Unrelated Lineages Research Articles

Diverse Origins of Near-Identical Antifreeze Proteins in Unrelated Fish Lineages Provide Insights Into Evolutionary Mechanisms of New Gene Birth and Protein Sequence Convergence.

Determining the origins of novel genes and the mechanisms driving the emergence of new functions is challenging yet crucial for understanding evolutionary innovations. Recently evolved fish antifreeze proteins (AFPs) offer a unique opportunity to explore these processes, particularly the near-identical type I AFP (AFPI) found in four phylogenetically divergent fish taxa. This study tested the hypothesis of protein sequence convergence beyond functional convergence in three unrelated AFPI-bearing fish lineages. Through comprehensive comparative analyses of newly sequenced genomes of winter flounder and grubby sculpin, along with available high-quality genomes of cunner and 14 other related species, the study revealed that near-identical AFPI proteins originated from distinct genetic precursors in each lineage. Each lineage independently evolved a de novo coding region for the novel ice-binding protein while repurposing fragments from their respective ancestors into potential regulatory regions, representing partial de novo origination-a process that bridges de novo gene formation and the neofunctionalization of duplicated genes. The study supports existing models of new gene origination and introduces new ones: the innovation-amplification-divergence model, where novel changes precede gene duplication; the newly proposed duplication-degeneration-divergence model, which describes new functions arising from degenerated pseudogenes; and the duplication-degeneration-divergence gene fission model, where each new sibling gene differentially degenerates and renovates distinct functional domains from their parental gene. These findings highlight the diverse evolutionary pathways through which a novel functional gene with convergent sequences at the protein level can evolve across divergent species, advancing our understanding of the mechanistic intricacies in new gene formation.

Diverse origins of near-identical antifreeze proteins in unrelated fish lineages provide insights into evolutionary mechanisms of new gene birth and protein sequence convergence.

Determining the origins of novel genes and the genetic mechanisms underlying the emergence of new functions is challenging yet crucial for understanding evolutionary innovations. The convergently evolved fish antifreeze proteins provide excellent opportunities to investigate evolutionary origins and pathways of new genes. Particularly notable is the near-identical type I antifreeze proteins (AFPI) in four phylogenetically divergent fish taxa. This study tested the hypothesis of protein sequence convergence beyond functional convergence in three unrelated AFPI-bearing fish lineages, revealing different paths by which a similar protein arose from diverse genomic resources. Comprehensive comparative analyses of de novo sequenced genome of the winter flounder and grubby sculpin, available high-quality genome of the cunner and 14 other relevant species found that the near-identical AFPI originated from a distinct genetic precursor in each lineage. Each independently evolved a coding region for the novel ice-binding protein while retaining sequence identity in the regulatory regions with their respective ancestor. The deduced evolutionary processes and molecular mechanisms are consistent with the Innovation-Amplification-Divergence (IAD) model applicable to AFPI formation in all three lineages, a new Duplication-Degeneration-Divergence (DDD) model we propose for the sculpin lineage, and a DDD model with gene fission for the cunner lineage. This investigation illustrates the multiple ways by which a novel functional gene with sequence convergence at the protein level could evolve across divergent species, advancing our understanding of the mechanistic intricacies in new gene formation.

Group-selection via aggregative propagule-formation enables cooperative multicellularity in an individual based, spatial model.

