Large Offspring Research Articles

Reduction of variability of individual colonization programs in black-headed gulls (Larus ridibundus) leads to diminished reproductive success

The study is devoted to the problem of adaptive significance of territorial antagonism in colonial birds. Many of them are characterized by a high intensity and diversity of territorial demonstrations, along with tolerance of each other and a tendency to aggregate. Here we consider the effects of territorial behavior on the viability of a breeding colony. We analyze the breeding of black-headed gull in two colonies formed under the impact of a short-term temperature fall in 2008, which resulted in a 7-day shift in the timing of egg laying. Compared with the colonies at the same reservoirs, one in 2007 and one in 2009, the number of nests and their density in 2008 were much smaller, whereas the duration of settling, nest density growth, and average size of breeding territories did not change. The average body weight of adult birds during incubation was stable throughout all years; however, the correlations typical for 2007 and 2009 (negative between the female mass and date of clutching start and positive between masses of parents) were absent, suggesting that assortative mating by body mass and territory size was not the case in 2008. The average clutch, egg, and hatching sizes were on average smaller in 2008, while mortality due to attacks of aerial predators was much higher than in other years. In 2007 and 2009, birds that started egg-laying in the first 5 days after the first egg appeared in the colony (pioneer settlers) were larger than others (the so-called followers) and produced a larger offspring. These differences were not observed in 2008. According to our data, due to the impact of cold weather, some birds abandoned their nesting sites and others were sick, but they mostly behaved as pioneer settlers and formed underpopulated and sparse colonies. We assume that the formation of a viable colony requires the interaction of highly territorial “pioneers” and a certain number of less competitive followers. The withdrawal of the latter results in a general reproductive failure of the colony. Thus, the pattern of colony formation in black-headed gull turns natural selection towards a maintenance of the variety of individual programs of territorial competition.

Litter Size Reduction Alters the Lipid Metabolism of Adult Male Rat Offspring of Dams Fed a Diet with Caloric Restriction

Recent studies have showed that nutritional changes during critical periods of development can lead to permanent alterations in the metabolism of the offspring which can become more susceptible to chronic diseases in adult age. The aim of this study was to evaluate the effect of litter size on the body weight and the lipid metabolism of adult male offspring rats born to caloric restricted dams. Dams were fed with either ad libitum standard diet (C) or a 30% caloric restricted diet (R) throughout gestation. After birth, litters were reduced to eight pups or four pups in both C and R dams. All dams were fed ad libitum during lactation. After weaning (3 wk), the male rat offspring born to control dams (C8 and C4) and male rat offspring born to restricted dams (R8 and R4) were maintained in individual cages until they were 20 weeks old. An interaction between the diet of control or restricted dams and the litter size was observed for the hepatic lipid % (P=0.015). Reduction of litter size decreased the hepatic lipid % in control rats but increased it in rats to restricted dams. The caloric restriction in the dams decreased the hepatic lipids only in the large litter offspring, but no effect on the small litter was observed. There was no interaction between litter size reduction and the diet of the dams (P=0.689). The reduction of litter size induced an increase (P=0.035) of carcass weight, regardless the diet of the dams. No effects of caloric restriction during gestation and of the litter size on body weight (P=0.187) and on blood cholesterol (P=0.171) were found in C or R adult male rat offspring. It is concluded that the effect of reduction of litter size on hepatic lipid metabolism depends on the diet of the dams during gestation. The increase of carcass weight resulting from litter size reduction is not affected by the diet of the dams.Support or Funding InformationResearch supported by Institute of Biosciences

Genetic evidence for prevalence of alloparental care in a socially monogamous biparental cichlid fish, Perissodus microlepis, from Lake Tanganyika supports the "selfish shepherd effect" hypothesis.

