Effects of constant incubation regimes on eggs and hatchlings of the egg-laying skink, Oligosoma suteri

<p>The conditions under which reptilian eggs are incubated affect survival probability and physiological attributes of the progeny. The egg-laying skink, Oligosoma suteri, is the only endemic oviparous lizard in New Zealand. No controlled laboratory incubation had previously been undertaken, and thus no information was available on the requirements for successful captive incubation. I studied the effects of incubation regime on the eggs and hatchlings of O. suteri to four months of age. Oligosoma suteri eggs (n = 174) were randomly distributed among three constant incubation temperatures (18°C, 22°C and 26°C) and two water potentials (-120 kPa and -270 kPa). Hatching success and hatchling survival were greatest at 22°C and 26°C, with hatchlings from 18°C incubation suffering from physical abnormalities. Incubation regime and maternal influence did not affect sex of individuals, with equal sex ratios occurring from each incubation treatment. Hatchlings from the 22°C and -120 kPa incubation treatments were larger, for most measurements, and warmer incubation temperatures resulted in increased growth rates. Juveniles from 22°C and 26°C and individuals with greater mass per unit length (condition index) sprinted faster over 0.25 m. Sprint speed was positively correlated with ambient temperature. At four months of age sprint speed decreased in 18°C individuals and individuals incubated at 26°C and -270 kPa compared to their performance at one month. The results suggest that the most successful captive incubation regime for O. suteri is 22°C and -120 kPa. This study also shows that temperature-dependent sex determination does not occur in O. suteri, but that fitness traits are influenced by incubation temperature.</p>

Effects of constant incubation regimes on eggs and hatchlings of the egg-laying skink, Oligosoma suteri

<p>The conditions under which reptilian eggs are incubated affect survival probability and physiological attributes of the progeny. The egg-laying skink, Oligosoma suteri, is the only endemic oviparous lizard in New Zealand. No controlled laboratory incubation had previously been undertaken, and thus no information was available on the requirements for successful captive incubation. I studied the effects of incubation regime on the eggs and hatchlings of O. suteri to four months of age. Oligosoma suteri eggs (n = 174) were randomly distributed among three constant incubation temperatures (18°C, 22°C and 26°C) and two water potentials (-120 kPa and -270 kPa). Hatching success and hatchling survival were greatest at 22°C and 26°C, with hatchlings from 18°C incubation suffering from physical abnormalities. Incubation regime and maternal influence did not affect sex of individuals, with equal sex ratios occurring from each incubation treatment. Hatchlings from the 22°C and -120 kPa incubation treatments were larger, for most measurements, and warmer incubation temperatures resulted in increased growth rates. Juveniles from 22°C and 26°C and individuals with greater mass per unit length (condition index) sprinted faster over 0.25 m. Sprint speed was positively correlated with ambient temperature. At four months of age sprint speed decreased in 18°C individuals and individuals incubated at 26°C and -270 kPa compared to their performance at one month. The results suggest that the most successful captive incubation regime for O. suteri is 22°C and -120 kPa. This study also shows that temperature-dependent sex determination does not occur in O. suteri, but that fitness traits are influenced by incubation temperature.</p>

Elephant Endotheliotropic Herpesvirus Impact in the European Asian Elephant (Elephas maximus) Population: Are Hereditability and Zoo-Associated Factors Linked with Mortality?

EEHV is a ubiquitous virus, which most likely has co-evolved with elephants and is shed by healthy individuals and maintained in the herds. Yet, the factors determining calf susceptibility to the virus remain unknown. Here, we explored the impact of EEHV-HD in the European captive Asian elephant population in a retrospective statistical study spanning the last 35 years. We show that EEHV-HD was implicated in more than half of all deaths recorded in calves older than one months old. Moreover, the median age across EEHV-HD fatalities was significantly lower compared to other death causes. Finally, we investigated if heredity and zoo-associated factors could be linked to a higher susceptibility of calves to this disease. We used a univariable logistic regression model to evaluate if either fathers, mothers, or zoos could, separately, be considered as risk factors to the development of the disease. Afterwards, we used a two multivariable model, combining: (1) fathers and zoos, and (2) mothers and zoos. Overall, we found that two fathers, one mother, and four zoos had three or more times higher risk of their calves becoming sick when compared to all others, pointing us to the presence of a management or environmental element, which can have paternal and maternal influence and leads to calf susceptibility or resistance to EEHV-HD.

Cage and maternal effects on the bacterial communities of the murine gut

Findings from gut microbiome studies are strongly influenced by both experimental and analytical factors that can unintentionally bias their interpretation. Environment is also critical. Both co-housing and maternal effects are expected to affect microbiomes and have the potential to confound other manipulated factors, such as genetics. We therefore analysed microbiome data from a mouse experiment using littermate controls and tested differences among genotypes (wildtype versus colitis prone-mdr1a−/−), gut niches (stool versus mucus), host ages (6 versus 18 weeks), social groups (co-housed siblings of different genotypes) and maternal influence. We constructed a 16S phylogenetic tree from bacterial communities, fitting random forest models using all 428,234 clades identified. Models discriminated all criteria except host genotype, where no community differences were found. Host social groups differed in abundant, low-level, taxa whereas intermediate phylogenetic and abundance scales distinguished ages and niches. Thus, a carefully controlled experiment treating evolutionary clades of microbes equivalently without reference to taxonomy, clearly identifies whether and how gut microbial communities are distinct across ecologically important factors (niche and host age) and other experimental factors, notably cage effects and maternal influence. These findings highlight the importance of considering such environmental factors in future microbiome studies.

