Female Reproductive Status Research Articles

Female Reproductive System and Thyroid Dysfunction: Findings from a 12-Year Follow-Up in the Tehran Thyroid Study.

Background: The impact of thyroid dysfunction (TD) on the female reproductive system has been extensively documented. While there is evidence suggesting that alteration in female reproductive status may affect thyroid function, conflicting results have prevented definitive conclusions. This study aimed to investigate the associations of parity, spontaneous abortion (mentioned as abortion throughout this study), and menopause status with the prevalence and incidence of TD. Methods: From the Tehran thyroid study population, 2711 participants were included in the cross-sectional analysis to explore associations between female reproductive status and TD. Overall, 2191 participants with euthyroid were included in the survival study and followed up in 3-year intervals. Multinomial logistic regression was adopted in cross-sectional analysis and multivariable Cox proportional hazard model was used to determine associations between the incidence of TD with parity, abortion, and menopause status, adjusting for age, smoking, body mass index, and thyroid peroxidase antibodies positivity. Results: At the baseline, multiple parities (≥4) were significantly associated with overt hypothyroidism (odds ratio [OR] = 1.12; confidence interval [CI] 1.0-1.26) and subclinical hyperthyroidism (OR = 1.11 [CI 1.03-1.21]). Furthermore, multiple abortions were associated with overt hyperthyroidism (OR = 2.09 [CI 1.02-4.26]). Over the course of the study, multiple parities were significantly associated with the incident subclinical and clinical hypothyroidism. Conversely, a history of abortion was associated with a reduced risk of incident overt hypothyroidism. We found no significant association between menopause status and the prevalence or incidence of either hypothyroidism or hyperthyroidism. Conclusions: Our results suggest that the female reproductive system may be associated with thyroid function. Parity and abortion are associated with the occurrence of TD. A deeper understanding of the underlying mechanisms of the cellular and molecular alterations in signaling cascades during pregnancy is necessary to fully elucidate these associations.

Temporal variation and age influence activity budget more than sex and reproductive status in wild brown howler monkeys (Alouatta guariba clamitans) inhabiting a large, continuous forest.

Activity budget analyses are important for understanding how animals spend their time in daily activities like resting, foraging, moving and socializing. These behaviors are closely linked to energy management, so habitat quality and resource availability are known to influence the activity budgets of species. Therefore, many studies have examined the consequences of habitat loss and fragmentation on the energetic demands and activity budgets of species. However, we still have limited knowledge of how animals behave in large, continuous, and protected environments, as such habitats are currently rare. The present study analyzed how temporal variation, age, sex and reproductive status influenced the activity budget of wild red howler monkeys (Alouatta guariba clamitans), in one of the last Atlantic Forest remnants that remains large and protected. Between November 2017 and December 2018, we monitored two groups, G3 and G4, in Parque Estadual Carlos Botelho, São Paulo, Brazil. The groups were composed of one adult male, two adult females and their offspring and one (G3) or two (G4) subadult males, using scan sampling for behavioral for data collection every 20min. The most common behavior was resting, followed by foraging, moving and social interactions, with inter-group differences. Temporal variation explained most of the fluctuations in the activity budget, so did age and sex, but to a lesser degree. The reproductive status of females did not alter their activity budget. These findings reveal that even neighboring groups display distinct and intricate relationships with their habitat. Future studies should be conducted in continuous forests to determine what is the expected range of variation in activity budget, particularly in those species considered as flexible and inhabiting endangered habitats, such as the Atlantic Forest.

POPULATION DYNAMICS OF ENTERIC PARASITES IN THE ENDANGERED VANCOUVER ISLAND MARMOT (MARMOTA VANCOUVERENSIS).

