1) Two species of Asellus (aquaticus and coxalis) have been found in the natural state in sympatric conditions, though they are normally found in allopatric conditions. 2) An experimental laboratory study has been made of the competition between the two species. 3) The damage is mutual (statistically significant data). 4) The hypothesis is suggested that the two species are not evolving toward a sympatric life, but that coxalis is about to gain the upper hand over aquaticus; it is not unlikely that in polluted waters the species coxalis has a greater adaptive capacity than aquaticus.
Referenze Bibliografiche
[1] MONTALENTI G. e VITAGLIANO G. (1946) - Analisi della distribuzione dei chiasmi in Asellus aquaticus (L), «Ric. Sci. e Ricostr.», 16, 944-948.
[2] MONTALENTI G. e ROCCHI A. (1964) - Il corredo cromosomico di Asellus coxalis (Crust.Isop.), «Rend. Acad. Naz. Lincei», 36, 443-445.
[3] MONTALENTI G. e ROCCHI A. (1964) - Note cariologiche sul genere Asellus, «Boll. Zool.», 31, 341-349.
[4] CHAPPUIS R. A. (1949) - Les Asellides d'Europe et pays limitrophes, «Arch. Zool. exp. Paris», 86, 78-94.
[5] BALESDENT-MARQUET M. L. (1964) - Recherches sur la sexualité et le dêteimlnisme des caractères sexuels d'Asellus aquaticus (L.) (Crust. Isop.). Thèse Univers. Nancy.
[6] RUGGIU D. (1967) - Lago di Bolsena: distribuzione e variazioni stagionali di Asellus (Proasellus) coxalis Dollfus, «Mem. Ist. Ital. Idrobiol.», 21, 181-195.
[7] BALESDENT-MARQUET M. L. (1963) - Répartition des cellules de Zenker et détermination spécifique de Asellus (Asellus) aquaticus Linné sensu Racovitza et Asellus (Proasellus) meridianus Racovitza, «C. R. Acad. Sc.», 256, 262-264.
[8] BERNER L. (1956) - Note sur les Aselles d'eau douce (Crust. Isop.), «Arch. Hydrobiol.», 51, 410-414.
[9] ARCANGELI A. (1941-1942) - Il genere Asellus in Italia, con speciale riguardo alla diffusione del sottogenere Proaselius, «Boll. Musei Zool. Anat. comp. Torino», 49, ser. IV (126), 175-202.
[10] WILLIAMS W. D. (1962) - The geographical distribution of the isopods Asellus aquaticus (L.) and A. meridianus Rac., «Proc. Zool. Soc. London», 139, 75-96.
[11] ANDERSON E. (1969) - Life-cycle and growth of Asellus aquaticus (L.), Institute of Freshwater Research Drottingam, rep. n. 49, 6-26.
[12] FEHLMANN J. W. (1912) - Die Tiefenfauna des Luganer Sees., «Int. Rev. ges. Hydrobiol., Biol. Suppl.», ser. IV, 1, 1-52.
[13] VIVIER P. (1961) - La vie dans les eaux douces. Que sais-je? Presses Univ. de France, p. 128.
Con il contributo del Ministero per i Beni e le Attività Culturali