The emergence of multicellularity is one of the major transitions in evolution that happened multiple times independently. During aggregative multicellularity, genetically potentially unrelated lineages cooperate to form transient multicellular groups. Unlike clonal multicellularity, aggregative multicellular organisms do not rely on kin selection instead other mechanisms maintain cooperation against cheater phenotypes that benefit from cooperators but do not contribute to groups. Spatiality with limited diffusion can facilitate group selection, as interactions among individuals are restricted to local neighbourhoods only. Selection for larger size (e.g. avoiding predation) may facilitate the emergence of aggregation, though it is unknown, whether and how much role such selection played during the evolution of aggregative multicellularity. We have investigated the effect of spatiality and the necessity of predation on the stability of aggregative multicellularity via individual-based modelling on the ecological timescale. We have examined whether aggregation facilitates the survival of cooperators in a temporally heterogeneous environment against cheaters, where only a subset of the population is allowed to periodically colonize a new, resource-rich habitat. Cooperators constitutively produce adhesive molecules to promote aggregation and propagule-formation while cheaters spare this expense to grow faster but cannot aggregate on their own, hence depending on cooperators for long-term survival. We have compared different population-level reproduction modes with and without individual selection (predation) to evaluate the different hypotheses. In a temporally homogeneous environment without propagule-based colonization, cheaters always win. Predation can benefit cooperators, but it is not enough to maintain the necessary cooperator amount in successive dispersals, either randomly or by fragmentation. Aggregation-based propagation however can ensure the adequate ratio of cooperators-to-cheaters in the propagule and is sufficient to do so even without predation. Spatiality combined with temporal heterogeneity helps cooperators via group selection, thus facilitating aggregative multicellularity. External stress selecting for larger size (e.g. predation) may facilitate aggregation, however, according to our results, it is neither necessary nor sufficient for aggregative multicellularity to be maintained when there is effective group-selection.

Detection of relatedness in chemical alarm cues by a selfing vertebrate depends on population and the life stage producing the alarm cue

Aquatic prey have impressive abilities to extract information from a variety of chemical cues. For example, they can use the alarm cues released by wounded individuals during a predator attack to learn about predation risk, and they can also distinguish kin from non-kin individuals during interactions. However, it remains unclear whether animals can combine this information on predation risk with kin recognition of the particular individuals under threat. To examine how the relatedness of the individuals in alarm cue affects behaviour we used the self-fertilizing hermaphroditic mangrove rivulus (Kryptolebias marmoratus), in which lineages produce genetically identical offspring through selfing. We explored this in two populations that differ in their level of outcrossing. We measured activity before and after exposure to alarm cue made from individuals (either adults or embryos) from their own lineage or an unrelated lineage from the same population. Fish responded weakly to embryo alarm cues, but tended to reduce their activity more when the alarm cues were from an unrelated lineage compared to alarm cues from their own lineage, particularly in fish from the outcrossing population. In contrast, there was no effect of cue relatedness on the response to adult alarm cues but there was a strong population effect. Specifically, individuals from the outcrossing population tended to react more strongly to alarm cues compared to individuals from the predominantly selfing population. We discuss the potential roles of the major histocompatibility complex in cue detection, differences between adult vs embryo alarm cues in terms of concentration and information, and underlying differences among populations and genetic lineages in their production and detection of chemical cues. Whether this kin recognition offers adaptive benefits or is simply a consequence of being able to detect relatedness in living individuals would be an exciting area for future research.

Orthoceratoid and coleoid cephalopods from the Middle Triassic of Switzerland with an updated taxonomic framework for Triassic Orthoceratoidea

Orthoconic cephalopods are subordinate, but persistent, widespread and regionally abundant components of Triassic marine ecosystems. Here, we describe unpublished specimens from the Anisian (Middle Triassic) Besano Formation at Monte San Giorgio, Switzerland. They can be assigned to two major but unrelated lineages, the Coleoidea and the Orthoceratoidea. The orthoceratoids belong to Trematoceras elegans (Münster, 1841) and occur regularly within the Besano Formation, are uniform in size, and have few available morphological characters. In contrast, coleoids are more diverse and appear to be restricted to shorter intervals. A new coleoid is described as Ticinoteuthis chuchichaeschtli gen. et sp. nov. To better put the orthoceratoids of the Besano Formation into perspective, we also synthesise the current taxonomy of Triassic orthoceratoids on a global scale. The currently used scheme is largely outdated, with very little taxonomic progress in the past 100 years. Despite previous research showing the distinctness of Triassic orthoceratoids from Palaeozoic taxa, they are still commonly labelled as “Orthoceras” or “Michelinoceras”, which are confined to the Palaeozoic. We show that Triassic orthoceratoids probably belong to a single lineage, the Trematoceratidae, which can be assigned to the Pseudorthocerida based on the embryonic shell and endosiphuncular deposits. Many Triassic species can probably be assigned to Trematoceras, but there are at least two additional Triassic orthoceratoid genera, Paratrematoceras and Pseudotemperoceras. Finally, we review the palaeobiogeographic and stratigraphic distribution of the group and outline possible future research directions.