Alloparental care – care for unrelated young – is rare in animals, and its ecological or evolutionary advantages or, alternative maladaptive nature, remain unclear. We investigate alloparental care in the socially monogamous cichlid fish Perissodus microlepis from Lake Tanganyika that exhibits bi‐parental care. In a genetic parentage analysis, we discovered a surprisingly high percentage of alloparental care represented by brood mixing, extra‐pair paternity and extra‐pair maternity in all broods that we investigated. The percentage of nondescendant juveniles of other parents, i.e., brood mixing, ranged from 5% to 57% (mean = 28%). The distribution of genetic parentage also suggests that this socially monogamous species has, in fact, polygamous mating system. The prevalence of genetically mixed broods can be best explained by two, not mutually exclusive hypotheses on farming‐out and fostering behaviors. In the majority of broods, the sizes of the parents’ own (descendant) offspring were significantly larger than those of the adopted (nondescendant) juveniles, supporting the ‘selfish shepherd effect’ hypothesis, i.e., that foster parents preferentially accept unrelated “smaller or not larger” young since this would tend to lower the predation risks for their own larger offspring. There was also a tendency for larger parents particularly mothers, more so than smaller parents, to care predominantly for their own offspring. Larger parents might be better at defending against cuckoldry and having foreign young dumped into their broods through farming‐out behavior. This result might argue for maladaptive effects of allopatric care for the foster parents that only larger and possibly more experienced pairs can guard against. It needs to be determined why, apparently, the ability to recognize one's own young has not evolved in this species.

Suboptimal culture conditions induce more deviations in gene expression in male than female bovine blastocysts.

BackgroundSince the development of in vitro embryo production in cattle, different supplements have been added to culture media to support embryo development, with serum being the most popular. However, the addition of serum during embryo culture can induce high birthweights and low viability in calves (Large Offspring Syndrome). Analysis of global gene expression in bovine embryos produced under different conditions can provide valuable information to optimize culture media for in vitro embryo production.ResultsWe used RNA sequencing to examine the effect of in vitro embryo production, in either serum-containing or serum-free media, on the global gene expression pattern of individual bovine blastocysts. Compared to in vivo derived embryos, embryos produced in serum-containing medium had five times more differentially expressed genes than embryos produced in serum-free conditions (1109 vs. 207). Importantly, in vitro production in the presence of serum appeared to have a different impact on the embryos according to their sex, with male embryos having three times more genes differentially expressed than their female counterparts (1283 vs. 456). On the contrary, male and female embryos produced in serum-free conditions showed the same number (191 vs. 192) of genes expressed differentially; however, only 44 of those genes were common in both comparisons. The pathways affected by in vitro production differed depending on the type of supplementation. For example, embryos produced in serum-containing conditions had a lower expression of genes related to metabolism while embryos produced in serum-free conditions showed aberrations in genes involved in lipid metabolism.ConclusionsSerum supplementation had a major impact on the gene expression pattern of embryos, with male embryos being the most affected. The transcriptome of embryos produced in serum-free conditions showed a greater resemblance to that of in vivo derived embryos, although genes involved in lipid metabolism were altered. Male embryos appeared to be most affected by suboptimal in vitro culture, i.e. in the presence of serum.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2393-z) contains supplementary material, which is available to authorized users.

Maternal age at maturation underpins contrasting behavior in offspring

In species where parental care occurs primarily via the provisioning of eggs, older females tend to produce larger offspring that have better fitness prospects. Remarkably however, a relationship between age of mother and fitness of offspring has also been reported independently of effects on offspring size suggesting that there may be other factors at play. Here, using experimental matings between wild Atlantic salmon that differed in their age at sexual maturation, we demonstrate distinct size-independent variation in the behavior of their offspring that was related to the maturation age of the mother (but not the father). We found that when juvenile salmon were competing for feeding territories, offspring of early-maturing mothers were more aggressive than those of late-maturing mothers, but were out-competed for food by them. This is the first demonstration of a link between natural variation in parental age at maturation and variation in offspring behavior.

