Evolution of social hybridogenesis in Cataglyphis desert ants

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Evolution of social hybridogenesis in Cataglyphis desert ants

Trabalho final de mestrado integrado em Medicina (Ética), apresentado á Faculdade de Medicina da Universidade de CoimbraObjetivos - O Diagnóstico Genético Pré-implantatório (DGPI), estuda geneticamente embriões obtidos por fertilização in vitro para detetar doenças genéticas graves. Este método surgiu pela primeira vez em 1989 no Reino Unido. Em Portugal, o enquadramento legal sobre esta matéria começa em 2006. Com este trabalho fez-se uma revisão sobre o DGPI na sua indicação de seleção do sexo fetal considerando a sua dimensão ética, moral, legal e cultural. Métodos - Realizou-se uma pesquisa considerando a literatura nacional e internacional, que envolveu artigos científicos conseguidos através do motor de busca PubMed assim como outras obras literárias, pareceres, convenções, relatórios e documentos legais sobre o assunto. Resultados - Salientam-se questões éticas inerentes ao DGPI como o consentimento informado, o estatuto do embrião humano ou o risco eugénico do diagnóstico. O DGPI para seleção fetal do sexo por razões não médicas é proibido por lei em quase todos os países, porém esta limitação legal nem sempre é suficiente. Em alguns países asiáticos há uma forte preferência pelo sexo masculino mas em países ocidentais e economicamente desenvolvidos a principal razão é por “family balancing”. Conclusões: O DGPI é um tema contemporâneo e quando se discute a sua aplicabilidade para selecionar o sexo do embrião levantam-se muitas questões éticas e morais de difícil consenso. Apesar de haver legislação que regula a prática deste tipo de diagnóstico, é essencial que se promova a divulgação e atualização sobre o assunto tendo em conta todas as suas dimensões.Objectives: The Pre-implantation genetic diagnosis (PGD or PIGD) studies, genetically, in vitro fertilization obtained embryos to detect harmful genetic diseases. This method appeared for the first time in 1989 in the United Kingdom. In Portugal, its legal framing started only in 2006. With this work, it is intended to revise the PGD’s usage to select the baby’s sex considering its ethical, moral, legal and cultural dimensions. Methods: A revision of national and international scientific articles, obtained through PubMed, was conducted for this work. Scientific books, technical opinions, conventions, reports and legal documents were also consulted. Results: The ethical issues are three-folded: the informed consent, the by-law for the Human Embryo and the Eugenics associated with the diagnosis. Legally, the PGD for non-medical reasons is forbidden almost worldwide, but this legal constrain is not enough. The reasons to choose the baby’s sex differ across countries. In Asia, for example, there is a preference for the masculine sex, while in Europe and North America the main reason is family balancing. Conclusion: The PGD is a current issue and its applicability to select the baby’s sex raises many ethical and moral questions. Despite the fact that the current legislation regulates 5 this practice, it is essential to promote and update the subject considering all its above-mentioned dimension

Isolation and characterization of novel microsatellite markers for a globally distributed invasive ant Paratrechina longicornis (Hymenoptera: Formicidae)

The longhorn crazy ant, Paratrechina longicornis (Latreille), is a ubiquitous agricultural and urban pest that has invaded most tropical and subtropical regions. Although P. longicornis has been found worldwide for more than a century, the genetic structure, origin, and invasion history of this species have not yet been extensively studied, partially because of the limited number of genetic markers currently available. In the present study, we developed 36 polymorphic microsatellite markers for P. longicornis and characterized these markers by genotyping P. longicornis workers from 74 colonies in East and Southeast Asia. All loci were polymorphic, with the number of alleles per locus ranging from 3 to 18 (8.5 on average). Extremely high levels of heterozygosity were found in all populations, suggesting that workers are invariably produced from the mating of divergent queen and male lineages. Queens and males possess non-overlapping allele size ranges at 18 loci, indicating the potential resolving power of the subset of markers in inferring the history of queen and male lineages. Genetic differentiation among three studied populations was low yet significant and may likely reflect their close association with human activities. Overall, the new microsatellite markers developed in the present study serve as a practical tool to reconstruct routes of invasion and assess the population genetics of this invasive ant

The rise and fall of the ancient northern pike master sex-determining gene

The understanding of the evolution of variable sex determination mechanisms across taxa requires comparative studies among closely related species. Following the fate of a known master sex-determining gene, we traced the evolution of sex determination in an entire teleost order (Esociformes). We discovered that the northern pike (Esox lucius) master sex-determining gene originated from a 65 to 90 million-year-old gene duplication event and that it remained sex linked on undifferentiated sex chromosomes for at least 56 million years in multiple species. We identified several independent species- or population-specific sex determination transitions, including a recent loss of a Y chromosome. These findings highlight the diversity of evolutionary fates of master sex-determining genes and the importance of population demographic history in sex determination studies. We hypothesize that occasional sex reversals and genetic bottlenecks provide a non-adaptive explanation for sex determination transitions

