Genomics, environment and balancing selection in behaviorally bimodal populations : the caribou case

Selection forces that favor different phenotypes in different environments can change frequencies of genes between populations along environmental clines. Clines are also compatible with balancing forces, such as negative frequency‐dependent selection (NFDS), which maintains phenotypic polymorphisms within populations. For example, NFDS is hypothesized to maintain partial migration, a dimorphic behavioral trait prominent in species where only a fraction of the population seasonally migrates. Overall, NFDS is believed to be a common phenomenon in nature, yet, a scarcity of studies were published linking naturally occurring allelic variation with bimodal or multimodal phenotypes and balancing selection. We applied a Pool‐seq approach and detected selection on alleles associated with environmental variables along a North‐South gradient in western North American caribou, a species displaying partially migratory behavior. On 51 loci, we found a signature of balancing selection, which could be related to NFDS and ultimately the maintenance of the phenotypic polymorphisms known within these populations. Yet, remarkably, we detected directional selection on a locus when our sample was divided in two behaviorally distinctive groups regardless of geographic provenance (a subset of GPS‐collared migratory or sedentary individuals), indicating that, within populations, phenotypically homogeneous groups were genetically distinctive. Loci under selection were linked to functional genes involved in oxidative stress response, body development and taste perception. Overall, results indicated genetic differentiation along an environmental gradient of caribou populations, which we found characterized by genes potentially undergoing balancing selection. We suggest that the underlining balancing force, NFDS plays a strong role within populations harboring multiple haplotypes and phenotypes, as it is the norm in animals, plants and humans too

Predicting the effects of restoring linear features on woodland caribou populations

Serrouya R, Dickie M, DeMars C, Wittmann M, Boutin S. Predicting the effects of restoring linear features on woodland caribou populations. Ecological Modelling. 2019;416: 108891.Predator-prey dynamics are increasingly being modified by the alteration of natural habitats. Such alteration has led to increased predation rates and local extirpation of woodland caribou (Rangifer tarandus caribou) in western Canada. Linear features such as roads or seismic lines (narrow corridors used for petroleum exploration that are cleared of vegetation) increase predation rates on caribou by increasing wolf (Canis lupus) movement rates and by facilitating access into caribou habitat. Linear feature restoration is therefore hypothesised to help reverse caribou declines. However, with the high financial cost to restore approximately 350,000 km of seismic lines within western Canada’s boreal forests, theoretical predictions can clarify the efficacy of such actions. We use a mathematical model based on coupled ordinary differential equations representing predator-prey dynamics to estimate equilibrium densities of caribou, moose (Alces alces) and wolves under various parameter scenarios. Changes in equilibrium density serve as a proxy for the expected effect of linear feature restoration on population densities. Our model captures dynamical feedbacks between caribou and wolf densities, and also includes moose, which are the wolf’s primary prey species. With our best estimates of parameter values, caribou density increased 2.51-fold if all linear features were restored and 1.61-fold if only seismic lines were restored. As a comparison, simulated predator reductions increased caribou densities 3.92-fold, nearly twice the total response of linear feature restoration. The effect of restoration was increased if caribou group size was smaller, yet was less pronounced if carrying capacity for ungulates was higher. By varying the parameter values and fixing population densities, our approach allowed us to partition the caribou populations’ response from restoration into the contributions of the various mechanisms and feedbacks. In particular, contrasting simulation results where wolf densities are kept fixed with those where they are free to respond to prey allowed us to disentangle the relative importance of wolf functional and numerical response. This novel approach indicates that most of the increase in caribou densities after restoration was due to reduced foraging efficiency of wolves, especially reduced habitat overlap. Overall, our results suggest that restoration could substantially benefit caribou populations, but only if all linear features are restored, which is far from realistic. Linear feature restoration alone may not lead to population recovery, and should therefore be coupled with other direct management actions to successfully recover caribou

