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1.
Trends Ecol Evol ; 39(3): 217-220, 2024 03.
Artículo en Inglés | MEDLINE | ID: mdl-38278702

RESUMEN

Current reductionist approaches to environmental governance cannot resolve social-ecological crises. Siloed institutions fail to address linked social and ecological processes, thereby neglecting issues of equity, justice, and cumulative effects. Global insights can be gained from Indigenous-led initiatives that support the resilience of relationships within and among places.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Política Ambiental , Medio Social
2.
Environ Manage ; 2023 Dec 25.
Artículo en Inglés | MEDLINE | ID: mdl-38145447

RESUMEN

Natural resource governance challenges are often highly complex, particularly in Indigenous contexts. These challenges involve numerous landscape-level interactions, spanning jurisdictional, disciplinary, social, and ecological boundaries. In Eeyou Istchee, the James Bay Cree Territory of northern Quebec, Canada, traditional livelihoods depend on wild food species like moose. However, these species are increasingly being impacted by forestry and other resource development projects. The complex relationships between moose, resource development, and Cree livelihoods can limit shared understandings and the ability of diverse actors to respond to these pressures. Contributing to this complexity are the different knowledge systems held by governance actors who, while not always aligned, have broadly shared species conservation and sustainable development goals. This paper presents fuzzy cognitive mapping (FCM) as a methodological approach used to help elicit and interpret the knowledge of land-users concerning the impacts of forest management on moose habitat in Eeyou Istchee. We explore the difficulties of weaving this knowledge together with the results of moose GPS collar analysis and the knowledges of scientists and government agencies. The ways in which participatory, relational mapping approaches can be applied in practice, and what they offer to pluralistic natural resource governance research more widely, are then addressed.

3.
Glob Chang Biol ; 29(2): 432-450, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36270797

RESUMEN

Over the last few decades, there has been an increasing recognition for seagrasses' contribution to the functioning of nearshore ecosystems and climate change mitigation. Nevertheless, seagrass ecosystems have been deteriorating globally at an accelerating rate during recent decades. In 2017, research into the condition of eelgrass (Zostera marina) along the eastern coast of James Bay, Canada, was initiated in response to reports of eelgrass decline by the Cree First Nations of Eeyou Istchee. As part of this research, we compiled and analyzed two decades of eelgrass cover data and three decades of eelgrass monitoring data (biomass and density) to detect changes and assess possible environmental drivers. We detected a major decline in eelgrass condition between 1995 and 1999, which encompassed the entire east coast of James Bay. Surveys conducted in 2019 and 2020 indicated limited changes post-decline, for example, low eelgrass cover (<25%), low aboveground biomass, smaller shoots than before 1995, and marginally low densities persisted at most sites. Overall, the synthesized datasets show a 40% loss of eelgrass meadows with >50% cover in eastern James Bay since 1995, representing the largest scale eelgrass decline documented in eastern Canada since the massive die-off event that occurred in the 1930s along the North Atlantic coast. Using biomass data collected since 1982, but geographically limited to the sector of the coast near the regulated La Grande River, generalized additive modeling revealed eelgrass meadows are affected by local sea surface temperature, early ice breakup, and higher summer freshwater discharge. Our results caution against assuming subarctic seagrass ecosystems have avoided recent global declines or will benefit from ongoing climate warming.


Asunto(s)
Ecosistema , Zosteraceae , Cambio Climático , Biomasa , Temperatura
4.
Ecology ; 104(2): e3882, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36208219

RESUMEN

Climate warming is causing asynchronies between animal phenology and environments. Mismatched traits, such as coat color change mismatched with snow, can decrease survival. However, coat change does not serve a singular adaptive benefit of camouflage, and alternate coat change functions may confer advantages that supersede mismatch costs. We found that mismatch reduced, rather than increased, autumn mortality risk of snowshoe hares in Yukon by 86.5% when mismatch occurred. We suggest that the increased coat insulation and lower metabolic rates of winter-acclimatized hares confer energetic advantages to white mismatched hares that reduce their mortality risk. We found that white mismatched hares forage 17-77 min less per day than matched brown hares between 0°C and -10°C, thus lowering their predation risk and increasing survival. We found no effect of mismatch on spring mortality risk, during which mismatch occurred at warmer temperatures, suggesting a potential temperature limit at which the costs of conspicuousness outweigh energetic benefits.


