PRELIMS MOD 1 & 2 Flashcards
Attributes or features of
organisms
Character
Similarity due to descent from a
common ancestor
Homologous Character
Similar-appearing structure
evolved in entirely unrelated
groups
Convergent Character
various conditions of
homologous character ex. fins
of fish, arms of humans, forelegs
horses
Character state
Direction of change…Ancestral
and derived…is relative
Character Polarity
Key rules of Cladistics taxonomy
Only shared derived homologous characters determine phylogeny : synapomorphies
All species in a grouping must share a recent common ancestor
All species derived from a common ancestor as well as
that ancestor must be included in the taxon
* All species must be in monophyletic taxa
(true reflection of evolutionary history)
Homologous characters are shared characters that result from common ancestry.
Homology
shared characters that are not a result
of common ancestry, but of independent evolution of similar characters (they are not homologous). Can result from convergent evolution.
Homoplasy
occurs when natural
selection, working under
similar environmental
pressures, produces similar
(analogous) adaptations in
organisms from different
Convergent Evolution
When trying to determine evolutionary
relationships, we
only want to consider homologous
characters. Homoplasies can create errors.
Phylogeny
refers to the ancestral
character state
Plesiomorphy
a character state different
than the ancestral state, or DERIVED STATE
Apomorphy
a derived character state (apomorphy) that is SHARED by two or more taxa due to inheritance from a common ancestor these character states are phylogenetically informative using the parsimony or cladistic criterion
Synapomorphy
Uniquely derived character state
Autamorphy
(which version of the trait is ancestral) is
determined by using outgroup comparison.
Polarity
is closely related, but not part of the
group being examined (the ingroup).
Outgroup
An ancestral character is one that is found in both the study group and the outgroup. Derived character groups are those found in the study
groups but not the outgroups.
Polarity
a taxonomic grouping of species that evolved from a single ancestor and includes all descendants of that ancestor
Monophyletic
taxon is composed of unrelated organisms descended from more than one ancestor. groups are formed when two lineages convergently evolve similar character states.
Organisms classified into the same polyphyletic group share phenetic homoplasies as opposed to homologies.
Polyphyletic
taxon is composed of unrelated organisms descended from more than one ancestor. an incorrect grouping of species sharing an immediate ancestor but not including all descendants of that ancestor.
Paraphyletic
Independent evolution of same feature from same ancestral condition
Parallel Evolution
Independent evolution of same feature from different ancestral condition
Convergent Evolution
Reversion to ancestral condition
Secondary Loss
“We can eat these plants, but not these.”
Edibility
“These animals are sacred, these are evil.”
Cultural Meaning
“These animals pull our plows, those we shear for wool.”
Utility
study of evolutionary relationships among
organisms, both extant and extinct.
Systematics
study of the evolution of biological diversity
Systematics
identifying, naming, describing classifying
Taxonomy
Two part name (genus, species)
Binomial Nomenclature
Seven Taxonomic Categories
Hierarchical Classification
includes determination of an unknown specimen, and then assigning it a correct name and rank in an established system of classification.
Identification
Ways to identify unknown species
- sending the specimen to a subject expert in the relevant field or by visiting herbarium and comparing the specimen with already identified specimen that are present in the herbarium.
- By use of already published literature of an area having description of similar kind of plants such as Floras, Revisions, Monographs and Manuals.
- Use of virtual herbarium/database/website
involves listing its features by recording its
character state. diagnostic features are recorded which separates the taxa from others. diagnostic features determine the circumscription.
Description
determination of the correct name of a taxon Binomial nomenclature
Nomenclature
Who made Binomial Nomenclature
Carolus Von Linnaeus
Two-word naming system
Genus
* Noun, Capitalized, Underlined or Italicized
Species
* Descriptive, Lower Case,
Underlined or Italicized
Taxonomic Categories
King Philip Came Over For Green Soup
a group organisms considered by taxonomists
to form a related unit.
Taxon
assembled on the basis of recency of descent from common ancestor.
Taxa
is the application of names to
organisms recognized as part of a particular taxon.
Biological Nomenclature
Taxa are organized in a —– of
taxonomic ranks, from largest (most inclusive) to
smallest (least inclusive).
Nested hierarchy
Three aspects of taxon
Name, order, content
Systematics is the study of the evolution of biological diversity and combines data from the following areas.
Fossil record
Comparative homologies
Cladistics
Comparative sequencing of DNA/RNA among organisms
Molecular clocks
accumulation of all fossils found within layers of
sedimentary rock and helps to reconstruct a geological time scale. Fossils are the remnants or impressions of organisms that lived in the past.
Fossil Record
similarities among species attributed to the
inheritance of a feature from a common ancestor. homologous vs homoplasious
Homologies
A correspondence of structures in two life forms with a common evolutionary origin, such as flippers and hands.
Homology
The relationship between characteristics that are apparently similar but did not develop from the same structure
Analogy
A correspondence between the parts or organs of different species acquired as the result of parallel evolution or convergence.
Homoplasy
Homologous sequences are considered paralogous if they were separated by a gene duplication event; if a gene in an organism is duplicated to occupy two different positions in the same genome, then the two copies are
Paralogous
typically have the same or similar function, but sometimes do not. It is considered that due to lack of the original selective pressure upon
one copy of the duplicated gene, this copy is free to mutate and acquire new functions.
Paralogs
physically similar structures between two taxa that evolved separately (rather than being present in the last common ancestor).
Analogous Structure
is based on the idea that members of a group share a common evolutionary history and are more closely related to members within their group than to other organisms.
Cladistics
groups are recognized as sharing unique, derived features not present in distant ancestors.
Cladistics
branching diagram that illustrates hypothesized relationships based on shared, derived characteristics.
Cladogram
studies compare sequences of macromolecules
(proteins and nucleic acids) among species, assuming that these macromolecules evolve at constant rates throughout time, and for different lineages.
Molecular Clocks
He proclaimed that “our classifications will come to be, as far as they can be so made, genealogies”.
Charles Darwin
Evolution on a scale of separated gene pools
[2] can result in the speciation or emergence of new species
Macroevolution
Change that occurs at or above the level of species
Microevolution
2 major categories of evolutionary change
Anagenesis and Cladogenesis
Three domain system
Bacteria, archaea, eukarya
Six kingdom system
Bacteria, Archaea, Animalia, Plantae, Fungi, Protista
Traditional 5 kingdom system
Monera, Animalia, Planta, Fungi, Protista
