Population genetic structure and the effect of founder events on the genetic variability of moose, Alces alces, in Canada

Moose, Alces alces, occur naturally throughout most of Canada but successful introductions of known numbers of animals have been made to the islands of Newfoundland and Cape Breton. Five microsatellite loci were used to investigate the population genetic structure and any change in genetic variability due to founder events of moose in Canada. Comparisons of allele frequencies for moose from 11 regions of the country suggested that there are at least seven genetically distinct populations (P < 0.05) in North America, namely Alberta, eastern Ontario, New Brunswick, Cape Breton, Labrador, western Newfoundland, and the Avalon Peninsula of Newfoundland. The average population heterozygosity was approximately 33% (range from 22 to 41%). UPGMA analysis of Nei's genetic distances produced phenograms similar to what would be expected when geographical location and population history are considered. The loss of heterozygosity due to a single founder event (n = 3; two introductions and a natural colonization) ranged from 14 to 30%, and the cumulative loss of heterozygosity due to two successive founder events (an introduction followed by a natural colonization) was 46%. In these examples loss of genetic variability has not been associated with any known phenotypic deviances, suggesting that populations may be established from a small number of founders. However, the viability of these founded populations over evolutionary timescales cannot be determined and is highly dependent upon chance.     

小兴安岭黑河胜山林区冬季驼鹿的生境选择

2002年、2003年和2004年的12月至3月,在小兴安岭黑河胜山林场开展了驼鹿生境选择的研究。研究中选择了9类与驼鹿生境选择相关的生态因子：植被型、离公路距离、离采伐点距离、平均雪深、隐蔽程度、坡向、坡位、坡度、海拔,运用SPSS软件进行交叉汇总定量分析。结果表明,胜山驼鹿冬季以落叶阔叶林、灌丛为主要生境,影响驼鹿分布的主要生态因子为隐蔽程度、坡位,其次为雪深、坡向、离采伐点距离、离公路距离,坡度、海拔对驼鹿分布的影响不明显。     

The declining occurrence of moose (Alces alces) at the southernmost edge of its range raise conservation concerns

The border region between Austria, the Czech Republic, and Germany harbors the most south‐western occurrence of moose in continental Europe. The population originated in Poland, where moose survived, immigrated from former Soviet Union or were reintroduced after the Second World War expanded west‐ and southwards. In recent years, the distribution of the nonetheless small Central European population seems to have declined, necessitating an evaluation of its current status. In this study, existing datasets of moose observations from 1958 to 2019 collected in the three countries were combined to create a database totaling 771 records (observations and deaths). The database was then used to analyze the following: (a) changes in moose distribution, (b) the most important mortality factors, and (c) the availability of suitable habitat as determined using a maximum entropy approach. The results showed a progressive increase in the number of moose observations after 1958, with peaks in the 1990s and around 2010, followed by a relatively steep drop after 2013. Mortality within the moose population was mostly due to human interactions, including 13 deadly wildlife‐vehicle collisions, particularly on minor roads, and four animals that were either legally culled or poached. Our habitat model suggested that higher altitudes (ca. 700–1,000 m a.s.l.), especially those offering wetlands, broad‐leaved forests and natural grasslands, are the preferred habitats of moose whereas steep slopes and areas of human activity are avoided. The habitat model also revealed the availability of large core areas of suitable habitat beyond the current distribution, suggesting that habitat was not the limiting factor explaining the moose distribution in the study area. Our findings call for immediate transboundary conservation measures to sustain the moose population, such as those aimed at preventing wildlife‐vehicle collisions and illegal killings. Infrastructure planning and development activities must take into account the habitat requirements of moose.     

Geographical and latitudinal variation in growth patterns and adult body size of Swedish moose (Alces alces)

We examined the geographical pattern in growth and adult body size among 14 populations of Swedish moose (Alces alces) using data from 4,294 moose (1.5 years old) killed during the hunting season in 1989–1992. In both sexes, adult body mass was significantly positively correlated with latitude. Moose in northern populations had a 15–20% larger adult body mass than moose in the south. Juvenile body mass was correlated with neither latitude nor adult body mass. Thus, variation in time (years) and rate of body growth after the juvenile stage were responsible for most of the variation in adult body mass among populations. Moose in northern populations grew for approximately 2 more years of life than southern moose. In contrast to adult body mass, skeletal size (measured as jawbone length) was not correlated with latitude, suggesting that variation in adult body mass was primarily due to differences in fat reserves. Discrimination between population characteristics, such as moose density, climate, and the amount of browse available to moose, showed climatic harshness to be the most important variable explaining geographical variation in body mass among populations. The results support the notion that in mammals body size increases with latitude in accordance with Bergmann's rule. We conclude that (1) variation in patterns of growth after the juvenile stage is the main cause of the latitudinal trend in adult body size in moose, and (2) climatic conditions are a more important factor than population density and availability of food in explaining geographical variation in growth patterns and adult body mass between populations of Swedish moose.     