Asunto(s)
Mimetismo Biológico , Liebres , Animales , Herbivoria , Fenotipo , Estaciones del Año , Nieve , Sobrevida , Regulación de la Temperatura Corporal
5.
J Comp Physiol B ; 192(1): 193-206, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34677660

RESUMEN

Previous research demonstrated that cities are similar to individual mammals in their relationship between the rate of energy use for heating and outdoor air temperature (Ta). At Tas requiring heating of indoor living spaces, the energy-Ta plot of a city contains information on city-wide thermal insulation (I), making it possible to quantify city-wide I by use of the city as the unit of measure. We develop methods for extracting this insulation information, deriving the methods from prior research on mammals. Using these methods, we address the question: in North America, are cities built in particularly cold locations constructed in ways that provide greater thermal insulation than ones built in thermally more moderate locations? Using data for 42 small and medium-size cities and two information-extraction methods, we find that there is a statistically significant inverse relationship between city-wide I and T10-year, the average city Ta over a recent 10-year period (range of T10-year: - 11 to 26 °C). This relationship represents an energy-conserving trend, indicating that cities in cold climates have greater built-in thermal insulation than cities in warm climates. However, the augmentation of insulation in cold climates is only about half as great as would be required to offset fully the increased energy cost of low Tas in a cold climate, and T10-year explains just 5-11% of the variance in measured insulation, suggesting that cities in North America vary greatly in the extent to which thermal insulation has been a priority in city development.


Asunto(s)
Clima , Frío , Animales , Ciudades , América del Norte , Temperatura
6.
Ecology ; 102(9): e03456, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-34165786

RESUMEN

Food availability and temporal variation in predation risk are both important determinants of the magnitude of antipredator responses, but their effects have rarely been examined simultaneously, particularly in wild prey. Here, we determine how food availability and long-term predation risk affect antipredator responses to acute predation risk by monitoring the foraging response of free-ranging snowshoe hares (Lepus americanus) to an encounter with a Canada lynx (Lynx canadensis) in Yukon, Canada, over four winters (2015-2016 to 2018-2019). We examined how this response was influenced by natural variation in long-term predation risk (2-month mortality rate of hares) while providing some individuals with supplemental food. On average, snowshoe hares reduced foraging time up to 10 h after coming into close proximity (≤75 m) with lynx, and reduced foraging time an average of 15.28 ± 7.08 min per lynx encounter. Hares tended to respond more strongly when the distance to lynx was shorter. More importantly, the magnitude of hares' antipredator response to a lynx encounter was affected by the interaction between food-supplementation and long-term predation risk. Food-supplemented hares reduced foraging time more than control hares after a lynx encounter under low long-term risk, but decreased the magnitude of the response as long-term risk increased. In contrast, control hares increased the magnitude of their response as long-term risk increased. Our findings show that food availability and long-term predation risk interactively drive the magnitude of reactive antipredator response to acute predation risk. Determining the factors driving the magnitude of antipredator responses would contribute to a better understanding of the indirect effects of predators on prey populations.


Asunto(s)
Cadena Alimentaria , Conducta Predatoria , Animales , El Yukón
7.
J Anim Ecol ; 89(11): 2397-2414, 2020 11.
Artículo en Inglés | MEDLINE | ID: mdl-32929740

RESUMEN

Long-term studies of wild animals provide the opportunity to investigate how phenotypic plasticity is used to cope with environmental fluctuations and how the relationships between phenotypes and fitness can be dependent upon the ecological context. Many previous studies have only investigated life-history plasticity in response to changes in temperature, yet wild animals often experience multiple environmental fluctuations simultaneously. This requires field experiments to decouple which ecological factor induces plasticity in fitness-relevant traits to better understand their population-level responses to those environmental fluctuations. For the past 32 years, we have conducted a long-term integrative study of individually marked North American red squirrels Tamiasciurus hudsonicus Erxleben in the Yukon, Canada. We have used multi-year field experiments to examine the physiological and life-history responses of individual red squirrels to fluctuations in food abundance and conspecific density. Our long-term observational study and field experiments show that squirrels can anticipate increases in food availability and density, thereby decoupling the usual pattern where animals respond to, rather than anticipate, an ecological change. As in many other study systems, ecological factors that can induce plasticity (such as food and density) covary. However, our field experiments that manipulate food availability and social cues of density (frequency of territorial vocalizations) indicate that increases in social (acoustic) cues of density in the absence of additional food can induce similar life-history plasticity, as does experimental food supplementation. Changes in the levels of metabolic hormones (glucocorticoids) in response to variation in food and density are one mechanism that seems to induce this adaptive life-history plasticity. Although we have not yet investigated the energetic response of squirrels to elevated density or its association with life-history plasticity, energetics research in red squirrels has overturned several standard pillars of knowledge in physiological ecology. We show how a tractable model species combined with integrative studies can reveal how animals cope with resource fluctuations through life-history plasticity.


