Reproductive Fitness Research Articles

Skin immunity during pregnancy

Abstract Pregnancy presents a challenging immunological dilemma. The maternal immune system must tolerate fetal antigens, which implies pregnancy may induce specific mechanisms of immunoregulation. Yet within this regulatory milieu, protection against pathogens must be maintained. How does the maternal immune system navigate these opposing demands? Successfully navigating this immunological dilemma is essential for supporting the reproductive fitness of the organism, and generally, the survival of any mammalian species. Of particular importance in this context are barrier tissues, like the skin, which represent the primary portal of entry for pathogens. These barrier tissues are an especially important first line of defense during pregnancy, since adaptive immunity must be regulated to tolerate the fetal antigens which distribute throughout maternal tissues. However, little is known about how immunity in barrier tissues is altered during pregnancy. Our preliminary studies have identified an increase in ceramide levels in the skin during pregnancy. Ceramides have been shown to be critical mediators of skin barrier function, and may prevent pathogens from breaching the skin. Additionally, in the setting of S. aureus infection, pregnant skin demonstrated increased infiltration of innate immune cells, as well as an increase in type I immunity among adaptive cells. Together, these data suggest that the protective mechanisms of the skin are altered during pregnancy. Further insights in this area may elucidate an especially critical role for barrier tissue immunity in defending against infection during pregancy, and may eventually help guide improved clinical strategies to prevent and treat infections in pregnant mothers. Supported by Perelman School of Medicine's Medical Scientist Training Program and intramural research funding from NIAID.

The MOV10 RNA helicase is a dosage-dependent host restriction factor for LINE1 retrotransposition in mice.

Transposable elements constitute nearly half of the mammalian genome and play important roles in genome evolution. While a multitude of both transcriptional and post-transcriptional mechanisms exist to silence transposable elements, control of transposition in vivo remains poorly understood. MOV10, an RNA helicase, is an inhibitor of mobilization of retrotransposons and retroviruses in cell culture assays. Here we report that MOV10 restricts LINE1 retrotransposition in mice. Although MOV10 is broadly expressed, its loss causes only incomplete penetrance of embryonic lethality, and the surviving MOV10-deficient mice are healthy and fertile. Biochemically, MOV10 forms a complex with UPF1, a key component of the nonsense-mediated mRNA decay pathway, and primarily binds to the 3' UTR of somatically expressed transcripts in testis. Consequently, loss of MOV10 results in an altered transcriptome in testis. Analyses using a LINE1 reporter transgene reveal that loss of MOV10 leads to increased LINE1 retrotransposition in somatic and reproductive tissues from both embryos and adult mice. Moreover, the degree of LINE1 retrotransposition inhibition is dependent on the Mov10 gene dosage. Furthermore, MOV10 deficiency reduces reproductive fitness over successive generations. Our findings demonstrate that MOV10 attenuates LINE1 retrotransposition in a dosage-dependent manner in mice.

Spatiotemporal variation of chasmogamy and cleistogamy in a native perennial grass: fecundity, reproductive allocation and allometry.

It is difficult to assess the relative variability or stability of chasmogamous (CH) and cleistogamous (CL) reproduction in perennial herbs with mixed mating because long-term data in natural populations are unavailable. Here, the aim was to quantify and compare spatial (between-habitat) and temporal (among-year) variation in CH and CL reproduction over 5 years in two subpopulations of the native perennial grass Danthonia compressa. This species produces CH spikelets on terminal panicles in early summer, while axillary CL spikelets, including a basal cleistogene, mature into the autumn. Flowering tillers were collected from a sunny woodland edge and an adjacent shady interior habitat for 5 consecutive years (2017-21). Seed set, fecundity, seed mass and biomass allocation were recorded for the two floral types along with tiller vegetative mass. Bivariate line fitting was used for allometric analysis of CH and CL fecundity. Seed set, fecundity, mass per seed and allocation to seeds differed between floral types and showed significant variation between habitats and among years. Seed set and fecundity in CH panicles were greater than that of axillary CL panicles in most years. Tiller mass positively affected axillary CL seed production and mass of the basal cleistogene. Fecundity and allocation among years were more variable for CH compared to CL reproduction. High seed set and fecundity of CH spikelets suggest that pollination does not limit reproduction via chasmogamy. Late maturation of axillary CL spikelets provides additional fecundity, especially in larger plants along sunny woodland edges. The heavy cleistogene at the tiller base could be important to population persistence, analogous to the axillary bud bank of other perennial grasses that are not cleistogamous. The spatiotemporal stability of CL reproduction underscores the ecological significance of cleistogamy to reproductive fitness.

