Population fragmentation compromises population viability, reduces a species ability to respond to climate change, and ultimately may reduce biodiversity. We studied the current state and potential causes of fragmentation in grizzly bears over approximately 1,000,000 km² of western Canada, the northern United States (US), and southeast Alaska. We compiled much of our data from projects undertaken with a variety of research objectives including population estimation and trend, landscape fragmentation, habitat selection, vital rates, and response to human development. Our primary analytical techniques stemmed from genetic analysis of 3,134 bears, supplemented with radiotelemetry data from 792 bears. We used 15 locus microsatellite data coupled with measures of genetic distance, isolation‐by‐distance (IBD) analysis, analysis of covariance (ANCOVA), linear multiple regression, multi‐factorial correspondence analysis (to identify population divisions or fractures with no a priori assumption of group membership), and population‐assignment methods to detect individual migrants between immediately adjacent areas. These data corroborated observations of inter‐area movements from our telemetry database. In northern areas, we found a spatial genetic pattern of IBD, although there was evidence of natural fragmentation from the rugged heavily glaciated coast mountains of British Columbia (BC) and the Yukon. These results contrasted with the spatial pattern of fragmentation in more southern parts of their distribution. Near the Canada–US border area, we found extensive fragmentation that corresponded to settled mountain valleys and major highways. Genetic distances across developed valleys were elevated relative to those across undeveloped valleys in central and northern BC. In disturbed areas, most inter‐area movements detected were made by male bears, with few female migrants identified. North–south movements within mountain ranges (Mts) and across BC Highway 3 were more common than east–west movements across settled mountain valleys separating Mts. Our results suggest that relatively distinct subpopulations exist in this region, including the Cabinet, Selkirk South, and the decades‐isolated Yellowstone populations. Current movement rates do not appear sufficient to consider the subpopulations we identify along the Canada–US border as 1 inter‐breeding unit. Although we detected enough male movement to mediate gene flow, the current low rate of female movement detected among areas is insufficient to provide a demographic rescue effect between areas in the immediate future (0–15 yr). In Alberta, we found fragmentation corresponded to major east–west highways (Highways 3, 11, 16, and 43) and most inter‐area movements were made by males. Gene flow and movement rates between Alberta and BC were highest across the Continental Divide south of Highway 1 and north of Highway 16. In the central region between Highways 1 and 11, we found evidence of natural fragmentation associated with the extensive glaciers and icefields along the Continental Divide. The discontinuities that we identified would form appropriate boundaries for management units. We related sex‐specific movement rates between adjacent areas to several metrics of human use (highway traffic, settlement, and human‐caused mortality) to understand the causes of fragmentation. This analysis used data from 1,508 bears sampled over a 161,500‐km² area in southeastern BC, western Alberta, northern Idaho, and northern Montana during 1979–2007. This area was bisected by numerous human transportation and settlement corridors of varying intensity and complexity. We used multiple linear regression and ANCOVA to document the responses of female and male bears to disturbance. Males and females both demonstrated reduced movement rates with increasing settlement and traffic. However, females reduced their movement rates dramatically when settlement increased to >20% of the fracture zone. At this same threshold, male movement declined more gradually, in response to increased traffic and further settlement. In highly settled areas (>50%), both sexes had a similar reduction in movements in response to traffic, settlement, and mortality. We documented several small bear populations with male‐only immigration, highlighting the importance of investigating sex‐specific movements. Without female connectivity, small populations are not viable over the long term. The persistence of this regional female fragmented metapopulation likely will require strategic connectivity management. We therefore recommend enhancing female connectivity among fractured areas by securing linkage‐zone habitat appropriate for female dispersal, and ensuring current large source subpopulations remain intact. The fragmentation we documented may also affect other species with similar ecological characteristics: sparse densities, slow reproduction, short male‐biased dispersal, and a susceptibility to human‐caused mortality and habitat degradation. Therefore, regional inter‐jurisdictional efforts to manage broad landscapes for inter‐area movement will likely benefit a broad spectrum of species and natural processes, particularly in light of climate change. © 2011 The Wildlife Society.

