Taxonomy and systematics Flashcards
what is taxonomy?
Taxonomy is the science that identifies, names, and classifies living and extinct organisms and viruses.
the first modern practitioner of taxonomy?
Carolus Linnaeus
explain the binomial nomenclature
Linnaeus invented a system of binomial nomenclature in which each species is given a unique two-part name, called a binomial
The first part of the name identifies the
genus (plural, genera), and the second part is the specific epithet, or species name
the taxonomic hierarchy
*Domain
* Kingdom
* Phylum
* Class
* Order
* Family
*Genus
* Species
* Subspecies
what are systematics?
study of biological diversity and the evolutionary relationships among organisms, both extinct and modern
Taxonomy groups are based on?
hypotheses regarding evolutionary relationships derived from systematics
Phylogenetic tree
depicts the evolutionary history of a group of organisms and allows biologists to define evolutionary classifications
Branch points in a phylogenetic tree are called?
nodes
Clade
consists of a common ancestral species and all of its descendant species
monophyletic lineages are called?
clades
two lineages that share a node are called?
sister clades
monophyletic taxa
includes one ancestral species and all its descendants
polyphyletic taxa
includes species from separate lineages
paraphyletic taxa
contains an ancestor and some but not all descendants
Homologies
homologous characters resulting from common ancestry, so phenotypic similarities between organisms reflect underlying genetic similarities
Homoplasies (analogies)
analogous characters do not result from common ancestry
what is convergent evolution?
convergent evolution is the evolution of similar adaptations in distantly related organisms that occupy similar environments.
what is homoplasy?
phenotypic similarity that evolved independently in different lineages
what does traditional classification use?
it uses phenotypic similarities and differences
the cladistic revolution
Cladistic analyses focus on recently evolved character states
Cladistics uses synapomorphies to reconstruct evolutionary history and classify organisms
Each character can exist in two forms, described as character states, they are?
- Ancestral characters (plesiomorphic)- Old forms of traits
- Derived characters (apomorphic)- New forms of traits, relative to other organisms
shared derived characters are?
synapomorphies ( Shared by two or more species or taxa and has originated in their most recent common ancestor)
shared ancestral traits are?
symplesiomorphies (Shared by two or more different taxa and inherited from ancestors older than their last common ancestor)
what are cladistics?
study and classification of species based on evolutionary relationships.
phylogenetic trees are also called?
cladograms
branch point
two species differ in shared derived characters
Ingroup
group we are interested in (in the cladogram)
Outgroup
species or group of species that is assumed to have diverged before the species in the ingroup
steps in constructing a cladogram
- choose species
- choose characters
- determine polarity of character states
- analyze cladogram
Molecular clocks
- Favourable mutations are rare, detrimental mutations are quickly eliminated so most mutations are neutral
- If neutral mutations occur at a constant rate they can be used to measure evolutionary time
- Not perfectly linear over long periods of time
(Not all organisms evolve at the same rate, Differences in generation times between different species)
what is horizontal gene transfer?
the transfer of genes between different species, any process in which an organism
incorporates genetic material from another
organism without being the offspring of that organism