From color to shape: ontogenetic shifts in traits of the freshwater crab Dilocarcinus pagei (Brachyura: Trichodactylidae)

Crustaceans usually undergo a series of changes after the puberty molt. These changes are often associated with size increases in the body and in structures such as the abdomen and claws so that they can achieve higher reproductive fitness. These morphological changes allow the animal to fight, court, and signal for its conspecific with better performance. To compare ontogenetic changes, we used the freshwater crab Dilocarcinus pagei Stimpson, 1851 as a model. We analyzed differences in carapace and claw shape, force generation (via the apodeme area), morphological integration of claws, and color changes among demographic groups. Adult crabs had an increase in claw and carapace size followed by a shape change that makes the claws more robust. In addition, the animals changed from a dark brown coloration in juveniles to a dark red coloration in adult males, while adult females presented a dark red-brown coloration. Presumably, phenotypic changes may enhance crabs’ ability to obtain different food sources, as well as fight for sexual partners, and manipulate females during courtship. Color changes can be a strategy by which adult males can signal to females, while the dark brown coloration of juveniles can help in camouflage in the substrate.

MiR-2b-2-5p regulates lipid metabolism and reproduction by targeting CREB in Bactrocera dorsalis

ABSTRACT In female animals, metabolic homoeostasis and reproductive fitness are critical to population expansion. The trade-off between lipid storage and reproduction inevitably occurs. However, most studies have focused on the complex network of relationships between reproductive and metabolic physiology at the transcriptional level. In this study, we identified a microRNA, miR-2b-2-5p, in a highly invasive quarantine pest, Bactrocera dorsalis. Knockdown of miR-2b-2-5p by antagomiR microinjection impaired ovarian development, reduced fecundity, and decreased triglyceride (TAG) storage in the fat body, whereas overexpression of miR-2b-2-5p by injection of its mimic caused reproductive defects similar to knockdown but increased TAG. Bioinformatics analysis and dual luciferase assay indicated that cyclic AMP response element (CRE)-binding protein (CREB) was the target gene of miR-2b-2-5p. RNAi-mediated knockdown of CREB led to excessive lipid storage and reproductive defects. Further starvation treatment revealed that miR-2b-2-5p functions by fine-tuning CREB expression in response to dietary stimuli. These results suggest that miR-2b-2-5p acts as a monitor to regulate CREB mRNA levels in the fat body, maintaining lipid homoeostasis and keeping the reproductive system on track. Thus, our study not only provides new insights into the interaction between metabolism and reproduction at the posttranscriptional level in B. dorsalis, but also providing a potential eco-friendly control strategy (RNAi-based biopesticides targeting essential miRNAs) for this notorious agricultural pest.

Type 6 secretion system components hcp and vgrG support mutualistic partnership between Xenorhabdus bovienii symbiont and Steinernema jollieti host

Xenorhabdus, like other Gram-negative bacteria, possesses a Type 6 Secretion System (T6SS) which acts as a contact-dependent molecular syringe, delivering diverse proteins (effectors) directly into other cells. The number of T6SS loci encoded in Xenorhabdus genomes are variable both at the inter and intraspecific level. Some environmental isolates of Xenorhabdus bovienii, encode at least one T6SS locus while others possess two loci. Previous work conducted by our team demonstrated that X. bovienii [Jollieti strain SS-2004], which has two T6SSs (T6SS-1 and T6SS-2), hcp genes are required for biofilm formation. Additionally, while T6SS-1 hcp gene plays a role in the antibacterial competition, T6SS-2 hcp does not. In this study, we tested the hypothesis that vgrG genes are also involved in mutualistic and pathogenic interactions. For this purpose, targeted mutagenesis together with wet lab experiments including colonization, competition, biofilm, and virulence experiments, were carried out to assess the role of vgrG in the mutualistic and antagonistic interactions in the life cycle of XBJ. Our results revealed that vgrG genes are not required for biofilm formation but play a role in outcompeting other Xenorhabdus bacteria. Additionally, both vgrG and hcp genes are required to fully colonize the nematode host. We also demonstrated that hcp and vgrG genes in both T6SS clusters are needed to support the reproductive fitness of the nematodes. Overall, results from this study revealed that in X. bovieni jollieti strain, the twoT6SS clusters play an important role in the fitness of the nematodes in relation to colonization and reproduction. These results lay a foundation for further investigations on the functional significance of T6SSs in the mutualistic and pathogenic lifecycle of Xenorhabdus spp.

