstrating a theory

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10
Q

Cladistics

A

An approach to classification in which groups of species that share a common ancestor are identified but are not given a taxonomic rank.

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11
Q

Clade

A

A group of organisms that have evolved from a common ancestor. (Including ancestral species and all species that evolved from it)

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12
Q

Clade can include many living species, or just a few

A

True

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13
Q

What do mutations cause?

A

Differences in the base sequence and therefore the amino acid sequence of proteins.

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14
Q

Over long periods of time between two or more species

A

Differences in DNA sequences accumulate

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15
Q

Molecular clock methods

A

A method used to estimate the time since two species diverged from a common ancestor based on the differences accumulated in DNA/amino acid sequences over time, assuming that the differences have accumulated at a constant rate.

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16
Q

The larger the number of sequence differences…

A

The longer since two species diverged from a common ancestor

17
Q

Things that effect mutation rate

A

Generation time, size if the population, intensity of selective pressure.

18
Q

Most recent common ancestor for humans lived…

A

Estimated to have lived around 150,000 years ago

19
Q

Cladogram

A

A branching diagram that represents ancestor-descendent relationships, and is constructed by sequencing analysis.

20
Q

Maximum Parsimony

A

How species could have evolved with the fewest sequence changes.

21
Q

Terminal branches

A

Ends that represent individual clades, species or groups that are not subdivided on the cladogram.

22
Q

Nodes

A

Branching points in a cladogram that represent the the point at which a hypothetical ancestral species split to form 2 or more clades.

23
Q

Root

A

Base of the cladogram and represents the hypothetical common ancestor of the entire clade.

24
Q

Cladograms that are drawn to scale are based on…

A

Estimates of the time since each species split

25
Q

Phylogeny

A

evolutionary origins

26
Q

How can we test cladogram accuracy?

A

Several cladograms can be produced using different genes and checked if they have the same pattern of branching, which ensures the evidence of the evolution is strong.

27
Q

Hypothesis

A

A provisional explanation for a pattern

28
Q

Cladistics on traditional morphology-based classifications of species

A
  • Confirmed that traditional classification corespond to evolutionary relationships in many cases.
  • Indicated that the species in a taxonomic group do not all share a common ancestor in some cases.
  • Indicates that species with a common ancestor have been placed in different groups in other cases
29
Q

Three major domains of organisms

A

Eubacteria, Archaea, and Eukaryotes