Enteric parasites can have wide-ranging effects throughout an ecosystem, often driving coevolutionary and ecological processes. Parasites have long been overlooked in conservation efforts because of the negative impact inflicted on their hosts; however, parasites make up a significant component of Earth's biodiversity and host conservation efforts need to be parasite inclusive. The Vancouver Island marmot (VIM), Marmota vancouverensis, is an endangered alpine rodent endemic to Vancouver Island, British Columbia, Canada. Captive-bred VIMs are released to augment the wild population, but their susceptibility to parasites is unknown. The objectives of this study were to describe the diversity, prevalence, severity, and temporal variation of VIM enteric parasites. Noninvasive fecal samples were collected from wild and captive marmots and analyzed using a modified McMaster fecal egg floatation technique to indicate parasite prevalence and relative mean abundance. We identified oocysts and ova from 3 parasite taxa including a protozoan coccidium not previously described in the VIM (prevalence 68%), an ascarid nematode Baylisascaris laevis (prevalence 82%), and an anoplocephalid cestode Diandrya vancouverensis (prevalence 8%). Depending on the species, comparisons revealed variation in parasite infection by sex, by colony, and between wild and captive VIMs, but not among age classes or by female reproductive status. Finally, captive VIMs displayed significant monthly variation in parasite prevalence and mean egg abundance, suggesting a seasonal influence on parasite egg shedding. This information is critically important for future research investigating the influences of these trends on the health, ecology, and conservation of VIMs and their parasites.

Impact of climate change on the reproductive diapause and voltinism of the carrot weevil, Listronotus oregonensis

The impacts of climate change on the development of insects are of great concern due to potential alterations in population dynamics and pest pressure. The carrot weevil, Listronotus oregonensis, is a major agricultural pest, and its development is influenced by temperature and photoperiod. In this study, our aim was to investigate the impact of temperature increases on the voltinism and reproductive diapause of the carrot weevil under field conditions and bioclimatic models. Field observations were conducted over two growing seasons using structures that allowed for temperature increases. The developmental stages of the carrot weevil, including female reproductive status, oviposition and larval stage, were monitored weekly to measure the proportion of individuals undergoing an additional generation. Concurrently, bioclimatic models were used to simulate the probability of a second generation under current (1981–2010) and future (2041–2070) climates, considering a lower and a higher change in emission scenarios. Results showed that rising temperatures led to an increase in the proportion of carrot weevils undergoing inhibition of the reproductive diapause and a higher number of eggs laid in the field. The models indicated a substantial rise in the probability of a second generation developing, from 24% to 37% to 62%–99% under current and future climates, respectively. These findings demonstrate the potential for significant alterations in carrot weevil population dynamics, resulting in increased pest pressure on crops. Further research is needed to fully understand the implications of these findings and to develop effective adaptation measures to mitigate the negative impacts of global warming on insect populations and agriculture.

Reproductive factors and subsequent pregnancy outcomes in patients with prior pregnancy loss

BackgroundAt present, individualized interventions can be given to patients with a clear etiology of pregnancy loss to improve the subsequent pregnancy outcomes, but the current reproductive status of the patient cannot be changed. The aim of this study was to investigate the association between female reproductive status and subsequence pregnancy outcome in patients with prior pregnancy loss (PL).MethodsA prospective, dynamic population cohort study was carried out at the Second Hospital of Lanzhou University. From September 2019 to February 2022, a total of 1955 women with at least one previous PL were enrolled. Maternal reproductive status and subsequent reproductive outcomes were recorded through an electronic medical record system and follow-up. Logistic regression was used to evaluate the association between reproductive status and the risk of subsequent reproductive outcomes.ResultsAmong all patients, the rates of subsequent infertility, early PL, late PL, and live birth were 20.82%, 24.33%, 1.69% and 50.77% respectively. In logistic regression, we found that age (OR 1.08, 95% CI 1.04–1.13) and previous cesarean delivery history (OR 2.46, 95% CI 1.27–4.76) were risk factors for subsequent infertility in patients with PL. Age (OR 1.06, 95% CI 1.03–1.10), age at first pregnancy (OR 1.06, 95% CI 1.03–1.10), BMI (OR 1.06, 95% CI 1.02–1.11), previous PL numbers (OR 1.18, 95% CI 1.04–1.57) and without pre-pregnancy intervention (OR 1.77, 95% CI 1.35–2.24) were risk factors for non-live birth. Age (OR 1.06, 95% CI 1.03–1.09), age at first pregnancy (OR 1.06, 95% CI 1.02–1.09), BMI (OR 1.07, 95% CI 1.02–1.11), previous PL numbers (OR 1.15, 95% CI 1.02–1.31) and without pre-pregnancy intervention (OR 2.16, 95% CI 1.65–2.84) were risk factors for PL.ConclusionsThe reproductive status of people with PL is strongly correlated with the outcome of subsequent pregnancies. Active pre-pregnancy intervention can improve the subsequent pregnancy outcome.Trial registrationThis study was registered in the Chinese Clinical Trial Registry with the registration number of ChiCTR2000039414 (27/10/2020).