175 CONSEQUENCES OF IN VITRO PRODUCTION OF EMBRYOS WITH OR WITHOUT COLONY-STIMULATING FACTOR 2 IN CULTURE MEDIUM ON MORPHOMETRIC FEATURES OF THE BOVINE CONCEPTUS AT DAY 86 OF GESTATION

In vitro production (IVP) of embryos can disrupt fetal and placental development and increase risk of abnormal fetal growth. Maternal factors play a role in developmental programming of the early embryo. Colony-stimulating factor 2 (CSF2) is present in the oviduct and endometrium and has improved competence of the pre-implantation embryo to establish pregnancy in cattle. The objective was to determine whether CSF2 during embryo culture alters fetal development and alleviates abnormalities associated with IVP. Holstein oocytes were matured and fertilised in vitro with X-sorted semen from a Holstein bull. Putative zygotes were cultured in SOF-BE1 at 5% CO2 and 5% O2 for 5 days and then randomly assigned to receive vehicle (IVP-control) or 10 ng mL–1 CSF2 (IVP-CSF2). Grade I blastocysts were transferred on Day 7 to Holstein recipients that were previously randomised to receive an IVP-control or an IVP-CSF2 embryo. A third group of cows included in the randomization was assigned to be artificially inseminated on Day 0 using the same bull as for IVP (AI). Pregnancy was terminated on Day 85 or 86. Statistical analysis was performed by analysis of variance using the GLM procedure of SAS with contrasts for AI v. (IVP-control+IVP-CSF2) (contrast 1; C1) and IVP-control v. IVP-CSF2 (contrast 2; C2). Results are least squares means ± s.e.M. A total of 23 morphometric measurements of placenta and fetus were made on 9 AI, 12 IVP and 7 CSF2 female singletons. Conceptuses derived by IVP (IVP-control and IVP-CSF2) differed from those derived by AI for 4 characteristics including fetal bodyweight (142.9 ± 4.7, 157.2 ± 4.4, and 162.6 ± 6.1 g for AI, IVP-control and IVP-CSF2, respectively; C1, P = 0.0237), eviscerated weight (102.9 ± 3.4, 113.6 ± 3.2, and 112.2 ± 4.4 g; C1, P = 0.0602), crown-rump length (CRL) (13.7 ± 0.2, 14.0 ± 0.2, and 14.7 ± 0.3 g; C1, P = 0.0434; C2, P = 0.0631) and umbilical cord diameter (0.85 ± 0.08, 1.1 ± 0.08, and 0.91 ± 0.1 cm; P = 0.0519). Note that while IVP-CSF2 conceptuses were generally similar to those for IVP-control, CRL tended to be highest for IVP-CSF2. Also, umbilical cord diameter for IVP-CSF2 was similar to AI and lower than IVP-control. Data from 1 fetus in the IVP-CSF2 group was excluded from analysis because it had a phenotype consistent with large offspring syndrome. Bodyweight (354 g) was 2-fold larger than other fetuses (average = 155 g) and placental weight was 7-fold greater (1505 v. 211 g). In addition, organs were enlarged and severe ascites and hemorrhagic cotyledons were observed. In conclusion, IVP resulted in increased fetal size and umbilical cord diameter without other significant effects on placental morphometry. CSF2 did not alleviate adverse effects of culture on fetal growth, exacerbating effects on CRL, but did reduce effects of IVP on umbilical cord diameter. Gene expression analysis may be useful for further characterisation of effects and elucidation of mechanisms involved. This project was supported by USDA NIFA Grant 2011–67015–30688.