Eusociality through conflict dissolution

Eusociality, where largely unreproductive offspring help their mothers reproduce, is a major form of social organization. An increasingly documented feature of eusociality is that mothers induce their offspring to help by means of hormones, pheromones or behavioural displays, with evidence often indicating that offspring help voluntarily. The co-occurrence of maternal influence and offspring voluntary help may be explained by what we call the converted helping hypothesis, whereby maternally manipulated helping subsequently becomes voluntary. Such hypothesis requires that parent-offspring conflict is eventually dissolved—for instance, if the benefit of helping increases sufficiently over evolutionary time. We show that help provided by maternally manipulated offspring can enable the mother to sufficiently increase her fertility to transform parent-offspring conflict into parent-offspring agreement. This conflict-dissolution mechanism requires that helpers alleviate maternal life-history trade-offs, and results in reproductive division of labour, high queen fertility and honest queen signalling suppressing worker reproduction—thus exceptionally recovering diverse features of eusociality. As such trade-off alleviation seemingly holds widely across eusocial taxa, this mechanism offers a potentially general explanation for the origin of eusociality, the prevalence of maternal influence, and the offspring’s willingness to help. Overall, our results explain how a major evolutionary transition can happen from ancestral conflict.

The «Mal de la Madre» and the Failure of Maternal Influence in Celestina

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11 Understanding today’s sow and challenging ourselves for the future

The impact of maternal influence across all species on lifelong health and performance is a topic that while recognized as important in the past was not heavily explored until more recently. Over the years, production has focused on sow nutrition and its role in improving birth weights and weaning weights. Today’s sow has approximately 3 more pigs per litter compared to sows 12 years ago and is producing more milk than that of a sow a quarter of a century ago (Nielsen et al. 2018; Rosero, et al, 2016). The biological challenges of supporting the increased total born and milk production, the change in the genetics and lean mass of the sow, along with the environmental challenges such as disease, temperature and social interactions have created an ever changing dynamic that has the potential to influence the sow’s nutritional demands, but also complicates the interpretation of data generated in sow facilities. Along with the increase in total born, other issues such as pelvic organ prolapses and agalactia have also started to increase. While little is known at this time as to the causative nature of these conditions, the goal to quickly resolve such challenges has become absolute. Furthermore, many wonder what else is on the horizon for the modern day sow? Researchers are working to better understand the basis of sow to piglet interaction in terms of immunology, microbiome hereditability and progeny wean to finish performance alongside those working to better understand nutritional requirements to improve longevity of the female. The presentation will focus on these aspects associated with predicting issues for the sows and proactively addressing these concerns along with exploring knowledge advancements and aligning them with sow performance and production.

Eusociality through conflict dissolution

Eusociality, where largely unreproductive offspring help their mothers reproduce, is a major form of social organization in social insects and other animals. An increasingly documented feature of eusociality is that mothers induce their offspring to help by means of hormones, pheromones, or behavioral displays, with evidence often indicating that offspring help voluntarily. The co-occurrence of widespread maternal influence and voluntary offspring help may be explained by what we call the converted helping hypothesis, whereby helping originally arising from maternal manipulation subsequently becomes voluntary. This hypothesis requires that parent-offspring conflict is eventually dissolved—for instance, if the benefit of helping increases sufficiently over evolutionary time. Here we show that maternal manipulation of offspring help enables the mother to increase her fertility to such extent that parent-offspring conflict is transformed into parent-offspring agreement. Such conflict dissolution mechanism requires that helpers alleviate the total percent life-history trade-off limiting maternal fertility, and results in reproductive division of labor, high queen fertility, and honest queen signaling suppressing worker reproduction, thus exceptionally recovering diverse features of eusociality. This mechanism is widely applicable, thus suggesting a general explanation for the origin of eusociality, the prevalence of maternal influence, and the offspring’s willingness to help. Overall, our results explain how a major evolutionary transition can happen from ancestral conflict.

A Revolutionizing Approach to Autism Spectrum Disorder Using the Microbiome

The study of human microbiota and health has emerged as one of the ubiquitous research pursuits in recent decades which certainly warrants the attention of both researchers and clinicians. Many health conditions have been linked to the gut microbiota which is the largest reservoir of microbes in the human body. Autism spectrum disorder (ASD) is one of the neurodevelopmental disorders which has been extensively explored in relation to gut microbiome. The utilization of microbial knowledge promises a more integrative perspective in understanding this disorder, albeit being an emerging field in research. More interestingly, oral and vaginal microbiomes, indicating possible maternal influence, have equally drawn the attention of researchers to study their potential roles in the etiopathology of ASD. Therefore, this review attempts to integrate the knowledge of microbiome and its significance in relation to ASD including the hypothetical aetiology of ASD and its commonly associated comorbidities. The microbiota-based interventions including diet, prebiotics, probiotics, antibiotics, and faecal microbial transplant (FMT) have also been explored in relation to ASD. Of these, diet and probiotics are seemingly promising breakthrough interventions in the context of ASD for lesser known side effects, feasibility and easier administration, although more studies are needed to ascertain the actual clinical efficacy of these interventions. The existing knowledge and research gaps call for a more expanded and resolute research efforts in establishing the relationship between autism and microbiomes.