Polytypic Species and Infra-species Flashcards
those who support establishing a system for infraspecific categories
splitters
stated that species does not essentially differ from the term variety
any recognizable variety are as good as a separate species
Darwin
categories below the species level
infraspecies
often used for members that are in different geographical locations and shows a specific variation
var.
refer to a population that a taxonomist considers to differ sufficiently from previously named population of species
subspecies
those who believe that system is unnecessary and there’s no need to establish subspecies concept
lumpers
often used for members that are in different geographical locations and shows a specific variation
var.
recognition of subspecies (with Ernst Hartet and Walter Rothschild)
Karl Jordan
proposed the Formenkreis theory
Otto Kleinschmidt
created the catalog of American birds
prefixed subspecies by “var.” in his collection of birds
Elliot Coues
proposed the term Rassenkreis (circle of races) and Artenkreis (circle of species)
Bernhard Rensch
equivalent to species composed of races or subspecies
incipient species and will soon be totally replaced by the geographical species
Rassenkreis
dropped the use of “var.” in his descriptions of organisms
Robert Ridgeway
consists of multiple Rassenkreis
species that are able to overcome the incipient stage of being Rassenkreis and become geographically distinct
Artenkreis
proposed or translated the terms of Rassenkreis into: subspecies, semispecies, and superspecies
Mayr
Promoted subspecies and trinomial nomenclature on geographically distinct populations
Includes variations according to the locality of distribution
However, it doesn’t lead to a speciation
Was later rejected by taxonomists
Formenkreis theory
polytypic species
subspecies
incipient species undergoing speciation; described to be interbreeding with their ancestor but are having characteristics different from the ancestor
semispecies
artenkreis; have undergone speciation
superspecies
attacked on “subspecies” or the trinomial concept; “as more studies would be provided, the concept of having subspecies will soon disappear as these variations are not enough support to provide such concept
Brown & Wilson
a population that a taxonomist considers to differ sufficiently from previously named population of a species; replaced variety
Subspecies (ssp.)
species that are not subdivided into subspecies
monotypic species
species w members of a population that look different from each other; species that contain 2 or more subspecies
polytypic species
doesn’t necessarily require changes in the genetic composition; variation that is is fixed at birth, incorporated in their genetic material
Non-genetic Variation
Variation within population
Intrapopulation Variation
variation depending on time; ex. age variation
Temporal Variation
variation wherein in different stages in their life they would assume different characteristics; common in insects
age variation
seasonal variations of the same individual; many physical appearances depending on season
seasonal polyphenism
Mainly due to environmental factors: ex. density dependent (if they’re alone or with a colony)
Ecological Variation
high or low density
in solitary; in colony
low density; high density
the causes in the differences in the morphology are not genetic, it would depend on the “social status” or caste polymorphism of your organism (ex. honey bee, ants)
variation depends on the role they perform
social variation
appearance depends on where it is feeding on
Host-dependent
variation depends on their function or work
Allometric
phenotypic plasticity
ex. short if it’s in its natural habitat, taller if not
Ecotypic variation
some arthropods with wolbachia become parthenogenetic (manipulative behavioral changes)
Endosymbiont-induced
mostly parasite-induced; ex. parasite causes a trauma changing the morphology/appearance of the organism
Traumatic variation
changes in morphology due to differences in genetic composition
Genetic Variation
morphology is dependent on sex (ex. in some insects, male would look more colorful bc they have to attract females for mating)
Sexual dimorphism
aka Diplo-haplontic life cycle
variation depending on diploid/haploid stage (n of chromosomes)
exhibited by bryophytes (ferns and mosses)
Alternation of generation or Reproductive different
generation
variation caused by multiple alleles that are present in locus/loci in a certain chromosome
Polymorphism
changes in morphology due to differences in genetic composition
Genetic Variation
multi-loci control of genes, more variation; highly affected by environmental factors (ex. exposure to sunlight)
ex. skin color, height, eye color
Continuous variation
give rise to genetic difference among many members of a population