193 IMPROVED POST-THAW SURVIVAL OF BOVINE EMBRYOS PRODUCED IN SERUM-FREE IN VITRO PRODUCTION SYSTEM

Over a few decades the bovine in vitro embryo production (IVP) systems have been improving rapidly. Still, the goal to produce the same quality embryos in vitro as in vivo has not yet been reached. The FCS is usually added to media during IVP to provide growth factors and energy sources. Currently, serum-free culture systems are often preferred due to the lower risk of contamination and prevention of the development of large offspring syndrome. The aim of this study was to establish whether complete elimination of FCS from the bovine IVP system has an effect on blastocyst rates, embryo quality, and embryo survival rates after slow freezing. We replaced our conventional in vitro maturation (IVM) medium [tissue culture medium-199, 10% (v/v) FCS, 10 µg mL–1 epidermal growth factor (EGF), 1500 U mL–1 serum gonadotropin and chorionic gonadotropin (PG600), Na-pyruvate 0.5 mM, gentamycin sulfate 50 µg mL–1 and l-glutamine 1 mM] with SOF (SOFaaci) supplemented with 0.4% fatty acid-free BSA fraction V, 10 µg mL–1 EGF, and 1500 U mL–1 PG600. Matured cumulus-oocyte complexes (COC) from both experimental groups (total of 1145 from serum-free IVP and 687 from our conventional IVP system) were used for in vitro fertilisation and culture. Blastocyst rates were similar in the serum-free and our usual IVP protocol, 18 and 22%, respectively. Seventy-seven Grade 1 (according to IETS) Day 7 blastocysts from the serum-free IVP system and 80 Grade 1 Day 7 blastocysts from our conventional IVP system were frozen in 1.5 M ethylene glycol and 0.1 M sucrose containing cryopreservation medium. The post-thaw survival rates after 24 h of culture and evaluated as percentages of re-expanded embryos were 63.6% for the serum-free IVP and 46.3% for the conventional IVP system (P < 0.05, Z Test for 2 population proportions). These results indicate that it is possible to have a completely serum-free bovine IVP system and based on the slow freezing and thawing results the quality of serum-free IVP embryos might be better than of the embryos matured in our conventional maturation media. However, more experiments and increased sample sizes are needed to confirm the results. This study was supported by Project 3.2.0701.12–0036 of Archimedes Foundation, AP 2.4 of CCRMB, and institutional research funding (IUT 08–01) of the Estonian Ministry of Education and Research.

In vitro fertilization (IVF) in mammals: epigenetic and developmental alterations. Scientific and bioethical implications for IVF in humans.

The advent of in vitro fertilization (IVF) in animals and humans implies an extraordinary change in the environment where the beginning of a new organism takes place. In mammals fertilization occurs in the maternal oviduct, where there are unique conditions for guaranteeing the encounter of the gametes and the first stages of development of the embryo and thus its future. During this period a major epigenetic reprogramming takes place that is crucial for the normal fate of the embryo. This epigenetic reprogramming is very vulnerable to changes in environmental conditions such as the ones implied in IVF, including in vitro culture, nutrition, light, temperature, oxygen tension, embryo-maternal signaling, and the general absence of protection against foreign elements that could affect the stability of this process. The objective of this review is to update the impact of the various conditions inherent in the use of IVF on the epigenetic profile and outcomes of mammalian embryos, including superovulation, IVF technique, embryo culture and manipulation and absence of embryo-maternal signaling. It also covers the possible transgenerational inheritance of the epigenetic alterations associated with assisted reproductive technologies (ART), including its phenotypic consequences as is in the case of the large offspring syndrome (LOS). Finally, the important scientific and bioethical implications of the results found in animals are discussed in terms of the ART in humans.

Cytokine gene expression at the maternal-fetal interface after somatic cell nuclear transfer pregnancies in small ruminants.