Asunto(s)
Animales Salvajes , Cola (estructura animal) , Animales , Canadá , Sciuridae , Estados Unidos , El Yukón
8.
Am J Physiol Regul Integr Comp Physiol ; 319(4): R455-R465, 2020 10 01.
Artículo en Inglés | MEDLINE | ID: mdl-32783688

RESUMEN

Hibernators suppress physiological processes when expressing torpor, yet little is known about the effects of torpor on male reproductive physiology. Studies of hibernating mammals suggest that deep torpor negatively impacts spermatogenesis and that transitions between torpor and euthermic arousals increase cellular oxidative stress, with potentially damaging effects on sperm. Here, we hypothesize that variation in torpor expression affects the reproductive readiness of hibernators by impacting their sperm production. To test this, we examined the relationship between torpor expression and spermatogenesis in captive eastern chipmunks (Tamias striatus). We determined torpor depth with temperature data loggers and assessed its relationship with spermatogenesis by examining spermatogenic progression, cell division, sperm counts, sperm maturity, and DNA damage. We show that deep hibernators (high levels of torpor) largely halted spermatogenesis in late hibernation in comparison with shallow hibernators (low levels of torpor), where ongoing spermatogenesis was observed. Despite these differences in spermatogenic state during hibernation, spermatogenic progression, sperm numbers, and maturity did not differ in spring, potentially reflecting similar degrees of reproductive readiness. Interestingly, shallow hibernators exhibited higher rates of DNA damage in spermatogenic cells during hibernation, with this trend reversing in spring. Our results thus indicate that once heterothermy is terminated, deep hibernators resume spermatogenesis but are characterized by higher rates of DNA damage in spermatogenic cells at the seasonal stage when spring mating commences. Therefore, our study confirmed posthibernation recovery of sperm production but also a potential impact of deep torpor expression during winter on DNA damage in spring.


Asunto(s)
Temperatura Corporal/fisiología , Hibernación/fisiología , Sciuridae/fisiología , Espermatogénesis/fisiología , Letargo/fisiología , Animales , Daño del ADN/fisiología , Metabolismo Energético/fisiología , Masculino , Recuento de Espermatozoides , Temperatura
9.
J Anim Ecol ; 88(9): 1305-1318, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31236935

RESUMEN

Intraguild (IG) interactions are common among mammalian carnivores, can include intraguild predation (IGP) and interspecific killing (IK), and are often asymmetrical, where a larger more dominant species (IGpredator ) kills a smaller one (IGprey ). According to ecological theory, the potential for an IGpredator and IGprey to coexist depends on whether the direct consumptive benefits for the IGpredator are substantial (IGP) or insignificant (IK), the extent to which the IGprey is the superior exploitative competitor on shared prey resources, and overall ecosystem productivity. We used resource selection models and spatially explicit age and harvest data for two closely related mesopredators that engage in IG interactions, American martens (Martes americana; IGprey ) and fishers (Pekania pennanti; IGpredator ), to identify drivers of distributions, delineate areas of sympatry and allopatry, and explore the role of an apex predator (coyote; Canis latrans) on these interactions. Model selection revealed that fisher use of this landscape was strongly influenced by late winter abiotic conditions, but other bottom-up (forest composition) and top-down (coyote abundance) factors also influenced their distribution. Overall, fisher probability of use was higher where late winter temperatures were warmer, snowpack was deeper, and measures of productivity were greater. Martens were constrained to areas of the landscape where the probability of fisher use, coyote abundance, and productivity were low and selected for forest conditions that presumably maximized prey availability. Marten age data indicated an increased proportion of juveniles outside of the predicted area of sympatry, suggesting that few animals survived >1.5 years in this area that supported higher densities of fishers and coyotes. Consistent with asymmetrical IG interaction theory, the IGpredator (fishers and, to a lesser degree, coyotes) competitively excluded the IGprey (martens) from more productive, milder temperature habitats, whereas IGpredators and IGprey coexisted in low productivity environments, where a combination of abiotic and biotic conditions enabled the IGprey to be the superior exploitative competitor.


