Biparental care in Hymenoptera is a little studied behaviour. This kind of parental care was discovered and the ethological aspect described in the bee Ceratina nigrolabiata from the Czech Republic and is well understood on the ethological level. However, biparental care is not a common behaviour and the lack of genomic studies of this behaviour complicates the understanding of the origin of the biparental care and its underlying pathways on the genomic and physiological level. This master's thesis presents the genome analyses of a biparental bee Ceratina nigrolabiata. It consists of a brief summary of the known parental behaviour across insects, characteristics of the genus Ceratina, summary of the used genomic methods and presents a candidate genes for the transcriptomic study of the biparental behaviour of Ceratina nigrolabiata. Key words: biparental care, genomics, Hymenoptera, Insecta, Ceratina, small carpenter bees

Many animal species invest in extended parental care for their offspring. Parental care is costly, and natural selection favors investment strategies which maximize reproductive success. Biparental care is relatively rare, but when it does occur it has been found to increase success in terms of offspring survival and growth and in terms of future reproductive opportunities. In burying beetles (<i>Nicrophorus</i> spp.), both male and female participate in extended parental care. However, the fitness benefits of biparental care in burying beetles have been difficult to establish, with some studies reporting significantly smaller broods produced when both male and female are present. Variation in environmental conditions, such as temperature, is an important part of the context in which biparental care evolves. I hypothesize that biparental care acts as a buffer against environmental variation. This hypothesis predicts that biparental care will lead to greater reproductive success compared to uniparental care when temperature is increased during a reproductive attempt. I also tested the load-lightening hypothesis, which holds that biparental care benefits future reproduction by lowering the costs of reproduction. This predicts that the additional care by the other parent will allow females to rear higher quality second broods. I conducted a male removal experiment at two temperature treatments, using the species <i>Nicrophorus orbicollis</i>. I measured reproductive success during manipulated first brood and during second broods which females reared without a male, regardless of prior experience. I found that, contrary to my hypothesis, biparental care at the higher temperature resulted in reduced reproductive success compared to uniparental care. I found no effect of biparental care on the success of second broods. Instead, I found evidence of reproductive restraint associated with the higher temperature treatment in delayed egg-laying and increased feeding during second broods.

Les soins biparentaux impliquent que mâles et femelles travaillent ensemble et ajustent leur comportement l’un à l’autre. De nombreuses études théoriques et empiriques se sont intéressées à la façon dont un parent réagit face à une augmentation ou une diminution de l’effort parental de son partenaire. Mais très peu se sont intéressées aux mécanismes qui permettent cet ajustement. C’est chez les oiseaux qu’on trouve le plus d’espèces à soins biparentaux. Parce que ce sont des animaux qui produisent beaucoup de sons, la communication acoustique pourrait jouer un rôle dans l’organisation des soins parentaux. Le but de cette thèse est de contribuer à vérifier cette hypothèse en comparant deux espèces d’oiseaux qui diffèrent dans la façon dont le mâle et la femelle se partagent les soins parentaux. Chez le diamant mandarin, le mâle et la femelle participent tous les deux à l’incubation des oeufs tandis que c’est la femelle seule qui se charge de cette tâche chez la mésange charbonnière. Cette dernière est alors nourrie en partie par le mâle. Chez ces deux espèces, j’ai d’abord observé en milieu naturel dans quels contextes les parents communiquent avec des sons au nid etquelle est la structure de leurs échanges vocaux. J’ai pu ainsi formuler des premières hypothèses sur les fonctions de cette communication. J’ai ensuite testé expérimentalement une de ces hypothèses pour chaque espèce. Chez le diamant mandarin, j’ai montré que la communication au nid permet aux parents de se partager le temps d’incubation. Chez la mésange charbonnière la communication au nid permet à la femelle d’indiquer ses besoins en nourriture au mâle. La communication acoustique joue donc bien un rôle dans l’organisation des soins parentaux chez ces deux espèces et pourrait être un élément clef dans les études futures s’intéressant à l’ajustement de l’effort parental entre les mâles et les femelles / Biparental care involves that male and female work as a team and each individual adjusts its behaviour to that of its partner. Many theoretical and empirical studies have investigated how each parent adjusts its behaviour to an increase or a decrease in the parental effort of its partner. But fewer have explored the mechanism allowing this adjustment. Biparental care is widespread in birds. Because birds are vocal animals, acoustic communication may play a role in organizing parental care. The aim of this thesis is to contribute to answer this question by comparing two bird species that differ in sex roles during parental care. In the zebra finch, both male and female incubate the eggs, whereas in the great tit, the female incubates alone and is partly fed by the male. In both species, I first observed in which contexts parents communicate with sounds at the nest and described the structure of their vocal exchanges. This allowed me to formulate hypotheses on the functions of this communication. Then, I experimentally tested one of these hypotheses for each species. In the zebra finch, I demonstrated that communication at the nest allows the pair to share incubation time. In the great tit, communication at the nest allows the female to communicate her needs for food to her mate. Acoustic communication thus plays a role in organizing parental care in these two species and could be a key factor in future studies on the adjustment of parental effort between males and females