The present retrospective study investigated pregnancy rates, the incidence of pregnancy loss and large offspring syndrome (LOS) and immune-related gene expression of sheep and goat somatic cell nuclear transfer (SCNT) pregnancies. We hypothesised that significantly higher pregnancy losses observed in sheep compared with goat SCNT pregnancies are due to the increased amounts of T-helper 1 cytokines and proinflammatory mediators at the maternal-fetal interface. Sheep and goat SCNT pregnancies were generated using the same procedure. Control pregnancies were established by natural breeding. Although SCNT pregnancy rates at 45 days were similar in both species, pregnancy losses between 45 and 60 days of gestation and the incidence of LOS were significantly greater in sheep than in goats. At term, the expression of proinflammatory genes in sheep SCNT placentas was increased, whereas that in goats was similar to that in control animals. Genes with altered expression in sheep SCNT placentas included cytotoxic T-lymphocyte-associated protein 4 (CTLA4), interleukin 2 receptor alpha (IL2RA), cluster of differentiation 28 (CD28), interferon gamma (IFNG), interleukin 6 (IL6), interleukin 10 (IL10), transforming growth factor beta 1 (TGFB1), tumor necrosis factor alpha (TNF-α), interleukin 1 alpha (IL1A) and chemokine (C-X-C motif) ligand 8 (CXCL8). Major histocompatibility complex-I protein expression was greater in sheep and goat SCNT placentas at term than in control pregnancies. An unfavourable immune environment is present at the maternal-fetal interface in sheep SCNT pregnancies.

The positive correlation between maternal size and offspring size: fitting pieces of a life-history puzzle.

The evolution of investment per offspring (I) is often viewed through the lens of the classic theory, in which variation among individuals in a population is not expected. A substantial departure from this prediction arises in the form of correlations between maternal body size and I, which are observed within populations in virtually all taxonomic groups. Based on the generality of this observation, we suggest it is caused by a common underlying mechanism. We pursue a unifying explanation for this pattern by reviewing all theoretical models that attempt to explain it. We assess the generality of the mechanism upon which each model is based, and the extent to which data support its predictions. Two classes of adaptive models are identified: models that assume that the correlation arises from maternal influences on the relationship between I and offspring fitness [w(I)], and those that assume that maternal size influences the relationship between I and maternal fitness [W(I)]. The weight of evidence suggests that maternal influences on w(I) are probably not very general, and even for taxa where maternal influences on w(I) are likely, experiments fail to support model predictions. Models that assume that W(I) varies with maternal size appear to offer more generality, but the current challenge is to identify a specific and general mechanism upon which W(I) varies predictably with maternal size. Recent theory suggests the exciting possibility that a yet unknown mechanism modifies the offspring size-number trade-off function in a manner that is predictable with respect to maternal size, such that W(I) varies with size. We identify two promising avenues of inquiry. First, the trade-off might be modified by energetic costs that are associated with the initiation of reproduction ('overhead costs') and that scale with I, and future work could investigate what specific overhead costs are generally associated with reproduction and whether these costs scale with I. Second, the trade-off might be modified by virtue of condition-dependent offspring provisioning coupled with metabolic factors, and future work could investigate the proximate cause of, and generality of, condition-dependent offspring provisioning. Finally, drawing on the existing literature, we suggest that maternal size per se is not causatively related to variation in I, and the mechanism involved in the correlation is instead linked to maternal nutritional status or maternal condition, which is usually correlated with maternal size. Using manipulative experiments to elucidate why females with high nutritional status typically produce large offspring might help explain what specific mechanism underlies the maternal-size correlation.

Host-specific variation in off-host performance of a temperate ectoparasite

Antagonistic host–parasite interactions are rarely considered from an ecological perspective of the parasite. We used a blood-feeding ectoparasite of boreal cervids, the deer ked (Lipoptena cervi L., Hippoboscidae), to study host-dependent variation in a parasite's ability to cope with an abiotic environment during the free-living stage(s) in two allopatric Fennoscandian populations. We found that a strongly host-specific deer ked population in eastern Fennoscandia, exploiting only moose (Alces alces), produced the largest offspring that were the most cold-tolerant and emerged the earliest as adults, when compared with the western Fennoscandian population that exploited two hosts efficiently. Within the western population, however, offspring produced on roe deer (Capreolus capreolus) were significantly larger, more cold-tolerant, and had higher survival than those produced on moose in the same area. We discuss potential causes for both host-specific and geographical differences in off-host performance: (1) maternal host directly affects the offspring survival prospects; (2) divergent co-evolution with local main host(s) has shaped the parasite's life history; and/or (3) off-host performance is shaped by adaptation to the local abiotic environment. In conclusion, this study increases our understanding of the evolution of host–parasite interactions by demonstrating how geographical differences in host exploitation may result in differences in survival prospects outside the host.

