Observation of Adoption in Polar Bears (Ursus maritimus)

We observed a case of adoption of a single four-month-old polar bear cub (Ursus maritimus) into an existing litter of two cubs on Hopen Island, Svalbard. We believe the high density of maternity dens in the study area may increase the likelihood of natural adoption. Speculation about theoretical implications of adoption is of scientific interest. However, we believe that the probability of adoption may increase when family groups are captured, and the scientific interpretation of such events is of questionable value. We urge researchers to exercise caution in handling family groups in high-density den areas.Dans l'île Hopen au Svalbard, on a observé le cas d'adoption d'un ourson polaire (Ursus maritimus) unique âgé de quatre mois au sein d'une portée de deux oursons. On pense que la forte densité de tanières de mise bas dans la zone d'étude pourrait accroître la probabilité de l'adoption naturelle. Les hypothèses concernant les implications théoriques de l'adoption relèvent d'un intérêt scientifique. Nous croyons cependant que la probabilité de l'adoption peut augmenter quand les groupes familiaux sont capturés, et on peut se poser des questions quant à l'interprétation scientifique de telles manifestations. Nous recommandons fortement aux chercheurs de prendre des précautions lors de la manipulation de groupes familiaux dans des aires de mise bas à forte densité

Infanticide and Cannibalism of Juvenile Polar Bears (Ursus maritimus) in Svalbard

Two instances of infanticide and cannibalism in polar bears (Ursus maritimus) were observed in SE Svalbard, at Hopen Island. In the first, an adult male killed three young cubs at a den site and consumed one of them. In the second, an adult male actively pursued, killed, and consumed a dependent yearling. Infanticide of dependent polar bear offspring by adult males may be more common in Svalbard than in other populations because the population is close to carrying capacity or because geographic features reduce spatial segregation of age and sex classes.On a observé deux cas d'infanticide et de cannibalisme chez l'ours polaire (Ursus maritimus) à l'île Hopen, dans le sud-est du Svalbard. Dans le premier cas, un mâle adulte a tué trois oursons dans leur tanière et en a dévoré un. Dans le second, un mâle adulte a pourchassé, tué et dévoré un ourson d'un an non autonome. Il se peut que, chez l'ours polaire, l'infanticide des petits non autonomes par des mâles adultes soit plus commun au Svalbard que dans d'autres populations en raison de la taille de la population qui est proche de la capacité biogénique ou parce que les caractéristiques géographiques réduisent la ségrégation spatiale des catégories d'âges et de sexes

Identification of HSP70 homologues in chloroplasts.

Cytoplasmic members of the heat shock protein hsp70 family have recently been implicated in the transport of proteins to the endoplasmic reticulum and mitochondria. In addition, other hsp70 homologues have been found in the endoplasmic reticulum and mitochondria and, at least for the endoplasmic reticulum hsp70 homologue, may be involved in the proper folding and assembly of newly transported proteins. Since chloroplasts are an important site of protein transport in plant cells, we were interested in determining whetherhsp70 proteins might be located in this organelle. By using immune-blotting techniques and two antibody separations against hsp70 proteins, we have identified three chloroplast icproteins of approximately 70k Dathatae related to hsp70 proteins. One of these proteins was tightly associated with the outer envelope membrane and was not exposed at the outer surface of the chloroplasts. The other two were soluble proteins located in the stroma. Steady-state levels of the chloroplastic hsp70 homologues did not change after heat stress nor were any additional hsp70 homologues detected in chloroplasts isolated from heat- stressed plants. We discuss the possible functions of these hsp7O homologues in the transport of proteins into and within chloroplasts