Perception, regulation, and fitness effects of pollen phytosterols in the bumble bee, Bombus terrestris.

Many flowering plants depend on insects for pollination and thus attract pollinators by offering rewards, mostly nectar and pollen. Bee pollinators rely on pollen as their main nutrient source. Pollen provides all essential micro- and macronutrients including substances that cannot be synthesized by bees themselves, such as sterols, which bees need for processes such as hormone production. Variations in sterol concentrations may consequently affect bee health and reproductive fitness. We therefore hypothesized that (1) these variations in pollen sterols affect longevity and reproduction in bumble bees and (2) can thus be perceived via the bees' antennae before consumption. We studied the effect of sterols on longevity and reproduction of Bombus terrestris workers in feeding experiments and investigated sterol perception using chemotactile proboscis extension response (PER) conditioning. Workers could perceive several sterols (cholesterol, cholestenone, desmosterol, stigmasterol, β-sitosterol) via their antennae but not differentiate between them. However, when sterols were presented in pollen, and not as a single compound, the bees were unable to differentiate between pollen differing in sterol content. Additionally, different sterol concentrations in pollen neither affected pollen consumption nor brood development or worker longevity. Since we used both natural concentrations and concentrations higher than those found in pollen, our results indicate that bumble bees may not need to pay specific attention to pollen sterol content beyond a specific threshold. Naturally encountered concentrations might fully support their sterol requirements and higher concentrations do not seem to have negative effects.

Practical Uses for Ultrasound in Managing Beef Cattle Reproduction

This publication aims to discuss the use of ultrasound to assist with beef cattle reproduction, which includes evaluation of the pre-service status of heifers and cows, diagnosis of pregnancy, determination of fetal age and sex, and evaluation of reproductive fitness of embryo recipients. Written by Mario Binelli, Thiago Martins, John Arthington, Kalyn Waters, Vitor Mercadante, Philipe Moriel, and Angela Gonella-Diaza, and published by the UF/IFAS Department of Animal Sciences, revised April 2023.

No evidence for schistosome parasite fitness trade-offs in the intermediate and definitive host

BackgroundThe trematode parasite Schistosoma mansoni uses an aquatic snail intermediate and a vertebrate definitive host to complete its life cycle. We previously showed that a key transmission trait—the number of cercariae larvae shed from infected Biomphalaria spp. snails—varies significantly within and between different parasite populations and is genetically controlled by five loci. We investigated the hypothesis that the success of parasite genotypes showing high propagative fitness in the intermediate snail host may be offset by lower reproductive fitness in the definitive vertebrate host.MethodsWe investigated this trade-off hypothesis by selecting parasite progeny producing high or low number of larvae in the snail and then comparing fitness parameters and virulence in the rodent host. We infected inbred BALB/c mice using two Schistosoma mansoni parasite lines [high shedder (HS) and low shedder (LS) lines] isolated from F2 progeny generated by genetic crosses between SmLE (HS parent) and SmBRE (LS parent) parasites. We used the F3 progeny to infect two populations of inbred Biomphalaria glabrata snails. We then compared life history traits and virulence of these two selected parasite lines in the rodent host to understand pleiotropic effects of genes determining cercarial shedding in parasites infecting the definitive host.ResultsHS parasites shed high numbers of cercariae, which had a detrimental impact on snail physiology (measured by laccase-like activity and hemoglobin rate), regardless of the snail genetic background. In contrast, selected LS parasites shed fewer cercariae and had a lower impact on snail physiology. Similarly, HS worms have a higher reproductive fitness and produced more viable F3 miracidia larvae than LS parasites. This increase in transmission is correlated with an increase in virulence toward the rodent host, characterized by stronger hepato-splenomegaly and hepatic fibrosis.ConclusionsThese experiments revealed that schistosome parasite propagative and reproductive fitness was positively correlated in intermediate and definitive host (positive pleiotropy). Therefore, we rejected our trade-off hypothesis. We also showed that our selected schistosome lines exhibited low and high shedding phenotype regardless of the intermediate snail host genetic background. ​Graphical

Glyphosate Interference in Follicular Organization in the Wall Lizard Podarcis siculus.

