Search results
Results From The WOW.Com Content Network
While this model of speciation is useful in that it avoids non-monophyletic groupings, it has its criticisms as well. N.I. Platnick, for example, believes the autapomorphic species concept to be inadequate because it allows for the possibility of reproductive isolation and speciation while revoking the "species" status of the mother population.
It was based on the assumption that higher-ranked taxa could represent specific morphological innovations. Although this approach was criticized as it relied on artificial and non-monophyletic taxa, it provided valuable insights into the evolution of disparity. Some conclusions have been confirmed by subsequent quantitative metrics.
A clade is by definition monophyletic, meaning that it contains one ancestor which can be an organism, a population, or a species and all its descendants. [note 1] [10] [11] The ancestor can be known or unknown; any and all members of a clade can be extant or extinct.
An evolutionary grade is a group of species united by morphological or physiological traits, that has given rise to another group that has major differences from the ancestral group's condition, and is thus not considered part of the ancestral group, while still having enough similarities that we can group them under the same clade.
The term monophyly, or monophyletic, derives from the two Ancient Greek words μόνος (mónos), meaning "alone, only, unique", and φῦλον (phûlon), meaning "genus, species", [4] [5] and refers to the fact that a monophyletic group includes organisms (e.g., genera, species) consisting of all the descendants of a unique common ancestor.
The term paraphyly, or paraphyletic, derives from the two Ancient Greek words παρά (pará), meaning "beside, near", and φῦλον (phûlon), meaning "genus, species", [2] [3] and refers to the situation in which one or several monophyletic subgroups of organisms (e.g., genera, species) are left apart from all other descendants of a unique common ancestor.
Evolutionary taxonomy, evolutionary systematics or Darwinian classification is a branch of biological classification that seeks to classify organisms using a combination of phylogenetic relationship (shared descent), progenitor-descendant relationship (serial descent), and degree of evolutionary change.
Maslow proposed his hierarchy of needs in his 1943 paper "A Theory of Human Motivation" in the journal Psychological Review. [1] The theory is a classification system intended to reflect the universal needs of society as its base, then proceeding to more acquired emotions. [18]