Re-evaluation of Exserticlava and other genera in Chaetosphaeriaceae with chalara-, phaeostalagmus-, phialocephala- and stanjehughesia-like morphotypes

In this study, we undertook a re-evaluation of species classified in genera Exserticlava, Phaeostalagmus, Phialocephala, and several chalara- and stanjehughesia-like fungi, whose placement has been determined within Chaetosphaeriaceae. They exhibit morphotypes that are either not exclusive to Chaetosphaeriaceae and have evolved in distantly related groups or have not been conclusively established as monophyletic within the family. Our study is based on phylogenetic reconstruction of three DNA markers and comparative morphological studies involving 21 strains, including all available ex-type strains. The non-monophyletic nature of the genus Exserticlava was elucidated and consequently, its generic concept has been emended, leading to the introduction of a segregate genus Exserticlavopsis. Chalara-like fungi occurred in three unrelated lineages, including a strongly supported clade comprising Chalarosphaeria and Fusichalara, a distinct lineage representing the newly introduced genus Chalarina gen. nov., and Sporoschisma, which produces the chalara-like synasexual morph. The genus Stanjehughesia is documented as a monophyletic, strongly supported clade. The notable similarity with other stanjehughesia-like genera is discussed. The phialocephala-like morphotype is infrequent within Chaetosphaeriaceae and is confined to two unrelated clades, specifically represented by Chloridium sect. Pseudophialocephala and Spadicocephala gen. nov., the latter being established to accommodate Phialocephala fusca. A monophyletic clade comprising members of Phaeostalagmus and Sporendocladia has been identified based on new molecular data. Since the relationship between the type species P. cyclosporus and P. tenuissimus could not be fully resolved, the clade is defined as a natural group characterized by distinct morphological patterns in conidiophore branching and aggregation of conidia. This definition is provisional, pending broader and more comprehensive taxon sampling. In this study, we introduced three new genera, two new species, and proposed six combinations. These findings emphasize the ongoing need for research to further refine the classification and enhance our understanding of the evolutionary relationships within Chaetosphaeriaceae.

Reduced social function in experimentally evolved Dictyostelium discoideum implies selection for social conflict in nature.

Many microbes interact with one another, but the difficulty of directly observing these interactions in nature makes interpreting their adaptive value complicated. The social amoeba Dictyostelium discoideum forms aggregates wherein some cells are sacrificed for the benefit of others. Within chimaeric aggregates containing multiple unrelated lineages, cheaters can gain an advantage by undercontributing, but the extent to which wild D. discoideum has adapted to cheat is not fully clear. In this study, we experimentally evolved D. discoideum in an environment where there were no selective pressures to cheat or resist cheating in chimaeras. Dictyostelium discoideum lines grown in this environment evolved reduced competitiveness within chimaeric aggregates and reduced ability to migrate during the slug stage. By contrast, we did not observe a reduction in cell number, a trait for which selection was not relaxed. The observed loss of traits that our laboratory conditions had made irrelevant suggests that these traits were adaptations driven and maintained by selective pressures D. discoideum faces in its natural environment. Our results suggest that D. discoideum faces social conflict in nature, and illustrate a general approach that could be applied to searching for social or non-social adaptations in other microbes.

The smallest stag beetles (Coleoptera, Lucanidae): hidden paleodiversity in mid-Cretaceous Kachin amber from northern Myanmar

The fossil record of stag beetles (Lucanidae), especially in Mesozoic amber, is sparse. Four additional fossil lucanids preserved in mid-Cretaceous Kachin amber from northern Myanmar are here reported. All of these species are included in the primitive subfamily Aesalinae, and have been identified as: Protonicagus mandibularissp. nov. (tribe Nicagini); Cretognathus minutissimusgen. et sp. nov. (tribe Ceratognathini); Ceratognathini gen. et sp. indet. 1 (provisional assignment); and Ceratognathini gen. et sp. indet. 2 (provisional assignment). Except for Protonicagus mandibularissp. nov., the stag beetles appear to be connected to the continent of Gondwana, as with the Kachin amber paleofauna. More interestingly, these species have significantly smaller bodies than the extant species, with three of them measuring less than 3 mm, which makes them the smallest known species of Lucanidae. This finding is congruent with a trend toward miniaturization in several unrelated lineages of Kachin amber beetles, and it shows hidden paleodiversity of stag beetles during the Cretaceous.