Glyphosate (Gly) is a broad-spectrum herbicide widely used thanks to its high efficiency and low toxicity. However, evidence exists of its toxic effects on non-target organisms. Among these, the animals inhabiting agricultural fields are particularly threatened. Recent studies demonstrated that exposure to Gly markedly affected the morphophysiology of the liver and testis of the Italian field lizard Podarcis siculus. The present study aimed to investigate the effects of the herbicide on the female reproductive system of this lizard in order to have a full picture of Gly-induced reproductive impairment. The animals were exposed to 0.05 and 0.5 μg/kg of pure Gly by gavage for 3 weeks. The results demonstrated that Gly, at both doses tested, profoundly interfered with ovarian function. It induced germ cells' recruitment and altered follicular anatomy by anticipating apoptotic regression of the pyriform cells. It also induced thecal fibrosis and affected oocyte cytoplasm and zona pellucida organizations. At the functional levels, Gly stimulated the synthesis of estrogen receptors, suggesting a serious endocrine-disrupting effect. Overall, the follicular alterations, combined with those found at the level of the seminiferous tubules in males, suggest serious damage to the reproductive fitness of these non-target organisms, which over time could lead to a decline in survival.

Social Familiarity and Spatially Variable Environments Independently Determine Reproductive Fitness in a Wild Bird.

AbstractThe social interactions that an individual experiences are a key component of its environment and can have important consequences for reproductive success. The dear enemy effect posits that having familiar neighbors at a territory boundary can reduce the need for territory defense and competition and potentially increase cooperation. Although fitness benefits of reproducing among familiar individuals are documented in many species, it remains unclear to what extent these relationships are driven by direct benefits of familiarity itself versus other socioecological covariates of familiarity. We use 58 years of great tit (Parus major) breeding data to disentangle the relationship between neighbor familiarity, partner familiarity, and reproductive success while simultaneously considering individual and spatiotemporal effects. We find that neighbor familiarity was positively associated with reproductive success for females but not males, while an individual's familiarity with their breeding partner was associated with fitness benefits for both sexes. There was strong spatial heterogeneity in all investigated fitness components, but our findings were robust and significant over and above these effects. Our analyses are consistent with direct effects of familiarity on individuals' fitness outcomes. These results suggest that social familiarity can yield direct fitness benefits, potentially driving the maintenance of long-term bonds and evolution of stable social systems.

Measures of Adrenal and Gonadal Hormones in Relation to Biological and Management Factors among Captive Red Pandas in Indian Zoos.

Animals in human care are affected by stressors that can ultimately reduce fitness. When reproduction is affected, endangered species conservation programs can be severely compromised. Thus, understanding factors related to stress and reproduction, and related hormones, is important to ensure captive breeding success. Red pandas (Ailurus fulgens) are endangered, and populations in the wild are threatened with extinction. A global captive breeding program has been launched to conserve the species with the goal of reintroduction. However, there is little information on how stressors impact physiological aspects of the species. This study measured fecal glucocorticoid (fGCM), progestagen (fPM), and androgen (fAM) metabolite concentrations in 12 female and 8 male red pandas at 3 zoos in India to determine predictors of adrenal and gonadal steroid activity, and the influence of fGCM on reproduction. Based on the generalized linear mixed model (GLMM), fGCM concentrations were positively correlated with the number of visitors, number of nests and enclosure areas, and negatively related to frequency of feedings, log density, and social time, while fPM concentrations were negatively associated with enclosure areas. A confounder for enclosure areas and number of nests was the fact that these spaces were relatively barren, with limited hiding spaces, compared to the smaller enclosures. By contrast, no significant relationships were found for fAM, perhaps due to the smaller sample size. A negative relationship between fGCM and fPM was observed, indicating increasing adrenal hormones may decrease reproductive function among female red pandas. Results suggest that zoo management should consider increasing feeding frequency, providing larger enclosures with more enrichment and more nests in larger spaces, and regulating visitor numbers to support good welfare and potentially improve reproductive fitness of red pandas in captivity.