Reproductive state alters vocal characteristics of female North American red squirrels (Tamiasciurus hudsonicus)

Abstract Female advertisement of reproductive state and receptivity has the potential to play a large role in the mating systems of many taxa, but investigations of this phenomenon are underrepresented in the literature. North American red squirrels (Tamiasciurus hudsonicus) are highly territorial and engage in scramble competition mating, with males converging from spatially disparate territories to engage in mating chases. Given the narrow estrus window exhibited in this species, the ubiquitous use of vocalizations to advertise territory ownership, and the high synchronicity of males arriving from distant territories, we hypothesized that female vocalizations contain cues relating to their estrous state. To test this hypothesis, we examined the spectral and temporal properties of female territorial rattle vocalizations collected from females of known reproductive condition over 3 years. While we found no distinct changes associated with estrus specifically, we did identify significant changes in the spectral characteristics of rattles relating to both female body mass and reproductive state relative to parturition. To the best of our knowledge, this is the first evidence of changes in vocal characteristics associated with late pregnancy in a nonhuman mammal.

Analytical and biological validation of a noninvasive measurement of glucocorticoid metabolites in feces of Geoffroy's spider monkeys (Ateles geoffroyi).

We report on an analytical and biological validation of a commercial cortisol enzyme immunoassay (EIA)to measure glucocorticoids (GC)in feces of Geoffroy's spider monkeys (Ateles geoffroyi). Validation of endocrinological methods for each sample matrix and study species is crucial to establish that the methods produce reliable results. For the analytical validation of the EIA, we assessed parallelism, accuracy, and precision. We carried out a biological validation based on three well-studied GC patterns with the following predictions: (1) increased fecal GC metabolite (fGCM)concentrations after veterinary intervention; (2) increased fGCM concentrations during early morning hours; and (3) higher fGCM concentrations during gestation than in other female reproductive states. For the first prediction, we sampled feces of two zoo-housed females 2 days before, the day of, and 2 days after a veterinary intervention. For the second prediction, we analyzed 284 fecal samples collected from 12 wild males using a linear mixed model (LMM).For the third prediction, we analyzed 269 fecal samples of eight wild females using an LMM. Analytical validation revealed that the EIA showed parallelism, was accurate, and precise within each assay. However, there was elevated variation in between-assay precision. The biological validation supported all predictions: (1) the two zoo-housed females showed a substantial increase in fGCM concentrations 2.5and 11 h after veterinary intervention; (2) there was a negative effect of sample collection time on fGCM concentrations (i.e., higher concentrations during early morning); (3) gestating females had significantly higher fGCM concentrations than lactating females. Thus, we analytically validated the commercial EIA and, despite between-assay variation, we were able to find three biologically relevant GC signals in captive and wild settings, and in males and females. We are therefore confident that the method can be used to noninvasively address behavioral endocrinology questions in Geoffroy's spider monkeys.

Non-invasive assessment of hormonal fluctuations during pregnancy in guanacos (Lama guanicoe) and its application in a wild population.

Obtaining endocrinological profiles using non-invasive methodologies by the measurement of hormone fecal metabolites is a widely used method to monitor ovarian activity and pregnancy in wild species. These tools allow the obtention of physiological information without causing capture-related stress on the individuals. In this research, we aimed to 1) biologically validate a non-invasive method to assess fecal progestagens and estrogens fluctuations during gestation in guanacos (Lama guanicoe) and 2) apply this technique to assess pregnancy in a wild free-ranging population. Fecal samples were collected through the gestation period (~12months) of female guanacos in a 6.5-ha paddock. An increase in fecal metabolites of both hormones was detected. Progestagens increased gradually, in contrast to estrogens, which remained at basal values for most of the gestation period and peaked only a few days before calving. To assess pregnancy in wild free-ranging animals, fecal samples were collected from a population of La Payunia provincial reserve (Mendoza, Argentina) during the beginning of gestation and at the end of gestation. Through the first months of possible gestation, pregnant females represented between 40 and 80% of the population; at the end of gestation, only 20-40% of the females had confirmed pregnancies. Our results demonstrated that the polyclonal antisera and sexual hormone metabolite assays used here detect variations in the metabolites excreted through feces in guanacos and provide the possibility of non-invasive hormone monitoring of female reproductive status. Also, the findings in wild conditions suggest that natural abortions could have occurred during the first months of gestation. Although some abortions may be natural, the harsh environmental conditions that challenge the support of such a long gestational process may be another relevant factor to consider. The results obtained here enhance our understanding of the reproductive physiology of one of the most emblematic ungulates in South America.