alters individual’s genetic composition
mutation and recombination
most familiar classification scheme; established 250 years ago (1758)
– by Carolus Linnaeus
– one category includes less inclusive groups (which also contains less
inclusive groups)
Hierarchical classification
variation caused by the multiple alleles (ex. black & white; kinky & straight) that are present in one locus in a certain chromosome
Discontinuous variation
foundation for evolution
genetic variation
a branching diagram, or tree, depicting the relationships among group of organisms
Cladogram/evolutionary trees/dendrogram/branching trees
required that every organism have a two-part scientific name (“binomen”)
Binomial Nomenclature
represents the oldest (earliest) ancestors
Base
groups at every taxonomic level; includes an ancestor and all its descendants
Monophyletic
a group comprising species that arose from two or more different immediate ancestors
does not include common ancestor in the group
Polyphyletic
morphological feature/character that share descent from a common ancestor
features having common ancestry
ex. hands of chimpanzees and humans
Homologues
a group whose member species are all descendants of a common ancestor, but does not contain all the species descended from that ancestor
includes common ancestor
Paraphyletic
the recurrence of similarity and evolution
features that simply look alike but is not necessary of same ancestry or function
Homoplasy
phenomenon wherein similar-appearing structures may evolve in entirely unrelated groups of organisms in quite different ways
2 formerly dissimilar traits become similar
Convergent evolution
indicates successively more recent divisions of evolutionary lineages
Higher branches:
attributes, or features, of organisms or groups of organisms (taxa) that biologists rely on to indicate
their relatedness to other similar organisms (or other taxa) and to distinguish them from other
groups.
Character
result of “distant” or “underlying” homology
occurs when two or more species (or lineages) change similarly so that, despite evolutionary activity, they remain similar in some ways, or become more similar over time
Parallel Evolution
result of “distant” or “underlying” homology
occurs when two or more species (or lineages) change similarly so that, despite evolutionary activity, they remain similar in some ways, or become more similar over time
Parallel Evolution
occurs when two or more lineages (or characters)
evolve independently to become less similar
Divergent Evolution / Divergence
a feature reverts back to a previous, ancestral condition
Evolutionary reversal
monophyletic group or branch of a tree, which may undergo very little or a great deal of
diversification
– a group of species related by direct descent
Clade
multiple divergences from a common ancestor that result in more than two descendant lineages.
Radiations
group of species (or higher taxa) defined by somewhat more abstract measures
– a group defined by a particular level of functional or morphological complexity
– can be polyphyletic, paraphyletic, or monophyletic (thus, it can also be a clade)
Grade
attributes of species that are relatively “old” and have been retained from some remote ancestor
– also referred to as “ancestral characters” or “primitive character states”
Plesiomorphic character states
direction of evolutionary change
Polarity
attributes of species that are relatively recent origin
-also referred to as “derived (advanced) character states”
Apomorphic character states
signature or novel character; the character originated
from the ancestor as an evolutionary novelty
unique characteristics of a lineage
Autapomorphic character
– a derived character shared by the most recent common
ancestor and by 2 or more descendants of that ancestor
– define clades, that is, they determine which species (or
other groups) are most closely related to each other
shared change condition
Synapomorphic character
shared ancestral trait
Symplesiomorphic character
reflects overall similarity alone, regardless of that similarity reflects common ancestry or not
Phenetics (Numerical Taxonomy)
decides which characters are most likely to hold the greatest amount of phylogenetic info.
– focuses on homology ⟶ homologous characters are used to deduce general relationships (extent to which various species differ/ resemble each other)
– often leads to the formation of paraphyletic groups (e.g. Class Aves excluded from Class Reptilia)
Evolutionary Systematics (Classical Taxonomy)
make use of highly sophisticated computer programs
– focuses on synapomorphic characters (shared characters derived from a common ancestor in which
the characters originated)
– focuses only in homologous characters that are NOT present in any earlier ancestors; only
evolutionary novelties are used
Cladistics (Phylogenetic Systematics)