Unión de hecho

Trabajo de Suficiencia ProfesionalEn primer orden en nuestro país no existe una estadística real que refleje la problemática legal que asumen las parejas en la unión de hecho. Tanto es así que podemos verificar que no está totalmente definida. Mayormente la detectamos en los indicadores de violencia familiar, maltrato infantil, etc. Existen muchas iniciativas para enmendar los vacíos y/o deficiencias imperantes que podrían ser muy bien asumidas a un nivel macro con la participación efectiva de la experiencia tomada por otras realidades sin ir muy lejos a nivel de los países de América Latina. Solo depende de nosotros asumir el reto. Los primeros pasos ya lo han dado otros países vecinos. A través de la actual Carta Magna, al igual que la Constitución Política del Perú de 1979, se brinda reconocimiento constitucional a las uniones de hecho en sentido estricto integradas por un varón y una mujer, libres de impedimento matrimonial, que forman un hogar de hecho y que da lugar a una comunidad de bienes sujeta al régimen de la sociedad de gananciales en cuanto sea aplicable. Asimismo, el acceso al Registro Personal de las uniones de hecho y su cese, permitirán publicitar ante los terceros el inicio y fin de estas comunidades de bienes sujetas al régimen de sociedad de gananciales, en cuanto le sea aplicable; lo cual, además de contribuir a proteger al conviviente frente a actos indebidos de apropiación del otro conviviente, es de fundamental interés para el tráfico jurídico patrimonial

Changes in landscape composition influence the decline of a threatened woodland caribou population

Large-scale habitat loss is frequently identified with loss of biodiversity, but examples of the direct effect of habitat alterations on changes in vital rates remain rare. Quantifying and understanding the relationship between habitat composition and changes in vital rates, however, is essential for the development of effective conservation strategies. It has been suggested that the decline of woodland caribou Rangifer tarandus caribou populations in North America is precipitated by timber harvesting that creates landscapes of early seral forests. Such habitat changes have altered the predator-prey system resulting in asymmetric predation, where predators are maintained by alternative prey (i.e. apparent competition). However, a direct link between habitat condition and caribou population declines has not been documented. We estimated survival probabilities for the threatened arboreal lichen-feeding ecotype of woodland caribou in British Columbia, Canada, at two different spatial scales. At the broader scale, observed variation in adult female survival rates among 10 distinct populations (range = 0.67-0.93) was best explained by variation in the amount of early seral stands within population ranges and population density. At the finer scale, home ranges of caribou killed by predators had lower proportions of old forest and more mid-aged forest as compared with multi-annual home ranges where caribou were alive. These results are consistent with predictions from the apparent competition hypothesis and quantify direct fitness consequences for caribou following habitat alterations. We conclude that apparent competition can cause rapid population declines and even extinction where changes in species composition occur following large scale habitat change. © 2007 The Authors. Journal compilation © 2007 British Ecological Society

Predator-mediated Allee effects in multi-prey systems

Allee effects can have significant consequences for small populations and understanding the causal mechanisms for such effects is important for guiding conservation actions. One proposed mechanism is through predation, in which a type II functional response leads to increasing predation rates as prey numbers decline. However, models to support this mechanism have incorporated only a single declining prey species in the functional response, which is probably an oversimplification. We reevaluated the potential for predator-mediated Allee effects in a multi-prey system using Holling's disc equation. We also used empirical data on a large herbivore to examine how grouping behavior may influence the potential for predation-mediated Allee effects. Results based on a multi-prey expression of the functional response predict that Allee effects caused by predation on relatively rare secondary prey may not occur because handling time of the abundant prey dominates the functional response such that secondary prey are largely "bycatch." However, a predator-mediated Allee effect can occur if secondary prey live in groups and if, as the population declines, their average group size declines (a relationship seen in several species). In such a case, the rate at which the number of groups declines is less than the rate at which the population declines. Thus the rate at which a predator encounters a group remains relatively stable, but when a predator kills one animal from smaller groups, the predation rate increases. These results highlight the need to evaluate risks associated with potential changes in group size as populations decline. © 2010 by the Ecological society ot America

