Evaluation of d2, a microsatellite measure of inbreeding and outbreeding, in wolves with a known pedigree

We have evaluated a microsatellite measure proposed as an indicator of inbreeding and outbreeding using a captive wolf population with known inbreeding levels and founder sources. The measure, which is based on the difference in the repeat number for microsatellite alleles within an individual, was not more predictive of the known inbreeding coefficient than microsatellite heterozygosity (it was actually less predictive). We also found no support that the measure was predictive of the level of outbreeding. However, we could not determine if the measure was predictive of very low levels of inbreeding due to matings between remote relatives. Overall, it appears that the usefulness of this measure to identify individuals on the inbred-outbred continuum beyond that of heterozygosity and identify biologically important associations with fitness-related traits may be limited. We suggest that the measure be examined theoretically to determine when (and how much) the predictive value of the measure is different from that of heterozygosity for inbreeding or outbreeding levels in a variety of different scenarios.     

Correlates of Mortality in an Exploited Wolf Population

Abstract We investigated the influence of habitat use on risk of death from hunting and trapping of 55 radiocollared gray wolves (Canis lupus) from an exploited insular population in Southeast Alaska, USA. We compared mortality rates for resident and nonresident wolves and used Cox proportional hazards regression to relate habitat composition within 100-m circular buffers around radiolocations to risk of death of resident and nonresident wolves. In addition, we included covariates representing distances to roads, logged stands, and lakes and streams in those analyses. We also compiled harvest data from 31 harvest units within the study area to compare densities of roads and distances from human settlements with rates of harvest. During our study 39 wolves died, of which 18 were harvested legally, 16 were killed illegally, and 5 died from natural causes. Legal and illegal harvest accounted for >87% of the mortality of radiocollared resident and nonresident wolves. Mean annual survival was 0.54 (SE = 0.17) for all wolves. Annual survival was 0.65 (SE = 0.17) for resident wolves and 0.34 (SE = 0.17) for nonresidents. Very few (19%) nonresident wolves survived to colonize vacant territories or join existing wolf packs. Roads, muskegs, and distances from lakes and streams were covariates positively associated with death of resident wolves. Clear-cuts were positively associated with risk of death of nonresident wolves. Rate of harvest increased with density of roads; however, road densities >0.9 km/km² had little additional effect on harvest rates. Harvest rates decreased with ocean distances from nearest towns or settlements. Roads clearly increased risk of death for wolves from hunting and trapping and contributed to unsustainable rates of harvest. Wildlife managers should consider effects of roads and other habitat features on harvest of wolves when developing harvest recommendations. They should expect substantial illegal harvest where wolf habitat is accessible to humans. Moreover, high rates of mortality of nonresident wolves exposed to legal and illegal harvest may reduce or delay successful dispersal, potentially affecting linkages between small disjunct wolf populations or population segments. We conclude that a combination of conservative harvest regulations and large roadless reserves likely are the most effective measures for conserving wolves where risks from human-caused mortality are high.     

Genetic evidence for a recent origin by hybridization of red wolves

Genetic data suggest that red wolves ( Canis rufus ) resulted from a hybridization between coyotes ( C. latrans ) and grey wolves ( C. lupus ). The date of the hybridization, however, is uncertain. According to one hypothesis, the two species came into contact as coyotes increased their geographical range in conjunction with the advance of European settlers and as grey wolves were extirpated from the American south. Alternatively, the red wolves could have originated tens of thousands of years ago as a result of climate and habitat changes that disturbed the ecology of the two parent species. To obtain an upper limit on the date of hybridization that would help to distinguish the two scenarios, we compared microsatellite allele length distributions from red wolves, coyotes and grey wolves. Subject to the assumptions of our analysis, we conclude that the red wolves originated as a result of hybridizations that occurred during the past 12 800 years, and probably during the past 2500 years.     

