The right tools for the job: Cooperative breeding theory and an evaluation of the methodological approaches to understanding the evolution and maintenance of sociality

© 2017 Hing, Klanten, Dowton and Wong. Why do we observe so many examples in nature in which individuals routinely delay or completely forgo their own reproductive opportunities in order to join and remain within a group? Cooperative breeding theory provides a rich framework with which to study the factors that may influence the costs and benefits of remaining philopatric as a non-breeder. This is often viewed as an initial step in the development of costly helping behavior provided by non-breeding subordinates. Despite many excellent empirical studies testing key concepts of the theory, there is still debate regarding the relative importance of various evolutionary forces, suggesting that there may not be a general explanation but rather a dynamic and taxonomically varied combination of factors influencing the evolution and maintenance of sociality. Here, we explore two potential improvements in the study of sociality that could aid in the progress of this field. The first addresses the fact that empirical studies of social evolution are typically conducted using either comparative, observational or manipulative methodologies. Instead, we suggest a holistic approach, whereby observational and experimental studies are designed with the explicit view of advancing comparative analyses of sociality for the taxon, and in tandem, where comparative work informs targeted research effort on specific (usually understudied) species within the lineage. A second improvement relates to the broadening of tests of cooperative breeding theory to include taxa where subordinates do not necessarily provide active cooperation within the group. The original bias toward "helpful subordinates" arose from a focus on terrestrial taxa. However, recent consideration of other taxa, especially marine taxa, is slowly revealing that the theory can and should encompass a continuum of cooperative social systems, including those where subordinates do not actively help. This review summarizes the major hypotheses of cooperative breeding theory, one of the dominant frameworks to examine social evolution, and highlights the potential benefits that a combined methodological approach and a broader application could provide to the study of sociality

Uneven declines between corals and cryptobenthic fish symbionts from multiple disturbances

With the onset and increasing frequency of multiple disturbances, the recovery potential of critical ecosystem-building species and their mutual symbionts is threatened. Similar effects to both hosts and their symbionts following disturbances have been assumed. However, we report unequal declines between hosts and symbionts throughout multiple climate-driven disturbances in reef-building Acropora corals and cryptobenthic coral-dwelling Gobiodon gobies. Communities were surveyed before and after consecutive cyclones (2014, 2015) and heatwaves (2016, 2017). After cyclones, coral diameter and goby group size (i.e., the number of gobies within each coral) decreased similarly by 28-30%. After heatwave-induced bleaching, coral diameter decreased substantially (47%) and gobies mostly inhabited corals singly. Despite several coral species persisting after bleaching, all goby species declined, leaving 78% of corals uninhabited. These findings suggest that gobies, which are important mutual symbionts for corals, are unable to cope with consecutive disturbances. This disproportionate decline could lead to ecosystem-level disruptions through loss of key symbiont services to corals

Repeated cyclone events reveal potential causes of sociality in coral-dwelling Gobiodon fishes

© 2018 Hing et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Social organization is a key factor influencing a species’ foraging and reproduction, which may ultimately affect their survival and ability to recover from catastrophic disturbance. Severe weather events such as cyclones can have devastating impacts to the physical structure of coral reefs and on the abundance and distribution of its faunal communities. Despite the importance of social organization to a species’ survival, relatively little is known about how major disturbances such as tropical cyclones may affect social structures or how different social strategies affect a species’ ability to cope with disturbance. We sampled group sizes and coral sizes of group-forming and pair-forming species of the Gobiid genus Gobiodon at Lizard Island, Great Barrier Reef, Australia, before and after two successive category 4 tropical cyclones. Group sizes of group-forming species decreased after each cyclone, but showed signs of recovery four months after the first cyclone. A similar increase in group sizes was not evident in group-forming species after the second cyclone. There was no change in mean pair-forming group size after either cyclone. Coral sizes inhabited by both group- and pair-forming species decreased throughout the study, meaning that group-forming species were forced to occupy smaller corals on average than before cyclone activity. This may reduce their capacity to maintain larger group sizes through multiple processes. We discuss these patterns in light of two non-exclusive hypotheses regarding the drivers of sociality in Gobiodon, suggesting that benefits of philopatry with regards to habitat quality may underpin the formation of social groups in this genus

Accelerated Evolution of Mitochondrial but Not Nuclear Genomes of Hymenoptera: New Evidence from Crabronid Wasps

Mitochondrial genes in animals are especially useful as molecular markers for the reconstruction of phylogenies among closely related taxa, due to the generally high substitution rates. Several insect orders, notably Hymenoptera and Phthiraptera, show exceptionally high rates of mitochondrial molecular evolution, which has been attributed to the parasitic lifestyle of current or ancestral members of these taxa. Parasitism has been hypothesized to entail frequent population bottlenecks that increase rates of molecular evolution by reducing the efficiency of purifying selection. This effect should result in elevated substitution rates of both nuclear and mitochondrial genes, but to date no extensive comparative study has tested this hypothesis in insects. Here we report the mitochondrial genome of a crabronid wasp, the European beewolf (Philanthus triangulum, Hymenoptera, Crabronidae), and we use it to compare evolutionary rates among the four largest holometabolous insect orders (Coleoptera, Diptera, Hymenoptera, Lepidoptera) based on phylogenies reconstructed with whole mitochondrial genomes as well as four single-copy nuclear genes (18S rRNA, arginine kinase, wingless, phosphoenolpyruvate carboxykinase). The mt-genome of P. triangulum is 16,029 bp in size with a mean A+T content of 83.6%, and it encodes the 37 genes typically found in arthropod mt genomes (13 protein-coding, 22 tRNA, and two rRNA genes). Five translocations of tRNA genes were discovered relative to the putative ancestral genome arrangement in insects, and the unusual start codon TTG was predicted for cox2. Phylogenetic analyses revealed significantly longer branches leading to the apocritan Hymenoptera as well as the Orussoidea, to a lesser extent the Cephoidea, and, possibly, the Tenthredinoidea than any of the other holometabolous insect orders for all mitochondrial but none of the four nuclear genes tested. Thus, our results suggest that the ancestral parasitic lifestyle of Apocrita is unlikely to be the major cause for the elevated substitution rates observed in hymenopteran mitochondrial genomes

