Segurét A., Stolle E., Fleites-Ayil F.A., Quezada-Euán J.J.G., Hartfelder K., Meusemann K., Harrison M.C., Soro A., Paxton R.J. (2021) Transcriptomic signatures of ageing vary in solitary and social forms of an Orchid bee. Genome Biology and Evolution Volume 13, Issue 6, June 2021, evab075

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En la mayoría de los animales existe una evidente separación o “trade-off” entre fecundidad y longevidad, a mayor fecundidad la longevidad se reduce y viceversa. Las reinas de los insectos sociales son una excepción a esta regla ya que son altamente fecundas y viven por períodos largos de tiempo en comparación con las obreras. A pesar de que esta característica puede tener una explicación genética, hasta ahora pocos estudios han analizado el papel de diferentes genes para su mejor entendimiento. Euglossa viridissima es una especie de abeja con comportamiento social facultativo, lo que permite comparar diferencias genéticas entre hembras dominantes y subordinadas, así como en hembras solitarias. En este trabajo identificamos múltiples genes y sus inter-conexiones que incluyen las rutas antioxidativas y de la rapamicina, y que se involucran en la reprogramación del envejecimiento y el intercambio entre longevidad/fecundidad aun en formas sociales incipientes como esta abeja de las orquídeas.

Friedel Anna, Lattorf H. Michael G., Quezada-Euán J. Javier. G., Boff Samuel (2020) Shared reproduction and sex ratio adjustment to clutch size in a socially polymorphic orchid bee. Ethology 126: 88-96. https://doi.org/10.1111/eth.12963

Abstract

 Nests of the primitively eusocial orchid bee Euglossa viridissima are generally founded by a solitary female but can be reactivated by female offspring, in the presence or absence of the mother. The population therefore exists of solitary and social nests that co‐occur in an area. A female can stay as a subordinate helper under a dominant female or disperse to become a solitary foundress. Yet, the costs and benefits of the different social phenotypes are so far little understood. Here, we compared solitary and social nests of orchid bees. We used offspring of solitary and social nests to calculate offspring sex ratio, and applied molecular markers to calculate intranidal relatedness, infer maternity and test whether sociality may have a genetic component. We found that social nests had on average more brood than solitary nests. The overall sex ratio in the population did not differ from 1:1. However, social nests tended to produce a split sex ratio with some nests producing mainly males and others mainly female offspring. Regardless of social phenotype, the number of offspring was correlated with the sex ratio, with smaller nests having a more female‐biased offspring. In social nests, not all offspring resulted from a single‐mated mother, which was also the case for some solitary nests. This suggests shared reproduction in social nests and may be an indication that intraspecific parasitism and nest takeover are not uncommon. Structure analyses did not reveal different genetic background of the two social phenotypes. Our results suggest that there is no clear benefit that favours one of the two social phenotypes over the other and that the population is kept at balance in terms of sex ratio.

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Expresión de genes en Euglossa de Yucatán
 Boff S, Friedel A, Miertsch A, Quezada-Euàn JJG, Paxton RJ, Lattorff HMG (2018) A scientifc note on validation of housekeeping genes for the primitively eusocial bee Euglossa viridissima Friese (Apidae: Euglossini). Sociobiology 65: 766-769.
Abstract- Studies on the expression of genes in different contexts are essential to our understanding of the functioning of organisms and their adaptations to the environment. Gene expression studies require steps of normalization, which are done using the stable expression pattern of reference genes. For many different eusocial bees reference genes have been discovered, but not for the primitively eusocial Euglossini bees. We used available genomic resources of Euglossini species and the gene information of Apis mellifera Linnaeus to develop a set of reference genes for the primitive eusocial bee Euglossa viridissima Friese. We tested nine genes, in distinct developmental stages, using three different algorithms, to infer stability of gene expression. The TATA-binding protein (TBP) and 14-3-3 epsilon were the most stable genes across all developmental stages. The strongest deviation in gene expression pattern occurred in pupae, which require a different set of genes for normalizing gene expression.

Profesor Rob J. Paxton, y estudiantes de Doctorado Alice Seguret y Anna Friedel de la Universidad de Halle, Alemania en estancia del 15 al 23 de febrero en el Laboratorio de Apicultura Tropical para el desarrollo del Proyecto sobre Socialidad y Longevidad en Euglossa (abejas de las orquídeas) en conjunto con el Dr. Javier Quezada Euán, integrantes del Cuerpo Académico y estudiantes del CAAT.

