Recherche

Van Wijk, Sonia; Bélisle, Marc; Garant, Dany; Pelletier, Fanie — 2015-10-26 The study of iridescent coloration in birds emerged only recently, mainly due to the difficulty inherent in quantifying its directionality. Directionality restrains color perception to a limited angle and thereby causes drastic changes in brightness when an animal is in motion. Although a versatile goniometer for quantifying iridescent coloration has been developed recently, so far, it has only been applied to measuring the highly directional iridescent coloration in a hummingbird species. Thus, the reliability of the goniometer for species displaying more common and less directional iridescent coloration has yet to be evaluated. Additionally, two important methodological aspects remain to be assessed before this apparatus can be used confidently: 1) whether directionality, which could be subject to sexual selection, can be quantified in a repeatable way; and 2) whether the apparatus gives more precise and accurate measurements than a less complex traditional method. Using feathers collected from 271 male tree swallows Tachycineta bicolor over two years, we found that the goniometer provided repeatable measurements of directionality across individuals and across three body regions, namely the crown, mantle and rump. The apparatus was also more repeatable than a traditional method involving a bifurcated probe and reduced a brightness bias associated with individual differences in barbule tilt. We strongly encourage researchers to invest in this methodological change considering the multiple advantages demonstrated and to quantify the directionality of iridescent coloration as to unveil its role in signaling and sexual selection.

Schmitt, Clarence; Garant, Dany; Bélisle, Marc; Pelletier, Fanie — 2017-03-07 Unravelling the genetic basis of phenotypic variation among individuals is an important step in our understanding of evolution. Recent studies of innate immune genes, such as β -defensins, revealed that these genes had high levels of polymorphism. However, researchers have yet to quantify the effects of such variability on immune responses and fitness-related traits in wild populations. In this study, we assessed how the variability at six avian β -defensin (AvBD) genes was linked to an immune function and reproductive success in adult tree swallows (Tachycineta bicolor). We investigated the links between genetic variations using single nucleotide polymorphisms at AvBD genes, immune function as the bacterial killing ability (BKA) and fledging success. We assessed how female immunogenetics were linked to the presence of eggshell bacteria in their clutches and hatching success. We found weak associations between the presence of AvBD genes, BKA and eggshell bacteria. Our results suggested that homozygosity at some loci may be advantageous for defence against bacteria. Variability at β -defensin genes was not related to either hatching or fledging success. BKA of parents was positively linked with fledging success. More studies are needed to assess whether or not β -defensin genes are significantly affecting fitness-related traits in wild populations.

Gervais, Amélie; Courtois, Ève; Fournier, Valérie; Bélisle, Marc — 2020-06-26 <p style="margin-bottom:16px;text-align:justify;">Here, we assessed how the morphology, weight and foraging behavior of individual workers are affected by their surrounding landscape. We hypothesized that colonies established in landscapes showing high cover of intensive crops and low cover of flowering crops, as well as low amounts of local floral resources, would produce smaller workers, which would perform fewer foraging trips and collect pollen loads less constant in species composition. We tested these predictions with 80 colonies of commercially reared <i>Bombus impatiens</i> Cresson placed in 20 landscapes spanning a gradient of agricultural intensification in southern Québec, Canada. We estimated weekly rate at which workers entered and exited colonies and captured eight workers per colony over a period of 14 weeks during the spring and summer of 2016. Captured workers had their wing, thorax, head, tibia, and dry weight measured, as well as their pollen load extracted and identified to the lowest possible taxonomic level. We did not detect any effect of landscape habitat composition on worker morphology or body weight, but found that foraging activity decreased with intensive crops. Moreover, higher diversity of local floral resources led to lower pollen constancy in intensively cultivated landscapes. Finally, we found a negative correlation between the size of workers and the diversity of their pollen load. Our results provide additional evidence that conservation actions regarding pollinators in arable landscapes should be made at the landscape rather than at the farm level.</p>

Courtois, Ève; Bélisle, Marc; Garant, Dany; Pelletier, Fanie — 2022-11-04 <p>Animals are expected to select a breeding habitat using cues that should reflect, directly or not, the fitness outcome of the different habitat options. However, human-induced environmental changes can alter the relationships between habitat characteristics and their fitness consequences, leading to maladaptive habitat choices. The most severe case of such nonideal habitat selection is the ecological trap, which occurs when individuals prefer to settle in poor-quality habitats while better ones are available. Here we studied the adaptiveness of nest box selection in a tree swallow (<i>Tachycineta bicolor</i>) population breeding over a 10-year period in a network of 400 nest boxes distributed along a gradient of agricultural intensification in southern Québec, Canada. We first examined the effects of multiple environmental and social habitat characteristics on nest box preference to identify potential settlement cues. We then assessed the links between those cues and habitat quality as defined by the reproductive performance of individuals that settled early or late in nest boxes. We found that tree swallows preferred nesting in open habitats with high cover of perennial forage crops, high spring insect biomass, and high density of house sparrows (<i>Passer domesticus</i>), their main competitors for nest sites. They also preferred nesting where the density of breeders and their mean number of fledglings during the previous year were high. However, we detected mismatches between preference and habitat quality for several environmental variables. The density of competitors and conspecific social information showed severe mismatches, as their relationships to preference and breeding success went in opposite direction under certain circumstances. Spring food availability and agricultural landscape context, while related to preferences, were not related to breeding success. Overall, our study emphasizes the complexity of habitat selection behavior and provides evidence that multiple mechanisms may potentially lead to an ecological trap in farmlands. </p>

