Wolverine denning behaviour and its implications for monitoring reproductive females

Knowledge about the number of reproductive females is important for monitoring population dynamics, and can be critical for managing human-wildlife conflicts. For wolverines Gulo gulo, counts of reproductive females is the basis for estimates of population size in Scandinavia, as well as a key measure for compensation payments to Sami reindeer-herders in Sweden. However, documenting wolverine reproductive events in the field is challenging and requires knowledge of female denning behaviour. Furthermore, females may shift den sites, presenting difficulties in determining whether two den sites belong to the same or two neighbouring females. In this study, we used data from 18 GPS-collared wolverine females, monitored intensively during the denning season (15 February-31 May) in 2004-2014, to provide baseline information on denning behaviour. We documented reproductive events in 32 of 54 potential denning seasons, and identified a total of 245 den sites. Females used 8.8 +/- 8.5 (mean +/- SD) den sites per denning season (median = 6, range: 1-28). The number of den site shifts, the distance between subsequent den sites, and the time and distance females spent away from a den site increased during the denning season; while distances between neighbouring females' den sites remained constant. From late April, the distance between consecutive den sites used by the same female overlapped with distances between neighbouring females' den sites, resulting in increased uncertainty regarding whether two den sites belonged to one or two females. Using Bayesian modelling we calculated probabilities that two den sites belonged to the same female, or neighbouring females, conditional on the time of season and the distance between den sites. These findings will allow the monitoring program to adapt its methods for determining if multiple den sites belong to one or two reproductive events, using seasonally-dynamic threshold based on an understanding of wolverine denning behaviour

Dynamin-like proteins are potentially involved in membrane dynamics within chloroplasts and cyanobacteria

Dynamin-like proteins are a family of membrane-active proteins with low sequence identity. The proteins operate in different organelles in eukaryotic cells, where they trigger vesicle formation, membrane fusion or organelle division. As discussed here, representatives of this protein family have also been identified in chloroplasts and DLPs are very common in cyanobacteria. Since cyanobacteria and chloroplasts, an organelle of bacterial origin, have similar internal membrane systems, we suggest that dynamin-like proteins are involved in membrane dynamics in cyanobacteria and chloroplasts. Here, we discuss the features and activities of dynamin-like proteins with a focus on their potential presence and activity in chloroplasts and cyanobacteria

Recolonization following past persecution questions the importance of persistent snow cover as a range limiting factor for wolverines

Globally, climate is changing rapidly, which causes shifts in many species' distributions, stressing the need to understand their response to changing environmental conditions to inform conservation and management. Northern latitudes are expected to experience strongest changes in climate, with milder winters and decreasing snow cover. The wolverine (Gulo gulo) is a circumpolar, threatened carnivore distributed in northern tundra, boreal, and subboreal habitats. Previous studies have suggested that wolverine distribution and reproduction are constrained by a strong association with persistent spring snow cover. We assess this hypothesis by relating spatial distribution of 1589 reproductive events, a fitness-related proxy for female reproduction and survival, to snow cover over two decades. Wolverine distribution has increased and number of reproductive events increased 20 times in areas lacking spring snow cover during our study period, despite low monitoring effort where snow is sparse. Thus, the relationship between reproductive events and persistent spring snow cover weakened during this period. These findings show that wolverine reproductive success and hence distribution are less dependent on spring snow cover than expected. This has important implications for projections of future habitat availability, and thus distribution, of this threatened species. Our study also illustrates how past persecution, or other factors, that have restricted species distribution to remote areas can mask actual effects of environmental parameters, whose importance reveals when populations expand beyond previously restricted ranges. Overwhelming evidence shows that climate change is affecting many species and ecological processes, but forecasting potential consequences on a given species requires longitudinal data to revisit hypotheses and reassess the direction and magnitude of climate effects with new data. This is especially important for conservation-oriented management of species inhabiting dynamic systems where environmental factors and human activities interact, a common scenario for many species in different ecosystems around the globe

No Allee effect detected during the natural recolonization by a large carnivore despite low growth rate

Eurasian lynx (Lynx lynx) have recently naturally recolonized southern Sweden. The first documented reproduction of lynx in recent times occurred in 2003, and the population increased from 2 to 48 family groups (the unit of measurement in Swedish monitoring) during its first 18 years (2003/2004-2020/2021). We did not detect any Allee effect, that is, lower growth rate at low population density, during the recolonization of southern Sweden, although our population simulations revealed a non-negligible (30%) chance that population observed development could include an Allee effect. The probable absence of an Allee effect was likely because colonizing females did not lack mating partners, as a larger number of wide-ranging males were established in the area before documented reproduction took place. Despite the absence of an Allee effect, the growth rate during recolonization was lower in southern Sweden (lambda = 1.20) than in central Sweden (lambda = 1.29). We have no evidence of higher mortality, including that from poaching, or lower reproduction in southern Sweden could explain the lower growth rate. Instead, we suggest that the lower growth rate during the recolonization of southern Sweden was explained by fewer immigrants arriving from central Sweden due to areas of less suitable habitat between central and southern Sweden, partially preventing immigration southward. From a conservation point of view, it is positive that this small population could recover without being negatively influenced by an Allee effect, as small populations with an Allee effect experience lower viability than those without

Phosphatidylcholine is transferred from chemically-defined liposomes to chloroplasts through proteins of the chloroplast outer envelope membrane

AbstractChloroplasts maintain their lipid balance through a tight interplay with the endoplasmic reticulum (ER). The outer envelope membrane of chloroplasts contains a large proportion of the phospholipid phosphatidylcholine (PC), which is synthesized in the ER and also a possible precursor for thylakoid galactolipids. The mechanism for PC transport from the ER to chloroplasts is not known. Using isolated chloroplasts and liposomes containing radiolabeled PC we investigated non-vesicular transport of PC in vitro. PC uptake in chloroplasts was time and temperature dependent, but nucleotide independent. Increased radius of liposomes stimulated PC uptake, and protease treatment of the chloroplasts impaired PC uptake. This implies that the chloroplast outer envelopes contains an exposed proteinaceous machinery for the uptake of PC from closely apposed membranes