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2,608 results for “breed”

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dryad36/100

Data from: phenology and environmental determinants of explosive breeding in gliding treefrogs: diel timing of rainfall matters

The influence of abiotic and biotic factors on the temporal pattern of calling and breeding for many temperate anurans is well understood. However, few studies have documented patterns of reproduction in explosive-breeding tropical frogs or incorporated multiple environmental factors in their analyses, especially across multiple breeding seasons. We combine long-term natural history observations and automated data collection methods with boosted regression tree (BRT) analysis to determine the phenology and determinants of explosive breeding in the gliding treefrog, Agalychnis spurrelli. We monitored breeding for a total of 418 days across three breeding seasons and determined the relative importance of several environmental factors on the probability of calling and breeding activity. Our study population of A. spurrelli on Costa Rica's Osa Peninsula forms breeding aggregations up to 11 times per year during 1–2-day long explosive-breeding events, from late May to mid-September. Calling and breeding activity are strongly and positively related to accumulated rainfall during the previous 24 and 48–24 hours before, particularly rainfall during the afternoon and evening. Day-of-year, days since breeding occurred, and lunar phase also influence reproductive activity. This study provides the first description and analysis of the phenology and factors that predict explosive breeding in A. spurrelli and illustrates the value of using automated data collection paired with BRTs for analysis of complex ecological data.

opencc-zeroSep 2023View details →

dryad36/100

Data from: Evaluation of breeding distribution and chronology of North American scoters

Aim: North America's scoter species are poorly monitored relative to other waterfowl. Black (Melanitta americana), surf (M. perspicillata), and white-winged (M. deglandi) scoter abundance and trend estimates are thus uncertain in many parts of these species' ranges. The most extensive source of waterfowl abundance and distribution data in North America is the Waterfowl Breeding Population and Habitat Survey (WBPHS). Although the WBPHS effectively monitors most species, both its timing and geographic coverage may not allow for accurate scoter monitoring. Therefore, our goal was to better define when and where scoters breed to help interpret survey results and optimize survey methods for scoters. Location: Canadian boreal shield, taiga shield, and low-Arctic tundra; Alaska. Taxon: Scoters (Genus: Melanitta) Methods: We integrated satellite telemetry tracking data from scoters marked at multiple molting, staging, breeding, and wintering areas along the Atlantic and Pacific coasts to quantify continent-wide breeding chronology and distribution. We also examined possible drivers of variation in timing of arrival, length of stay, and departure at nesting locations. Results: We documented a northwest-to-southeast distribution of breeding sites across Alaska and Canada. On average, scoters arrived at nest sites on June 1. Surf scoters arrived earliest, stayed for shorter periods, and departed earliest. Pacific-wintering scoters began breeding earlier than Atlantic-wintering birds. Additionally, birds arrived at nesting locations earlier in years with earlier snowmelt, and later snowmelt reduced lengths of stay for males. Breeding chronology also varied by age group, with adults arriving earlier than subadults. Main conclusions: Our study is the first to comprehensively describe spatial variation in timing of breeding of both Atlantic and Pacific populations of all three scoter species across North America. Our results increase our understanding of how current surveys enumerate scoters and will inform possible supplemental efforts to improve continental monitoring of scoter populations.

opencc-zeroSep 2023View details →

dryad36/100

Data from: breeding under pressure: corticosterone is associated with reproductive investment under fluctuating predation risk in a long-lived sea duck

