A3.2 cladistics/classification

Question 1

List the levels of classification in the traditional hierarchy of taxa.

Answer 1

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

Question 1

​Define “taxonomy”

Answer 1

classification of living things

Question 2

Outline the benefits of having a system of classification of organisms.

Answer 2

-communication info btwn scientists
-predictions of characteristics (info about taxonomic grp is known, info abt species is known)
-info abt how species evolved

Question 3

What is the most exclusive grouping?

Answer 3

species

Question 4

Discuss limitations of the traditional classification system.

Answer 4

-don’t always correspond to patterns of divergence generated by evolution
-diverging populations hard to distinguish as unique species
-similar grps may be the result of convergent evolution/not actually members of the same species

Question 5

​Discuss advantages of a classification system that corresponds to evolutionary relationships.

Answer 5

cladistics (classification system) displays
-common ancestor
-inherited homologous traits
-predictions abt characteristics of a grp
-classification can include as many/few levels in a hierarchy of clades

Question 6

Define clade.

Answer 6

A group of organisms evolved from a common ancestor, including those that have become extinct

Question 7

List evidence used for placing organisms in a clade.​

Answer 7

-molecular data (DNA and protein sequences)
-morphological traits (physical characteristics)
-embryonic development

Question 7

Identify a clade as a _____ in a cladogram.

Answer 7

branch

Question 8

Outline the relationship between time, evolutionary relationships and biological sequences (nitrogenous base or amino acid).

Answer 8

more similar sequences indicate a more recent shared ancestor, while more differences suggest greater evolutionary distance and time since divergence.

Question 8

State the source of differences between biological sequences (nitrogenous base or amino acid).

Answer 8

mutations

Question 9

____ and _____ _____ sequences can be the basis for constructing cladograms.

Answer 9

DNA & amino acid

Question 9

Outline the use of a “molecular clock” to determine time since divergence between two clades.​

Answer 9

Estimates the time of divergence between two clades by assuming mutations accumulate at a roughly constant rate over time

Question 10

Outline the relationship between time, evolutionary relationships and biological sequence (nitrogenous base or amino acid) similarities between species.

Answer 10

more time leads to more accumulated mutations in biological sequences (DNA, RNA, or proteins), which results in greater similarity between closely related species and greater differences between distantly related ones

Question 11

Define “parsimony” as used in a biological context.

Answer 11

A parsimonious tree is the one that requires the fewest evolutionary changes to explain the relationships between organisms.
-simplest explanation when constructing phylogenetic trees

Question 12

Outline how the principle of parsimony relates to evolutionary divergence between the members of a clade.

Answer 12

-few evolutionary changes=more parsimonious

Question 13

Summarize the process of creating cladograms using bioinformatic tools.​

Answer 13

-few differences in base sequences & amino acid sequences
—> less time for mutations to accumulate btwn the sequences
—> organisms are more closely related

Question 14

-List the three domains of life.
-Discuss evidence from rRNA base sequences that led to the reclassification of life from two cell types (prokaryotic and eukaryotic) to three domains.
-Interpret the tree diagram that illustrates the evolutionary relationship between organisms of the three domains.

Answer 14

-Eubacteria, Archaea, Eukaryotes

Question 14

Define “cladogram”.
Outline what is represented by a “root”, “node” and “terminal branch” on a cladogram.

Answer 14

cladogram: diagram based on common ancestry
root-starting point
node-3-way intersection
terminal branch- ending point (species name)

Question 15

Explain why the development of cladistics lead to the reclassification of some species.
-Outline an example of reclassification as a result analysis of molecular sequence data.

Answer 15

-cladistics based on evolutionary origin and gene sequencing
-sometimes, reclassification is necessary
-Figwort Family:
-5000 species/none share common ancestor
-moved some to diff. families of plants
-created new taxonomic grps
-reclassified all of them

Question 16

List the three domains of life.

Answer 16

Prokaryotes: Eubacteria, Archaea

Eukaryotes

Question 17

Discuss evidence from rRNA base sequences that led to the reclassification of life from two cell types (prokaryotic and eukaryotic) to three domains.

Answer 17

what were once considered a single group of prokaryotes (Bacteria) are, in fact, two distinct evolutionary lineages.