Effects of willow nutrition and morphology on calving success of moose

Across much of North America, populations of moose (Alces alces) are declining because of disease, predation, climate change, and anthropogenic-driven habitat loss. Contrary to this trend, populations of moose in Colorado, USA, have continued to grow. Studying successful (i.e., persistent or growing) populations of moose can facilitate continued conservation by identifying habitat features critical to persistence of moose. We hypothesized that moose using habitat with higher quality willow (Salix spp.) would have a higher probability of having a calf-at-heel (i.e., calving success). We evaluated moose calving success using repeated ground observations of collared individuals with calves in an occupancy model framework to account for detection probability. We then evaluated the impact of willow habitat quality and nutrition on moose calving success by studying 2 spatially segregated populations of moose in Colorado. Last, we evaluated correlations between willow characteristics (browse intensity, height, cover, leaf length, and species) and willow nutrition (dry matter digestibility [DMD]) to assess the utility of using those characteristics to assess willow nutrition. We found willow height and cover had a high probability of being positively associated with higher individual-level calving success. Willow DMD, browse intensity, and leaf length were not predictive of individual moose calving success; however, the site with higher mean DMD consistently had higher mean estimates of calving success for the same year. Our results suggest surveying DMD is likely not a useful metric for assessing differences in calving success of individual moose but may be of use at population levels. Further, the assessment of willow morphology and density may be used to identify areas that support higher levels of moose calving success.     

Large-scale climatic fluctuation and population dynamics of moose and white-tailed deer

1. Mech et al . (1987) documented cumulative, negative effects of previous winters' snow on rates of population increase in moose ( Alces alces ) and white-tailed deer ( Odocoileus virginianus ), but noted no effect of predation by wolves ( Canis lupus ). Those results were contested by Messier (1991), who analysed smoothed versions of the original abundance data and reported no effect of snow accumulation on population dynamics of either species, but strong effects of wolf predation and food competition.
2. McRoberts, Mech & Peterson (1995) contended that the conclusions reached by Messier (1991) were an artefact of the use of smoothed data. In a subsequent re-analysis of the smoothed data, Messier (1995) argued that the lack of an effect of snow after one year precluded the potential for a cumulative effect beyond one year.
3. We re-analysed original and smoothed data on dynamics of moose and white-tailed deer densities using the same methods as Mech et al . (1987) and Messier (1991), but we used a measure of global climatic fluctuation, the North Atlantic Oscillation (NAO) index. The NAO is the atmospheric process determining most interannual variation in snowfall and winter temperatures in northern latitudes, and its phases drive decadal trends in wintertime precipitation.
4. We observed that rates of increase of moose and white-tailed deer in both the original and smoothed data were influenced by global climatic fluctuation at 2- and 3-year lags, as well as by delayed density-dependent feedback and wolf predation.     

Polymorphisms and variants in the prion protein sequence of European moose (Alces alces), reindeer (Rangifer tarandus), roe deer (Capreolus capreolus) and fallow deer (Dama dama) in Scandinavia

The prion protein (PrP) sequence of European moose, reindeer, roe deer and fallow deer in Scandinavia has high homology to the PrP sequence of North American cervids. Variants in the European moose PrP sequence were found at amino acid position 109 as K or Q. The 109Q variant is unique in the PrP sequence of vertebrates. During the 1980s a wasting syndrome in Swedish moose, Moose Wasting Syndrome (MWS), was described. SNP analysis demonstrated a difference in the observed genotype proportions of the heterozygous Q/K and homozygous Q/Q variants in the MWS animals compared with the healthy animals. In MWS moose the allele frequencies for 109K and 109Q were 0.73 and 0.27, respectively, and for healthy animals 0.69 and 0.31. Both alleles were seen as heterozygotes and homozygotes. In reindeer, PrP sequence variation was demonstrated at codon 176 as D or N and codon 225 as S or Y. The PrP sequences in roe deer and fallow deer were identical with published GenBank sequences.     

Polymorphisms and variants in the prion protein sequence of European moose (Alces alces), reindeer (Rangifer tarandus), roe deer (Capreolus capreolus) and fallow deer (Dama dama) in Scandinavia

The prion protein (PrP) sequence of European moose, reindeer, roe deer and fallow deer in Scandinavia has high homology to the PrP sequence of North American cervids. Variants in the European moose PrP sequence were found at amino acid position 109 as K or Q. The 109Q variant is unique in the PrP sequence of vertebrates. During the 1980s a wasting syndrome in Swedish moose, Moose Wasting Syndrome (MWS), was described. SNP analysis demonstrated a difference in the observed genotype proportions of the heterozygous Q/K and homozygous Q/Q variants in the MWS animals compared with the healthy animals. In MWS moose the allele frequencies for 109K and 109Q were 0.73 and 0.27, respectively, and for healthy animals 0.69 and 0.31. Both alleles were seen as heterozygotes and homozygotes. In reindeer, PrP sequence variation was demonstrated at codon 176 as D or N and codon 225 as S or Y. The PrP sequences in roe deer and fallow deer were identical with published GenBank sequences.     

