Evolution of Lizard Viviparity

There are few more impressive examples of convergent evolution in animals than the repeated origins of live birth

Paternal nutrient provisioning during male pregnancy in the seahorse Hippocampus abdominalis

Vertebrates that incubate embryos on or within the body cavity exhibit diverse strategies to provide nutrients to developing embryos, ranging from lecithotrophy (solely yolk-provided nutrition) to substantial matrotrophy (supplemental nutrients from the mother before birth). Syngnathid fishes (seahorses, pipefishes and sea dragons) are the only vertebrates to exhibit male pregnancy. Therefore, they provide a unique opportunity for comparative evolutionary research, in examining pregnancy independent of the female reproductive tract. Here, we tested the hypothesis that the most complex form of syngnathid pregnancy involves nutrient transport from father to offspring. We compared the dry masses of newly fertilised Hippocampus abdominalis eggs with those of fully developed neonates to derive a patrotrophy index. The patrotrophy index of H. abdominalis was 1, indicating paternal nutrient supplementation to embryos during gestation. We also measured the lipid content of newly fertilised eggs and neonates and found that there was no significant decrease in lipid mass during embryonic development. Since lipids are likely to be the main source of energy during embryonic development, our results suggest that lipid yolk reserves being depleted by embryonic metabolism are replaced by the brooding father. The results of our study support the hypothesis that nutrient transport occurs in the most advanced form of male pregnancy in vertebrates

Service users’ experiences and views of aggressive situations in mental health care: a systematic review and thematic synthesis of qualitative studies

Background: Aggressive situations occurring within mental health services can harm service users, staff, and the therapeutic environment. There is a consensus that the aggression phenomenon is multidimensional, but the picture is still unclear concerning the complex interplay of causal variables and their respective impact. To date, only a small number of empirical studies include users’ views of relevant factors. The main objective of this review is to identify and synthesize evidence relating to service users’ experiences and views of aggressive situations in mental health settings. Methods: We included qualitative studies of any design reporting on service users’ own experiences of conditions contributing to aggressive situations in mental health care and their views on preventative strategies. Eligible articles were identified through an electronic database search (PsycINFO, PubMed, Ovid Nursing Database, Embase, and CINAHL), hand search, and cross-referencing. Extracted data were combined and interpreted using aspects of thematic synthesis. Results: We reviewed 5,566 records and included 13 studies (ten qualitative and three mixed methods). Service users recognized that both their own mental state and negative aspects of the treatment environment affected the development of aggressive situations. Themes were derived from experiential knowledge and included calls to be involved in questions regarding how to define aggression and relevant triggers, and how to prevent aggressive encounters effectively. The findings suggest that incidents are triggered when users experience staff behavior as custodial rather than caring and when they feel ignored. Conclusion: The findings highlight the importance of staffs’ knowledge and skills in communication for developing relationships based on sensitivity, respect, and collaboration with service users in order to prevent aggressive situations. An important factor is a treatment environment with opportunities for meaningful activities and a preponderance of trained staff who work continuously on the development of conditions and skills for collaborative interaction with users.Service users’ experiences and views of aggressive situations in mental health care: a systematic review and thematic synthesis of qualitative studiespublishedVersio

Seahorse Brood Pouch Transcriptome Reveals Common Genes Associated with Vertebrate Pregnancy

Viviparity (live birth) has evolved more than 150 times in vertebrates, and represents an excellent model system for studying the evolution of complex traits. There are at least 23 independent origins of viviparity in fishes, with syngnathid fishes (seahorses and pipefish) unique in exhibiting male pregnancy. Male seahorses and pipefish have evolved specialized brooding pouches that provide protection, gas exchange, osmoregulation, and limited nutrient provisioning to developing embryos. Pouch structures differ widely across the Syngnathidae, offering an ideal opportunity to study the evolution of reproductive complexity. However, the physiological and genetic changes facilitating male pregnancy are largely unknown. We used transcriptome profiling to examine pouch gene expression at successive gestational stages in a syngnathid with the most complex brood pouch morphology, the seahorse Hippocampus abdominalis. Using a unique time-calibrated RNA-seq data set including brood pouch at key stages of embryonic development, we identified transcriptional changes associated with brood pouch remodeling, nutrient and waste transport, gas exchange, osmoregulation, and immunological protection of developing embryos at conception, development and parturition. Key seahorse transcripts share homology with genes of reproductive function in pregnant mammals, reptiles, and other live-bearing fish, suggesting a common toolkit of genes regulating pregnancy in divergent evolutionary lineage