Soro A, Quezada-Euán J J G, Theodorou P, Moritz R F A, Paxton R J (2017) The population genetics of two orchid bees suggests high dispersal, low diploid male production and only an effect of island isolation in lowering genetic diversity. Conservation Genetics 18(3): 607-619. DOI:10.1007/s10592-016-0912-8

Abstract

  Orchid bees (Hymenoptera, Apidae, Euglossini) are important pollinators of many plant families in Neotropical forests, habitats that have become increasingly degraded and fragmented by agricultural practices. To understand the extent to which loss of natural habitat and isolation has affected the genetic diversity and diploid male production (DMP) of two orchid bee species,Euglossa dilemma and Euglossa viridissima, we collected and genotyped 1686 males at five microsatellite loci and tested for differences in allelic richness, heterozygosity and DMP across three different types of land use (natural, agricultural and urban) and between mainland and island populations in the Yucatan Peninsula of Mexico. We also investigated the impact of land use and geographic isolation on gene flow. Euglossa dilemma and E. viridissima seemed to be particularly resilient to loss of natural habitat; in locations with human impact, we did not find reduced genetic diversity, and populations generally showed very little population genetic structure. Only on islands did E. dilemma show significantly reduced genetic diversity. Even after accounting for putative null alleles, DMP was very low (0.2–1.3%) across all sampling sites, including on islands. We therefore suggest that DMP is an insensitive measure of inbreeding and population decline in our two study species.

 

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Medina RG, Fairbairn DJ, Bustillos A, Moo-Valle H, Medina S, Quezada-Euán J J G (2016) Variable patterns of intraspecific sexual size dimorphism and allometry in three species of eusocial corbiculate bees. Insectes Sociaux 63: 493-500

 

Abstract

Sexual size dimorphism (SSD), in which one sex is larger than the other, has remained understudied in social insects, particularly bees. Using weight and linear structural measurements, we quantified the magnitude of SSD and its variation across nests in three species of corbiculate bees, two belonging to the highly eusocial Apini (Apis mellifera) and Meliponini (Melipona beecheii), and one to the primitively eusocial Euglossini (Euglossa viridissima). We asked if similar to most insects, including Hymenoptera, SSD is female-biased in these eusocial species. Contrary to expectations, we found that SSD was moderately male-biased in the two highly eusocial species and slightly male-biased for weight and not significant for linear size in E. viridissima. The possible roles of queen protogyny and reduced brood provisioning by queens in shaping these patterns of SSD are discussed. The allometry of SSD among nests differed among species as well, ranging from hypoallometry in A. mellifera, to isometry in M. beecheii, to hyperallometry in E. viridissima. This variation indicates that the phenotypic response of body size to differing conditions across nests differs both between sexes and among species. The variation detected among the three studied species in both SSD and allometry for SSD precludes any broad generalizations to other corbiculate bees. However, it does suggest that corbiculate bees can provide a new and diverse framework to analyze the effects of social environment on the evolution of animal sexual dimorphism.

 

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Visitantes: Philipp Brand (Davis California) e Ismael Hinojosa (UNAM) en compañia de Rubén Medina (estudiante de Doctorado) y Javier Quezada colectando abejas euglossinas como contribución al análisis genómico de las mismas

 

P Brand, SR Ramírez, F Leese, JJG Quezada-Euan, R Tollrian, T Eltz (2015) Rapid evolution of chemosensory receptor genes in a pair of sibling species of orchid bees (Apidae: Euglossini)

 Abstract

Background

Insects rely more on chemical signals (semiochemicals) than on any other sensory modality to find, identify, and choose mates. In most insects, pheromone production is typically regulated through biosynthetic pathways, whereas pheromone sensory detection is controlled by the olfactory system. Orchid bees are exceptional in that their semiochemicals are not produced metabolically, but instead male bees collect odoriferous compounds (perfumes) from the environment and store them in specialized hind-leg pockets to subsequently expose during courtship display. Thus, the olfactory sensory system of orchid bees simultaneously controls male perfume traits (sender components) and female preferences (receiver components). This functional linkage increases the opportunities for parallel evolution of male traits and female preferences, particularly in response to genetic changes of chemosensory detection (e.g. Odorant Receptor genes). To identify whether shifts in pheromone composition among related lineages of orchid bees are associated with divergence in chemosensory genes of the olfactory periphery, we searched for patterns of divergent selection across the antennal transcriptomes of two recently diverged sibling species Euglossa dilemma and E. viridissima.