Mazerolle, Marc J.; Dubois-Gagnon, Marie-Pier; Bernatchez, Louis; Bélisle, Marc; Dubois, Yohann — 2021-09-13 <p>The boreal chorus frog (<em>Pseudacris maculata</em>) is at risk of extinction in parts of its range in Canada. Our objectives were to quantify the influence of local and landscape characteristics on the occurrence of the species in wetlands in southern Québec. We hypothesized that site occupancy depends on local characteristics and landscape characteristics contributing to site connectivity. We developed an environmental DNA (eDNA) method to detect the species and compared the detection probability of this method to traditional call surveys. We collected water samples at a total of 180 sites (90 in 2017, 110 in 2018), whereas we surveyed a subset of 63 sites using both eDNA and call surveys in 2018. Site occupancy varied across years, but was higher in sites where the species had been previously detected during the last 12 years by other studies. Site occupancy did not vary with other local and landscape characteristics, in part due to an apparent decrease in the number of sites occupied by the species since the last 12 years. Detection probability via eDNA (0.81; 95% CI: [0.31; 0.98]) did not differ from that of call surveys (0.62; 95% CI: [0.25; 0.89]). To identify the optimal sampling period for the boreal chorus frog, future studies should estimate the detection probability of eDNA during the breeding season and the larval development period of the species.</p> https://creativecommons.org/publicdomain/zero/1.0/

Gow, Elizabeth A.; Burke, Lauren; Winkler, David W.; Knight, Samantha M.; Clark, Robert G.; Bélisle, Marc; Berzins, Lisha L.; Blake, Tricia; Bridge, Eli S.; Dawson, Russell D.; Dunn, Peter O.; Garant, Dany; Holroyd, Geoff; Horn, Andrew G.; Hussell, David J.T.; Lansdorp, Olga; Laughlin, Andrew J.; Leonard, Marty L.; Pelletier, Fanie; Shutler, Dave; Siefferman, Lynn; Taylor, Caz M.; Trefry, Helen; Vleck, Carol M.; Vleck, David; Whittingham, Linda A.; Norris, D. Ryan — 2018-12-13 Latitudinal differences in timing of breeding are well documented but how such differences carry over to influence timing of events in the annual cycle of migratory birds is not well understood. We examined geographic variation in timing of events throughout the year using light-level geolocator tracking data from 133 migratory tree swallows (Tachycineta bicolor) originating from 12 North American breeding populations. A swallow’s breeding latitude influenced timing of breeding, which then carried over to affect breeding ground departure. This resulted in subsequent effects on the arrival and departure schedules at fall stopover locations and timing of arrival at non-breeding locations. This “domino effect” between timing events was no longer apparent by the time individuals departed for spring migration. Our range-wide analysis demonstrates the lasting impact breeding latitude can have on migration schedules but also highlights how such timing relationships can reset when individuals reside at non-breeding sites for extended periods of time.

Bourret, Audrey; Bélisle, Marc; Pelletier, Fanie; Garant, Dany — 2016-12-20 Despite accumulating examples of selection acting on heritable traits in the wild, predicted evolutionary responses are often different from observed phenotypic trends. Various explanations have been suggested for these mismatches. These include within-individual changes across lifespan that can create important variation in genetic architecture of traits and selection acting on them, but also potential problems with the methodological approach used to predict evolutionary responses of traits. Here, we used an 8-year data set on tree swallow (Tachycineta bicolor) to first assess the effects of differences among three nestling life-history stages on the genetic (co)variances of two morphological traits (body mass and primary feather length) and the selection acting on them over three generations. We then estimated the evolutionary potential of these traits by predicting their evolutionary responses using the breeder's equation and the secondary theorem of selection approaches. Our results showed variation in strength and direction of selection and slight changes in trait variance across ages. Predicted evolutionary responses differed importantly between both approaches for half of the trait–age combinations we studied, suggesting the presence of environmentally induced correlations between focal traits and fitness possibly biasing breeder's equation predictions. Our results emphasize that predictions of evolutionary potential for morphological traits are likely to be highly variable, both in strength and direction, depending on the life stage and method used, thus mitigating our capacity to predict adaptation and persistence of wild populations.