The genealogy and genetic viability of reintroduced Yellowstone grey wolves

The recovery of the grey wolf in Yellowstone National Park is an outstanding example of a successful reintroduction. A general question concerning reintroduction is the degree to which genetic variation has been preserved and the specific behavioural mechanisms that enhance the preservation of genetic diversity and reduce inbreeding. We have analysed 200 Yellowstone wolves, including all 31 founders, for variation in 26 microsatellite loci over the 10-year reintroduction period (1995-2004). The population maintained high levels of variation (1995 H(0) = 0.69; 2004 H(0) = 0.73) with low levels of inbreeding (1995 F(IS) = -0.063; 2004 F(IS) = -0.051) and throughout, the population expanded rapidly (N(1995) = 21; N(2004) = 169). Pedigree-based effective population size ratios did not vary appreciably over the duration of population expansion (1995 N(e)/N(g) = 0.29; 2000 N(e)/N(g) = 0.26; 2004 N(e)/N(g) = 0.33). We estimated kinship and found only two of 30 natural breeding pairs showed evidence of being related (average r = -0.026, SE = 0.03). We reconstructed the genealogy of 200 wolves based on genetic and field data and discovered that they avoid inbreeding through a wide variety of behavioural mechanisms including absolute avoidance of breeding with related pack members, male-biased dispersal to packs where they breed with nonrelatives, and female-biased subordinate breeding. We documented a greater diversity of such population assembly patterns in Yellowstone than previously observed in any other natural wolf population. Inbreeding avoidance is nearly absolute despite the high probability of within-pack inbreeding opportunities and extensive interpack kinship ties between adjacent packs. Simulations showed that the Yellowstone population has levels of genetic variation similar to that of a population managed for high variation and low inbreeding, and greater than that expected for random breeding within packs or across the entire breeding pool. Although short-term losses in variation seem minimal, future projections of the population at carrying capacity suggest significant inbreeding depression will occur without connectivity and migratory exchange with other populations.     

Is incest common in gray wolf packs?

Wolf packs generally consist of a breeding pair and their maturingoffspring that help provision and protect pack young. Becausethe reproductive tenure in wolves is often short, reproductivelymature offspring might replace their parents, resulting in siblingor parent-offspring matings. To determine the extent of incestuouspairings, we measured relatedness based on variability in 20microsatellite loci of mated pairs, parent-offspring pairs,and siblings in two populations of gray wolves. Our 16 sampledmated pairs had values of relatedness not overlapping thoseof known parent-offspring or sibling dyads, which is consistentwith their being unrelated or distantly related. These resultssuggest that full siblings or a parent and its offspring rarelymate and that incest avoidance is an important constraint ongray wolf behavioral ecology     

Recovering Riparian Plant Communities with Wolves in Northern Yellowstone,U.S.A.

Gray wolves (Canis lupus) were extirpated from Yellowstone National Park in the 1920s. The ensuing seven decades marked a period when wild ungulates, principally Elk (Cervus elaphus), extensively used woody browse species in the upper Gallatin and northern winter ranges, thus limiting the capability of establishing plants to grow more than 100 cm in height. Following the reintroduction of wolves in the mid‐1990s, we evaluated patterns of woody browse species recovery within riparian areas of these winter ranges. Measurements indicated that cottonwood (Populus spp.) recruitment (growth of seedlings/sprouts into tall saplings and trees) was occurring for the first time in several decades. A spatially patchy increase in the heights of young willow (Salix sp.) and cottonwood in the upper Gallatin and northern winter ranges, respectively, was also found within riparian transects comprising nearly 20 km in total length. Within some transects, heights of woody species have begun to exceed 200 cm (the approximate upper browse level of Elk). Results are consistent with the reestablishment of a tri‐level trophic cascade involving wolves, ungulates, and riparian vegetation. We additionally present conceptual models of vegetation recovery, illustrating differences in plant height responses to behaviorally and density‐mediated trophic cascades. Northern Yellowstone’s “experiment in time,” whereby wolves were removed and then reintroduced, provides new insights regarding how top predators can influence the structure and biodiversity of terrestrial ecosystems. Restoration ecologists and policymakers should consider the potential benefits of large predators as an option for helping restore degraded ecosystems.     