A comparison of uterine contractile responsiveness to arginine vasopressin in oviparous and viviparous lizards

Nonapeptides and their receptors regulate a diverse range of physiological processes. We assessed the contractile responsiveness of uteri from the squamate viviparous-oviparous species pair, Pseudemoia entrecasteauxii and Lampropholis guichenoti, as well as the bimodally reproductive species, Saiphos equalis, to arginine vasopressin (AVP). We assessed the resulting uterine contractility as a function of pregnancy status, species and parity mode. We also measured mRNA abundance for the nonapeptide receptor, oxytocin receptor (oxtr), in uteri from P. entrecasteauxii and L. guichenoti and compared expression across pregnancy status and parity mode. We found that pregnant uteri exhibited a significantly greater contractile response to AVP than non-pregnant uteri in all three lizard species studied. Cross-species comparisons revealed that uteri from viviparous P. entrecasteauxii were significantly more responsive to AVP than uteri from oviparous L. guichenoti during both pregnant and non-pregnant states. Conversely, for non-pregnant S. equalis, uteri from viviparous individuals were significantly less responsive to AVP than uteri from oviparous individuals, while during pregnancy, there was no difference in AVP contractile responsiveness. There was no difference in expression of oxtr between L. guichenoti and P. entrecasteauxii, or between pregnant and non-pregnant individuals within each species. We found no significant correlation between oxtr expression and AVP contractile responsiveness. These findings indicate that there are differences in nonapeptide signalling across parity mode and suggest that in these lizards, labour may be triggered either by an increase in plasma nonapeptide concentration, or by an increase in expression of a different nonapeptide receptor from the vasopressin-like receptor family

Paternal protein provisioning to embryos during male seahorse pregnancy

In brief: Seahorses exhibit male pregnancy and are thus valuable comparative models for the study of the physiology and evolution of pregnancy. This study shows that protein is transported from fathers to developing embryos during gestation, and provides new knowledge about paternal contributions to embryonic development. Abstract: Syngnathid embryos (seahorses, pipefishes and seadragons) develop on or in the male in a specialised brooding structure (brood pouch). Seahorse brood pouches supply nutrients, including lipids, to developing embryos (patrotrophy). We tested the hypothesis that proteins, vital for gene regulation and tissue growth during embryogenesis, are also transported from father to embryos, using the Australian pot-bellied seahorse, Hippocampus abdominalis. We used dry masses and total nitrogen content to estimate the total protein content of newly fertilised egg and neonate H. abdominalis. Neonates contained significantly greater protein mass than newly fertilised eggs. This result indicates that paternal protein transport to developing embryos occurs during H. abdominalis pregnancy. This study is the first to show paternal protein transport during pregnancy in seahorses, and furthers our understanding of paternal influence on embryonic development in male pregnant vertebrates

Structural changes to the brood pouch of male pregnant seahorses (Hippocampus abdominalis) facilitate exchange between father and embryos

Introduction Embryonic growth and development require efficient respiratory gas exchange. Internal incubation of developing young thus presents a significant physiological challenge, because respiratory gas diffusion to embryos is impeded by the additional barrier of parental tissue between the embryo and the environment. Therefore, live-bearing species exhibit a variety of adaptations facilitating respiratory gas exchange between the parent (usually the mother) and embryos. Syngnathid fishes are the only vertebrates to exhibit male pregnancy, allowing comparative studies of the biology and evolution of internal incubation of embryos, independent of the female reproductive tract. Here, we examine the fleshy, sealed, seahorse brood pouch, and provide the first quantification of structural changes to this gestational organ across pregnancy. Methods We used histological analysis and morphometrics to quantify the surface area for exchange across the brood pouch epithelium, and the structure of the vascular bed of the brood pouch. Results We show dramatic remodelling of gestational tissues as pregnancy progresses, including an increase in tortuosity of the gestational epithelium, an increase in capillary density, and a decrease in diffusion distance between capillaries and the pouch lumen. Discussion These changes produce an increased surface area and expansion of the vascular bed of the placenta that likely facilitates respiratory gas exchange. These changes mirror the remodelling of gestational tissue in viviparous amniotes and elasmobranchs, and provide further evidence of the convergence of adaptations to support pregnancy in live-bearing animals