Evolutionary Analysis of Mitogenomes from Parasitic and Free-Living Flatworms

Copyright: © 2015 Solà et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article

The highly rearranged mitochondrial genomes of the crabs Maja crispata and Maja squinado (Majidae) and gene order evolution in Brachyura

Abstract We sequenced the mitochondrial genomes of the spider crabs Maja crispata and Maja squinado (Majidae, Brachyura). Both genomes contain the whole set of 37 genes characteristic of Bilaterian genomes, encoded on both \u3b1- and \u3b2-strands. Both species exhibit the same gene order, which is unique among known animal genomes. In particular, all the genes located on the \u3b2-strand form a single block. This gene order was analysed together with the other nine gene orders known for the Brachyura. Our study confirms that the most widespread gene order (BraGO) represents the plesiomorphic condition for Brachyura and was established at the onset of this clade. All other gene orders are the result of transformational pathways originating from BraGO. The different gene orders exhibit variable levels of genes rearrangements, which involve only tRNAs or all types of genes. Local homoplastic arrangements were identified, while complete gene orders remain unique and represent signatures that can have a diagnostic value. Brachyura appear to be a hot-spot of gene order diversity within the phylum Arthropoda. Our analysis, allowed to track, for the first time, the fully evolutionary pathways producing the Brachyuran gene orders. This goal was achieved by coupling sophisticated bioinformatic tools with phylogenetic analysis

The taming of an impossible child: a standardized all-in approach to the phylogeny of Hymenoptera using public database sequences

<p>Abstract</p> <p>Background</p> <p>Enormous molecular sequence data have been accumulated over the past several years and are still exponentially growing with the use of faster and cheaper sequencing techniques. There is high and widespread interest in using these data for phylogenetic analyses. However, the amount of data that one can retrieve from public sequence repositories is virtually impossible to tame without dedicated software that automates processes. Here we present a novel bioinformatics pipeline for downloading, formatting, filtering and analyzing public sequence data deposited in GenBank. It combines some well-established programs with numerous newly developed software tools (available at <url>http://software.zfmk.de/</url>).</p> <p>Results</p> <p>We used the bioinformatics pipeline to investigate the phylogeny of the megadiverse insect order Hymenoptera (sawflies, bees, wasps and ants) by retrieving and processing more than 120,000 sequences and by selecting subsets under the criteria of compositional homogeneity and defined levels of density and overlap. Tree reconstruction was done with a partitioned maximum likelihood analysis from a supermatrix with more than 80,000 sites and more than 1,100 species. In the inferred tree, consistent with previous studies, "Symphyta" is paraphyletic. Within Apocrita, our analysis suggests a topology of Stephanoidea + (Ichneumonoidea + (Proctotrupomorpha + (Evanioidea + Aculeata))). Despite the huge amount of data, we identified several persistent problems in the Hymenoptera tree. Data coverage is still extremely low, and additional data have to be collected to reliably infer the phylogeny of Hymenoptera.</p> <p>Conclusions</p> <p>While we applied our bioinformatics pipeline to Hymenoptera, we designed the approach to be as general as possible. With this pipeline, it is possible to produce phylogenetic trees for any taxonomic group and to monitor new data and tree robustness in a taxon of interest. It therefore has great potential to meet the challenges of the phylogenomic era and to deepen our understanding of the tree of life.</p

A Comparative Analysis of Mitochondrial Genomes in Coleoptera (Arthropoda: Insecta) and Genome Descriptions of Six New Beetles

Coleoptera is the most diverse group of insects with over 360,000 described species divided into four suborders: Adephaga, Archostemata, Myxophaga, and Polyphaga. In this study, we present six new complete mitochondrial genome (mtgenome) descriptions, including a representative of each suborder, and analyze the evolution of mtgenomes from a comparative framework using all available coleopteran mtgenomes. We propose a modification of atypical cox1 start codons based on sequence alignment to better reflect the conservation observed across species as well as findings of TTG start codons in other genes. We also analyze tRNA-Ser(AGN) anticodons, usually GCU in arthropods, and report a conserved UCU anticodon as a possible synapomorphy across Polyphaga. We further analyze the secondary structure of tRNA-Ser(AGN) and present a consensus structure and an updated covariance model that allows tRNAscan-SE (via the COVE software package) to locate and fold these atypical tRNAs with much greater consistency. We also report secondary structure predictions for both rRNA genes based on conserved stems. All six species of beetle have the same gene order as the ancestral insect. We report noncoding DNA regions, including a small gap region of about 20 bp between tRNA-Ser(UCN) and nad1 that is present in all six genomes, and present results of a base composition analysis