Cannibalism of an endemic island lizard (genus Gallotia)

Cannibalism is not rare among animals, and particularly in reptiles it is favored by a strong ontogenetic shift in body size and generalized carnivore habits. We looked for evidence of this behavior in a medium-sized lizard, endemic of oceanic islands (Canary Islands), with a high prevalence of a parasite transmitted by cannibalism. Conspecific predation appeared in this lizard, with a rather low incidence (0.76% of fecal pellets included conspecifics), although the analysis of a very large sample (n=11,651 pellets) indicated ontogenetic, sexual, and seasonal patterns of such predation. Only the largest individuals were cannibal, invariably males, which only depredated immature individuals, almost exclusively during the post-hatching period (summer and autumn). Together with other natural-history traits already known for the species (e.g., high density, low breeding output, large offspring), cannibalism adds further evidence that this lizard fits the island syndrome.

Old male sex: large ejaculate, many sperm, but few offspring

Reproduction induces non-trivial costs, such that both males and females should choose their mates carefully and invest their resources prudently. Male performance and thus their investment into ejaculates are often predicted to decrease with age and mating frequency, which may in turn negatively affect female fitness and thus feedback on the attractiveness of old males. Such reproductive senescence may be mediated by changes in the males’ oxidative status. Here, we investigated the effects of male mating frequency and age on male reproduction and oxidative status, and the respective consequences for female reproduction. We used the tropical butterfly Bicyclus anynana, in which counterintuitively older males have a higher mating success than younger ones. In once-mated males, spermatophore mass and sperm numbers strongly increased with age, while antioxidant defences and oxidative damage declined with age. In repeatedly mated males, spermatophore mass and sperm number showed little variation being similar to young once-mated males, while antioxidant defences increased and oxidative damage decreased with mating frequency. Female reproductive success was highest when mating with young once-mated males, although these produced small spermatophores with low sperm numbers. Our findings suggest that in B. anynana, (1) ejaculate size and sperm number are not reliable proxies of male quality, (2) ejaculate quality diminishes with age and mating number, and that (3) old male mating advantage likely results from sexual conflict owing negative effects on female fitness.

Comparative life histories of fishes in the subgenus Limia (Pisces: Poeciliidae).

This study presents life-history descriptions for 12 species in the subgenus Limia, which are endemic to the Greater Antilles. All species in this study lack evidence of superfoetation, producing a single brood of offspring before developing subsequent broods. Interbrood intervals (number of days between parturition events) are also consistent with intervals of species that lack superfoetation. Maternal provisioning, characterized by matrotrophy index, is <1.0 for all species of Limia. This is consistent with species that provide little or no maternal provisioning to developing embryos after ovum fertilization (lecithotrophic). Four species exhibit potentially bi-modal size distributions of mature males. Work on other poeciliids suggests that such bimodal distributions can be caused by genetic polymorphisms in some species. Principle component analyses revealed an axis of interspecific variation in life histories that separated species with small size at maturity and the production of many, small offspring from those with large size at maturity and that produce few, large offspring. This pattern of life-history diversity occurs in many other groups of organisms.

Caracterização das proteínas caveolinas -1 e -2 na placenta de conceptos bovinos clonados transgênicos