Genetic rescue and inbreeding depression in Mexican wolves

Although inbreeding can reduce individual fitness and contribute to population extinction, gene flow between inbred but unrelated populations may overcome these effects. Among extant Mexican wolves (Canis lupus baileyi), inbreeding had reduced genetic diversity and potentially lowered fitness, and as a result, three unrelated captive wolf lineages were merged beginning in 1995. We examined the effect of inbreeding and the merging of the founding lineages on three fitness traits in the captive population and on litter size in the reintroduced population. We found little evidence of inbreeding depression among captive wolves of the founding lineages, but large fitness increases, genetic rescue, for all traits examined among F1 offspring of the founding lineages. In addition, we observed strong inbreeding depression among wolves descended from F1 wolves. These results suggest a high load of deleterious alleles in the McBride lineage, the largest of the founding lineages. In the wild, reintroduced population, there were large fitness differences between McBride wolves and wolves with ancestry from two or more lineages, again indicating a genetic rescue. The low litter and pack sizes observed in the wild population are consistent with this genetic load, but it appears that there is still potential to establish vigorous wild populations.     

Polymorphism of transferrin and esterase in Alaskan wolves: evidence of close molecular homology with the dog

By the use of isoelectric focusing in polyacrylamide gels serum samples from 146 Alaskan wolves were studied with regard to transferrin (Tf) and esterase (ArE) polymorphism, comparing the phenotypic band patterns with those of selected Norwegian dogs. The study revealed Tf and ArE polymorphisms in the wolf with phenotypic band patterns being indistinguishable from the corresponding ones in dogs. This suggests the occurrence of the same two common Tf alleles in the wolf as in the dog. In the ArE system the results are consistent with the occurrence of three alleles which also occur in dogs whereas a fourth allele, so far not seen in dogs, is seen in Alaskan wolves.     

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.     

动物的生境选择

动物的生境选择颜忠诚陈永林（中国科学院动物研究所,北京１０００８０）ＨａｂｉｔａｔＳｅｌｅｃｔｉｏｎｉｎＡｎｉｍａｌｓ．ＹａｎＺｈｏｎｇｃｈｅｎｇ,ＣｈｅｎＹｏｎｇｌｉｎ（ＩｎｓｔｉｔｕｔｅｏｆＺｏｏｌｏｇｙ,ＡｃａｄｅｍｉａＳｉｎｉｃａ,Ｂｅｉｊｉ...     

Demography and feeding behavior of the kelp crab Taliepus marginatus in subtidal habitats dominated by the kelps Macrocystis pyrifera or Lessonia trabeculata

We studied the population and feeding ecology of the kelp crab Taliepus marginatus in subtidal kelp forests dominated by either of two morphologically different kelp species (Macrocystis pyrifera or Lessonia trabeculata) in northern Chile. The sizes and abundances of T. marginatus differed between the two kelp habitats. Kelp crabs were more abundant in the M. pyrifera forest than in the L. trabeculata forest. Size‐frequency distributions showed that juvenile and immature crabs were more common in the M. pyrifera forest than in the L. trabeculata forest, where reproductive adults predominated. The smaller crabs in the M. pyrifera habitat also consumed a higher proportion of kelp tissues than the larger crabs in the L. trabeculata habitat, which had a higher proportion of animal food in their diet. In both kelp forests, individuals of T. marginatus showed a similar pattern of nocturnal feeding over a 24‐h period, consuming more food at night than during the day. The more complex and dense forests of M. pyrifera appear to present better nursery habitats for juvenile kelp crabs than the more open and less dense forests dominated by L. trabeculata. These results suggest that the role of the two kelp habitats for T. marginatus varies during the life cycle of the kelp crabs, with M. pyrifera tending to have nursery function and L. trabeculata being more suitable as a reproductive habitat.     