Carle-Pruneau, Esther; Garant, Dany; Bélisle, Marc; Pelletier, Fanie — 2021-11-08 <p>Recruitment and dispersal are important demographic rates and studying their determinants is particularly important in the current context of global anthropogenic perturbations. In birds, and especially for migratory species, assessing these rates is challenging because of the difficulties involved in tracking individuals beyond fledging. Here we assessed the determinants of nest box local recruitment and natal dispersal distances in a declining aerial insectivore, the Tree swallow (<em>Tachycineta bicolor</em>). We used a 16-year dataset obtained from the long-term monitoring of a population breeding within a 10,200-km² study system located along a gradient of agricultural intensification in southern Québec, Canada. Yearly nest box local recruitment rates ranged there in between 1.0% and 3.2%. Heavier nestlings who fledged earlier were more likely to recruit. Natal dispersal distances were generally short (mean ± SD = 12.7 ± 13.8 km) in the study system and were influenced by different factors depending on sex. Females dispersed over shorter distances when conspecific occupancy on breeding site was high, while males dispersed farther in the presence of competing House sparrows (<em>Passer domesticus</em>) and when their mother was young. Selection of breeding locations appeared to take place at multiple scales and individuals recruited in sites with characteristics similar to their natal sites. Our results provide important information concerning the factors influencing nest box local recruitment and natal dispersal dynamics of this migratory species. These factors should be considered in conservation practices for this species in order to support production of recruits in habitats favorable to their survival.</p>

Rioux Paquette, Sébastien; Pelletier, Fanie; Garant, Dany; Bélisle, Marc — 2014-04-25 Migratory bird species that feed on air-borne insects are experiencing widespread regional declines, but these remain poorly understood. Agricultural intensification in the breeding range is often regarded as one of the main drivers of these declines. Here, we tested the hypothesis that body mass in breeding individuals should reflect habitat quality in an aerial insectivore, the tree swallow (Tachycineta bicolor), along a gradient of agricultural intensity. Our dataset was collected over 7 years (2005–2011) and included 2918 swallow captures and 1483 broods. Analyses revealed a substantial decline of the population over the course of the study (−19% occupancy rate), mirrored by decreasing body mass. This trend was especially severe in females, representing a total loss of 8% of their mass. Reproductive success was negatively influenced by intensive agriculture, but did not decrease over time. Interestingly, variation in body mass was independent of breeding habitat quality, leading us to suggest that this decline in body mass may result from carry-over effects from non-breeding areas and affect population dynamics through reduced survival. This work contributes to the growing body of evidence suggesting that declines in migratory aerial insectivores are driven by multiple, complex factors requiring better knowledge of year-round habitat use.

Pellerin, Stéphanie; Rioux Paquette, Sébastien; Pelletier, Fanie; Garant, Dany; Bélisle, Marc — 2015-12-11 Egg production is a costly component of reproduction for female birds in terms of energy expenditure and maternal investment. Because resources are typically limited, clutch size and egg mass are expected to be constrained, and this putative trade-off between offspring number and size is at the core of life history theory. Nevertheless, empirical evidence for this trade-off is equivocal at best, as individual heterogeneity in resource acquisition and allocation may hamper the detection of the negative correlation between egg number and mass within populations. Here, we investigated how female body mass and landscape composition influences clutch size, egg mass, and the relationship between these two traits. To do so, we fitted linear mixed models using data from tree swallows Tachycineta bicolor breeding in a network of 400 nestboxes located along a gradient of agricultural intensity between 2004 and 2011. Our dataset comprised 1463 broods for clutch size analyses and 4371 eggs (from 847 broods laid between 2005–2008) for egg mass analyses. Our results showed that agricultural intensity negatively impacted clutch size, but not egg mass nor the relationship between these two traits. Female mass, on the other hand, modulated the trade-off between clutch size and egg mass. For heavier females, both traits increased jointly, without evidence of a trade-off. However, for lighter females, there was a clear negative relationship between clutch size and egg mass. This work shows that accounting for individual heterogeneity in body mass allows the detection of a clutch size/egg mass trade-off that would have remained undetected otherwise. Identifying habitat and individual effects on resource allocation towards reproductive traits may help bridging the gap between predictions from theory and empirical evidence on life history trade-offs.

Jain, Aditya; Cunha, Fagner; Bunsen, Michael James; Cañas, Juan Sebastián; Pasi, Léonard; Pinoy, Nathan; Helsing, Flemming; Russo, JoAnne; Botham, Marc; Sabourin, Michael; Frechette, Jonathan; Anctil, Alexandre; Lopez, Yacksecari; Navarro, Eduardo; Pimentel, Filonila Perez; Zamora, Ana Cecilia; Silva, José Alejandro Ramirez; Gagnon, Jonathan; August, Tom; Bjerge, Kim; Segura, Alba Gomez; Bélisle, Marc; Basset, Yves; McFarland, Kent P.; Roy, David; Høye, Toke Thomas; Larrivée, Maxim; Rolnick, David — 2024-06-26 The dataset created as part of the work "Insect Identification in the Wild: The AMI Dataset". The arXiv version is available here. The AMI (Automated Monitoring of Insects) dataset, consists of two parts: 1) AMI-GBIF, a dataset of ∼2.5M human-captured insect images curated from citizen science platforms and museum collections, 2) AMI-Traps, an expert-annotated dataset of 2,893 insect camera trap images (representing 52,948 labeled insects) collected from a global network of automated camera traps, designed to test in-the-wild performance. https://opensource.org/licenses/MIT