Ringed seal demography in a changing climate

Climate change is affecting species’ distributions and abundances worldwide. Baseline population estimates, against which future observations may be compared, are necessary if we are to detect ecological change. Arctic sea ice ecosystems are changing rapidly and we lack baseline population estimates for many ice‐associated species. Provided we can detect them, changes in Arctic marine ecosystems may be signaled by changes in indicator species such as ringed seals (Pusa hispida). Ringed seal monitoring has provided estimates of survival and fertility rates, but these have not been used for population‐level inference. Using matrix population models, we synthesized existing demographic parameters to obtain estimates of historical ringed seal population growth and structure in Amundsen Gulf and Prince Albert Sound, Canada. We then formalized existing hypotheses about the effects of emerging environmental stressors (i.e., earlier spring ice breakup and reduced snow depth) on ringed seal pup survival. Coupling the demographic model to ice and snow forecasts available from the Coupled Model Intercomparison Project resulted in projections of ringed seal population size and structure up to the year 2100. These projections showed median declines in population size ranging from 50% to 99%. Corresponding to these projected declines were substantial changes in population structure, with increasing proportions of ringed seal pups and adults and declining proportions of juveniles. We explored if currently collected, harvest‐based data could be used to detect the projected changes in population stage structure. Our model suggests that at a present sample size of 100 seals per year, the projected changes in stage structure would only be reliably detected by mid‐century, even for the most extreme climate models. This modeling process revealed inconsistencies in existing estimates of ringed seal demographic rates. Mathematical population models such as these can contribute both to understanding past population trends as well as predicting future ones, both of which are necessary if we are to detect and interpret future observations

A chloroplast-localized heat shock protein is a member of a eukaryotic superfamily of heat shock proteins

We have isolated cDNA clones from soybean and pea that specify nuclear-encoded heat shock proteins (HSPs) which localize to chloroplasts. The mRNAs for these HSPs are undetectable at control temperatures, but increase approximately 150-fold during a 2-h heat shock. Hybridization-selection followed by in vitro translation demonstrates that these HSPs are synthesized as precursor proteins which are processed by the removal of 5-6.5 kd during import into isolated chloroplasts. The nucleotide sequence of the cDNAs shows the derived amino acid sequences of the mature pea and soybean proteins are 79% identical. While the predicted transit peptide encoded by the pea cDNA has some characteristics typical of transit sequences, including high Ser content, multiple basic residues and no acidic residues, it lacks two domains proposed to be important for import and maturation of other chloroplast proteins. The carboxy-terminal region of the chloroplast HSP has significant homology to cytoplasmic HSPs from soybean and other eukaryotes. We hypothesize that the chloroplast HSP shares a common structural and functional domain with low mol. wt HSPs which localize to other parts of the cell, and may have evolved from a nuclear gene

Can whisker spot patterns be used to identify individual polar bears?

Studies of population dynamics, movement patterns and animal behavior usually require identification of individuals. We evaluated the reliability of using whisker spot patterns to noninvasively identify individual polar bears Ursus maritimus. We obtained the locations of polar bear whisker spots from photographs taken in western Hudson Bay, tested the independence of spot locations, estimated the complexity of each spot pattern in terms of information and determined whether each whisker spot pattern was reliable from its information content. Of the 50 whisker spot patterns analyzed, 98% contained enough information to be reliable, and this result varied little among observers. Photographs taken \u3c50 m from polar bears were most useful. Our results suggest that individual identification of polar bears in the field based on whisker spot pattern variations is reliable. Researchers studying polar bear behavior or estimating population parameters can benefit from this method if proximity to the bears is feasible. © 2007 The Zoological Society of London

Barents Sea polar bears ( Ursus maritimus

This paper examines how anthropogenic threats, such as disturbance, pollution and climate change, are linked to polar bear (Ursus maritimus) population biology in the Svalbard and Barents Sea area, with the aim to increase our understanding of how human activity may impact the population. Overharvesting drastically reduced the population of polar bears in the Barents Sea region from about 1870 to 1970. After harvesting was stopped—in 1956 in Russia and 1973 in Norway—the population grew to an estimated 2650 individuals (95% confidence interval 1900–3600) in 2004, and maternity denning in the Svalbard Archipelago became more widely distributed. During recent decades, the population has faced challenges from a variety of new anthropogenic impacts: a range of pollutants, an increasing level of human presence and activity as well as changes in ice conditions. Contaminants bioaccumulate up through the marine food web, culminating in this top predator that consumes ringed, bearded and harp seals. Females with small cubs use land-fast sea ice for hunting and are therefore vulnerable to disturbance by snowmobile drivers. Sea-ice diminution, associated with climate change, reduces polar bears’ access to denning areas and could negatively affect the survival of cubs. There are clear linkages between population biology and current anthropogenic threats, and we suggest that future research and management should focus on and take into consideration the combined effects of several stressors on polar bears