Konsep SpesiesRYZKITA P. ALMAIDAH3415126640MARZUKI FATHUL ROHMAN3415126633

KONSEP SPESIES

1. The Biological Species Concept (BSC, Dobzhansky, Mayr)Mayr (1940): species are groups of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

1. The Biological Species Concept (BSC, Dobzhansky, Mayr)

Dobzhansky (1937): species are the largest and most inclusive reproductive community of sexual and cross-fertilizing individuals that share a common gene pool.

The Western meadowlark (left) and the Eastern meadowlark (right) appear to be identical, and their ranges overlap, but their distinct songs prevent interbreeding.

Mayr divided the BSC into the nondimensional and the multidimensional species concept:

Nondimensional Multidimensional species concept species conceptspecies sympatric species are allopatricand synchronous and/or allochronous

Species ASpecies ASpecies BSpecies B

2.The Typological Species Concept (TSC, Linnaeus)Definition: a group of individuals that differ from other groups by possessing constant diagnostic characters. based on collecting and describing a type specimen for a given species.

3. The Evolutionary Species Concept (ESC, Simpson, 1951)Definition: an evolutionary species is a lineage evolving separately from others with its own unitary evolutionary role and tendencies.

initially developed to define fossil species. TimeShell width Species ASpecies B

4. The Phylogenetic Species Concept (PSC, Cracraft, 1983)Definition: the smallest diagnosable monophyletic group of populations within which there is a parental pattern of ancestry and descent.

two recent extensions are the internodal species concept and the genealogical species concept.

5. Phenetic Species ConceptDefinition: Phenetic species concept defines a species as a set of organisms that look similar to each other and distinct from other sets.

More formally, it would specify some exact degree of phenetic similarity, and similarity would be measured distance statisticBased on numerical taxonomy, which by a phenetic measures and records similarities for large numbers of characters

According to Patterson (1985, 993), species have a specific mate recognition system (SMRS)Species can be defined as a set of organisms with a common method of recognizing matesAdvantages:SMRSs are easier to observe than interbreeding in natureThe recognition species concept may more accurately represent what happens when a new species originates

6. The Recognition Species Concept (RSC, Paterson, 1985)

7. The Ecological Species ConceptThe ecological species concept defines a species as a set of organisms exploiting a single niche (adaptive zone)The ESC supposes that ecological niches in nature occupy discrete zones, with gaps between them

Ecological influences on the form of a species areshown by the phenomenon of character displacementEcological competition can influence the form of a species.Character displacement can arise in the following conditions. Two closely related species exist a species that may be ecological competitors. Character displacement means that individuals of the two species differ more if they are sampled from a place where both species are present (sympatry, same place) than do individuals sampled from places where only one of the species is present (allopatry, other place). In these terms, character displacement means that sympatric populations of two species differ more than do allopatric populations of the same two species.

An example of character displacement comes from two species of salamander, Plethodon cinereus and P. hoffmani. P. cinereus lives throughout much of northeastern USA, except for parts of Pennsylvania and Virginia, whereas P. hoffmani lives in parts of Pennsylvania where P. cinereus is absent. The two species also live together, sympatrically, in a small region of overlap in Pennsylvania. The two species differ in the shape of their heads and jaws: P. hoffmani has a jaw that is relatively weak but can be closed fast and P. cinereus has a stronger jaw but is slow to snap it shut. P. hoffmani is better adapted to eat large prey items, which are caught by immediately closing the mouth on them, whereas P. cinereus is better adapted to eat smaller prey, which are eaten by pressing them between the tongue and teeth.

***********