Biogeography and Karyotypes of Freshwater Planarians (Platyhelminthes, Tricladida, Paludicola) in Southern Brazil

Abstract

In the Tricladida (Platyhelminthes), the incidence of different biotypes identified by several ploidy levels is very common. Planarians collected in the State of Rio Grande do Sul were identified using cytogenetics. Different species distributions were observed with respect to Rio Grande do Sul's geomorphology, which could have been caused by their different microhabitats. Girardia tigrina and G. anderlani consisted of diploid and triploid individuals, whereas G. schubarti showed diploids, triploids, and mixoploids; for all these species, individuals of different ploidies were sympatric. Only for diploid G. anderlani were B chromosomes observed. These B chromosomes seem to have an irregular segregational behavior during mitosis, and possibly also during meiosis. However the processes (e.g., selection, mutation) of maintaining 2n, 3n, and 2n/3n individuals within natural populations of G. schubarti remain to be clarified.

Chromosome polymorphism and complements in populations of Girardia species (Platyhelminthes, Tricladida, Paludicola) from southern Brazil

“…The population of pure triploid (i.e. 3n = 12) specimens of G. schubarti found at Linha Júlio de Castilho (municipality of Salvador do Sul, Rio Grande do Sul State), in addition to those sampled by Knakievicz et al (2007) in two other localities, emphasizes, amplifies, and serves as a further reference to the occurrence and level of genetic plasticity (especially at the intraspecific, interorganismal level) in specimens of this species originating from populations found in this region of Brazil. High variability of genetic plasticity and/or high genetic variance may serve as tools in determining phenotypic plasticity for populations under specific environmental conditions and/or within specific geographic regions.…”

“…at least one stable mixoploid specimen) for G. anderlani (e.g. diploid 2n = 18, and triploid 3n = 27 specimens) (Kawakatsu et al 1983;Knakievicz et al, 2007), interorganismal (i.e. intraspecific), and intraorganismal genetic plasticity for G. schubarti (e.g.…”

“…intraspecific), and intraorganismal genetic plasticity for G. schubarti (e.g. diploid 2n = 8, 3n = 12, 4n = 16 specimen; 2n, 4n specimen, and 2n, 3n specimens) (Kawakatsu et al, 1984), and pure triploids of both species and of G. tigrina (Knakievicz et al, 2007). The population of pure triploid (i.e.…”

Estado do conhecimento dos macroturbelários (Platyhelminthes) do Brasil

“…4, Out./Dez. 2008 Referência Assunto Táxon principal Heller (1985b) bio Paludicola Hensel (1980) bio Paludicola Hyman (1955) div Polycladida, Maricola, Terricola Jung et al (1981) bio Paludicola Kawakatsu (1989) div Paludicola Kawakatsu et al (1976) div Paludicola Kawakatsu et al (1980) div Paludicola Kawakatsu et al (1981) div Paludicola Kawakatsu et al (1982) div Paludicola Kawakatsu et al (1983a) div Paludicola Kawakatsu et al (1983b) div Paludicola Kawakatsu et al (1984) div Paludicola Kawakatsu et al (1985) div Paludicola Kawakatsu et al (1986) div Paludicola Kawakatsu & E.M. Froehlich (1992) div Cavernicola div Paludicola Kenk (1974) div Paludicola Knakievicz & Bunselmeyer (2008) tec Paludicola Knakievicz et al (2006) bio Paludicola Knakievicz et al (2007) div Paludicola Lacerda et al (2005) tec Paludicola Lau et al (2007) tec Paludicola Leal-Zanchet & Hauser (1999) bio Paludicola Leal-Zanchet & Carbayo (2000) div Leuck & Luz (1980) bio Paludicola Lima (1981) tec Paludicola Lima (1982) tec Paludicola Lima (1984) tec Paludicola Marcus (1946) div Paludicola Marcus (1947) div Polycladida, Maricola Marcus (1948) div Maricola, Paludicola, Polycladida Marcus (1949) div Polycladida Marcus (1950) div Polycladida Marcus (1951) div Terricola Marcus (1952) div Polycladida, Terricola Marcus (1954) div Polycladida Marcus (1963) div Maricola …”

Freshwater planarians as novel organisms for genotoxicity testing: Analysis of chromosome aberrations

“…The planarian species Girardia schubarti Marcus and G. tigrina Girard are widely distributed in freshwater environments, such as streams and lakes, and can be found under stones, among the roots and leaves of aquatic plants, and on the bottoms of lakes or in stream beds. The chromosome number in both species (2N ¼ 8 for G. schubarti and 2N ¼ 16 for G. tigrina) is relatively low and the homologs can be identified without banding [Benazzi and Lentati, 1976;Kawakatsu et al, 1982;Kawakatsu et al, 1985;Knakievicz et al, 2007]. Planarians have a high regeneration capacity.…”