The Relationship Between Mood and Sleep in Different Female Reproductive States.

Mood and sleep are tightly interrelated. Mood and sleep symptoms and disorders are more common in women than in men and often associated with reproductive events. This article reviews the current literature on the reciprocal relationships between mood and sleep across reproductive phases in women, such as menstrual cycle and related disorders, pregnancy, climacteric, and use of hormonal contraception and hormone replacement therapy. Mood and sleep symptoms seem to covary in relation to physiologic and pathologic reproductive conditions, although the relationship seems more clear for subjective than objective sleep.

Bile acids as putative social signals in Mozambique tilapia (Oreochromis mossambicus)

Chemical cues provide potential mates with information about reproductive status and resource-holding potential. In the Mozambique tilapia (Oreochromis mossambicus), males can distinguish female reproductive status through chemical cues, and accessibility of males to females depends on their position in the hierarchy, determined in part by chemical cues. Here, we hypothesized that tilapia faecal cues are attractive to conspecifics once released into the water. C18 solid-phase extracts of faeces from dominant males and pre-ovulatory females evoked stronger olfactory epithelium electrical responses (EOG) than, respectively, subordinate males and post-spawning females. Mass spectrometry of the reverse-phase C18 high-performance liquid chromatography fractions of these extracts with highest EOG, identified by amino acids and bile acids. Faeces from pre-ovulatory females contain significantly higher concentrations of cholic acid (CA) and taurocholic acid (TCH) than both post-spawning females and males. A pool of amino acids had no effect on aggression or attraction in males. However, males were attracted to the scent of pre-ovulatory female faeces, as well as CA and TCH, when applied separately. This attraction was accompanied by increased digging behaviour compared to the odour of post-spawning females. CA and TCH exert their action through separate receptor mechanisms. These findings are consistent with a role for faeces – and bile acids therein – in chemical communication in this species, acting as an attractant for males to reproductive females.

Neural substrates underlying rhythmic coupling of female reproductive and thermoregulatory circuits.

Coordinated fluctuations in female reproductive physiology and thermoregulatory output have been reported for over a century. These changes occur rhythmically at the hourly (ultradian), daily (circadian), and multi-day (ovulatory) timescales, are critical for reproductive function, and have led to the use of temperature patterns as a proxy for female reproductive state. The mechanisms underlying coupling between reproductive and thermoregulatory systems are not fully established, hindering the expansion of inferences that body temperature can provide about female reproductive status. At present, numerous digital tools rely on temperature to infer the timing of ovulation and additional applications (e.g., monitoring ovulatory irregularities and progression of puberty, pregnancy, and menopause are developed based on the assumption that reproductive-thermoregulatory coupling occurs across timescales and life stages. However, without clear understanding of the mechanisms and degree of coupling among the neural substrates regulating temperature and the reproductive axis, whether such approaches will bear fruit in particular domains is uncertain. In this overview, we present evidence supporting broad coupling among the central circuits governing reproduction, thermoregulation, and broader systemic physiology, focusing on timing at ultradian frequencies. Future work characterizing the dynamics of reproductive-thermoregulatory coupling across the lifespan, and of conditions that may decouple these circuits (e.g., circadian disruption, metabolic disease) and compromise female reproductive health, will aid in the development of strategies for early detection of reproductive irregularities and monitoring the efficacy of fertility treatments.