Changes in selection of resources with reproductive state in a montane ungulate

Animals select habitats based on food, water, space, and cover. Each of those components are essential to the ability of an individual to survive and reproduce in a particular habitat. Selection of resources is linked to reproductive fitness and individuals likely vary in how they select resources relative to their reproductive state: during pregnancy, while provisioning young when nutritional needs of the mother are high, but offspring are vulnerable to predation, or if they lose young to mortality. We investigated the effects of reproductive state on selection of resources by maternal female desert bighorn sheep (Ovis canadensis nelsoni) by comparing selection during the last trimester of gestation, following parturition when females were provisioning dependent young, and if the female lost an offspring. We captured, and recaptured each year, 32 female bighorn sheep at Lone Mountain, Nevada, during 2016–2018. Captured females were fit with GPS collars and those that were pregnant received vaginal implant transmitters. We used a Bayesian approach to estimate differences in selection between females provisioning and not provisioning offspring, as well as the length of time it took for females with offspring to return levels of selection similar to that observed prior to parturition. Females that were not provisioning offspring selected areas with higher risk of predation, but greater nutritional resources than those that were provisioning dependent young. When females were provisioning young immediately following parturition, females selected areas that were safe from predators, but had lower nutritional resources. Females displayed varying rates of return to selection strategies associated with access to nutritional resources as young grew and became more agile and less dependent on mothers. We observed clear and substantial shifts in selection of resources associated with reproductive state, and females exhibited tradeoffs in favor of areas that were safer from predators when provisioning dependent young despite loss of nutritional resources to support lactation. As young grew and became less vulnerable to predators, females returned to levels of selection that provided access to nutritional resources to restore somatic reserves lost during lactation.

Evaluating the evolutionary mechanisms maintaining alternative mating strategies in a simulated bull trout (Salvelinus confluentus) population.

The coexistence of distinct alternative mating strategies (AMS) is often explained by mechanisms involving trade-offs between reproductive traits and lifetime fitness; yet their relative importance remains poorly understood. Here, we used an established individual-based, spatially explicit model to simulate bull trout (Salvelinus confluentus) in the Skagit River (Washington, USA) and investigated the influence of female mating preference, sneaker-specific mortality, and variation in age-at-maturity on AMS persistence using global sensitivity analyses and boosted regression trees. We assumed that two genetically fixed AMS coexisted within the population: sneaker males (characterized by younger age-at-maturity, greater AMS-specific mortality, and lower reproductive fitness) and territorial males. After 300 years, variation in relative sneaker success in the system was explained by sneaker males' reproductive fitness (72%) and, to a lesser extent, the length of their reproductive lifespan (21%) and their proportion in the initial population (8%). However, under a wide range of parameter values, our simulated scenarios predicted the extinction of territorial males or their persistence in small, declining populations. Although these results do not resolve the coexistence of AMS in salmonids, they reinforce the importance of mechanisms reducing sneaker's lifetime reproductive success in favoring AMS coexistence within salmonid populations but also limit the prediction that, without any other selective mechanisms at play, strong female preference for mating with territorial males and differences in reproductive lifespan allow the stable coexistence of distinct AMS.

Fire effects on plant reproductive fitness vary among individuals, reflecting pollination-dependent mechanisms.