RESUMO:A utilização da transgenia com a proteína fluorescente verde (GFP) como marcador de células de origem fetal nas placentas de clones bovinos servirá de modelo inédito para estudo morfofisiológico e imunológico da interação materno-fetal, visto que possibilitará o seu mapeamento, diferenciando as células fetais das maternas. Tal modelo terá aplicação direta, principalmente porque estes são animais que apresentam problemas em relação ao seu desenvolvimento. Com o auxílio deste modelo, pretende-se verificar o transporte de substâncias entre a mãe e o feto via endocitose, pela imunolocalização das proteínas chamadas de caveolinas. Para tanto foram utilizados 06 bovinos clonados e 30 bovinos de inseminação artificial (IA) com idade até 90 dias de gestação, os quais tiveram seu desenvolvimento interrompido mediante abate humanitário das receptoras e ovariosalpingohisterectomia, com posterior recuperação do útero gestante. Foram coletados os placentônios e o cório. Uma parte das amostras foi recortada e fixada, por imersão, em solução de parafolmaldeído a 4% ou formoldeído a 10% em tampão fosfato de sódio (PBS) a 0,1M pH 7.4, solução de Zamboni (4% de paraformoldeído, 15% de ácido pícrico, em tampão fosfato de sódio a 0,1M pH 7.4), metacarn (60% de metanol, 30% de clorofórmio, e 10% de ácido acético glacial), para verificação da morfologia e realização de imuno-histoquímica para as proteínas caveolinas -1 e -2 (CAV -1 e CAV-2). As caveolinas -1 foram localizadas nos vilos fetais e maternos, mas sua marcação mais forte foi observada no estroma endometrial. As caveolinas -2 tiveram marcação positiva no trofoblasto e membrana córioalantoide, e, especificamente em célula trofoblástica gigante binucleada. Sendo assim, os resultados mostram que a proteína CAV-1 teve uma maior expressão em relação à proteína CAV-2 e que as proteínas CAV-1 e -2 são parte da composição das cavéolas, sendo estruturas importantes e relacionadas com a transferência de moléculas para o feto, realizando a nutrição do mesmo mediante endocitose e pinocitose.

Characterization of global loss of imprinting in fetal overgrowth syndrome induced by assisted reproduction

Embryos generated with the use of assisted reproductive technologies (ART) can develop overgrowth syndromes. In ruminants, the condition is referred to as large offspring syndrome (LOS) and exhibits variable phenotypic abnormalities including overgrowth, enlarged tongue, and abdominal wall defects. These characteristics recapitulate those observed in the human loss-of-imprinting (LOI) overgrowth syndrome Beckwith-Wiedemann (BWS). We have recently shown LOI at the KCNQ1 locus in LOS, the most common epimutation in BWS. Although the first case of ART-induced LOS was reported in 1995, studies have not yet determined the extent of LOI in this condition. Here, we determined allele-specific expression of imprinted genes previously identified in human and/or mouse in day ∼105 Bos taurus indicus × Bos taurus taurus F1 hybrid control and LOS fetuses using RNAseq. Our analysis allowed us to determine the monoallelic expression of 20 genes in tissues of control fetuses. LOS fetuses displayed variable LOI compared with controls. Biallelic expression of imprinted genes in LOS was associated with tissue-specific hypomethylation of the normally methylated parental allele. In addition, a positive correlation was observed between body weight and the number of biallelically expressed imprinted genes in LOS fetuses. Furthermore, not only was there loss of allele-specific expression of imprinted genes in LOS, but also differential transcript amounts of these genes between control and overgrown fetuses. In summary, we characterized previously unidentified imprinted genes in bovines and identified misregulation of imprinting at multiple loci in LOS. We concluded that LOS is a multilocus LOI syndrome, as is BWS.

Offspring size at weaning affects survival to recruitment and reproductive performance of primiparous gray seals.

