BIO110: Species

• the demarcation of species

  microtaxonomy
• the classification of species

  macrotaxonomy
• a group of closely related organisms that are very similar to each other and are usually capable of interbreeding and producing fertile offspring

  species
• supports the widely held view that "members of a species are individuals that look similar to one another"

  morphological species concept
• smallest groups that are consistently and persistently distinct, and distinguishable by ordinary means

  morphological species concept
• easily recognized kinds of organisms...on simple gross observation

  morphological species concept
• arbitrary; individuals of two populations were very hard to tell apart but would not mate with one another

  problems with MSC
• mimicry complexes supplied further evidence against the concept, as organisms of the same species can look very different, depending upon where they are reared or their life cycle stage

  problems with MSC
• mimic resembles a model that is poisonous or unpleasant to eat

  batesian mimicry
• ex. poisonous coral snake and scarlet king snake non-poisonous

  batesian mimicry
• two or more equally poisonous or distasteful species have a similar color pattern

  mullerian mimicry
• ex. wasp and bee

  mullerian mimicry
• a species is a group of actually or potentially interbreeding individuals who are reproductively isolated from other such groups

  biological species concept
• ex. horse, mule, and donkey

  biological species concept
• If they do not interbreed, then they are good species.

  sympatric species
• It may be difficult assess whether they are “potentially interbreeding”.

  allopatric populations
• testing on museum specimens and fossils and for interbreeding under natural conditions

  problems with BSC
• there are asexual organisms

  problems with BSC
• reproductive isolation is often incomplete

  problems with BSC
• ex. liger and tigon

  problems with BSC
• horizontal gene transfer

  biological species concept
• a lineage evolving separately from others with its own unitary evolutionary role and tendencies

  evolutionary species concept
• solves the problem of intermittent hybridization as it is allowed as long as it does not affect the evolutionary trajectory

  evolutionary species concept
• arbitrary; how do you define evolutionary independence

  problems with ESC
• the smallest diagnosable monophyletic group of populations within which there is a parental pattern of ancestry and descent

  phylogenetic species concept
• members share derived characters and treated as evidence of descent

  phylogenetic species concept
• distinguishing between gene trees and species trees

  problems with PSC
• what characters to use? what level of divergence constitutes a species?

  problems with PSC
• one species at a time in a lineage

  chronospecies
• inhabits various region

  cosmopolitan
• two or more taxa with single name, they are indistinguishable

  cryptic
• can only be seen in limited areas, and only in a specific habitat

  endemic
• typical of unstable or periodically extreme environments, characterized by a strong dispersal ability

  fugitive
• two or more subspecies

  polytypic
• remnants or living fossils that are widespread in the past

  relict
• thought to be extinct but has been rediscovered in several periods

  lazarus
• usually a permanent isolated race or they become somewhat different

  subspecies
• group of new species or subspecies that are different enough from other species to be considered an entity

  superspecies
• formation of new species because separated by geographic barrier

  vicariant
• two species that are each other's closest relatives

  sister