Phenotypic plasticity may enable individuals to cope with predictable and unpredictable environments during their life-cycle. In that context, studying glucocorticoids – corticosterone (CORT) in birds – is relevant because of their primary role in allostasis. Higher baseline CORT levels are classically associated with environmental constraints and lower fitness (the CORT-fitness hypothesis). However, in some environments, higher baseline CORT levels can promote reproduction, therefore being associated with higher fitness (the CORT-adaptation hypothesis). These two hypotheses have been tested in multiple systems, but rarely in a context of fluctuating predation threat. We used a long-term individual-based monitoring of baseline CORT levels in female common eiders Somateria mollissima (nCORT = 1537; nindividual = 790; 2009-2022) to disentangle the context-dependent links between environmental conditions, CORT and fitness. Importantly, the study population has been facing a drastic increase in predation pressure over the past decades, linked to the recovery of the white-tailed eagle Haliaeetus albicilla. Additionally, eiders breed on open or forested islands, further affecting adult and nest predation risk. This system allowed us to disentangle the relative contributions of within- and among-individual variation in baseline CORT levels under predation. Supporting the CORT-adaptation hypothesis, baseline CORT levels were positively associated with reproductive investment (clutch size), age and hatching success. By partitioning within- and among-individual effects, we showed that at the individual level, CORT flexibly increased with clutch size and age. Females displaying higher CORT levels were more successful, suggesting a link between CORT and individual quality. At both the population and individual levels, baseline CORT levels decreased over the study period. This decrease was correlated with an increase in predation risk. Females had reduced baseline CORT when nesting under high eagle abundance or adult predation risk (within-individual effect). Interestingly, apparent plasticity towards adult predation risk was only observed on open islands, likely reflecting habitat-dependent strategies. Consistent with the CORT-adaptation hypothesis, we show that changes in predation regime not only correlate with changes in reproductive investment, but also with rapid plastic adjustment of glucocorticoid levels and therefore individual strategies to cope with predation risk. Given the correlative nature of our study, we encourage further experimental studies testing for a causal relationship between predation and corticosterone levels.

opencc-zeroSep 2023View details →

dryad36/100

Data from: the Siam chicken bioresource project: genetic diversity and origin of Thai chicken breeds

Three separate studies have delved into the genetic characteristics, origins, and unique attributes of various chicken breeds in Thailand, providing crucial insights for future breeding programs. The first study focused on Chee Fah and Fah Luang, black-boned chicken breeds in Chiang Rai, Thailand. Despite their economic and cultural significance, little was known about their genetics. Mitochondrial DNA D-loop sequencing and microsatellite genotyping revealed shared genetic heritage with Chinese black-boned chickens, suggesting their origin. Distinct genetic patterns were identified compared to Thai domestic chickens and red junglefowl, indicating crossbreeding and introgression during domestication. Interestingly, the Chee Fah and Fah Luang chickens from different localities exhibited different gene pool structures, possibly influenced by environmental factors like elevation. The second study centered on the Mae Hong Son chicken, a local breed in Northern Thailand. Genetic analyses, including microsatellite markers and mitochondrial D-loop sequencing, unveiled high genetic diversity and unique allelic gene pool patterns. This breed likely originated as a crossbreed between red junglefowl and Thai indigenous village chickens, adapting to local environmental, social, and cultural conditions. The third study examined Lao Pa Koi (LPK) chickens, a popular fighting breed in Thailand. Genetic diversity assessments using microsatellite markers and mitochondrial DNA (mtDNA) D-loop sequences confirmed high variability and genetic admixture between red junglefowl and Thai domestic chickens. Spatial suitability analysis highlighted the importance of elevation in shaping LPK chicken distribution. In conclusion, these studies collectively enhance our understanding of the genetic foundations, origins, and adaptation of diverse chicken breeds in Thailand. This knowledge is crucial for developing effective breeding programs and preserving these valuable genetic resources.

opencc-zeroSep 2023View details →

zenodo36/100

Mothers in a cooperatively breeding bird increase investment per offspring at the pre-natal stage when they will have more help with post-natal care