Asunto(s)
Carnívoros , Mustelidae , Animales , Ecosistema , Cadena Alimentaria , Bosques , Dinámica Poblacional , Conducta Predatoria
10.
Ecol Evol ; 9(1): 619-630, 2019 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-30680142

RESUMEN

The miniaturization and affordability of new technology is driving a biologging revolution in wildlife ecology with use of animal-borne data logging devices. Among many new biologging technologies, accelerometers are emerging as key tools for continuously recording animal behavior. Yet a critical, but under-acknowledged consideration in biologging is the trade-off between sampling rate and sampling duration, created by battery- (or memory-) related sampling constraints. This is especially acute among small animals, causing most researchers to sample at high rates for very limited durations. Here, we show that high accuracy in behavioral classification is achievable when pairing low-frequency acceleration recordings with temperature. We conducted 84 hr of direct behavioral observations on 67 free-ranging red squirrels (200-300 g) that were fitted with accelerometers (2 g) recording tri-axial acceleration and temperature at 1 Hz. We then used a random forest algorithm and a manually created decision tree, with variable sampling window lengths, to associate observed behavior with logger recorded acceleration and temperature. Finally, we assessed the accuracy of these different classifications using an additional 60 hr of behavioral observations, not used in the initial classification. The accuracy of the manually created decision tree classification using observational data varied from 70.6% to 91.6% depending on the complexity of the tree, with increasing accuracy as complexity decreased. Short duration behavior like running had lower accuracy than long-duration behavior like feeding. The random forest algorithm offered similarly high overall accuracy, but the manual decision tree afforded the flexibility to create a hierarchical tree, and to adjust sampling window length for behavioral states with varying durations. Low frequency biologging of acceleration and temperature allows accurate behavioral classification of small animals over multi-month sampling durations. Nevertheless, low sampling rates impose several important limitations, especially related to assessing the classification accuracy of short duration behavior.

11.
Proc Biol Sci ; 285(1891)2018 11 21.
Artículo en Inglés | MEDLINE | ID: mdl-30464061

RESUMEN

Fisher's principle explains that population sex ratio in sexually reproducing organisms is maintained at 1 : 1 owing to negative frequency-dependent selection, such that individuals of the rare sex realize greater reproductive opportunity than individuals of the more common sex until equilibrium is reached. If biasing offspring sex ratio towards the rare sex is adaptive, individuals that do so should have more grandoffspring. In a wild population of North American red squirrels (Tamiasciurus hudsonicus) that experiences fluctuations in resource abundance and population density, we show that overall across 26 years, the secondary sex ratio was 1 : 1; however, stretches of years during which adult sex ratio was biased did not yield offspring sex ratios biased towards the rare sex. Females that had litters biased towards the rare sex did not have more grandoffspring. Critically, the adult sex ratio was not temporally autocorrelated across years, thus the population sex ratio experienced by parents was independent of the population sex ratio experienced by their offspring at their primiparity. Expected fitness benefits of biasing offspring sex ratio may be masked or negated by fluctuating environments across years, which limit the predictive value of the current sex ratio.


Asunto(s)
Adaptación Fisiológica , Ambiente , Sciuridae/fisiología , Razón de Masculinidad , Animales , Femenino , Masculino , Modelos Biológicos
13.
J Evol Biol ; 31(6): 810-821, 2018 06.
Artículo en Inglés | MEDLINE | ID: mdl-29518280