Handling Effects on Histological Identification of Female Reproductive Status: Examples from Tropical Deepwater Snappers

Post-mortem ovarian tissue degradation from handling effects, such as delays in preservation, can lead to inaccurate reproductive assessments. Therefore, it is important to understand the differences between handling effects and natural ovarian atresia. Seven treatments of various holding temperatures and times to preservation were applied to whole fish and extracted ovaries of three tropical deepwater snapper species. Ovarian post-mortem degradation was observed at 12 h at ambient temperature and after 48 h iced or refrigerated for both whole fish and extracted ovaries; however, degradation did not adversely affect correct reproductive phase classification in fishes stored in ice from 12 to 48 h post-capture. A clear histological indicator of post-mortem degradation was the breakdown of ooplasm organelles at the oocyte periphery observed in vitellogenic and cortical alveolar oocytes. However, the chorion typically remains intact during post-mortem degradation, in contrast to natural atresia. Effects on post-ovulatory follicles were most discernible after 96 h on ice or refrigeration. Freezing gonadal tissue resulted in drastic changes to oocyte shape and morphology, making reproductive phase classification challenging. We advise that (1) freezing ovaries should be avoided where possible, and (2) gonad tissue should ideally be preserved immediately but no later than 48 h post-capture.

Brain Gene Expression of Foraging Behavior and Social Environment in Ceratina calcarata.

Rudimentary social systems have the potential to both advance our understanding of how complex sociality may have evolved and our understanding of how changes in social environment may influence gene expression and cooperation. Recently, studies of primitively social Hymenoptera have greatly expanded empirical evidence for the role of social environment in shaping behavior and gene expression. Here, we compare brain gene expression profiles of foragers across social contexts in the small carpenter bee, Ceratina calcarata. We conducted experimental manipulations of field colonies to examine gene expression profiles among social contexts including foraging mothers, regular daughters, and worker-like dwarf eldest daughters in the presence and absence of mother. Our analysis found significant differences in gene expression associated with female age, reproductive status, and social environment, including circadian clock gene dyw, hexamerin, and genes involved in the regulation of juvenile hormone and chemical communication. We also found that candidate genes differentially expressed in our study were also associated with division of labor, including foraging, in other primitively and advanced eusocial insects. Our results offer evidence for the role of the regulation of key developmental hormones and circadian rhythms in producing cooperative behavior in rudimentary insect societies.

The effect of age and sex selective harvest patterns for baleen whales

The taking of calves and females accompanied by calves is prohibited under the original and current forms of the Schedule of the International Whaling Commission. Proposed regulations under the Revised Management Scheme would reduce catch limits according to the proportion of females in the landings when females make up more than one-half of the landings. The implications of regulations on age, sex and reproductive status were explored by examining the relative impacts of baleen whale harvests with different age, sex and female reproductive status selectivity patterns using a matrix population model. The effects of 11 harvest patterns with varying selectivity for females and calves were measured by computing the fraction of the population that would have to be killed to reduce the growth rate of the population model to zero and the corresponding fraction of the population that would be landed (harvest fraction). The harvest impact per whale landed was measured for each selectivity pattern by expressing the harvest fraction as a percentage of the value of that fraction for a harvest random across age, sex and reproductive status. The harvest impacts per whale landed of the 11 patterns ranged from 64% greater to 29% lower than a random harvest. The patterns with the lowest harvest impact per whale landed were the pattern consistent with the IWC Schedule of prohibiting harvest of calves and females accompanied by calves, and the pattern of harvesting only calves. The harvest selectivity patterns which increased the vulnerability of females had the greatest impact. Relative to the IWC’s Revised Management Procedure, this increased female vulnerability was roughly compensated for by the decrease in catch limits as the proportion of females in the catches increased.

Neopterin Levels in Bonobos Vary Seasonally and Reflect Symptomatic Respiratory Infections

As environmental changes exacerbate the threat coming from infectious diseases in wild mammal species, monitoring their health and gaining a better understanding of the immune functioning at the species level have become critically important. Neopterin is a biomarker of cell-mediated immune responses to intracellular infections. We investigated the variation of urinary neopterin (uNeo) levels of wild, habituated bonobos (Pan paniscus) in relation to individual and environmental factors. We used 309 urine samples collected between 2010 and 2018 at the LuiKotale field site, DRC. Based on current knowledge on zoo-housed conspecifics and closely related species, we predicted uNeo levels to increase (1) during infections, (2) with increasing age, (3) over the gestation period and in estrous females; and (4) to vary seasonally. Our results showed uNeo levels varied over a one-year period and increased in individuals showing respiratory symptoms. Contrary to chimpanzees, uNeo levels did not vary with age or female reproductive status, possibly due to our small sample size. Our study provides a baseline for a better understanding of bonobo’s immunocompetence in the context of socio-ecological pressures and for monitoring the health of wild populations.

Influence of female reproductive state and of fishing-capture stress on the oxygen uptake rate of a viviparous elasmobranch.

