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Predicted values from a linear mixed effect model estimating the birth mass (kg) of captive white-tailed deer at Kerr Wildlife Management Area, Kerr County, Texas, USA from 1977–2012. Predicted birth mass was estimated across the range of each variable deemed important while controlling for all other variables (variable constants included: Maternal age = 4, Litter type = female singleton, Study program = study program 1, and December temperature = 16.0°C). The solid lines represent the predicted estimate for birth mass and the dashed lines are the standard error envelopes for the estimates. Random effects were treated as categorical variables and included a unique identifier for each mother and the year of birth for each fawn.
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Natal features (e.g. Julian birth date and birth mass) often have fitness consequences and can be influenced by endogenous responses by the mother to seasonal fluctuations in nutritional quality and photoperiodic cues. We sought to further understand the biological and environmental factors that influence the natal features of a polytocous species...
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Population dynamics studies and harvesting strategies often take advantage of body size measurements. Selected elements of the skeletal system such as mandibles, are often used as retrospective indices to describe body size. The variation in mandibular measurements reflects the variation in the ecological context and hence the variation in animal p...
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... Maternal effects are the influences of the dams (mother) phenotype on offspring phenotype (Wolf and Wade 2009). In ungulates, offspring born to older dams tend to be heavier and have increased survival rates compared to those born to younger dams (Clutton-Brock 1984;Ozoga and Verme 1986;Verme 1989;Bårdsen et al. 2009;Wolcott et al. 2015). Older dams have already reached asymptotic body mass and unlike younger, sexually mature females do not have to allocate energy into somatic growth as well as the developing offspring. ...
... In Alaskan Moose (Alces alces gigas) litter size was inversely related to offspring survival to 1 year of age and offspring survival was positively related to birth mass (Keech et al. 2000). Wolcott et al. (2015) showed that variation in litter size and sexual composition, or litter type, influenced birth mass in Whitetailed Deer (Odocoileus virginianus). White-tailed Deer males born in singleton litters were, on average, heavier than males born to twin male or mixed-sex litters (Wolcott et al. 2015). ...
... Wolcott et al. (2015) showed that variation in litter size and sexual composition, or litter type, influenced birth mass in Whitetailed Deer (Odocoileus virginianus). White-tailed Deer males born in singleton litters were, on average, heavier than males born to twin male or mixed-sex litters (Wolcott et al. 2015). But how maternal effects such as litter type and maternal age affect antler scaling relationships has yet to be examined. ...
Antlers are a costly trait that require skeletal reserves to grow to a large size. Thus, insight into variation in antler size requires understanding the connection between antler and body size, which can be summarized through ontogenetic and static scaling relationships. Both types of scaling relationships are also needed to examine the influence of factors besides body mass on antler growth at different ages and whether the effects of these factors diminish with age. Dietary and maternal effects might decline with age as individuals attempt to mitigate size deficits. We examined the potential effects of diet and maternal attributes of dam (mother) age at birth and litter size on body–antler mass relationships throughout ontogeny and at discrete ages. Data on age, maternal characteristics, body mass, and antler mass were gathered from captive, pen-raised White-tailed Deer (n = 168) that consumed either a low-energy (1.77 kcal/g) or standard-energy diet (2.65 kcal/g) from the time they were weaned until they perished by 5.5 years of age. Both types of scaling relationships were estimated with linear mixed-effects models to account for repeated measurements of males, dams, and sires. Diet affected ontogenetic scaling relationships. Males eating the low-energy diet had faster antler growth when young and lighter in body mass than when they were older and heavier—whereas males fed the standard-energy diet had a similar rate of antler growth across the range of body masses. A Bayesian Information Criterion model selection analysis indicated that diet and litter size (singleton, multiple births), but not dam age at birth influenced static scaling relationships. Static scalar coefficients up to 3.5 years of age were positively allometric (>1.0), but isometric (1.0) in 4.5- and 5.5-year-old males. Furthermore, diet and litter size influenced both intercepts and slopes in only the youngest males (1.5 years) indicating that dietary and maternal effects can diminish with age. Body–antler mass relationships are complex. Young males that are small because of maternal effects, for example, might still be able to mitigate smaller body and antler sizes at older ages.
... In addition, according to the level of synchrony of births of the cohort (i.e., the group of individuals born during the same reproductive cycle and sharing the same early conditions for their development) and the density of the population, offspring are more or less subject to competition (Hodges 2008, Rasmussen andRudolf 2015). More generally, the timing of birth is an indicator of the condition experienced by the mother during pregnancy, and thus determines critical components of the offspring survival, such as birth mass, mediated by environmental and maternal effects (Wolcott et al. 2015). Early survival is generally the result of an interaction between all those factors (e.g., ). ...
