Many animals improve offspring survival through parental care. Research on coevolution between parents has provided key insight into the genesis and maintenance of biparental care. However, understanding family dynamics more broadly requires assessing potential male–female coevolutionary processes in the more widespread and common context of uniparental care. Here, we explore how pre‐zygotic maternal contributions, jelly coats and oviposition sites, influence offspring dependency and change with the evolution of male‐only care in glassfrogs. Egg care appears ubiquitous among glassfrogs, with repeated evolutionary transitions from brief female‐only to extended male‐only care. Glassfrogs also exhibit a diversity of sex‐specific parental traits involving maternal egg‐jelly contributions, oviposition‐site choice, and egg‐attendance behaviors. We hypothesize these form functionally interchangeable suites of traits that mediate embryos' susceptibility to environmental risk. First, using parent‐removal field experiments, egg‐hydration assays, and comparative analyses, we found no evidence that evolutionary transitions in caring sex or care duration alter the adaptive functions or overall benefits of care (across eight species). Rather, the jelly contributions and oviposition‐site use associated with brief care influence embryo susceptibility to the same risks that are reduced by prolonged care. Next, we examined the diversity and evolutionary history of pre‐ and post‐zygotic parental traits, applying phylogenetic comparative methods to literature records and our field observations of 40 species (71 total, ~ 47 % of the family). Because pre‐zygotic maternal contributions determine embryo requirements, the evolution of male care might enable and/or compensate for reduced maternal contributions. Supporting this hypothesis, we found that the repeated evolution of complex male care is always associated with reductions in egg‐jelly and changes in oviposition sites. This phylogenetic pattern suggests that clutch phenotype might provide a general mechanism for the coevolution of parental investment in species with uniparental care. If different combinations of egg phenotypes and post‐zygotic care are ecologically equivalent, their interchangeability could allow parental traits to coevolve between the sexes without compromising offspring survival. Male‐only care is widespread in oviparous metazoans, occurring among annelids, molluscs, arthropods, fishes, and amphibians. Investigations of egg and clutch phenotypes offer new prospects for broadening research on the coevolutionary dynamics of parental care.

中文翻译：

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玻璃蛙扩大父母监护的演变：卵离合表型是否介导两性之间的共同进化？

许多动物通过父母的照顾提高了后代的存活率。父母之间共同进化的研究为双亲照顾的起源和维持提供了重要的见识。但是，要更广泛地了解家庭动态，就需要在更广泛，更普遍的单亲医疗环境中评估潜在的男女共同进化过程。在这里，我们探讨了玻璃后蛙的纯合男性照料方式如何演变合子前的母体贡献，果冻皮和产卵部位如何影响后代依赖和变化。在玻璃蛙中，卵子的养护似乎无处不在，并且经历了从单纯的雌性到长期的仅雄性的反复进化过渡。frog蛙还表现出多种性别特定的父母性状，包括母性果冻的贡献，产卵位点的选择和出勤行为。我们假设这些形式可以在功能上互换，从而调节胚胎对环境风险的敏感性。首先，通过父母亲去除实地实验，卵水化试验和比较分析，我们没有发现证据表明照护性别或照护持续时间的进化转变会改变照护的适应功能或总体效益（横跨八个物种）。相反，与短暂护理相关的果冻贡献和产卵场所使用会影响胚胎对长期护理降低的风险的敏感性。接下来，我们研究了合子前后父母亲性状的多样性和进化史，将系统发育比较方法应用于文献记录和我们对40个物种（共71种，约占该家族的47％）的实地观察。由于合子前母亲的贡献决定了胚胎的需求，因此男性照护的发展可能使和/或补偿减少的母亲贡献。支持这一假设的我们发现，复杂的男性护理的反复发展总是与蛋冻的减少和产卵位的改变有关。这种系统发育模式表明，离合器表型可能为单亲照顾物种中父母投资的共同进化提供一般机制。如果卵表型和合子后护理的不同组合在生态学上是等效的，则它们的互换性可以使父母性状在两性之间进化，而不会影响后代的生存。仅卵生的照顾在卵生的后生动物中广泛存在，发生在肢体动物，软体动物，节肢动物，鱼类和两栖动物之间。