In animals discarded after a fishing capture event, the elicited stress response necessary to ensure their survival is energetically costly. This energy is diverted from other important biological activities, including growth and reproduction, possibly impairing them. Given that elasmobranchs are among the most threatened vertebrate groups, estimating capture-induced energetic changes and comparing these variations to the energy requirements of pregnancy maintenance is necessary. In pregnant southern fiddler rays (Trygonorrhina dumerilii), we measured changes in oxygen uptake rate (ṀO2 ; a proxy for metabolic rate and energy usage) in response to trawling simulation and air exposure, and estimated the oxygen requirements of sustaining late-term pregnancy and embryos. ṀO2 was measured in pregnant females, before (prestress ṀO2 ) and after trawling simulation (after-capture ṀO2 ), and again after females gave birth (postpartum ṀO2 ). After-capture ṀO2 was 31.7% lower than ṀO2 measured in minimally stressed females, suggesting a reduction in energy expenditure. This reduction is likely triggered by an initially excessive energetic investment in the stress response, and is aimed at shutting down nonessential activities to redirect energy to processes fundamental for survival. Prestress ṀO2 was 78.5% higher than postpartum ṀO2 . Capture simulation decreased ṀO2 to values similar to those observed postpartum, suggesting a capture-induced reduction in oxygen and energy allocation to pregnancy and embryonic respiration, which could be associated with reproductive impairments. These data, by better estimating the impact of capture and discard on energetic requirements and reproductive fitness, may support the introduction of area and/or seasonal closures to fishing.

Assessing stress in wild black-and-white colobus monkeys non-invasively

Analysis of glucocorticoid profiles serves as a valuable, multi-faceted tool for insight into the behavior and physiology of wild populations. Recently, the measurement of fecal glucocorticoid metabolites (FCMs) has exploded in popularity due to its compatibility with noninvasive techniques and remote environments A critical first step is to perform a biological validation to ensure that the assay accurately reflect changes in FCM levels. We use an enzyme immunoassay (EIA) to perform a biological validation on samples collected from two males and six females in a wild population of Colobus vellerosus in response to three naturally occurring potential stressors. We also describe the FCM response pattern in the week following parturition in three females and examine the influence of sex, reproductive state, and time of day on the concentrations of baseline samples collected daily from 13 adult individuals over a period of four months. We validated the assay: FCM levels increase in response to natural stressors with a two-day lag. In the two days surrounding parturition, FMC levels increased. Baseline concentrations were affected by collection time and female reproductive state, with lactating females having lower concentrations than pregnant or cycling females. Thus, we successfully carried out the first validation and characterization of FCMs in a wild African colobine. This will serve as an essential foundation for future studies of C. vellerosus and similar wild primates whose objective is to investigate the role glucocorticoids play in responses to social and ecological challenges.

Ecology and age, but not genetic ancestry, predict fetal loss in a wild baboon hybrid zone.

Pregnancy failure represents a major fitness cost for any mammal, particularly those with slow life histories such as primates. Here, we quantified the risk of fetal loss in wild hybrid baboons, including genetic, ecological, and demographic sources of variance. We were particularly interested in testing the hypothesis that hybridization increases fetal loss rates. Such an effect would help explain how baboons may maintain genetic and phenotypic integrity despite interspecific gene flow. We analyzed outcomes for 1020 pregnancies observed over 46 years in a natural yellow baboon-anubis baboon hybrid zone. Fetal losses and live births were scored based on records of female reproductive state and the appearance of live neonates. We modeled the probability of fetal loss as a function of a female's genetic ancestry (the proportion of her genome estimated to be descended from anubis [vs. yellow] ancestors), age, number of previous fetal losses, dominance rank, group size, climate, and habitat quality using binomial mixed effects models. Female genetic ancestry did not predict fetal loss. Instead, the risk of fetal loss is elevated for very young and very old females. Fetal loss is most robustly predicted by ecological factors, including poor habitat quality prior to a home range shift and extreme heat during pregnancy. Our results suggest that gene flow between yellow and anubis baboons is not impeded by an increased risk of fetal loss for hybrid females. Instead, ecological conditions and female age are key determinants of this component of female reproductive success.