Comparison of tannin-binding proteins in saliva of Scandinavian and North American moose (Alces alces)

Differences in the ability of salivary proteins from Scandinavian and North American moose (Alces alces) to bind tannins from various preferred food plant sources were studied. Both Scandinavian and North American moose produce a salivary tannin-binding protein which binds only condensed tannins common in their diet. The tannins of winter-browsed stems of Pinus sylvestris and Salix pentandra were more effectively bound by salivary tannin-binding protein from North American moose than by those from Scandinavian moose. Tannins of P. sylvestris and S. pentandra stems were also more effective binding agents than tannins from S. caprea and Betula species. The interactions between salivary tannin-binding protein and plant tannins may be one factor affecting food plant choice of moose. The chemical and biochemical characteristics of plant tannins and the ability of salivary tannin-binding proteins to react with tannins should be taken into account in diet selection.     

Limited polymorphism at major histocompatibility complex (MHC) loci in the Swedish moose A. alces

The Swedish moose was analysed for genetic variability at major histocompatibility complex (MHC) class I and class II DQA, DQB and DRB loci using restriction fragment length polymorphism (RFLP) and single strand conformation polymorphism (SSCP) techniques. Both methods revealed limited amounts of polymorphism. Since the SSCP analysis concerned an expressed DRB gene it can be concluded that the level of functional MHC class II polymorphism, at least at the DRB locus, is low in Swedish moose. DNA fingerprinting was used to determine if the unusual pattern of low MHC variability could be explained by a low degree of genome-wide genetic diversity. Hybridizations with two minisatellite probes gave similarity indices somewhat higher than the average for other natural population, but the data suggest that the low MHC variability cannot be explained by a recent population bottleneck. However, since minisatellite sequences evolve more rapidly than MHC sequences, the low levels of MHC diversity may be attributed to a bottleneck of more ancient origin. The selection pressure for MHC variability in moose may also be reduced and we discuss the possibility that its solitary life style may reduce lateral transmission of pathogens in the population.     

Encounter frequencies between GPS-collared wolves (Canis lupus) and moose (Alces alces) in a Scandinavian wolf territory

Over 6,000 GPS fixes from two wolves (Canis lupus) and 30,000 GPS fixes from five moose (Alces alces) in a wolf territory in southern Scandinavia were used to assess the static and dynamic interactions between predator and prey individuals. Our results showed that wolves were closer to some of the moose when inside their home ranges than expected if they had moved independently of each other, and we also found a higher number of close encounters (<500 m) than expected. This suggests that the wolves were actively seeking the individual moose within their territory. Furthermore, the wolves showed a preference for moving on gravel forest roads, which may be used as convenient travel routes when patrolling the territory and seeking areas where the moose are. However, due to the particularly large size of the wolf territory combined with relatively high moose densities, the wolves generally spent a very small proportion of their time inside the home range of each individual moose, and the frequency of encounters between the wolves and any particular moose was very low. We suggest that the high moose:wolf ratio in this large Scandinavian wolf territory compared to that typically occurring in North America, results in a relatively low encounter frequency and a low predation risk for individual moose, as the predation pressure is spread over a high number of prey individuals.     

Challenges and opportunities for estimating abundance of a low-density moose population

Monitoring large herbivores across their core range has been readily accomplished using aerial surveys and traditional distance sampling. But for peripheral populations, where individuals may occur in patchy, low-density populations, precise estimation of population size and trend remains logistically and statistically challenging. For moose (Alces alces) along their southern range margin in northern New York, USA, we sought robust estimates of moose distribution, abundance, and population trend (2016–2019) using a combination of aerial surveys (line transect distance-sampling), repeated surveys in areas where moose were known to occur to boost the number of detections, and density surface modeling (DSM) with spatial covariates. We achieved a precise estimate of density (95% CI = 0.00–0.29 moose/km²) for this small population (656 moose, 95% CI = 501–859), which was patchily distributed across a large and heavily forested region (the 24,280-km² Adirondack Park). Local moose abundance was positively related to active timber management, elevation, and snow cover, and negatively related to large bodies of water. As expected, moose abundance in this peripheral population was low relative to its core range in other northern forest states. Yet, in areas where abundance was greatest, moose densities in New York approached those where epizootics of winter tick (Dermacentor albipictus) have been reported, underscoring the need for effective and efficient monitoring. By incorporating autocorrelation in observations and landscape covariates, DSM provided spatially explicit estimates of moose density with greater precision and no additional field effort over traditional distance sampling. Combined with repeated surveys of areas with known moose occurrence to achieve viable sample sizes, DSM is a useful tool for effectively monitoring low density and patchy populations.