The Red Queen process does not select for high recombination rates in haplodiploid hosts

One of the main competing theories to describe the evolution of recombination is the Red Queen Hypothesis (RQH). Presently, many theoretical analyses of the RQH typically examine fitness interactions in host-parasite frameworks. Less emphasis has been placed on understanding the impact of host ploidy in these systems. In this study, we look to investigate the high observed rates of recombination observed in two common haplodiploid species (Apis mellifera and Bombus terrestris). We compared haplodiploid to diploid host populations under infection with haploid asexual parasites, using a Matching Allele (MAM) model. Results from a simulation analysis showed that the Red Queen does not run in haplodiploid hosts and is therefore, probably not responsible for the high recombination rates observed so far in haplodiploid hosts.Deutsche Forschungsgemeinschaft (DFG)as part of the SPP project number 1399.http://link.springer.com/journal/11692hb2013ab201

Host-parasite evolution in male-haploid hosts : an individual based network model

Host-parasite co-evolution is a key component of the Red Queen Hypothesis (RQH). The RQH currently being one of the main hypotheses describing the evolution of sex and recombination. However, most analyses in this area have either ignored parasite transmission or included it either with mean field or simple frequency based models. Moreover models have rarely addressed the issue of male haploid species. We here use agent based models to qualify the interactions between host- and parasite-based transmission parameters and virulence comparing diploid with male-haploid species. We found diploid hosts to have a higher fitness under the inverse matching allele mode compared to male haplodiploid hosts which in turn have a higher fitness under the matching allele model . Selection for recombination was rare but whenever selection for recombination was evident (\6.6 %), the resulting recombination rates were both consistently higher and more frequent in male haploids.Funding for the research was provided by the Deutsche Forschungsgemeinschaft within the priority program SPP 1399 and by yDiv, the Synthesis Centre for Biodiversity Sciences—a unit of the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, also funded by the Deutsche Forschunggemeinschaft (FZT 118).http://link.springer.com/journal/106822016-01-30hb201

Patterns of evolutionary conservation of microsatellites (SSRs) suggest a faster rate of genome evolution in hymenoptera than in Diptera

Microsatellites, or simple sequence repeats (SSRs), are common and widespread DNA elements in genomes of many organisms. However, their dynamics in genome evolution is unclear, whereby they are thought to evolve neutrally. More available genome sequences along with dated phylogenies allowed for studying the evolution of these repetitive DNA elements along evolutionary time scales. This could be used to compare rates of genome evolution. We show that SSRs in insects can be retained for several hundred million years. Different types of microsatellites seem to be retained longer than others. By comparing Dipteran with Hymenopteran species, we found very similar patterns of SSR loss during their evolution, but both taxa differ profoundly in the rate. Relative to divergence time,Diptera lost SSRs twice as fast as Hymenoptera.The loss of SSRs on the Drosophila melanogaster X-chromosome was higher than on the other chromosomes. However, accounting for generation time, the Diptera show an 8.5-fold slower rate of SSR loss than the Hymenoptera, which, in contrast to previous studies, suggests a faster genome evolution in the latter. This shows that generation time differences can have a profound effect. A faster genome evolution in these insects could be facilitated by several factors very different to Diptera, which is discussed in light of our results on the haplodiploid D. melanogaster X-chromosome. Furthermore, large numbers of SSRs can be found to be in synteny and thus could be exploited as a tool to investigate genome structure and evolution.German Science Foundation DFG.http://gbe.oxfordjournals.orgam201

The genomes of two key bumblebee species with primitive eusocial organization

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

Endoreplication Controls Cell Fate Maintenance

Cell-fate specification is typically thought to precede and determine cell-cycle regulation during differentiation. Here we show that endoreplication, also known as endoreduplication, a specialized cell-cycle variant often associated with cell differentiation but also frequently occurring in malignant cells, plays a role in maintaining cell fate. For our study we have used Arabidopsis trichomes as a model system and have manipulated endoreplication levels via mutants of cell-cycle regulators and overexpression of cell-cycle inhibitors under a trichome-specific promoter. Strikingly, a reduction of endoreplication resulted in reduced trichome numbers and caused trichomes to lose their identity. Live observations of young Arabidopsis leaves revealed that dedifferentiating trichomes re-entered mitosis and were re-integrated into the epidermal pavement-cell layer, acquiring the typical characteristics of the surrounding epidermal cells. Conversely, when we promoted endoreplication in glabrous patterning mutants, trichome fate could be restored, demonstrating that endoreplication is an important determinant of cell identity. Our data lead to a new model of cell-fate control and tissue integrity during development by revealing a cell-fate quality control system at the tissue level

Data from: The genomes of two key bumblebee species with primitive eusocial organisation

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation

RAD tag (SgrAI) derived SNPs from Bombus impatiens

RAD tag (SgrAI) derived SNPs from Bombus impatiens from Sadd et al. (2015) "The genomes of two key bumblebee species with primitive eusocial organisation

Data from: The genomes of two key bumblebee species with primitive eusocial organisation

Background: The shift from solitary to social behavior is one of the major evolutionary transitions. Primitively eusocial bumblebees are uniquely placed to illuminate the evolution of highly eusocial insect societies. Bumblebees are also invaluable natural and agricultural pollinators, and there is widespread concern over recent population declines in some species. High-quality genomic data will inform key aspects of bumblebee biology, including susceptibility to implicated population viability threats. Results: We report the high quality draft genome sequences of Bombus terrestris and Bombus impatiens, two ecologically dominant bumblebees and widely utilized study species. Comparing these new genomes to those of the highly eusocial honeybee Apis mellifera and other Hymenoptera, we identify deeply conserved similarities, as well as novelties key to the biology of these organisms. Some honeybee genome features thought to underpin advanced eusociality are also present in bumblebees, indicating an earlier evolution in the bee lineage. Xenobiotic detoxification and immune genes are similarly depauperate in bumblebees and honeybees, and multiple categories of genes linked to social organization, including development and behavior, show high conservation. Key differences identified include a bias in bumblebee chemoreception towards gustation from olfaction, and striking differences in microRNAs, potentially responsible for gene regulation underlying social and other traits. Conclusions: These two bumblebee genomes provide a foundation for post-genomic research on these key pollinators and insect societies. Overall, gene repertoires suggest that the route to advanced eusociality in bees was mediated by many small changes in many genes and processes, and not by notable expansion or depauperation.,RAD tag (SgrAI) derived SNPs from Bombus impatiensRAD tag (SgrAI) derived SNPs from Bombus impatiens from Sadd et al. (2015) &quot;The genomes of two key bumblebee species with primitive eusocial organisation&quot;Filtered_Bombus_imp_AEgenome.vcf,</span