The rise and fall of the ancient northern pike master sex determining gene

The understanding of the evolution of variable sex determination mechanisms across taxa requires comparative studies among closely related species. Following the fate of a known master sex-determining gene, we traced the evolution of sex determination in an entire teleost order (Esociformes). We discovered that the northern pike (Esox lucius) master sex-determining gene originated from a 65 to 90 million-year-old gene duplication event and that it remained sex-linked on undifferentiated sex chromosomes for at least 56 million years in multiple species. We identified several independent species- or population-specific sex determination transitions, including a recent loss of a Y-chromosome. These findings highlight the diversity of evolutionary fates of master sex-determining genes and the importance of population demographic history in sex determination studies. We hypothesize that occasional sex reversals and genetic bottlenecks provide a non-adaptive explanation for sex determination transitions

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Social hybridogenesis in ants of the genus Cataglyphis

Les Hyménoptères sociaux (abeilles, fourmis et guêpes) doivent leur succès écologique à une division dutravail marquée par l’existence de castes. Les reines sont spécialisées dans la reproduction, tandis que les ouvrières sont stériles et prennent en charge la construction du nid et sa défense, la récolte de nourriture et l’élevage des jeunes. Le développement d’un œuf femelle en une reine ou une ouvrière est généralement régi par des facteurs environnementaux, tels que la qualité ou la quantité de la nourriture.En réalisant une étude de génétique des populations chez la fourmi Cataglyphis hispanica, nous avons mis en évidence un mode de reproduction inhabituel appelé hybridogenèse sociale. Cette espèce est caractérisée par la co-existence de deux lignées génétiques au sein des populations. Les reines de chaque lignée s’accouplent systématiquement avec un mâle de l’autre lignée génétique. Ainsi, les reines de la lignée 1 s’accouplent toujours avec un mâle de la lignée 2, et les reines de la lignée 2 s’accouplent avec un mâle de la lignée 1. Les ouvrières sont issues du croisement entre les deux lignées :il s’agit donc d’individus hybrides. A l’inverse, les individus reproducteurs (nouvelles reines et mâles) sont produits exclusivement par reproduction asexuée. La caste femelle (reine ou ouvrière) est donc déterminée génétiquement; les ouvrières portent un génome hybride, alors que les reproducteurs possèdent un génome non-hybride hérité exclusivement de la mère.Les travaux réalisés dans le cadre de cette thèse de doctorat visent à comprendre l’origine et l’évolution de l’hybridogenèse sociale chez les fourmis Cataglyphis par le biais d’approches variées (génétique des populations, phylogéographie et manipulation de colonies en laboratoire). Ils sont articulés selon plusieurs axes complémentaires :la description du phénomène, l’étude de sa distribution géographique et phylogénétique au sein du genre Cataglyphis, et l'étude de ces mécanismes génétiques sous-jacents.In eusocial Hymenoptera, such as bees, wasp and ants, it is commonly accepted that the diploid female eggs are bipotent and develop either into a queen or a worker depending on environmental factors. While conducting a population genetic study of the ant Cataglyphis hispanica, we discovered an unusual reproductive system called social hybridogenesis. Under this system, queens and workers develop from eggs with different genetic make-up. Two divergent genetic lineages coexist within a population. Queens of each lineage mate with males originating from the other lineage. Workers are produced by sexual reproduction; hence, they are first generation hybrids of the two lineages. By contrast, new queens and males are produced by thelytokous and arrhenotokous parthenogenesis, respectively. By using alternative modes of reproduction, queens appear to maximize their reproductive success by increasing the transmission rate of their genes to the reproductive offspring while benefiting from genetic diversity and heterosis effects in their worker force. Males, however, do not contribute genes to the next generation as they only sire sterile workers. This system is expected to be evolutionary short-lived as lineages may be selected to stop the production of males with null direct fitness. This PhD project aims at understanding the origin and evolution of social hybridogenesis in Cataglyphis. Using several different approaches including population genetics methods based on microsatellite makers, phylogeography and experimental manipulations on lab colonies, I explored tthe characteristics of social hybridogenesis, the genetic mechanisms underlying the system and its distribution within the genus Cataglyphis. My results, together with other recent findings, question the paradigm of environmental caste determination in eusocial Hymenoptera and suggest that genetic influences on caste determination may be more common than previously thought.Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Extraordinary reproductive strategies in the ant Cataglyphis

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Comparative analysis and evolution of unusual mating systems in the ant genus Cataglyphis

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Phenotypic plasticity in an ant with strong caste genotype association.

Caste determination in social Hymenoptera (whether a female egg develops into a reproductive queen or a sterile worker) is a remarkable example of phenotypic plasticity where females with highly similar genomes exhibit striking differences in morphology and behaviour. This phenotypic dichotomy is typically influenced by environmental factors. However, recent studies have revealed a strong caste-genotype association in hybridogenetic ants: workers are all interlineage hybrids while queens are all purebred, suggesting that female caste fate is genetically determined. Using the hybridogenetic ant Cataglyphis mauritanica, we show that under laboratory conditions, purebred offspring develop into reproductive queens but occasionally give rise to workers. Moreover, while hybrids typically become workers, juvenile hormone treatment can switch their developmental pathway to the reproductive caste. These results indicate that phenotypic plasticity has been retained in an ant with a strong caste-genotype association, despite its lack of expression in natural conditions.SCOPUS: ar.jinfo:eu-repo/semantics/publishe