The phenology of births corresponds to the study of the position and duration of the period of births, related to its drivers and consequences on individuals and populations. Mainly regulated by environmental, biotic and internal factors through evolutionary processes and phenotypic adjustments, the date of birth has short- and long-term implications on individual survival and reproductive success. The phenology of births also affects population dynamics. Although the study of the phenology of births is an old discipline, it still arouses strong interest nowadays because of its sensitivity to climate change. The methods employed to study phenology are constantly progressing, but numerous interrogations remain regarding the diversity of phenology of births encountered in natura and the modifications to which they are exposed. The aim of this thesis is to study the phenology of births, from the validation of sampling methods to the identification of the ecological and evolutionary processes associated, with large herbivores as a case study.In the first chapter, I studied the ability of non-specialist volunteers to identify the presence or absence of young individuals in pictures produced by a camera trap grid located in Serengeti National Park, Tanzania. Some limitations still need to be accounted for before using such dataset to reconstruct phenology of births. In the second chapter, I explored and compared the different methods used to describe the phenology of births in large herbivores using simulated data. I reassessed the framework for studying phenology in terms of concepts and mathematical description, discussed the diversity of metrics, and proposed guidelines to help identify the most suitable method. In the third chapter, I explored the consequences of the timing of birth on the juveniles, yearlings and mares survival in plain zebras living in Hwange National Park, Zimbabwe. Survival decreased with an increasing proportion of time spent in dry season. Thus, climate change could have a detrimental effect on the population dynamics because of their phenology of births.Using direct observation data can be associated with several methodological limitations, but it is possible to account for them. Allometric relationships can also reduce the comparability of the studies between small and large organisms, and it could be interesting to account for this factor. Eventually, the study of the phenology of births is of major interest to understand the risks to which wild populations are exposed because of climate change. Involving the general public through citizen science is a great tool to raise awareness about such issues.
... Most ungulate populations, or at least those living at latitudes with clear day length variations throughout the year, typically show a tight reliance on photoperiod to trigger their reproduction (Zerbe et al. 2012). Nevertheless, evidence that favorable environmental and nutritional conditions facilitate a slightly earlier reproduction was frequently reported even in species whose predominant cue is photoperiodism (McGinnes and Downing 1977;Hamilton and Blaxter 1980;Flydal and Reimers 2002;Wolcott et al. 2015). Thus, a certain degree of plasticity in the reproductive timing (hereafter RT, always referred to the population level) seems to be quite spread among ungulate species and this can be expected to produce temporal displacements of breeding seasons among different years. ...
... Ovulation and pregnancy RTs were substantially anticipated under good environmental conditions (i.e., higher resources availability and warmer spring temperatures) in both age classes (Figure 2), thus showing the high degree of ecological plasticity of wild boar reproductive phenology. The physiological phenomenon was likely mediated by individual nutritional conditions (McGinnes and Downing 1977;Hamilton and Blaxter 1980;Flydal and Reimers 2002;Wolcott et al. 2015), which were directly improved either by resource abundance or by the advanced vegetation growth due to high spring temperatures. ...
On a population-level, individual plasticity in reproductive phenology can provoke either anticipations or delays in the average reproductive timing in response to environmental changes. However, a rigid reliance on photoperiodism can constraint such plastic responses in populations inhabiting temperate latitudes. The regulation of breeding season length may represent a further tool for populations facing changing environments. Nonetheless, this skill was reported only for equatorial, non-photoperiodic populations. Our goal was to evaluate whether species living in temperate regions and relying on photoperiodism to trigger their reproduction may also be able to regulate breeding season length. During 10 years, we collected 2,500 female reproductive traits of a mammal model species (wild boar Sus scrofa) and applied a novel analytical approach to reproductive patterns in order to observe population-level variations of reproductive timing and synchrony under different weather and resources availability conditions. Under favorable conditions, breeding seasons were anticipated and population synchrony increased (i.e., shorter breeding seasons). Conversely, poor conditions induced delayed and less synchronous (i.e., longer) breeding seasons. The potential to regulate breeding season length depending on environmental conditions may entail a high resilience of the population reproductive patterns against environmental changes, as highlighted by the fact that almost all mature females were reproductive every year.
... Environmental conditions during gestation and after birth (Wolcott et al. 2015), including those affected by parental behavioural decisions, can influence reproductive success (McNamara andHouston 1986, Byers andHogg 1995). For instance, choice of rearing habitat can be pivotal for offspring early survival (Refsnider and Janzen 2010). ...