In many cooperative societies, including our own, helpers assist with the post-natal care of breeders’ young and may thereby benefit the post-natal development of offspring. Here, we present evidence of a novel mechanism by which such post-natal helping could also have beneficial effects on pre-natal development: By lightening post-natal maternal workloads, helpers may allow mothers to increase their pre-natal investment per offspring. We present the findings of a decade-long study of cooperatively breeding white-browed sparrow-weaver, Plocepasser mahali, societies. Within each social group, reproduction is monopolized by a dominant breeding pair, and non-breeding helpers assist with nestling feeding. Using a within-mother reaction norm approach to formally identify maternal plasticity, we demonstrate that when mothers have more female helpers, they decrease their own post-natal investment per offspring (feed their nestlings at lower rates) but increase their pre-natal investment per offspring (lay larger eggs, which yield heavier hatchlings). That these plastic maternal responses are predicted by female helper number, and not male helper number, implicates the availability of post-natal helping per se as the likely driver (rather than correlated effects of group size), because female helpers feed nestlings at substantially higher rates than males. We term this novel maternal strategy “maternal front-loading” and hypothesize that the expected availability of post-natal help either allows or incentivizes helped mothers to focus maternal investment on the pre-natal phase, to which helpers cannot contribute directly. The potential for post-natal helping to promote pre-natal development further complicates attempts to identify and quantify the fitness consequences of helping.

openother-openSep 2023View details →

dryad36/100

Offspring sex ratio is affected by pre-breeding rainfall and hatching order in a cooperative breeding bird

Selection may favour sex ratio adjustment when the fitness benefits of producing male or female offspring vary. In birds, sex ratio bias at hatching has been particularly well-studied in cooperative breeding species, primarily in helper-at-the-nest systems wherein young remain with their parents and help raise subsequent broods. In these systems, breeding females are expected to skew offspring sex ratio in favour of the helping sex if sufficient resources exist. In communal laying systems multiple group members breed and raise the young and offspring dispersal varies, making it difficult to predict whether and how breeders should skew offspring sex ratio. We tested for sex ratio bias in smooth-billed anis (Crotophaga ani), a communal laying cuckoo with low within-group relatedness, high offspring dispersal, and high annual turnover in group membership. One male performs nocturnal incubation and sires more offspring, suggesting these males may have higher reproductive variance and thus that it may be beneficial for his mate to produce more male offspring. We hypothesized that pre-breeding rainfall influences food availability and thus offspring sex ratio, predicting that breeding females skew production towards the more beneficial sex (i.e., males) in high food years, consistent with the Trivers-Willard hypothesis. Females may also adjust sex ratio across the hatching order, so we predicted a male-bias in first hatched chicks in larger broods that should experience greater competition. Contrary to our first prediction, more male chicks hatched when pre-breeding rainfall was lower. In partial support of our second prediction, marginally more first hatched chicks were male in larger broods. Based on these results, we propose the nestling competition hypothesis and predict that when nestling competition is high (i.e., in poor years and in large joint broods), mothers should produce more of the more competitive sex.

opencc-zeroOct 2023View details →

dryad36/100

The impact of helping experience on helper life-history and fitness in a cooperatively breeding bird

The data and accompanying .R scripts were used to test whether having experience as a helper affected a number of different breeding and fitness related parameters in the Seychelles warbler (Acrocephalus sechellensis) in the paper "The impact of helping experience on helper life-history and fitness in a cooperatively breeding bird." Datasets statusInfo.xlsx: data collected over a focal individual's lifetime. natalInfo.xlsx: data pertaining to the natal environment of the focal bird. lastSeen.xlsx: data used to calculate when the bird was last seen alive. summerIndex.xlsx: data used to determine whether a particular field period was during a summer or winter season. territoryQuality.xlsx: data used to determine the territory quality of each territory during a particular field period. Statistical analyses experiencePrep.R: the script used to prepare the data and calculate the necessary model variables prior to running the analyses. experienceAnalyses.R: the script used to run the analyses and generate the related graphs. More detailed information regarding the contents of each dataset can be found in the READ.ME From this, we found that helping experience had no significant association with any of the metrics considered, except that individuals with helping experience had an older age at first dominance, and dominant females with helping experience had longer lifespans than those that had never helped. In addition, we found that females with co-breeding experience produced more adult offspring (≥1 year old) after acquiring dominance, and had a higher lifetime reproductive success than females that had never co-bred.

opencc-zeroOct 2023View details →

zenodo36/100

Analysis of genome-wide DNA arrays reveals the genomic population structure and diversity in autochthonous Greek goat breeds

Genotyping data in ped and map format (ped/map) for 72 goats and 53,347 genotypes.

opencc-by-4.0May 2019View details →

dryad36/100