Using predator-prey theory to predict outcomes of a broad-scale test of apparent competition

© 2015 by The University of Chicago. 0003-0147/2015/18505-55371$15.00. All rights reserved. Apparent competition is an important process influencing many ecological communities. We used predator-prey theory to predict outcomes of ecosystem experiments aimed at mitigating apparent competition by reducing primary prey. Simulations predicted declines in secondary prey following reductions in primary prey because predators consumed more secondary prey until predator numbers responded to reduced prey densities. Losses were exacerbated by a higher carrying capacity of primary prey and a longer lag time of the predator’s numerical response, but a gradual reduction in primary prey was less detrimental to the secondary prey. We compared predictions against two field experiments where endangered woodland caribou (Rangifer tarandus caribou) were victims of apparent competition. First, when deer (Odocoileus sp.) declined suddenly following a severe winter, cougar (Puma concolor) declined with a 1– 2-year lag, yet in the interim more caribou were killed by cougars, and caribou populations declined by 40%. Second, when moose (Alces alces) were gradually reduced using a management experiment, wolf (Canis lupus) populations declined but did not shift consumption to caribou, and the largest caribou subpopulation stabilized. The observed contrasting outcomes of sudden versus gradual declines in primary prey supported theoretical predictions. Combining theory with field studies clarified how to manage communities to mitigate endangerment caused by apparent competition that affects many taxa

Bighorn sheep and Elk Valley coal mines : ecology and winter range assessment

Rocky Mountain bighorn sheep inhabit the east side of the Elk Valley in southeastern British Columbia where forestry and 4 large, open pit coal mines are in operation. Sheep in this area generally winter at high elevation on windswept, south facing native grasslands, with some sheep also wintering on mine properties. Concurrent companion studies examined sheep habitat ecology and movements; and winter range plant communities and production, range condition, and winter diet. We monitored 41 ewes and rams over 26 months using GPS-collars. Most of the sheep monitored were seasonally migratory (79%) and showed high fidelity to winter ranges among years (88%). Use of mine properties varied seasonally, from ~10-18% during winter to peak at about 60-65% during autumn. Ewes lambed both in natural habitats and on mine properties. Fifteen winter ranges were identified, which in native habitats were typically a complex of grasslands, shrub lands, vegetated and non-vegetated rock outcrops, and cliffs. Sampling of these ranges found that standing crop production was highest in ranges with the greatest percentage cover of graminoids often dominated by rough fescue and where productive soils were prominent. High use by elk was observed on many of the ranges. Grazing was greatest on productive sites; sheep utilization declined with increasing distance from escape terrain. Three of the winter ranges are considered to be unhealthy ecologically.Non UBCUnreviewedOthe

Moose, caribou and fire: have we got it right yet?

Natural disturbance plays a key role in shaping community dynamics. Within Canadian boreal forests, the dominant form of natural disturbance is fire, and its effects are thought to influence the dynamics between moose (Alces alces (Linnaeus, 1758)) and the boreal ecotype of woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)). Boreal caribou are considered “threatened” and population declines are attributed, at least in part, to disturbance-mediated apparent competition (DMAC) with moose. Here, we tested a primary prediction of the DMAC hypothesis: that moose respond positively to burns within and adjacent to the caribou range. We assessed moose selection for ≤25-year-old burns (when selection is predicted to be strongest) at multiple spatial scales and evaluated whether moose density was correlated with the extent of ≤40-year-old burns (a time frame predicted to negatively affect caribou). Against expectation, moose showed avoidance and low use of ≤25-year-old burns at all scales, regardless of burn age, season, and type of land cover burned. These findings mirrored the demographic response, as we found no correlation between ≤40-year-old burns and moose density. By contradicting the prevailing hypothesis linking fires to caribou population declines, our results highlight the need to understand regional variation in disturbance impacts on caribou populations.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author