RESUMEN

Phenological shifts are the most widely reported ecological responses to climate change, but the requirements to distinguish their causes (i.e. phenotypic plasticity vs. microevolution) are rarely met. To do so, we analysed almost two decades of parturition data from a wild population of North American red squirrels (Tamiasciurus hudsonicus). Although an observed advance in parturition date during the first decade provided putative support for climate change-driven microevolution, a closer look revealed a more complex pattern. Parturition date was heritable [h2  = 0.14 (0.07-0.21 (HPD interval)] and under phenotypic selection [ß = -0.14 ± 0.06 (SE)] across the full study duration. However, the early advance reversed in the second decade. Further, selection did not act on the genetic contribution to variation in parturition date, and observed changes in predicted breeding values did not exceed those expected due to genetic drift. Instead, individuals responded plastically to environmental variation, and high food [white spruce (Picea glauca) seed] production in the first decade appears to have produced a plastic advance. In addition, there was little evidence of climate change affecting the advance, as there was neither a significant influence of spring temperature on parturition date or evidence of a change in spring temperatures across the study duration. Heritable traits not responding to selection in accordance with quantitative genetic predictions have long presented a puzzle to evolutionary ecologists. Our results on red squirrels provide empirical support for one potential solution: phenotypic selection arising from an environmental, as opposed to genetic, covariance between the phenotypic trait and annual fitness.


Asunto(s)
Adaptación Fisiológica/genética , Evolución Biológica , Sciuridae/genética , Sciuridae/fisiología , Animales , Ecosistema , Femenino , Masculino , Modelos Biológicos , Fenotipo , Reproducción/fisiología , Estaciones del Año , Selección Genética , El Yukón
14.
Microbiome ; 5(1): 163, 2017 12 21.
Artículo en Inglés | MEDLINE | ID: mdl-29268780

RESUMEN

BACKGROUND: Our understanding of gut microbiota has been limited primarily to findings from human and laboratory animals, but what shapes the gut microbiota in nature remains largely unknown. To fill this gap, we conducted a comprehensive study of gut microbiota of a well-studied North American red squirrel (Tamiasciurus hudsonicus) population. Red squirrels are territorial, solitary, and live in a highly seasonal environment and therefore represent a very attractive system to study factors that drive the temporal and spatial dynamics of gut microbiota. RESULT: For the first time, this study revealed significant spatial patterns of gut microbiota within a host population, suggesting limited dispersal could play a role in shaping and maintaining the structure of gut microbial communities. We also found a remarkable seasonal rhythm in red squirrel's gut microbial composition manifested by a tradeoff between relative abundance of two genera Oscillospira and Corpococcus and clearly associated with seasonal variation in diet availability. Our results show that in nature, environmental factors exert a much stronger influence on gut microbiota than host-associated factors including age and sex. Despite strong environmental effects, we found clear evidence of individuality and maternal effects, but host genetics did not seem to be a significant driver of the gut microbial communities in red squirrels. CONCLUSION: Taken together, the results of this study emphasize the importance of external ecological factors rather than host attributes in driving temporal and spatial patterns of gut microbiota in natural environment.


Asunto(s)
Microbioma Gastrointestinal , Sciuridae/microbiología , Estaciones del Año , Animales , Animales Salvajes/microbiología , Ecosistema , Ambiente , Herencia Materna , ARN Ribosómico 16S , Análisis Espacio-Temporal
15.
Integr Comp Biol ; 57(5): 961-976, 2017 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-29040576

RESUMEN

From a trophic perspective, a seasonal increase in air temperature and photoperiod propagates as bottom-up pulse of primary production by plants, secondary production by herbivores, and tertiary production by carnivores. However, food web seasonality reflects not only abiotic variation in temperature and photoperiod, but also the composition of the biotic community and their functional responses to this variation. Some plants and animals-here referred to as seasonal specialists-decouple from food webs in winter through migration or various forms of metabolic arrest (e.g., senescence, diapause, and hibernation), whereas some plants and resident animals-here referred to as seasonal generalists-remain present and trophically coupled in winter. The co-occurrence of species with divergent responses to winter introduces seasonal variation in interaction strengths, resulting in summer-to-winter differences in trophic organization. Autumn cooling and shortening day length arrests primary productivity and cues seasonal herbivores to decouple, leaving generalist carnivores to concentrate their predation on the few generalist herbivores that remain resident, active, and vulnerable to predation in winter, which themselves feed on the few generalist plant structures available in winter. Thus, what was a bottom-up pulse, spread among many species in summer, including highly productive seasonal specialists, reverses into strong top-down regulation in winter that is top-heavy, and concentrated among a small number of generalist herbivores and their winter foods. Intermediate-sized, generalist herbivores that remain active and vulnerable to predation in winter are likely to be keystone species in seasonal food webs because they provide the essential ecosystem service of turning summer primary productivity into winter food for carnivores. Empirical examination of terrestrial mammals and their seasonal trophic status in the boreal forest and across an arctic-to-tropics seasonality gradient indicates seasonal specialization is more common among herbivores, small body sizes, and in regions with intermediate seasonality, than among carnivores, large body size, and regions where summers are very short or very long. Better understanding of food webs in seasonal environments, including their vulnerability and resilience to climate change, requires a multi-season perspective.