中文翻译：

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加拿大西部和美国北部的灰熊种群分散和生态系统间的移动

种群分散会损害种群的生存能力，降低物种应对气候变化的能力，并最终可能减少生物多样性。我们研究了大约1,000,000 km ^2的灰熊的破碎状态和潜在原因加拿大西部，美国北部和阿拉斯加东南部。我们从以各种研究目标开展的项目中收集了许多数据，包括人口估计和趋势，景观破碎化，栖息地选择，生命率和对人类发展的响应。我们的主要分析技术源于对3,134头熊的遗传分析，并补充了792头熊的无线电遥测数据。我们使用了15个地点的微卫星数据以及遗传距离，距离隔离（IBD）分析，协方差分析（ANCOVA），线性多元回归，多因素对应分析（以无先验地确定人群划分或骨折）假定为团体成员）和人口分配方法，以检测紧邻区域之间的个体移民。这些数据证实了我们遥测数据库对区域间运动的观察。在北部地区，我们发现了IBD的空间遗传模式，尽管有证据表明不列颠哥伦比亚省（BC）和育空地区崎heavily的高冰川海岸山脉自然破碎。这些结果与分布的更南部部分的空间碎片格局形成对比。在加拿大-美国边境地区附近，我们发现了与定居的山谷和主要公路相对应的大片碎片。相对于不列颠哥伦比亚中部和北部不发达山谷的遗传距离，遗传距离增加了。在动荡地区，发现的大多数区域间移动都是由雄性熊造成的，很少发现女性移民。山脉（Mts）和不列颠哥伦比亚省高速公路3的南北运动比分隔Mts的定居山谷的东西向运动更为普遍。我们的研究结果表明，该地区存在相对不同的亚群，包括内阁，塞尔克克南部和数十年隔离的黄石种群。当前的移动速度似乎不足以考虑我们在加拿大-美国边界确定为1个杂交单位的亚种群。尽管我们检测到足够的雄性运动来介导基因流，但是目前在各个区域之间检测到的雌性运动的比率很低，不足以在不久的将来（0-15年）提供区域间的人口救援效果。在艾伯塔省，我们发现碎片与主要的东西向公路相对应（高速公路3、11、16，和43），大多数区域间运动都是由男性进行的。艾伯塔省和卑诗省之间的基因流动和移动速率在1号公路以南和16号公路以北的大陆分界线中最高。在1号公路和11号公路之间的中部地区，我们发现了自然碎裂的证据，该碎片与沿河的广阔冰川和冰原有关。大陆分界线。我们确定的不连续性将为管理部门形成适当的边界。我们将相邻区域之间特定性别的移动速度与人类使用的几个指标（高速公路交通，居住和人为造成的死亡率）相关联，以了解造成分裂的原因。该分析使用了在161,500-km范围内采样的1,508头熊的数据 艾伯塔省和卑诗省之间的基因流动和移动速率在1号公路以南和16号公路以北的大陆分界线中最高。在1号公路和11号公路之间的中部地区，我们发现了自然碎裂的证据，该碎片与沿河的广阔冰川和冰原有关。大陆分界线。我们确定的不连续性将为管理部门形成适当的边界。我们将相邻区域之间特定性别的移动速度与人类使用的几个指标（高速公路交通，居住和人为造成的死亡率）相关联，以了解造成分裂的原因。该分析使用了在161,500-km范围内采样的1,508头熊的数据 艾伯塔省和卑诗省之间的基因流动和移动速率在1号公路以南和16号公路以北的大陆分界线中最高。在1号公路和11号公路之间的中部地区，我们发现了自然碎裂的证据，该碎片与沿河的广阔冰川和冰原有关。大陆分界线。我们确定的不连续性将为管理部门形成适当的边界。我们将相邻区域之间特定性别的移动速度与人类使用的几个指标（高速公路交通，居住和人为造成的死亡率）相关联，以了解造成分裂的原因。该分析使用了在161,500-km范围内采样的1,508头熊的数据 我们确定的不连续性将为管理部门形成适当的边界。我们将相邻区域之间特定性别的移动速度与人类使用的几个指标（高速公路交通，居住和人为造成的死亡率）相关联，以了解造成分裂的原因。该分析使用了在161,500-km范围内采样的1,508头熊的数据 我们确定的不连续性将为管理部门形成适当的边界。我们将相邻区域之间特定性别的移动速度与人类使用的几个指标（高速公路交通，居住和人为造成的死亡率）相关联，以了解造成分裂的原因。该分析使用了在161,500-km范围内采样的1,508头熊的数据²1979-2007年间，位于卑诗省东南部，艾伯塔省西部，爱达荷州北部和蒙大拿州北部。该区域被众多强度和复杂程度不同的人类运输和定居走廊一分为二。我们使用多元线性回归和ANCOVA来记录雌性和雄性熊对干扰的反应。随着定居和交通的增加，男性和女性都显示出运动速度降低。但是，当沉降增加到骨折区域的20％以上时，雌性会大大降低其运动速度。在相同的门槛下，由于交通增加和进一步定居，男性运动逐渐下降。在高度定居的地区（> 50％），由于交通，定居和死亡率的影响，两性运动的减少幅度相似。我们记录了几个仅由男性移民的小熊种群，强调了调查特定性别运动的重要性。没有女性的联系，长期来看，人口稀少。这种区域性女性零散的人口的持久性可能需要进行战略连通性管理。因此，我们建议通过确保适合女性散布的链接区栖息地，并确保当前的大量来源亚群保持完整，来增强骨折地区之间的女性连通性。我们记录的碎片化可能还会影响具有相似生态特征的其他物种：稀疏的密度，缓慢的繁殖，短暂的男性偏向性扩散以及对人为致死和栖息地退化的敏感性。因此，跨区域管理跨区域运动的广阔景观的努力可能将使广泛的物种和自然过程受益，特别是考虑到气候变化。©2011野生动物协会。