| Abstract [eng] |
Fluctuating asymmetry (FA) it is a form of asymmetry which is related with random deviations off accurate body symmetry. It has been stated, that in animal populations a level of FA correlates with a level of environmental stresses which occure during animals ontogenetic development (Zakharov, 1989; Palmer, 1994). Therefore FA could be an indicator of environmental quality: the less asymmetric individuals in population, the better environment. Present beaver population is formed from several genetically different places in Lithuania. So it could be that genetically different local populations can react to environmental stresses differently. Level of FA in ten river watersheds in local beaver populations has been investigated. Level of FA in skulls of beavers according to 5 metric and 46 non metric traits has been assessed. Level of FA has been assessed according to differences between left and right skull side dispersion in first case, in second case – according to percentage of asymmetric individuals in population. Number of investigated individuals is 562. It has been stated, that level of FA depends on beaver sex at least according to non metric skull traits. Mostly it depends on age structure of individuals. At least asymmetric there are juveniles (level of FA was 34%), great level of FA has been stated in adults (46%). Also it has been stated, that beavers who have black skin are more asymmetric than brown skin ones and individuals who have tooth anomalies are more asymmetric than beavers without tooth anomalies. The most level of FA depends on beaver sex according to metric traits and it don‘t depend on other investigation aspects. Local beaver populations of Merkys, Šešupė, Jūra, Dubysa and Minija watersheds have had a great level of FA comparing these populations with each other according to non metric skull traits. There were many black skin beavers in these watersheds (except Dubysa). And there were many individuals with tooth anomalies in Šešupė, Jūra and Minija watersheds. These causes could take a great place in FA level. There weren‘t statistical significant differences according to metric traits. |
