Evaluating Reproductive Success and Changes in Genetic Diversity of Grizzly Bears in Northwestern Montana

Current range expansions of large terrestrial carnivores are occurring following anthropogenically-induced range contraction. Contractions are often incomplete, leaving small remnant groups in refugia throughout the former range. We know little about underlying eco-evolutionary processes that influence how remnant groups are affected during range expansion. We used data from a spatially-explicit, long-term genetic sampling effort of grizzly bears (Ursus arctos) in the Northern Continental Divide Ecosystem (NCDE) to identify the processes underlying spatial patterns of genetic diversity. We conducted parentage analysis to evaluate how reproductive success and migration contribute to spatio-temporal patterns of genetic diversity in remnant groups of grizzly bears existing in the southwestern (SW), southeastern (SE), and east-central (EC) regions of the NCDE. Highly skewed reproductive success and local inbreeding caused distinct signatures in remnants that eroded rapidly (~1 generation) during population expansion and migration into the regions. Our results highlight that individual-level genetic and reproductive dynamics play critical roles during genetic assimilation, and show that patterns of genetic distinctiveness on the leading edge of an expansion may result from historical demographic patterns that are highly ephemeral

Elk Near Fossil Butte National Monument in Southwest Wyoming Migrate Early to Escape Human Disturbance

Migration allows individuals to strike a balance between risk and reward, and use resources in the places and at times that maximize fitness. Large ungulates commonly migrate to increase access to quality forage in spring and decrease risks associated with winter weather in the fall in an effort to maintain the body condition necessary for winter survival and successful reproduction. However, foraging exists within a realm of strategies employed to maximize fitness, and so animals must take factors like safety into account when choosing to migrate. Here, we use 5 years of data from 73 female elk (Cervus canadensis), most of which are part of a subgroup of elk that utilize a protected area during hunting season, to identify the driving factors behind the initiation of migration from their late summer range. The onset of archery season, remotely sensed vegetation degradation, and having access to lands where hunting was prohibited (Fossil Butte National Monument) initiated autumn migration, with bad weather having a smaller effect. 67% of elk using the Monument initiated migration prior to the onset of archery hunting season (1 September), preemptively avoiding risk, while no elk from the subgroup not using the Monument left prior to archery season, despite spending summer at higher elevations. Departure from productive summer range nearly two months before vegetation senescence afforded protection on the Monument during hunting season, but decreased access to late summer-fall forage (integrated NDVI) by 21%. Our results illustrate the complexity of managing a wide-ranging ungulate across jurisdictions with multiple missions

Vegetation types alter soil respiration and its temperature sensitivity at the field scale in an estuary wetland.

Vegetation type plays an important role in regulating the temporal and spatial variation of soil respiration. Therefore, vegetation patchiness may cause high uncertainties in the estimates of soil respiration for scaling field measurements to ecosystem level. Few studies provide insights regarding the influence of vegetation types on soil respiration and its temperature sensitivity in an estuary wetland. In order to enhance the understanding of this issue, we focused on the growing season and investigated how the soil respiration and its temperature sensitivity are affected by the different vegetation (Phragmites australis, Suaeda salsa and bare soil) in the Yellow River Estuary. During the growing season, there were significant linear relationships between soil respiration rates and shoot and root biomass, respectively. On the diurnal timescale, daytime soil respiration was more dependent on net photosynthesis. A positive correlation between soil respiration and net photosynthesis at the Phragmites australis site was found. There were exponential correlations between soil respiration and soil temperature, and the fitted Q10 values varied among different vegetation types (1.81, 2.15 and 3.43 for Phragmites australis, Suaeda salsa and bare soil sites, respectively). During the growing season, the mean soil respiration was consistently higher at the Phragmites australis site (1.11 µmol CO2 m(-2) s(-1)), followed by the Suaeda salsa site (0.77 µmol CO2 m(-2) s(-1)) and the bare soil site (0.41 µmol CO2 m(-2) s(-1)). The mean monthly soil respiration was positively correlated with shoot and root biomass, total C, and total N among the three vegetation patches. Our results suggest that vegetation patchiness at a field scale might have a large impact on ecosystem-scale soil respiration. Therefore, it is necessary to consider the differences in vegetation types when using models to evaluate soil respiration in an estuary wetland