Estimating the fitness cost and benefit of antimicrobial resistance from pathogen genomic data.

Increasing levels of antibiotic resistance in many bacterial pathogen populations are a major threat to public health. Resistance to an antibiotic provides a fitness benefit when the bacteria are exposed to this antibiotic, but resistance also often comes at a cost to the resistant pathogen relative to susceptible counterparts. We lack a good understanding of these benefits and costs of resistance for many bacterial pathogens and antibiotics, but estimating them could lead to better use of antibiotics in a way that reduces or prevents the spread of resistance. Here, we propose a new model for the joint epidemiology of susceptible and resistant variants, which includes explicit parameters for the cost and benefit of resistance. We show how Bayesian inference can be performed under this model using phylogenetic data from susceptible and resistant lineages and that by combining data from both we are able to disentangle and estimate the resistance cost and benefit parameters separately. We applied our inferential methodology to several simulated datasets to demonstrate good scalability and accuracy. We analysed a dataset of Neisseria gonorrhoeae genomes collected between 2000 and 2013 in the USA. We found that two unrelated lineages resistant to fluoroquinolones shared similar epidemic dynamics and resistance parameters. Fluoroquinolones were abandoned for the treatment of gonorrhoea due to increasing levels of resistance, but our results suggest that they could be used to treat a minority of around 10% of cases without causing resistance to grow again.

Cyphelloporia bialoviesensis (Fungi, Agaricales)—a new genus and species for a giant cyphelloid fungus from Białowieża virgin forest in Poland

A striking species of cyphelloid fungus tentatively identified as a Henningsomyces or Rectipilus was collected in Białowieża virgin forest in Poland since 1962. After search in literature, morphological studies and phylogenetic analyses based on LSU and ITS rDNA sequences, the species turned out to be unknown to science with ≥ 5% difference in LSU rDNA sequence from nearest representatives of both cyphelloid and agaricoid fungi. We describe it here as a new genus Cyphelloporia and new species C. bialoviesensis. The species is still known only from the Białowieża forest, where it produces large basidiomata consisting of a well developed subiculum and densely aggregated, tubular receptacles up to 10 mm long on decaying trunks of Picea abies. A detailed morphological description accompanied by line drawings and photographs is provided, and differences from similar Rectipilus and Henningsomyces species are discussed. Phylogenies based on LSU and ITS sequences show that C. bialoviesensis belongs to the lineage formed by Rectipilus species together with Phyllotopsis nidulans and Pleurocybella porrigens, whereas true Henningsomyces species belong to a highly unrelated lineage labelled Niaceae or Cyphellaceae. Family position of C. bialoviesensis is discussed showing that Phyllotopsidaceae is well justified.

A trait-based approach to determining principles of plant biogeography.

Lineage-specific traits determine how plants interact with their surrounding environment. Unrelated species may evolve similar phenotypic characteristics to tolerate, persist in, and invade environments with certain characteristics, resulting in some traits becoming relatively more common in certain types of habitats. Analyses of these general patterns of geographical trait distribution have led to the proposal of general principles to explain how plants diversify in space over time. Trait-environment correlation analyses quantify to what extent unrelated lineages have similar evolutionary responses to a given type of habitat. In this synthesis, I give a short historical overview on trait-environment correlation analyses, from some key observations from classic naturalists to modern approaches using trait evolution models, large phylogenies, and massive data sets of traits and distributions. I discuss some limitations of modern approaches, including the need for more realistic models, the lack of data from tropical areas, and the necessary focus on trait scoring that goes beyond macromorphology. Overcoming these limitations will allow the field to explore new questions related to trait lability and niche evolution and to better identify generalities and exceptions in how plants diversify in space over time.