Predator avoidance and food availability are both factors known to influence habitat selection and site fidelity around calving in caribou and reindeer. Here, we assess habitat selection and site fidelity during the calving period in the solitary, Arctic Svalbard reindeer Rangifer tarandus platyrhynchus, which is subject to limited predation risk and human disturbance. In this largely predator-free environment, we explore and discuss if habitat selection during the first week after calving is driven by food availability or remnants of anti-predatory behaviour. Based on GPS-collar data and ultrasound scanning (2009–2017; n = 134 individual-years) from two study areas, we estimated individual calving dates using recursive partitioning and first passage time and compared habitat selection and site fidelity of reproductive versus non-reproductive females. The K-select analysis suggested similar habitat selection during calving in reproductive and non-reproductive females. Female reindeer generally selected for lowland, flat habitats with high proportion of heath and moss tundra, i.e. habitats typically rich in terms of forage plants. Individuals producing a calf had significantly higher site fidelity in the calving period compared to the null model, and the mean distance between consecutive years' calving areas ranged between 1.5 and 3.9 km. Our study provides support for the prediction that in the absence of significant predation, ungulate calving site selection in the Arctic is mainly driven by the availability of spatially and temporally varying food resources.
... Animal pregnancy and parturition are costly physiological processes, and the total energy consumption during reproduction is affected by litter size (Millar et al. 2004), while the litter type (i.e. litter size and sex ratio) is associated with parturition timing (Wolcott et al. 2015). In dioecious monogamous species, son-producing females gave birth later; while for polyembryonic species, the effect of litter size on parturition timing is also influenced by offspring sex. ...
... In dioecious monogamous species, son-producing females gave birth later; while for polyembryonic species, the effect of litter size on parturition timing is also influenced by offspring sex. For example, for white-tailed deer (Odocoileus virginianus), females who had mixedsex twins delivered significantly earlier than those that had single-sex twins or singletons, while the parturition timing of females with single-sex twins did not differ from those with singletons (Wolcott et al. 2015). Our study showed that in the captive forest musk deer of HMDF the parturition date of females who gave birth to singletons was slightly (i.e., 1-day) later than in those who gave birth to twins. ...
Reproductive rhythms, as a response to environmental seasonality, may maximize the survival possibility of both newborns and parents, which is vital for ex situ conservation and sustainable management in wildlife. Forest musk deer (Moschus berezovskii) is a critically endangered ungulate of China. In order to estimate its reproduction characteristics and performance in northern China, a historical distribution area, the parturition pattern of the northernmost captive forest musk deer in Huailai Musk Deer Farm from 2017 to 2018 was analyzed. We found that the parturition of forest musk deer was highly seasonal with a peak on May 27<sup>th</sup>, and 75% of parturitions were completed within 22 days from May to June, which could be an adaptation to the seasonality of local food resources. The parturition peak was four weeks before the best hydrothermal conditions when food resources were maximally provided. The time lag between the parturition date and the peak of food availability was affected by climatic conditions during lactation as warmer temperatures in the 4<sup>th</sup> and 5<sup>th</sup> week and heavier precipitation in the 4<sup>th</sup> week of lactation shortened the time lag by five days (P < 0.05). The synchronization between parturition rhythms and seasonality of climatic conditions indicated that the forest musk deer could be farmed in Northeastern Taihang Mountains and northern China, where there is a suitable climate for the musk deer reproduction. Sustainable musk production and musk deer release into the wild where there are suitable climatic conditions has been proved to be practicable, which can benefit the ex situ conservation of endangered forest musk deer and musk resources sustainability.
... Thus, there are many risk factors for GC; however, the epidemiological characteristics of GC are still largely uncertain. Evaluating the season of a person's birth has revealed that environmental factors in the antenatal and early postnatal periods, including nutrition, weather conditions, lighting, exposure to infectious agents and other factors (Wolcott et al. 2015), have significant effects on the physiology and pathology of the human body (Cervellin et al. 2016;Luykx et al. 2012;Park et al. 2016;Watson and McDonald 2007). ...