Fire induces flowering in many plant species worldwide, potentially improving reproductive fitness via greater availability of resources, as evident by flowering effort, and improved pollination outcomes, as evident by seed set. Postfire increases in flowering synchrony, and thus mating opportunities, may improve pollination. However, few studies evaluate fire effects on multiple components of fitness. Consequently, the magnitude and mechanism of fire effects on reproductive fitness remain unclear. Over multiple years and prescribed burns in a prairie preserve, we counted flowering stems, flowers, fruits, and seeds of three prairie perennials, Echinacea angustifolia, Liatris aspera, and Solidago speciosa. We used aster life-history models to assess how fire and mating opportunities influenced annual maternal fitness and its components in individual plants. In Echinacea and Liatris, but not in Solidago, fire increased head counts, and both fire and mating opportunities increased maternal fitness. Burned Echinacea and Liatris plants with many flower heads produced many seeds despite low seed set (fertilization rates). In contrast, plants with an average number of flower heads had high seed set and produced many seeds only when mating opportunities were abundant. Fire increased annual reproductive fitness via resource- and pollination-dependent mechanisms in Echinacea and Liatris but did not affect Solidago fitness. The consistent relationship between synchrony and seed set implies that temporal mating opportunities play an important role in pollination. While fire promotes flowering in many plant species, our results reveal that even closely related species exhibit differential responses to fire, which could impact the broader plant community.

Neural Control of Sexually Dimorphic Social Behavior: Connecting Development to Adulthood.

Rapid advances in the neural control of social behavior highlight the role of interconnected nodes engaged in differential information processing to generate behavior. Many innate social behaviors are essential to reproductive fitness and therefore fundamentally different in males and females. Programming these differences occurs early in development in mammals, following gonadal differentiation and copious androgen production by the fetal testis during a critical period. Early-life programming of social behavior and its adult manifestation are separate but yoked processes, yet how they are linked is unknown. This review seeks to highlight that gap by identifying four core mechanisms (epigenetics, cell death, circuit formation, and adult hormonal modulation) that could connect developmental changes to the adult behaviors of mating and aggression. We further propose that a unique social behavior, adolescent play, bridges the preweaning to the postpubertal brain by engaging the same neural networks underpinning adult reproductive and aggressive behaviors.

Bioenergetics: the evolutionary basis of progressive kidney disease.

Chronic kidney disease (CKD) affects >10% of the world population, with increasing prevalence in middle age. The risk for CKD is dependent on the number of functioning nephrons through the life cycle, and 50% of nephrons are lost through normal aging, revealing their vulnerability to internal and external stressors. Factors responsible for CKD remain poorly understood, with limited availability of biomarkers or effective therapy to slow progression. This review draws on the disciplines of evolutionary medicine and bioenergetics to account for the heterogeneous nephron injury that characterizes progressive CKD following episodes of acute kidney injury with incomplete recovery. The evolution of symbiosis in eukaryotes led to the efficiencies of oxidative phosphorylation and the rise of metazoa. Adaptations to ancestral environments are the products of natural selection that have shaped the mammalian nephron with its vulnerabilities to ischemic, hypoxic, and toxic injury. Reproductive fitness rather than longevity has served as the driver of evolution, constrained by available energy and its allocation to homeostatic responses through the life cycle. Metabolic plasticity has evolved in parallel with robustness necessary to preserve complex developmental programs, and adaptations that optimize survival through reproductive years can become maladaptive with aging, reflecting antagonistic pleiotropy. Consequently, environmental stresses promote trade-offs and mismatches that result in cell fate decisions that ultimately lead to nephron loss. Elucidation of the bioenergetic adaptations by the nephron to ancestral and contemporary environments may lead to the development of new biomarkers of kidney disease and new therapies to reduce the global burden of progressive CKD.

Genetic parameters for various semen production and quality traits and indicators of male and female reproductive performance in Nellore cattle