Asunto(s)
Ecosistema , Cadena Alimentaria , Hibernación , Mamíferos/fisiología , Estaciones del Año , Animales
16.
Integr Comp Biol ; 57(5): 921-933, 2017 11 01.
Artículo en Inglés | MEDLINE | ID: mdl-29045649

RESUMEN

Seasonality is a critically important aspect of environmental variability, and strongly shapes all aspects of life for organisms living in highly seasonal environments. Seasonality has played a key role in generating biodiversity, and has driven the evolution of extreme physiological adaptations and behaviors such as migration and hibernation. Fluctuating selection pressures on survival and fecundity between summer and winter provide a complex selective landscape, which can be met by a combination of three outcomes of adaptive evolution: genetic polymorphism, phenotypic plasticity, and bet-hedging. Here, we have identified four important research questions with the goal of advancing our understanding of evolutionary impacts of seasonality. First, we ask how characteristics of environments and species will determine which adaptive response occurs. Relevant characteristics include costs and limits of plasticity, predictability, and reliability of cues, and grain of environmental variation relative to generation time. A second important question is how phenological shifts will amplify or ameliorate selection on physiological hardiness. Shifts in phenology can preserve the thermal niche despite shifts in climate, but may fail to completely conserve the niche or may even expose life stages to conditions that cause mortality. Considering distinct environmental sensitivities of life history stages will be key to refining models that forecast susceptibility to climate change. Third, we must identify critical physiological phenotypes that underlie seasonal adaptation and work toward understanding the genetic architectures of these responses. These architectures are key for predicting evolutionary responses. Pleiotropic genes that regulate multiple responses to changing seasons may facilitate coordination among functionally related traits, or conversely may constrain the expression of optimal phenotypes. Finally, we must advance our understanding of how changes in seasonal fluctuations are impacting ecological interaction networks. We should move beyond simple dyadic interactions, such as predator prey dynamics, and understand how these interactions scale up to affect ecological interaction networks. As global climate change alters many aspects of seasonal variability, including extreme events and changes in mean conditions, organisms must respond appropriately or go extinct. The outcome of adaptation to seasonality will determine responses to climate change.


Asunto(s)
Adaptación Biológica , Evolución Biológica , Clima , Rasgos de la Historia de Vida , Fenotipo , Animales , Cambio Climático , Fenómenos Fisiológicos de las Plantas/genética , Estaciones del Año
17.
Sci Rep ; 7(1): 9335, 2017 08 24.
Artículo en Inglés | MEDLINE | ID: mdl-28839275

RESUMEN

The age trajectory of reproductive performance of many iteroparous species features an early - life increase in performance followed by a late - life senescent decline. The largest contribution of lifetime reproductive success is therefore gained at the age at which reproductive performance peaks. Using long term data on North American red squirrels we show that the environmental conditions individuals encountered could cause variation among individuals in the "height" and timing of this peak, contributing to life history variation and fitness in this population that experiences irregular resource pulses. As expected, high peak effort was positively associated with lifetime reproductive output up to a high level of annual effort. Furthermore, individuals that matched their peak reproductive effort to an anticipated resource pulse gained substantial fitness benefits through recruiting more offspring over their lifetime. Individual variation in peak reproductive effort thus has strong potential to shape life history evolution by facilitating adaptation to fluctuating environments.