Changes in participant behaviour and attitudes are associated with knowledge and skills gained by using a turtle conservation citizen science app

1. Citizen science has become a popular way to collect biodiversity data and engage the wider public in scientific research. It has the potential to improve the knowledge and skills of participants, and positively change their behaviour and attitude towards the environment. Citizen science outcomes are particularly valuable for wildlife conservation, as they could help alleviate human impacts on the environment. 2. We used an online questionnaire to investigate the consequences of participating in an Australian turtle mapping app, TurtleSAT, on skills and knowledge gain, and test for any association between these gains and behavioural or attitudinal changes reported by the participants. 3. One hundred and forty-eight citizen scientists completed our questionnaire, mostly from the states of New South Wales and Victoria. TurtleSAT was the third most common source of correct answers about turtle ecology and conservation, after a talk about turtles and personal observations/research. Citizen scientists who participated more often were more knowledgeable about turtles than infrequent users. Self-reported gains in knowledge and skills were positively linked to attitudinal and behavioural changes, such as being more aware of turtles on roads. However, behaviour and attitude changes were not related to participation rate. Respondents also reported that after learning about the current decline in turtle populations, they adopted several turtle-friendly practices, such as habitat restoration or moving turtles out of harm's way, underlining the importance of increasing people's awareness on species declines. 4. The reported changes in attitudes and behaviours are likely to positively impact the conservation of Australian freshwater turtles. Engagement with citizen science projects like TurtleSAT may result in participants being more interested in the natural world, by learning more about it and being more exposed to it, and therefore contributing more actively to its protection

Structure and permeability of the egg capsule of the placental Australian sharpnose shark, Rhizoprionodon taylori

Shark placentae are derived from modifications to the fetal yolk sac and the maternal uterine mucosa. In almost all placental sharks, embryonic development occurs in an egg capsule that remains intact for the entire pregnancy, separating the fetal tissues from the maternal tissues at the placental interface. Here, we investigate the structure and permeability of the egg capsules that surround developing embryos of the placental Australian sharpnose shark (Rhizoprionodon taylori) during late pregnancy. The egg capsule is an acellular fibrous structure that is 0.42 ± 0.04 μm thick at the placental interface between the yolk sac and uterine tissues, and 0.67 ± 0.08 μm thick in the paraplacental regions. This is the thinnest egg capsule of any placental shark measured so far, which may increase the diffusion rate of respiratory gases, fetal wastes, water and nutrients between maternal and fetal tissues. Molecules smaller than or equal to ~ 1000 Da can diffuse through the egg capsule, but larger proteins (~ 3000–26,000 Da) cannot. Similar permeability characteristics between the egg capsule of R. taylori and other placental sharks suggest that molecular size is an important determinant of the molecules that can be exchanged between the mother and her embryos during pregnancy

Different Genes are Recruited During Convergent Evolution of Pregnancy and the Placenta

The repeated evolution of the same traits in distantly related groups (convergent evolution) raises a key question in evolutionary biology: do the same genes underpin convergent phenotypes? Here, we explore one such trait, viviparity (live birth), which, qualitative studies suggest, may indeed have evolved via genetic convergence. There are >150 independent origins of live birth in vertebrates, providing a uniquely powerful system to test the mechanisms underpinning convergence in morphology, physiology, and/or gene recruitment during pregnancy. We compared transcriptomic data from eight vertebrates (lizards, mammals, sharks) that gestate embryos within the uterus. Since many previous studies detected qualitative similarities in gene use during independent origins of pregnancy, we expected to find significant overlap in gene use in viviparous taxa. However, we found no more overlap in uterine gene expression associated with viviparity than we would expect by chance alone. Each viviparous lineage exhibits the same core set of uterine physiological functions. Yet, contrary to prevailing assumptions about this trait, we find that none of the same genes are differentially expressed in all viviparous lineages, or even in all viviparous amniote lineages. Therefore, across distantly related vertebrates, different genes have been recruited to support the morphological and physiological changes required for successful pregnancy. We conclude that redundancies in gene function have enabled the repeated evolution of viviparity through recruitment of different genes from genomic "toolboxes", which are uniquely constrained by the ancestries of each lineage