A remarkable new fossil species of Amplectister with peculiar hindleg modifications (Coleoptera: Histeridae): further evidence for myrmecophily in Cretaceous clown beetles

Myrmecophily is a phenomenon of the symbiosis of organisms that depend on various ant (Formicidae) societies. Such interspecies associations are found in several unrelated lineages within the clown beetle family Histeridae. Recent studies have suggested that the origin of myrmecophily can be traced back to mid-Cretaceous based on a few fossil records from Kachin amber from northern Myanmar. Here, we describe a remarkable new species, Amplectister terapoides n. sp., from Kachin amber. This is the second species of the extinct genus Amplectister Caterino and Maddison, which has been found from the same amber deposit and has also been considered to be myrmecophilous. The new species here described has the most heavily modified hindlegs in any fossil histerids or even beetles discovered until now, indicating further evidence for ant colony association. Our discovery demonstrates that significant and diverse morphological adaptations to myrmecophily had already occurred during the Cretaceous.

Whole Genome Sequencing and Molecular Analysis of Carbapenemase-Producing Escherichia coli from Intestinal Carriage in Elderly Inpatients.

The spread of carbapenemase-producing (CP) Enterobacterales is currently a worldwide concern, especially in the elderly. Twelve CP-E. coli isolated from rectal swabs of colonized inpatients aged ≥65 years from four hospitals in two Italian cities (Milan and Rome) were analyzed by whole genome sequencing (WGS) to obtain multi-locus sequence typing (MLST), identification of carbapenemase-encoding genes, resistome, plasmid content, and virulence genes. MLST analysis showed the presence of 10 unrelated lineages: ST410 (three isolates from three different hospitals in two cities) and ST12, ST38, ST69, ST95, ST131, ST189, ST648, ST1288, and ST1598 (one isolate each). Most isolates (9/12, 75%) contained a serine-β-lactamase gene (5 blaKPC-3, 2 blaKPC-2, and 2 blaOXA-181), while three isolates harbored a metallo-β-lactamase gene (two blaNDM-5 and one blaVIM-1). In most CP-E. coli, the presence of more than one plasmid was observed, with the predominance of IncF. Several virulence genes were detected. All isolates contained genes enhancing the bacterial fitness, such as gad and terC, and all isolates but one, fimH, encoding type 1 fimbriae. In conclusion, CP-E. coli clones colonizing elderly patients showed heterogeneous genetic backgrounds. We recommend strict surveillance to monitor and prevent the spread of successful, high-risk clones in healthcare settings.

The role of sexual selection in flowering plant origin and evolution and the potential significance of female competition and selection in ovules

Abstract Ever since Erasmus and Charles Darwin laid down the foundations of the concept, sexual selection has largely been regarded as a matter of male competition and female selection. While their role in plant evolution and the elusive origin of flowering plants has largely been neglected in contrast to the situation with animals, there is a growing body of evidence accumulated over the past 50 years supporting the hypothesis that, together with the flower and the carpel, increased pollination has led to an intensification of the competition between the fittest (and faster) pollen tubes and their selection by the surrounding maternal tissue. In contrast, the potential role of female competition was historically seldom considered but started to re-emerge a decade ago in both animal and plant evolution. Here, I review a large body of the vast embryological literature to re-evaluate unusual developmental traits in the plant female germline, traditionally considered as teratological occurrences of mere systematic interest, in the light of the current phylogenetic framework for flowering plants. After a summary of the basic tenets of sexual selection and the role of male competition and maternal selection in shaping plant evolution and diversity, I show how recent insights into the deepest nodes of flowering plant phylogeny and confirmation of their systematic relationships over the past 30 years have led to major shifts in our understanding of the reproductive biology of their most recent common ancestor. I also show that a re-evaluation of these unusual developmental traits in the female germline, especially in early-diverging lineages of flowering plants, may potentially be correlated with some floral structural traits. On the basis of these results, I argue that there is circumstantial evidence for mechanisms of female intrasexual competition and selection in individual ovules of flowering plants that are similar to those between pollen tubes competing inside the carpel. I also argue that although they may have evolved independently multiple times in unrelated lineages, they could also be the ‘burning embers’ of plesiomorphic traits that would have been largely selected against after the evolution of their most recent common ancestor.

Perspectives: SARS-CoV-2 Spike Convergent Evolution as a Guide to Explore Adaptive Advantage.

