A3.2 Classification and Cladistics Flashcards

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.
  • The boundary paradox
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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
Phylogeny
evolutionary origins
26
How can we test cladogram accuracy?
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
Hypothesis
A provisional explanation for a pattern
28
Cladistics on traditional morphology-based classifications of species
- 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
Three major domains of organisms
Eubacteria, Archaea, and Eukaryotes