BackgroundGiven the economic relevance of fertility and reproductive traits for the beef cattle industry, investigating their genetic background and developing effective breeding strategies are paramount. Considering their late and sex-dependent phenotypic expression, genomic information can contribute to speed up the rates of genetic progress per year. In this context, the main objectives of this study were to estimate variance components and genetic parameters, including heritability and genetic correlations, for fertility, female precocity, and semen production and quality (andrological attributes) traits in Nellore cattle incorporating genomic information.ResultsThe heritability estimates of semen quality traits were low-to-moderate, while moderate-to-high estimates were observed for semen morphological traits. The heritability of semen defects ranged from low (0.04 for minor semen defects) to moderate (0.30 for total semen defects). For seminal aspect (SMN_ASPC) and bull reproductive fitness (BULL_FIT), low (0.19) and high (0.69) heritabilities were observed, respectively. The heritability estimates for female reproductive traits ranged from 0.16 to 0.39 for rebreeding of precocious females (REBA) and probability of pregnancy at 14 months (PP14), respectively. Semen quality traits were highly genetically correlated among themselves. Moderate-to-high genetic correlations were observed between the ability to remain productive in the herd until four years of age (stayability; STAY) and the other reproductive traits, indicating that selection for female reproductive performance will indirectly contribute to increasing fertility rates. High genetic correlations between BULL_FIT and female reproductive traits related to precocity (REBA and PP14) and STAY were observed. The genetic correlations between semen quality and spermatic morphology with female reproductive traits ranged from -0.22 (REBA and scrotal circumference) to 0.48 (REBA and sperm vigor). In addition, the genetic correlations between REBA with semen quality traits ranged from -0.23 to 0.48, and with the spermatic morphology traits it ranged from -0.22 to 0.19.ConclusionsAll male and female fertility and reproduction traits evaluated are heritable and can be improved through direct genetic or genomic selection. Selection for better sperm quality will positively influence the fertility and precocity of Nellore females. The findings of this study will serve as background information for designing breeding programs for genetically improving semen production and quality and reproductive performance in Nellore cattle.

Widespread latitudinal asymmetry in the performance of marginal populations: A meta‐analysis

AbstractAimRange shifts are expected to occur when populations at one range margin perform better than those at the other margin, yet no global trend in population performances at range margins has been demonstrated empirically across a wide range of taxa and biomes. Here we test the prediction that, if impacts of ongoing climate change on performance in marginal populations are widespread, then populations from the high‐latitude margin (HLM) should perform as well as or better than central populations, whereas low‐latitude margin (LLM) populations should perform worse.LocationGlobal.Time period1995–2019.Major taxa studiedPlants and animals.MethodsTo test our prediction, we used a meta‐analysis to quantify empirical support for asymmetry in the performance of high‐ and low‐latitude margin populations compared to central populations. Performance estimates (survival, reproduction, or lifetime fitness) for populations occurring in their natural environment were derived from 51 papers involving 113 margin‐centre comparisons from 54 species and 705 populations from the Americas, Europe, Africa and Australia. We then related these performance differences to climatic differences among populations. We also tested whether patterns are consistent across taxonomic kingdoms (plants vs animals) and across realms (marine vs terrestrial).ResultsPopulations at margins performed significantly worse than central populations, and this trend was primarily driven by the low‐latitude margin. Although the difference was of small magnitude, it was largely consistent across biological kingdoms and realms. Differences in performance were weakly (p = .08) related to the difference in average temperatures between central and marginal populations.Main conclusionsThe observed asymmetry in performance in marginal populations is consistent with predictions about the effects of global climate change, though further research is needed to confirm the effect of climate. It indicates that changes in demographic rates in marginal populations can serve as early‐warning signals of impending range shifts.

Marine Pollutant Tributyltin Affects DNA Methylation and Fitness of Banded Murex (Hexaplex trunculus) Populations

Banded murex, Hexaplex trunculus, is a marine gastropod whose reproductive fitness can be severely affected by very low concentrations of antifouling compound tributyltin (TBT). TBT has strong xenoandrogen impacts on snails, causing the development of imposex (e.g., the superimposition of male sexual characteristic in females), thereby affecting the fitness of entire populations. TBT is also known as a DNA-demethylating agent and an obesogenic factor. The aim of this study was to unravel the interactions between TBT bioaccumulation, phenotypic responses, and epigenetic and genetic endpoints in native populations of H. trunculus. Seven populations inhabiting environments along the pollution gradient were sampled in the coastal eastern Adriatic. These included sites of intense marine traffic and boat maintenance activity and sites with low anthropogenic impact. Populations inhabiting intermediately and highly polluted sites exhibited higher TBT burdens, higher incidences of imposex, and higher wet masses of snails than populations in lowly polluted sites. Other morphometric traits and cellular biomarker responses did not show clear differentiation among populations in relation to marine traffic/pollution intensity. An analysis of methylation sensitive amplification polymorphism (MSAP) revealed environmentally driven population differentiation and higher epigenetics than genetic within-population diversity. Moreover, decreases in genome-wide DNA methylation coincided with the imposex level and snail mass, suggesting an epigenetic background of the animal phenotypic response.