Secret lives of maned wolves (Chrysocyon brachyurus Illiger 1815): as revealed by GPS tracking collars

The maned wolf Chrysocyon brachyurus is a nocturnal and shy species, which has proven difficult to study in the field; consequently, data about its behavioural biology are almost absent from the scientific literature. However, recent advances in global positioning system (GPS) technology mean that it is now possible to study the socio-spatial dynamics of this species in the field. In the present study three related maned wolves (an adult pair and their juvenile female offspring) were monitored by GPS tracking collars for a 6-month period, which included the birth of a litter of pups to the adult pair. The three GPS collars were programmed to record the position of the wearer every 2 h (simultaneously for all three individuals). Analyses of the data from the three individuals showed that the female had the largest home range, then the male and finally the juvenile. Furthermore, there was considerable overlap in home-range use by all three individuals. The home ranges of the adult pair also varied in relation to the birth of pups (decreasing dramatically and then showing a slow increase). During the night, which is the normal period of activity for this species, the three individuals avoided contact with each other. However, during the day, the adult pair usually slept together and their juvenile slept within a few hundred metres of their location. The distance travelled at night was greatest for the female, then the male and finally the juvenile. These data suggest that (1) the social bond between the male and female is strong, (2) maned wolves are highly tolerant of their juvenile offspring, even in the case of new pups being born, and (3) that maned wolves do not hunt together and, in fact, avoid each other when hunting.     

濒危乔木红豆杉不同更新阶段的生境特征比较

以福建梅花山自然保护区濒危乔木红豆杉(Taxus chinensis(Pilger)Rehd.)为对象,对红豆杉的种子排放、幼苗更新、幼树更新3个更新阶段的生境特征进行研究,并比较生态位的变化,以此评价红豆杉不同更新阶段的生境需求。结果显示:随着个体发育生长,红豆杉更新生境发生了明显转变,种子排放地与幼苗生境空间一致性较高,而它们与幼树生境存在明显的空间不一致性。从生态位角度来看,种子排放地和幼苗生境重叠指数≤0.5的仅有海拔和坡度2个因子,这说明幼苗的空间格局受到鸟类传播的强烈影响,鸟类传播所排放的种子能萌发并生长成幼苗。幼苗和幼树生境重叠指数≤0.5的因子有海拔、坡向、植被类型,说明在大尺度景观因子和庇护植被层面上,植物的更新需求出现了明显的不一致。研究结果表明红豆杉的更新生境存在明显的阶段变化,可能造成植物更新出现建成限制,使幼树阶段成为更新的瓶颈阶段。     

官山保护区白颈长尾雉栖息地适宜性评价

2009年4月-2009年5月和2009年12月-2010年1月,在江西官山国家级自然保护区对白颈长尾雉(Syrmaticus ellioti) 繁殖期和越冬期的栖息地进行调查。通过实地调查,结合已有研究结果,确定了官山自然保护区白颈长尾雉栖息地适宜性评价因子,即植被类型、海拔、坡度和坡向等4个栖息地因子。基于"被利用生境-可获得生境比较法",以对各评价因子不同梯度的资源选择指数为依据,确定了白颈长尾雉适宜性评价准则。应用ArcGIS 9.3空间分析功能和栖息地片断化指数,对官山保护区白颈长尾雉栖息地进行了适宜性评价。结果表明:在官山自然保护区适宜白颈长尾雉繁殖的栖息地斑块有502个,总面积为3307 hm²,占保护区总面积的28.6%,分离度指数和片断化程度指数分别为0.365和0.912;适宜白颈长尾雉越冬的栖息地斑块有514个,总面积2755 hm²,占保护区总面积的23.8%,分离度指数和片断化程度指数分别为0.443和0.939。官山保护区白颈长尾雉栖息地片断化较严重,片断化现象在白颈长尾雉越冬期加剧。因此,迫切需要采取措施白颈长尾雉现存栖息地进行保护,特别是要高度重视其越冬栖息地的保护。