Assessing reproduction in wolverines (Gulo gulo): Fecal progesterone levels in zoo and wild females

Wolverines (Gulo gulo) populations are under threat by increased human activities. A better understanding of their reproductive physiology would benefit research and monitoring of this species. The use of enzyme immunoassay (EIA) to measure fecal progesterone metabolites (FPM) is a powerful tool to understand wildlife reproductive physiology, and a non-invasive method for use in both zoo and wild populations. The main objective of this study was to determine reproductive status in female wolverines using FPM levels, first by monitoring of longitudinal changes in FPM in zoo housed females in breeding situations and second to compare those values to FPM measured in feces obtained from wild females observed in the field during reproductively active periods (Dec–Apr). Female reproductive physiology was assessed by measuring FPM in three zoo housed wolverines to determine species-specific levels arising from ovulation encompassing embryonic diapause and ovarian reactivation (resumption of ovarian luteal activity after diapause) during pregnancy or pseudopregnancy, which in turn enabled verification of reproductive status in 15 wild wolverines, monitored over three years. In the zoo females, FPM levels were sustained at basal levels if ovulation and/or breeding did not occur. After ovulation, both pregnancy or pseudopregnancy exhibited a bi-phasic pattern of FPM increases, with a 4.9-fold increase above baseline during embryonic diapause and a further 4.4-fold increase after ovarian reactivation. FPM levels during pregnancy and pseudopregnancy were indistinguishable, thus increases in FPM levels are only a confirmation of ovulation, and not diagnostic for pregnancy. In wild females, assessment of FPM levels in samples collected from December to February was able to predict a potentially pregnant/reproductively active female with levels above 8200 ng/g dried feces, or non-reproductive (nonovulatory) female during that period with levels below 1700 ng/g. Wild wolverine FPM levels indicative of pregnancy aligned with field observations of denning and/or lactation. FPM levels from samples collected from March and April were inconclusive as levels could be attributed to females being either postpartum or non-reproductive at that time. Timing of ovarian reactivation, and subsequent elevation of FPM, varied among individuals suggesting caution is warranted when assessing only one fecal sample per female. Understanding all factors that may impact reproductive success is essential for effective species conservation, particularly for species with low reproductive rates, like the wolverine. This study has demonstrated the potentially useful incorporation of non-invasive fecal hormone analysis for investigation of physiological parameters and reproductive status in wild wolverine females.

Environmental drivers of demography and potential factors limiting the recovery of an endangered marine top predator

AbstractUnderstanding what drives changes in wildlife demography is fundamental to the conservation and management of depleted or declining populations, though making inference about the intrinsic and extrinsic factors that influence survival and reproduction remains challenging. Here we use mark–resight data from 2000 to 2018 to examine the effects of environmental variability on age‐specific survival and natality for the endangered western distinct population segment (wDPS) of Steller sea lions (Eumetopias jubatus) in Alaska, USA. Though this population has been studied extensively over the last four decades, the causes of divergent abundance trends that have been observed across the wDPS range remain unknown. We developed a Bayesian multievent mark–resight model that accounts for female reproductive state uncertainty. Annual survival probabilities for male pups (0.44; 0.36–0.53), female yearlings (0.63; 0.49–0.73), and male yearlings (0.62; 0.51–0.71) born in the western portion of the wDPS range, estimated here for the first time, were lower than those in the eastern portion of the wDPS range, estimated as: male pups (0.69; 0.65–0.74), female yearlings (0.76; 0.71–0.81), and male yearlings (0.71; 0.65–0.78). There was a higher proportion of young female breeders in the western portion of the range, but overall natality was lower (0.69; 0.47–0.96) than in the eastern portion of the range (0.80; 0.74–0.84). Additionally, pup mass had a positive effect on pup survival in the eastern portion of the range and a negative effect in the western portion of the range, potentially due to earlier weaning of heavier pups. Local‐ and basin‐scale oceanographic features such as the Aleutian Low, the Arctic Oscillation Index, the North Pacific Gyre Oscillation, chlorophyll concentration, upwelling, and wind in certain seasons were correlated with vital rates. However, drawing strong inferences from these correlations is challenging given that relationships between ocean conditions and an adaptive top predator in a dynamic ecosystem are exceedingly complex. This study provides the first demographic rate estimates for the western portion of the range where abundance estimates continue to decline. These results will advance efforts to identify factors driving regionally divergent abundance trends, with implications for population‐level responses to future climate variability.