Birth season is an important risk factor for several cancers; for example, anatomic subsite risk factors for gastric cancer differ substantially by when patients were born. In this population-based retrospective study, we explored the relationship between birth season and gastric cancer of different anatomical sites, focusing on gastric cancer patients who were registered at the Beijing Institute for Cancer Research from 2003 to 2012. In total, 19,668 patients were divided into three groups according to the anatomical site of the primary lesion: cardia (n = 3911), noncardia (n = 5383) and unknown (n = 10,374). The 5383 patients in the noncardia group were further subdivided into the following subgroups: fundus (n = 455), corpus (n = 902), greater curvature (n = 110), lesser curvature (n = 512), antrum (n = 2635), pylorus (n = 106) and overlapping (n = 663). Finally, all gastric cancer cases, the three major groups, and the seven noncardia subgroups were, respectively, compared with inpatients from the Dongzhimen Hospital of Beijing from 2003 to 2013. A logistic regression method with sex and age as control factors was used to evaluate the relationship between birth season and gastric cancer with the level for statistical significance set at P < .05. Taking winter as the reference season, we found people born in summer had a lower probability of developing gastric cancer (summer: odds ratio [OR] = 0.925, 95% confidence interval [CI] = 0.875-0.978, P = .006). Among the three groups, the noncardia group had the lower probability of birth season being spring or summer (spring: OR = 0.917, 95% CI = 0.843-0.997, P = .042; summer: OR = 0.883, 95% CI = 0.810-0.962, P = .004), but the cardia and unknown anatomical groups showed no statistical significance for season of birth (P > .05). Among the seven subgroups, those born in summer were less likely to develop gastric cancer in the antrum and lesser curvature than those born in winter (antrum: OR = 0.861, 95% CI = 0.766-0.968, P = .012; lesser curvature: OR = 0.746, 95% CI = 0.579-0.961, P = .023); the other subgroups showed no significant differences by season of birth (P > .05). This study demonstrated that gastric cancer is related to birth season. For people born in summer, the risk of developing gastric cancer was comparatively lower than for people born in winter. Seasonal differences in immune function and maternal nutrition status during pregnancy may explain these findings; however, further large-scale prospective studies will be required to validate these findings.
... Multifactorial elements play a considerable part and complicate LBW newborn care, such as chronic family poverty leading to food insecurity, limited qualified and skilled healthcare providers (HCPs), insufficient equipment at health facilities, and lack of pregnant women's prosperity leading to future hopelessness. [1,7,10] Fortunately, Rwanda has the political will to strengthen MCH through different initiatives and strategies. In 2015, the Millennium Development Goals (MDG) era finished, and Rwanda achieved great success. ...
Background Low birth weight (LBW) is a major public health problem worldwide that is linked to childhood morbidity and mortality. Newborns considered ‘Very LBW’ have a high risk of disease and death during infancy. Maternal socioeconomic status, medical factors, and lifestyle are linked to LBW, but these factors remain unknown in Rwanda is unknown. Objective To describe the factors associated with LBW among newborns at a selected referral hospital in Rwanda. Methods A prospective, cross-sectional design study was used to assess 108 mothers who delivered a low birth weight newborn. Results Mothers had a mean age of 30.6 years, 79.6% married, 23.1% primary educated, 50.6% unemployed, and 61.9% lived in a rural area. The majority of LBW (63%) were in the first category of LBW (2500-1500g), and over a quarter (25.9%) with Very LBW (VLBW). Mothers were 89.7% multigravida, and 88.8% had a previous unsuccessful pregnancy, 81.3% premature birth, 97.9% LBW. Over half, 59.8% had hypertension during pregnancy. Lifestyle included 45.5% doing strenuous work, and 50.9% heavy lifting during pregnancy. The level of education (p=0.009), spouse employment (p=0.017), having previous premature baby (p=0.025), previous history of miscarriage (p=0.028), presence of hypertension (p=0.020) and antenatal care visits (p=0.025) the trimester of miscarriage were significantly associated to type of low birth weight. Conclusion Demographic, pregnancy history and lifestyle factors remain a concern to mothers and neonates born with low birth weight. Educational awareness campaigns among mothers with the factors above are crucial to reduce morbidity and mortality related to low birth weight. Rwanda J Med Health Sci 2020;3(2):214-224
... This suggests that animals would still be sensitive to weather conditions as environmental cues to adjust their reproductive phenology. In a recent study, environmental factors were shown to affect Julian birth date and birth mass of white-tailed deer (Odocoileus virginianus) even though mothers were continuously allowed access to a high-quality diet [65]. ...
Background:
The breeding time of many species has changed over the past 2-3 decades in response to climate change. Yet it is a key reproductive trait that affects individual's parturition time and reproductive success, and thereby population dynamics. In order to predict how climate change will affect species' viability, it is crucial to understand how species base their reproductive efforts on environmental cues.
