Overview

Comprehensive Description

General Description

Schmidtea mediterranea Benazzi et al., 1975 is a freshwater planarian (order Tricladida, suborder Continenticola, phylum Platyhelminthes) that is mostly known to the scientific community for its capacity to regenerate and has become a model organism for the functional analysis of the genes involved in pattern formation.

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Distribution

Barcelona, Spain
Collection date: 1975 or earlier
Kind: type locality
Comments: Asexual population. "panta de la Fuxarda" in the city of Barcelona. The panta de la Fuxarda is a small, slightly alkaline pond, artificially created around 1914. Specimens were collected from beneath Nymphaea sp. leaves.

Barcelona, Spain
Collection date: 1975 or earlier
Comments: Asexual population. "Font dels Tres Pins" in the city of Barcelona, a small fountain distant only 400 mts from panta de la Fuxarda.

Ruisseau d’Alistro, Corsica, France
Collection date: 1975 or earlier
Comments: Sexual populations. Corsica, a channel near Faro d'Alistro in the eastern coast, Bonifacio and Monacia in the South of the island.

La Ville de Bonifacio, Corsica, France
Collection date: 1975 or earlier
Comments: Sexual populations. Corsica, a channel near Faro d'Alistro in the eastern coast, Bonifacio and Monacia in the South of the island.

Monacia (Monacio), Corsica, France
Collection date: 1975 or earlier
Comments: Sexual populations. Corsica, a channel near Faro d'Alistro in the eastern coast, Bonifacio and Monacia in the South of the island.

Sardegna (Sardinia, Sardenya, Sardegne, Sardaigne, Sardinien), Italy
Collection date: 1975 or earlier
Comments: Sexual populations. Sardinia: various localities.

Palermo, Sicily, Italy
Collection date: 1975 or earlier
Comments: Sexual populations. Sicily: in the environs of Palermo and Mazara del Vallo (Province of Trapani).

Mazara del Vallo, Province of Trapani, Sicily, Italy
Collection date: 1975 or earlier
Comments: Sexual populations. Sicily: in the environs of Palermo and Mazara del Vallo (Province of Trapani).
  • Benazzi M, Baguna J, Ballester R, & del Papa R. 1975. index card avail.
     . Further contribution to the taxonomy of the "Dugesia lugubris-polychroa group" with description of Dugesia mediterranea N.sp. (Tricladida, Paludicola). Boll Zool 42:81-89.
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It is present in coastal locations and islands in the western Mediterranean: Catalonia, Menorca, Mallorca, Corsica, Sardinia, Sicily and Tunisia. Their populations are scattered.

In Catalonia, and in the whole Spain, only two populations are known. One is located in the Montjuïc Mountain, within Barcelona city. Specimens from Girona are also known, but recent searches didn't succeed in finding them.

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Source: Continenticola

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Ecology

Habitat

Despite its present distribution in the Mediterranean, S. mediterranea seems to be adapted to moderate summer temperatures. That leads to think that this species is probably trapped in the Mediterranean since this area had a more suitable climate.

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Life History and Behavior

Reproduction

There are either amphimictic and/or asexual fissiparous populations. In both types of reproduction most of the populations are diploids.

The individuals that reproduce by fission (either diploids and triploids) bear a heteromorphic translocation between first and third chromosomes. This translocation only affects one chromosome of each pair.

The asexual populations are only present in Catalonia, Mallorca and Menorca. There is no sexual population known in this locations. The Menorca asexual population is triploid, while Catalonia and Mallorca populations are exclusively diploids.

Most of sexual populations are diploids with an exception, one in Sardinia is triploid.

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Evolution and Systematics

Evolution

It has been suggested that the common ancestor of S. mediterranea and its sister species, S. polychroa, diverged around 43 mya. S. mediterranea appeared at some time between these 43 mya and 20-5 mya.