Results

We identified 3185 orthologous genes including 94 chemosensory loci from five different gene families (Odorant Receptors, Ionotropic Receptors, Gustatory Receptors, Odorant Binding Proteins, and Chemosensory Proteins). Our results revealed that orthologs with signatures of divergent selection between E. dilemma and E. viridissima were significantly enriched for chemosensory genes. Notably, elevated signals of divergent selection were almost exclusively observed among chemosensory receptors (i.e. Odorant Receptors).

Conclusions

Our results suggest that rapid changes in the chemosensory gene family occurred among closely related species of orchid bees. These findings are consistent with the hypothesis that strong divergent selection acting on chemosensory receptor genes plays an important role in the evolution and diversification of insect pheromone systems.

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Rubén Guillermo Medina Hernández

Tesis de Maestría: Dimorfismo sexual isométrico en Euglossa viridissima Friese (Hymenoptera:Apidae:Euglossini) durante dos temporadas climáticas.

Mayo 4 - 2015

Asesor: Dr J Javier Quezada Euán 

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Quezada-Euán J.J.G.; Sheets H.D.; De Luna E.; Eltz T. (2015) Identification of cryptic species and morphotypes in male Euglossa: morphometric analysis of forewings (Hymenoptera: Euglossini). Apidologie 46: 787-795

  Abstract

 Males of sibling orchid bees Euglossa viridissima and E. dilemma are morphologically cryptic, except for the number and shape of mandibular teeth. An alternative morph of E. viridissima has a third tooth similar to males of E. dilemma. We used this model system to evaluate the potential of wing morphometrics for the resolution of these groups. We found differences in the size characters of forewings of E. viridissima and E. dilemma albeit with substantial overlapping amongst them. However, geometric morphometrics of forewing vein intersections separated both species and, to a lesser extent, morphotypes. A discriminant analysis of the shape of the radial cell showed separation between all three groups, too, albeit with higher misclassification between E. viridissima and E. dilemma. We show that sibling cryptic species and morphotypes can be identified by geometric morphometrics, supporting its application with other methods as powerful aids to infrageneric taxonomy in bees.

• Boff S., Forfert N.,Paxton R. J., Montejo E., Quezada-Euan J. J. G. (2015) A behavioral guard caste in a primitively eusocial orchid bee, Euglossa viridissima, helps defend the nest against resin theft by conspecifics. Insectes Sociaux 62:247–249.

  DOI 10.1007/s00040-015-0397-3

 Abstract

Defense castes are known from highly eusocial insects yet have rarely been described in social species with a small colony size. In nests of Euglossa viridissima, an orchid bee exhibiting primitively eusocial behavior, we recorded one subordinate female per nest that specialized in guarding in the presence of a dominant and a second subordinate who specialized in foraging. Guarding may have arisen as a response to cleptobiosis by conspecifics, as nests with a guard more successfully avoided intrusion and resin theft.

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T. Eltz;  C. Bause;  K. Hund;  J. J. G. Quezada-Euan; T. Pokorny (2015) Correlates of perfume load in male orchid bees. Chemoecology 25: 193-199. DOI 10.1007/s00049-015-0190-9

Abstract 

Male neotropical orchid bees collect volatile substances from their environment and compose complex, species-specific odour blends in leg pouches. These perfumes are accumulated by the males over time and are exposed during pre-mating display. It has been hypothesized that perfumes are indicators of male genotypic quality and that females chose mates by the quality or intensity of their odour. Because direct experimental proof is lacking, we investigated whether the amount or complexity of male perfumes is related to male (1) size, (2) fluctuating (left–right) asymmetry, or (3) age, traits that are known to be sexually selected in other animals. We measured left and right forewings (cell node distances for 1 and 2, wing wear for 3) of Euglossa dilemma and Euglossa viridissima collected during dry and rainy seasons on the Yucatán peninsula, Mexico (total N = 768). Wing size was not related to the quantity or the complexity of perfume extracts in either species after excluding the effect of season, which positively affected both size and perfume load in E. dilemma. Wing asymmetry had also no effect, except in rainy season E. viridissima, where it was positively (not negatively) correlated with the quantity of perfume. Wing wear, an established age indicator of orchid bees, had the only consistent overall effect, being positively correlated with perfume amount and complexity in both species. This is in agreement with the idea that perfumes are an honest indicator of male survival capacity.

 

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