Results:
By using long-term datasets of mating behaviours and copulation dates recorded since 1996 on a semi-domesticated reindeer population, we showed that mating time occurred earlier in response to weather conditions at different key periods in their annual breeding cycle. The mating time occurred earlier following a reducing snow cover in early spring, colder minimum temperatures in the last 2 weeks of July and less precipitation in August-September.
Conclusions:
The mediated effect of a reduced snow cover in early spring on improving individuals' pre-rut body weight through a better availability of late winter food and reduced costs of locomotion on snow would explain that mating time has occurred earlier overtime. A lower level of insect harassment caused by colder maximum temperatures in July might have caused an advance in mating time. Less precipitation in August-September also caused the mating time to occur earlier, although the direct effects of the last two weather variables were not mediated through the pre-rut body weight of individuals. As such, the causal effects of weather conditions on seasonal timing of animals are still unclear and other mechanisms than just body weight might be involved (e.g. socio-biological factors). The plastic response of reindeer mating time to climatic variability, despite supplemental feeding occurring in late April, demonstrated that environmental factors may have a greater influence on reproductive outputs than previously thought in reindeer.
... According to the developmental origins of health and disease (DOHAD), there were causal associations between disadvantageous environmental factors in antenatal and early postnatal periods and many chronic diseases in later life (Barker, 2007). As an environmental factor, such as nutrition, weather conditions, lighting, and exposure to infectious agents (Wolcott, Reitz, & Weckerly, 2015), season of birth has been associated with the risk of adverse psychiatric and neurological outcomes (Castrogiovanni, Iapichino, Pacchierotti, & Pieraccini, 1998;Disanto et al., 2012). For example, one of the potential pathways may be different sun exposure in early life phases, due to seasonal change, which may affect vitamin D levels in human body (Palladino et al., 2015), which have been found to be correlated with the risk of different neurological disorders. ...
Objectives:
Previous studies showed inconsistent results regarding the association between season of birth and dementia later in life. Evidence has mainly come from developed countries with relatively homogeneous geographical features. In this study, we examined the association between season of birth and dementia among Chinese elderly as well as geographical region-specific and urban/rural-specific patterns.
Methods:
We utilized data from the Second China National Sample Survey on Disability in 2006, and employed multivariate logistic regression to estimate the association between dementia and birth seasonality. We conducted subsample analyses by urbanity and geographical region.
Results:
This study included 354 859 Chinese elderly aged 60 and above. Compared with the summer-born, the odds of dementia were significantly lower among those born in winter (OR: 0.82, 95% CI: 0.70, 0.96). Similar associations were also found in urban and northern subsamples.
Conclusion:
Winter birth was associated with a lower prevalence of dementia in old age, especially among those living in urban and northern areas of China. This association further suggests the critical role of early life period and environment on health in later life.
... This suggests that animals would still be sensitive to climatic conditions as environmental cues to adjust their reproductive phenology. In a recent study, environmental factors were shown to affect Julian birth date and birth mass of white-tailed deer (Odocoileus virginianus) even though mothers were continuously allowed access to a high-quality diet (Wolcott et al. 2015). The study on white-tailed deer therefore demonstrated first that environmental factors may have a greater influence on reproductive outputs than previously supposed in ungulates and that constant supplemental feeding was not enough to curtail the environmental effects on reproductive traits. ...
The timing of reproduction in plant and animal species is a strong determinant of offspring viability and reproductive success. The large changes in climate reported the last decades could therefore have unprecedented consequences on population dynamics. The breeding time of many species have changed over the past two to three decades in response to climate change, and a developing trophic mismatch between the peak of energy demands by reproducing animals and the peak of forage availability has caused many species’ reproductive success to decrease. The main aim of this thesis was to determine how reproductive phenology of reindeer (Rangifer tarandus) responds to the changes in its environment and whether there could be resulting fitness consequences. Using long-term datasets of 45 years of birth dates, 13 years of mating behaviors and 14 years of copulation dates of a semi-domesticated reindeer population in Kaamanen,
northern Finland, I showed that both the reindeer timing of mating and timing of calving have occurred earlier over time, in response to climate. Climatic variables at four key periods in the reproductive cycle of reindeer were identified as driving the changes in reindeer breeding phenology: winter, late winter/early spring, summer and autumn. Those phenological changes allowed reindeer to keep track of its changing environment, leading to an improvement in females’ reproductive success. I also found a “head-start” benefit with some females always doing better than others do. However, a later vegetative senescence in autumn negatively affected females’ physical condition in winter and the subsequent calf’s birth weight and calf’s first-summer survival. If climatic changes were to exacerbate, the population dynamics of several ungulate species will certainly be affected.