Nature vs. Nurture: Evidence for Social Learning of Conflict Behaviour in Grizzly Bears

<div><p>The propensity for a grizzly bear to develop conflict behaviours might be a result of social learning between mothers and cubs, genetic inheritance, or both learning and inheritance. Using non-invasive genetic sampling, we collected grizzly bear hair samples during 2011–2014 across southwestern Alberta, Canada. We targeted private agricultural lands for hair samples at grizzly bear incident sites, defining an incident as an occurrence in which the grizzly bear caused property damage, obtained anthropogenic food, or killed or attempted to kill livestock or pets. We genotyped 213 unique grizzly bears (118 M, 95 F) at 24 microsatellite loci, plus the amelogenin marker for sex. We used the program COLONY to assign parentage. We evaluated 76 mother-offspring relationships and 119 father-offspring relationships. We compared the frequency of problem and non-problem offspring from problem and non-problem parents, excluding dependent offspring from our analysis. Our results support the social learning hypothesis, but not the genetic inheritance hypothesis. Offspring of problem mothers are more likely to be involved in conflict behaviours, while offspring from non-problem mothers are not likely to be involved in incidents or human-bear conflicts themselves (Barnard’s test, <i>p</i> = 0.05, 62.5% of offspring from problem mothers were problem bears). There was no evidence that offspring are more likely to be involved in conflict behaviour if their fathers had been problem bears (Barnard’s test, <i>p</i> = 0.92, 29.6% of offspring from problem fathers were problem bears). For the mother-offspring relationships evaluated, 30.3% of offspring were identified as problem bears independent of their mother’s conflict status. Similarly, 28.6% of offspring were identified as problem bears independent of their father’s conflict status. Proactive mitigation to prevent female bears from becoming problem individuals likely will help prevent the perpetuation of conflicts through social learning.</p></div

Father-offspring behaviours.

<p>Frequency of problem and non-problem offspring grouped by behaviour type of their father.</p

Study Area.

<p>Map of the study area (BMA 6) and incident hair samples in southwestern Alberta. An incident is defined to be an occurrence in which the grizzly bear caused property damage, obtained anthropogenic food, or killed or attempted to kill livestock or pets.</p

Values of coefficients <i>a</i> and <i>b</i> of the Eq. (), the temperature sensitivity of soil respiration (<i>Q</i>₁₀) and their one-way ANOVA test among different vegetation patches during the growing season in a estuary wetland.

<p><i>a</i>, <i>b</i> are coefficients of the Eq. (), <i>Q</i>₁₀ is the temperature sensitivity of soil respiration (), <i>r</i>² is the determinant coefficient. n is the number of samples data. Numbers in brackets represent the standard error of the mean. A one-way ANOVA was used to compare <i>a</i>, <i>b</i>, and <i>Q</i>₁₀ values among different vegetation patches (n = 3). Different letters indicate significant difference (<i>P</i><0.05) among different vegetation patches.</p

Relationships between average monthly soil respiration and environmental factors among sites.

<p>Shoot biomass (A), root biomass (B), litter biomass (C), SOC (D), total C (E), and total N (F) of three adjacent vegetation types (<i>Phragmites australis</i>, <i>Suaeda salsa</i> and bare soil sites). Bars represent standard errors of the means. One point represents the average soil respiration and average environmental factors of each patch during one month of measurement. Closed circles (•) represent <i>Phragmites australis</i> community, open circles (○) represent <i>Suaeda salsa</i> community, and closed triangles (▴) represent bare soil site.</p

Diurnal variations in soil respiration and net photosynthesis and their relationships at <i>Phragmites australis</i> community.

<p>May 15 (A, E), May 27 (B, F), June 12 (C, G) and July 9 (D, H). Bars represent standard errors of the means.</p

Responses of soil respiration to soil temperature during the growing season among sites.

<p>Black lines are the best fits. Bars represent standard errors of the means.</p