Offspring size affects survival and subsequent reproduction in many organisms. However, studies of offspring size in large mammals are often limited to effects on juveniles because of the difficulty of following individuals to maturity. We used data from a long-term study of individually marked gray seals (Halichoerus grypus; Fabricius, 1791) to test the hypothesis that larger offspring have higher survival to recruitment and are larger and more successful primiparous mothers than smaller offspring. Between 1998 and 2002, 1182 newly weaned female pups were branded with unique permanent marks on Sable Island, Canada. Each year through 2012, all branded females returning to the breeding colony were identified in weekly censuses and a subset were captured and measured. Females that survived were significantly longer offspring than those not sighted, indicating size-selective mortality between weaning and recruitment. The probability of female survival to recruitment varied among cohorts and increased nonlinearly with body mass at weaning. Beyond 51.5 kg (mean population weaning mass) weaning mass did not influence the probability of survival. The probability of female survival to recruitment increased monotonically with body length at weaning. Body length at primiparity was positively related to her body length and mass at weaning. Three-day postpartum mass (proxy for birth mass) of firstborn pups was also positively related to body length of females when they were weaned. However, females that were longer or heavier when they were weaned did not wean heavier firstborn offspring.

Effects of Water Chemistry on the Life History of the Least KillifishHeterandria formosaand the Absence of Evidence for Local Adaptation

This study explored whether persistent differences in life history traits between populations of Least Killifish Heterandria formosa could be explained by differences in habitat-associated water type, reflecting either local adaptation or phenotypic plasticity. Fish native to a pond and a spring site were reared in the lab in either pond or spring water. Fish reared in pond water reached maturity faster and at the same size as fish reared in spring water, regardless of source population. There was no difference in daily mortality rate between fish raised in the different water types, but the longer time to maturity in spring water produced a lower cumulative survival to maturity. Water type did not affect fecundity, but fish from the spring population had larger offspring, contrary to patterns found in both the field and previously in the lab. Persistent differences among natural populations in life history traits have previously been attributed to differences in population density and predation pressure....

Life history of Gambusia nobilis (Pecos Gambusia) from Bitter Lake National Wildlife Refuge

Relatively little is known about variation in allocation to growth and reproduction of endangered and threatened fish species with small geographic distributions or isolated populations. We examined life history and reproductive variation among four ecologically distinct populations of the federally listed Pecos gambusia, Gambusia nobilis, from sinkholes at Bitter Lake National Wildlife Refuge in New Mexico, United States. Despite ecological variation between sinkholes, there were no significant differences in female reproductive traits between populations. Reproductive strategy shifted over the reproductive season from investment in many small embryos to fewer large offspring. Reproductive effort was not correlated with female size or condition (which varies between populations), suggesting that small or poor quality females invest similarly to larger or healthier females. Reproduction was asynchronous between populations and through the reproductive season. Embryo development patterns suggest that females often carry embryos of two or more developmental stages and provision them during gestation (matrotrophy). Understanding the life history strategies of this endangered species is important to the planning and implementation of conservation efforts.

Squamate hatchling size and the evolutionary causes of negative offspring size allometry

Although fecundity selection is ubiquitous, in an overwhelming majority of animal lineages, small species produce smaller number of offspring per clutch. In this context, egg, hatchling and neonate sizes are absolutely larger, but smaller relative to adult body size in larger species. The evolutionary causes of this widespread phenomenon are not fully explored. The negative offspring size allometry can result from processes limiting maximal egg/offspring size forcing larger species to produce relatively smaller offspring ('upper limit'), or from a limit on minimal egg/offspring size forcing smaller species to produce relatively larger offspring ('lower limit'). Several reptile lineages have invariant clutch sizes, where females always lay either one or two eggs per clutch. These lineages offer an interesting perspective on the general evolutionary forces driving negative offspring size allometry, because an important selective factor, fecundity selection in a single clutch, is eliminated here. Under the upper limit hypotheses, large offspring should be selected against in lineages with invariant clutch sizes as well, and these lineages should therefore exhibit the same, or shallower, offspring size allometry as lineages with variable clutch size. On the other hand, the lower limit hypotheses would allow lineages with invariant clutch sizes to have steeper offspring size allometries. Using an extensive data set on the hatchling and female sizes of >1800 species of squamates, we document that negative offspring size allometry is widespread in lizards and snakes with variable clutch sizes and that some lineages with invariant clutch sizes have unusually steep offspring size allometries. These findings suggest that the negative offspring size allometry is driven by a constraint on minimal offspring size, which scales with a negative allometry.