Asunto(s)
Exposición a Riesgos Ambientales , Sciuridae/fisiología , Conducta Sexual Animal , Animales , Variación Biológica Poblacional , Aptitud Genética , América del Norte
18.
Evolution ; 71(7): 1841-1854, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28543051

RESUMEN

Individuals often interact more closely with some members of the population (e.g., offspring, siblings, or group members) than they do with other individuals. This structuring of interactions can lead to multilevel natural selection, where traits expressed at the group-level influence fitness alongside individual-level traits. Such multilevel selection can alter evolutionary trajectories, yet is rarely quantified in the wild, especially for species that do not interact in clearly demarcated groups. We quantified multilevel natural selection on two traits, postnatal growth rate and birth date, in a population of North American red squirrels (Tamiasciurus hudsonicus). The strongest level of selection was typically within-acoustic social neighborhoods (within 130 m of the nest), where growing faster and being born earlier than nearby litters was key, while selection on growth rate was also apparent both within-litters and within-study areas. Higher population densities increased the strength of selection for earlier breeding, but did not influence selection on growth rates. Females experienced especially strong selection on growth rate at the within-litter level, possibly linked to the biased bequeathal of the maternal territory to daughters. Our results demonstrate the importance of considering multilevel and sex-specific selection in wild species, including those that are territorial and sexually monomorphic.


Asunto(s)
Evolución Biológica , Fenotipo , Sciuridae , Selección Genética , Animales , Femenino , Masculino , Territorialidad , Estados Unidos
19.
J Comp Physiol B ; 187(5-6): 749-757, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28353177

RESUMEN

Recent research is revealing incredible diversity in the thermoregulatory patterns of wild and captive endotherms. As a result of these findings, classic thermoregulatory categories of 'homeothermy', 'daily heterothermy', and 'hibernation' are becoming harder to delineate, impeding our understanding of the physiological and evolutionary significance of variation within and around these categories. However, we lack a generalized analytical approach for evaluating and comparing the complex and diversified nature of the full breadth of heterothermy expressed by individuals, populations, and species. Here we propose a new approach that decomposes body temperature time series into three inherent properties-waveform, amplitude, and period-using a non-stationary technique that accommodates the temporal variability of body temperature patterns. This approach quantifies circadian and seasonal variation in thermoregulatory patterns, and uses the distribution of observed thermoregulatory patterns as a basis for intra- and inter-specific comparisons. We analyse body temperature time series from multiple species, including classical hibernators, tropical heterotherms, and homeotherms, to highlight the approach's general usefulness and the major axes of thermoregulatory variation that it reveals.


Asunto(s)
Temperatura Corporal , Euterios/fisiología , Animales , Regulación de la Temperatura Corporal , Estaciones del Año
20.
Conserv Biol ; 30(6): 1277-1287, 2016 12.
Artículo en Inglés | MEDLINE | ID: mdl-27032080

RESUMEN

Many argue that monitoring conducted exclusively by scientists is insufficient to address ongoing environmental challenges. One solution entails the use of mobile digital devices in participatory monitoring (PM) programs. But how digital data entry affects programs with varying levels of stakeholder participation, from nonscientists collecting field data to nonscientists administering every step of a monitoring program, remains unclear. We reviewed the successes, in terms of management interventions and sustainability, of 107 monitoring programs described in the literature (hereafter programs) and compared these with case studies from our PM experiences in Australia, Canada, Ethiopia, Ghana, Greenland, and Vietnam (hereafter cases). Our literature review showed that participatory programs were less likely to use digital devices, and 2 of our 3 more participatory cases were also slow to adopt digital data entry. Programs that were participatory and used digital devices were more likely to report management actions, which was consistent with cases in Ethiopia, Greenland, and Australia. Programs engaging volunteers were more frequently reported as ongoing, but those involving digital data entry were less often sustained when data collectors were volunteers. For the Vietnamese and Canadian cases, sustainability was undermined by a mismatch in stakeholder objectives. In the Ghanaian case, complex field protocols diminished monitoring sustainability. Innovative technologies attract interest, but the foundation of effective participatory adaptive monitoring depends more on collaboratively defined questions, objectives, conceptual models, and monitoring approaches. When this foundation is built through effective partnerships, digital data entry can enable the collection of more data of higher quality. Without this foundation, or when implemented ineffectively or unnecessarily, digital data entry can be an additional expense that distracts from core monitoring objectives and undermines project sustainability. The appropriate role of digital data entry in PM likely depends more on the context in which it is used and less on the technology itself.


Asunto(s)
Computadores , Conservación de los Recursos Naturales , Recolección de Datos , Monitoreo del Ambiente , Australia , Canadá , Etiopía , Ghana , Humanos
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