Prior to the Holocene, the range of the saiga antelope (Saiga tatarica) spanned from France to the Northwest Territories of Canada. Although its distribution subsequently contracted to the steppes of Central Asia, historical records indicate that it remained extremely abundant until the end of the Soviet Union, after which its populations were reduced by over 95%. We have analysed the mitochondrial control region sequence variation of 27 ancient and 38 modern specimens, to assay how the species' genetic diversity has changed since the Pleistocene. Phylogenetic analyses reveal the existence of two well-supported, and clearly distinct, clades of saiga. The first, spanning a time range from >49,500 (14) C ybp to the present, comprises all the modern specimens and ancient samples from the Northern Urals, Middle Urals and Northeast Yakutia. The second clade is exclusive to the Northern Urals and includes samples dating from between 40,400 to 10,250 (14) C ybp. Current genetic diversity is much lower than that present during the Pleistocene, an observation that data modelling using serial coalescent indicates cannot be explained by genetic drift in a population of constant size. Approximate Bayesian Computation analyses show the observed data is more compatible with a drastic population size reduction (c. 66-77%) following either a demographic bottleneck in the course of the Holocene or late Pleistocene, or a geographic fragmentation (followed by local extinction of one subpopulation) at the Holocene/Pleistocene transition.

Male crabs infected by parasitic barnacles (Rhizocephala) are known to be morphologically feminized. Here, we investigate morphological chances in green crabs, Carcinus maenas, induced by the parasitic barnacle Sacculina carcini. Infected males acquire a broader, longer and segmented abdomen, fringed with marginal setae. Copulatory appendages and pereopods are reduced in length, and the chelae become smaller. The feminization show great individual variation. Males with scars from lost externae, the parasites reproductive organ situated under the abdomen, are less modified than males carrying an externa, and the feminization is more pronounced in smaller than in larger males. No super-feminization is evident in female crabs that remain morphologically unaffected by infection. The protective value of a parasitically induced enlargement of the male abdomen may constitute an adaptation that increases parasite longevity. The additional effects on male morphology are viewed as pleiotropic side effects of the main adaptive value of enlarging the abdomen.

ABSTRACT. Tissue samples of 69 Atlantic walruses (Odobenus rosmarus rosmurus) were collected in the Thule district, North Greenland, in May-July 1975 and 1977. The mean concentration of total mercury in liver was 1.78 mg kg1 (SD = 1.54; N = 46), wet weight basis, with the mean percentage of methyl mercury being 5.5%. The mean concentration in muscle was 0.08 mg kg' (SD = 0.05; N = 58; mean age = 10.9 years; range: 1-26 years; neonates excluded). In neonates (N = 9) the mean concentration of total mercury was 0.31 mg kg' (SD = 0.45) in liver (19.9% methyl mercury) and 0.06 mg kg' (SD = 0.03) in muscle.Mean Z DDT and PCB concentrations in blubber of 28 walruses (mean age = 7.4 years; range: 0-19 years) were 0.063 mg kg' (SD = 0.080) and 0.221 mg kg' (SD = 0.207), respectively. In males the concentration of PDDT and PCB increased with age. In females there was no correlation between the concentration of PDDTand age, while there was a negative correlation between the concentration of PCB and age.

Twenty-one enzymes and three proteins were resolved by starch gel electrophoresis from liver, muscle and blood samples of 102 Atlantic walruses (Odobenus rosmarus rosmarus (L.)) from the Thule district, North Greenland. Among 32 loci investigated, three were found to be polymorphic. Thus, the genetic variability in the Atlantic walrus is low as found in other large mammals, except man.