Viruses rapidly co-evolve with their hosts. The 9 million sequenced SARS-CoV-2 genomes by March 2022 provide a detailed account of viral evolution, showing that all amino acids have been mutated many times. However, only a few became prominent in the viral population. Here, we investigated the emergence of the same mutations in unrelated parallel lineages and the extent of such convergent evolution on the molecular level in the spike (S) protein. We found that during the first phase of the pandemic (until mid 2021, before mass vaccination) 31 mutations evolved independently ≥3-times within separated lineages. These included all the key mutations in SARS-CoV-2 variants of concern (VOC) at that time, indicating their fundamental adaptive advantage. The omicron added many more mutations not frequently seen before, which can be attributed to the synergistic nature of these mutations, which is more difficult to evolve. The great majority (24/31) of S-protein mutations under convergent evolution tightly cluster in three functional domains; N-terminal domain, receptor-binding domain, and Furin cleavage site. Furthermore, among the S-protein receptor-binding motif mutations, ACE2 affinity-improving substitutions are favoured. Next, we determined the mutation space in the S protein that has been covered by SARS-CoV-2. We found that all amino acids that are reachable by single nucleotide changes have been probed multiple times in early 2021. The substitutions requiring two nucleotide changes have recently (late 2021) gained momentum and their numbers are increasing rapidly. These provide a large mutation landscape for SARS-CoV-2 future evolution, on which research should focus now.

Multiple Independent Losses of Photosynthetic Ability in Eukaryotic Evolution and the Metabolism of Non-Photosynthetic Plastids

Multiple independent losses of photosynthesis have occurred among several unrelated eukaryotic lineages including red and green algae, land plants, alveolates, stramenopiles, cryptophytes and euglenophytes. Most plastid genomes of non-photosynthetic eukaryotes do not contain genes associated with photosynthesis, but they usually encode at least one gene product involved in an essential non-photosynthetic metabolic pathway. Complete loss of plastid genome and simultaneous retention of plastid compartment is rare, and complete plastid loss is documented only for few alveolate species. Non-photosynthetic plastids are often involved in essential fatty acid, isoprenoid, Fe-S cluster, and heme synthesis.

Blood parasite diversity (Apicomplexa: Haemogregarinidae) within the western populations of the European pond turtle Emys orbicularis.

Molecular tools have revolutionized assessments of blood parasites in freshwater turtles. In the Iberian Peninsula and North Africa, two native species of terrapins occur, Emys orbicularis (Linnaeus) and Mauremys leprosa (Schweigger). Both have been identified as hosts for the blood parasite Haemogregarina stepanowi Danilewsky, 1885, which has also been found in related species. However, recent assessments of M. leprosa have identified several distinct genetic lineages of these parasites in this host, while only three haemogregarine lineages were identified in E. orbicularis in Tunisia. Here, we screened 215 individuals of E. orbicularis from the Iberian Peninsula, Menorca Island and Morocco for haemogregarine parasites using partial 18S rRNA gene sequences to estimate relationships. Three unrelated lineages of parasites were detected, one presumed H. stepanowi and two lineages previously known from M. leprosa. A considerable undescribed diversity of parasites exists within these vertebrate host species, while mixed infection and host-sharing is also widespread. Considering that E. orbicularis is near threatened in this region, it is of great importance to identify the parasites infecting it, and to further assess the potential deleterious impact of these diverse parasites on their hosts.

Evolutionary rates of mitochondrial sequences and gene orders in Spirurina (Nematoda) are episodic but synchronised