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Conservation

Conservation Status

Schmidtea mediterranea populations are scattered and in some of the localities a population decline has been observed. This is the case of the asexual populations of Montjuïc (Barcelona) where it has apparently disappeared from two ponds after human intervention. In another pond of Montjuïc (Viver dels Tres Pins) the introduction of Schmidtea polychroa in 2007 seems to have had a deleterous effect on S. mediterranea population. The fourth pond with this species, “Pantà de la Fuxarda”, has been invaded by the crayfish Procambarus clarkii (Girard, 1852). Its introduction could menace S. mediterranea because its known to be able to change native plants and animal communities.

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Relevance to Humans and Ecosystems

Benefits

Uses

Schmidtea mediterranea is used in developmental and regeneration studies.

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Wikipedia

Schmidtea mediterranea

Schmidtea mediterranea is a freshwater planarian that lives in southern Europe and Tunisia.[2] It is a model for regeneration and development of tissues such as the brain and germline.[3][4]

Contents

Distribution[edit]

Schmidtea mediterranea is found in some coastal areas and islands in the Western Mediterranean: Catalonia, Menorca, Mallorca, Corsica, Sardinia, Sicily and Tunisia.[2][5][6][7][8]

Ecology[edit]

High water temperatures (25-27 °C) have deleterous effects on S. mediterranea populations, while variations in the pH of the water (6.9-8.9) don’t seem to have an important influence on the survival of this species.[2]

S. mediterranea can be found with associated fauna such as gastropods, bivalves, insects, leeches, and nematodes.[2]

Reproduction[edit]

The sexual specimens of Schmidtea mediterranea produce cocoons between November and April. In May, when water temperature rises above 20 °C, they lose their reproductive apparatus. Despite this, they don’t reproduce asexually (by fissiparity) during the summer months.[2]

References[edit]

  1. ^ E.M. Lazaro, A.H. Harrath, G.A. Stocchino, M. Pala, J. Baguna, M. Riutort, Schmidtea mediterranea phylogeography: an old species surviving on a few Mediterranean islands?, BMC Evolutionary Biology. 11 (2011) 274.
  2. ^ a b c d e Abdel Halim Harrath, Mohamed Charni, Ronald Sluys, Fathia Zghal & Saida Tekaya (2004). "Ecology and distribution of the freshwater planarian Schmidtea mediterranea in Tunisia". Italian Journal of Zoology 71 (3): 233–236. doi:10.1080/11250000409356577. 
  3. ^ Salo E, Baguñà J: Regeneration in planarians and other worms: New findings, new tools, and new perspectives. Journal of Experimental Zoology 2002, 292(6):528-539.
  4. ^ Reddien PW, Sanchez-Alvarado A: Fundamentals of planarian regeneration. Annu Rev Cell Dev Biol 2004, 20:725-757.
  5. ^ Benazzi M, Baguñà J, Ballester R, Puccinelli I, Papa RD: Further Contribution to the Taxonomy of the Dugesia lugubris-polychroa Group with Description of Dugesia mediterranea n. sp. (Tricladida, Paludicola). Bolletino di zoologia 1975, 42(1):81-89.
  6. ^ Ribas M: Cariologia, sistematica i biogeografia de les Planaries d'aigues dolces al Països Catalans. 1990.
  7. ^ Baguñà J. Carranza S, Pala M, Ribera C, Giribet G, Arnedo M, Ribas M, Riutort M: From morphology and kariology to molecules. New methods for taxonomical identification of asexual populations of freshwater planarians. A tribute to Professor Mario Benazzi. Italian Journal of Zoology 1999, 66:207-214.
  8. ^ De Vries EJ, Baguñà J, Ball IR: Chromosomal polymorphism in planarians and the plate tectonics of the western Mediterranean. Genetica 1984, 62:187-191.
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Names and Taxonomy

Taxonomy

Oviedo NJ, Newmark P, Alvarado AS 2003 (citation)-"Allometric scaling and proportion regulation in the freshwater planarian Schmidtea mediterranea."
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