Allozyme heterozygosity and fluctuating asymmetry in brown hares Lepus europaeus introduced to New Zealand: Developmental homeostasis in populations with a bottleneck history

The effect of genetic variability as indicated by allozyme heterozygosity o n developmental homeostasis as expressed by fluctuating morphological asymm etry (FA) is under current debate. Recent studies of brown hares Lepus euro paeus Pallas, 1778 in Austria (Hartl et al. 1995) revealed a negative relat ionship between FA and allozyme heterozygosity in non-metric but not in met ric skull characters. We aimed to find out whether non-metric traits of bro wn hares are generally more prone to FA than metric, or whether metric trai ts also show increased FA in populations with drastically reduced genetic v ariability. We studied variation in 34 enzyme systems and the relationship between overall individual heterozygosity based on polymorphic loci and FA in 27 non-metric and six metric bilateral skull characters of 96 brown hare s from three populations in Britain and two in New Zealand. All brown hares in New Zealand are considered to be descendents of only six founding indiv iduals from Britain and were expected to have considerably reduced gene poo l variability. Only six polymorphic loci were found. Allozyme heterozygosit y in the New Zealand populations was not significantly lower than in Britis h populations. However, both the New Zealand and the British populations ha d significantly lower genetic variability than the Austrian populations stu died earlier. This suggested a (historic) genetic bottleneck in British bro wn hares having preceeded the one in hares in New Zealand. It corresponds t o the hypothesis of the deliberate introduction of brown hares to Britain b y the ancient Romans. Neither at the individual nor at the population level was there any significant relationship between FA and allozyme heterozygos ity. Despite the significantly reduced genetic variability in hares from Ne w Zealand and Britain, their population-specific levels of non-metric and m etric FA were significantly lower than in hares from Austria. This might re sult eg, from genetic drift following the founding event in Britain, or fro m stronger selection against hares with low developmental homeostasis in Br itain and New Zealand than in Austria, due to environmental differences. Th e study demonstrates that in brown hares reduced genetic variability is not necessarily connected with low levels of developmental homeostasis as the earlier study of Austrian populations might have suggested. Rather, the par ticular phylogeny of populations has to be taken into account, when interpr eting relationships between developmental homeostasis and genetic variabili ty.