In contrast to highly conserved mitogenomic architecture in most metazoan lineages, which indicates that rearrangement events are generally strongly selected against, a limited number of often unrelated lineages exhibit highly elevated architectural evolution rates. The underlying reasons for this discontinuity in the mitogenomic evolution remain unknown. Previously we sequenced the mitochondrial genome of the first Camallanoidea species, Camallanus cotti (Nematoda: Chromadorea: Spirurina: Camallanidae), and found that it exhibited a highly disrupted architecture. We hypothesised that disrupted architecture might be a synapomorphic feature of the sister-clades Camallanoidea and Dracunculoidea. In this study, we sequenced mitogenomes of three freshwater fish-parasitic nematodes: Camallanus lacustris (Camallanidae), and two Philometridae (Dracunculoidea) species, Clavinema parasiluri, and Philometra sp. In partial agreement with the working hypothesis, both Camallanoidea species had exceptionally large mitogenomes of 18–19 Kbp, albeit the underlying reasons differed: in C. lacustris it was the existence of a single enlarged noncoding region of ≈5.5 Kbp. A segment of this region exhibited an inverted base composition skew, which is indicative of a sequence inversion or recombination event. Camallanidae is the second identified chromadorean (first for Spirurina) family that exhibits within-family protein-coding gene rearrangements, and the absence of trnL1 and trnF may be a synapomorphy for Camallanoidea. The underlying reason for the disrupted architecture of Camallanidae does not appear to be a particular event shared by their common ancestor, but rather an underlying mechanism that makes disruptive events more likely in this lineage. In disagreement with the working hypothesis, Spiruromorpha and Oxyuridomorpha exhibited even more highly rearranged gene orders and greater overall branch lengths than Camallanomorpha. However, within-infraorder architecture was highly conserved and leaf nodes very short. This indicates that common ancestors of Spiruromorpha and Oxyuridomorpha clades underwent a period of rapid mitochondrial evolution (both sequence and architecture), followed by a stabilisation after the taxonomic radiation. In contrast to this, Camallanomorpha, and particularly Camallanidae, appear to have entered a period of elevated evolutionary rates after the initial radiations of these two taxa. As a result of this evolutionary discontinuity, there was a strong correlation between the gene order rearrangement rate (GORR) and the overall branch length (0.81), but there was no correlation between the strength of purifying selection (ω ​= ​dN/dS) and the overall branch lengths (−0.05) and GORR (−0.04). These findings have important repercussions for future phylogenetic and other evolutionary studies of Spirurina.

Homoplasy and morphological stasis revealed through multilocus phylogeny of new myrmecophilous species in Armadillidiidae (Isopoda: Oniscidea)

Abstract The terrestrial isopod family Armadillidiidae presents higher diversity in karstic areas, with fewer species present in areas with reduced suitable subterranean habitats, such as siliceous sandy soils. Myrmecophily, although not widespread in the family Armadillidiidae, can help these animals to colonize sandy substrates, as is observed in several populations of myrmecophilous Armadillidiidae species in central and southern Spain. Morphological examination and multilocus phylogenetic analyses, including mitochondrial DNA (Cox1) and nuclear DNA (18S, 28S and H3) markers, indicate that these myrmecophilous populations represent four new taxa: Iberiarmadillidium pinicola gen. & sp. nov., Iberiarmadillidium psammophilum sp. nov., Iberiarmadillidium sakura sp. nov. and Cristarmadillidium myrmecophilum sp. nov. Some of the main diagnostic characters used in the taxonomy of Armadillidiidae are not clearly apomorphic. Among head morphologies, Eluma type seems to be the ancestral state, being typical of several unrelated lineages; duplocarinate and Armadillidium types are derived states observed in unrelated lineages. The presence of a schisma is a convergent character state, because it has been identified in several taxa nested in unrelated clades. The newly described taxa present patterns of morphological stasis and homoplasy, likely to be associated with their shared myrmecophilous habits. The generic taxonomy of the family needs a deep revision including phylogenetic approaches and thorough taxon sampling.

Molecular systematics and genital morphology of the Neotropical cockroaches from the genus Xestoblatta (Blattellidae).

The Neotropics harbors a tremendous diversity of cockroaches yet their evolutionary history is largely unknown. We reconstructed for the first time the phylogeny of the Neotropical genus Xestoblatta Hebard using mitochondrial and nuclear genes from 12 species distributed in Central America and northern South America. Additionally, we conducted a morphological analysis of external characters and male genitalia. In the phylogenetic analysis we recovered the genus Xestoblatta as non-monophyletic, resulting in three unrelated lineages. From the morphological variability described here, we identified three different morphological groups matching the phylogenetic results. The phylogenetic relationships of the three lineages within the Blattellidae were partially resolved. Lineage 1 was nested within a supported clade corresponding to the tribes Blattellini + Symplocini, while lineages 2 and 3 nested within the clade corresponding to the tribe Pseudomopini. Based on our results, we propose to divide Xestoblatta (sensu lato) into three monophyletic genera: Antroxestoblatta gen.n., Sinatablatta gen.n., and Xestoblatta (sensu stricto). We also describe a new species Sinatablatta magdalenensis sp.n. and propose a taxonomic rearrangement for Xestoblatta (sensu lato).