exam 1 (phylogeny and the tree of life

Question 1

Fields of Study, Terminology

Answer 1

• Phylogeny—the evolutionary history of species and
groups of organisms
– Commonly represented as a tree-like diagram
called a “phylogenetic tree” but this is changing
• Systematics is the field of science devoted to
classification and determination of evolutionary
relationships
• Taxonomy is the field of science involved with
naming and classifying species

Question 2

Classification and the Naming of Species

Answer 2

• Binomial nomenclature is used to assign unique,
latinized names to species
• Each name is composed of two words: Genus and
species (genus is always capitalized, species is not)
• Written as:
– Rhizopus stolonifer in print
– Rhizopus stolonifer when hand-written
– Once cited in a paper, the species name can be
abbreviated thereafter—R. stolonifer

Question 3

Classification of Life

Answer 3

• Hierarchical—a “nested hierarchy”
• Today’s classification scheme had its origins in the 1700’s
(Linnaeus)
• Each taxonomic grouping is termed a taxon (taxa is plural)
• Early classifications were based on morphological characteristics
– Drawbacks of relying only on morphology?
• Classification today reflects evolutionary relatedness
• Character analysis may still use morphological and other
characters, but today it relies heavily on molecular characters
(molecular phylogenetics)
– For example: DNA sequences, amino acid sequences of
proteins, ribosomal RNA sequences
• Phylogenetic trees integrate classification with
evolutionary relatedness and history
• They represent hypotheses and are subject to
modification

Question 4

“Shared, Derived Characters” are used to

construct phylogenetic trees

Answer 4

• Characters are heritable traits
• Shared characteristics are those that two or more
lineages have in common
• A derived character is a newly appearing trait that is
unique to a group (clade, taxon)
• An ancestral character is one that originated in an
ancestor of the group (clade, taxon)

Question 5

The role of horizontal gene transfer (HGT) in

evolution

Answer 5

• Genes from one organism become transferred to the

genome of another organism