BIO102_SYSTEMATICS MIDTERMS T1

• Microtaxonomy deals with species and is infraspecific (occuring within a species) category
• Mayr and Ashlock first put forward the concept of microtaxonomy in 1975
• The 2 levels of discontinuity (disruption of gene flow): (1) individuals, (2) reproductively isolated populations
• Incipient species have some of the properties of the species, but lack others
• Phenon - different forms or phenotypes that may occur in a single population; composed of intrapopulation variants
• In 1943, Camp & Gily described phenon as phenotypically homogenous samples at the species level
• Phenon includes many "varieties", sexes (when there is sexual dimorphism), age stages, seasonal varieties, & morphs (individual variants)
• Intrapopulation - occurring within or taking place between members of a population
• Phenon - any set of organisms grouped together by numerical taxonomy
• In 1963, Sokal & Sneath's Principles of Numerical Taxonomy, any evolutionary approach was avoided in favor of an operational method based on a direct comparison of phenotypes
• Taxon - populations which are the material of classifications
• Taxon is a named taxonomic group of any rank that is considered to be sufficiently distinct by taxonomists to be formally recognized & assigned to a definite category
• Taxon always refers to concrete zoological objects
• Geographic isolates within a species only become a taxa when they become a subspecies
• Subspecies replaced the term variety in the 19th century
• Subspecies is an aggregrate of phenotypically similar populations of a species inhabiting a geographic subdivision of that range of that species & differing taxonomically from other populations of that species
• Category is a class or division of organisms regarded as having particular shared (similar) characteristics
• 3 groups of categories: species, infraspecific, and collective, higher categories
• Species - vehicle of all macroevolution
• Species - keystone of evolution
• 3 Species Concept: Typological, Nominalistic, Evolutionary Species Concept
• Typological species concept is also called as the essentialist species concept
• Typological species concept goes back to the philosophy of Plato, and it was the species concept of Linnaeus and his followers
• In the typological species concept, the diversity of the universe reflects the existence of a limited number of "universals" or types (the Eidos of Plato)
• In the typological species concept, the main criterion of species status is the degree of morphological difference
• Conspecific - meaning belonging to the same species
• Sibling species differ hardly at all morphologically, but are good biological species
• Nominalistic species concept deny the existence of "universals." Only individuals exists, and species are abstractions by people
• An evolutionary species is a lineage (an ancestral-descendant sequence of populations) evolving separately from others & with its own unitary evolutionary role & tendencies.”
• Peripatric speciation is a special version of the allopatric speciation mode and happens when one of the isolated populations has very few individuals
• Allopatric speciation (from the ancient Greek allos, "other" + Greek patris, "fatherland") or geographic speciation is speciation that occurs when biological populations of the same species become vicariant — isolated from each other to an extent that prevents or interferes with genetic interchange
• Biological Species Concept emerge after 1750 and it combines elements of the typological & the nominalistic concepts by stating that species have independent reality & are typified by the statistics of populations of individuals
• Species is an ecological unit - interacts as a unit with other species with which it shares its environment
• Species is a genetic unit consisting of a large, intercommunicating gene pool, whereas the individual organism is merely a temporary vessel holding a small portion of the contents of the gene pool for a short period of time
• A species is a group of interbreeding natural populations that is reproductively isolated from other such groups
• Biological meaning of a species: it is a protected gene pool
• A species is a group of individuals that actually interbreed in nature producing viable offspring
• Biological Species Concept defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance.
• Problems with the Biological Species Concept: (1) Asexual organisms - don't fit the criteria (2) Fossils - impossible to observe mating process (3) Hybrids
• Recognition Species Concept - species are a set of organisms that can recognize each other as potential mates, even if prevented from mating