Phylogenetic evidence for loss of sound production and a shift in sexual recognition signals in Hamadryas butterflies (Nymphalidae: Biblidinae)

The neotropical butterfly genus Hamadryas Hübner comprises 20 species that exhibit an intriguing variation in their natural history traits. Although revised in 1983, no phylogenetic hypothesis was presented: the first phylogenetic hypothesis is estimated here based on 93 characters and including species from the three other genera in the tribe Ageroniini. The phylogeny is used to test the monophyly of the genus, establish the sister group of Hamadryas and identify its apomorphies. The tree allows the inference of patterns of character change in sound production and sexual dimorphism. Implied weights show that Hamadryas is monophyletic and corroborate Ectima Doubleday as a sister genus. Previously suggested subgenera for Hamadryas were non‐monophyletic, with the exception of the laodamia clade, supported by the presence of a complete sterigma. Sound production is inferred to be a derived condition in Hamadryas that has been lost in the laodamia clade. This, plus the presence of androconial organs and sexual dimorphism in the laodamia clade, suggests a shift in sexual recognition signalling. Furthermore, the phylogeny indicates that the colour pattern of males in the laodamia clade is novel, supporting a Darwinian origin of sexual dimorphism.     

Geometric morphometrics for the taxonomy of 11 species of Anopheles (Nyssorhynchus) mosquitoes

The subgenus Anopheles (Nyssorhynchus) (Diptera: Culicidae) includes the primary vectors of Plasmodium spp. in Colombia. Most adult females of this subgenus are difficult to identify in the field using the available keys. With the objective of further investigating the discriminatory power of modern morphometrics, both landmark‐based and outline‐based approaches were explored using the wing venation geometry of 11 Anopheles (Nyssorhynchus) species. Wing shape was able to separate the closest species of the subgenus. When the 11 species were analysed together, validated classification scores on average 5.3–8.6 times higher than those expected by chance were observed. These scores computed from the total sample of 11 species were not satisfactory for the recognition of Anopheles benarrochi B, Anopheles oswaldoi s.l. and Anopheles strodei. These sibling species were captured in sympatry. To improve the identification power of the morphometric tool, it was necessary to analyse these species separately from the remaining species. The best classification scores were obtained using a combination of 12 landmarks collected not only on the intersections of wing veins, but also on spots. An outline approach also gave excellent reclassification scores. Another pair of sibling species, collected in allopatry, Anopheles nuneztovari and Anopheles rangeli, also showed high classification scores.     

Hypoderma actaeon: an emerging myiasis in roe deer (Capreolus capreolus)

Subcutaneous larvae of Hypoderma spp. (Diptera: Oestridae) were detected in the dorsal region in 10 roe deer, Capreolus capreolus (Artiodactyla: Cervidae), hunted in central Spain between January and March 2016. All larvae were found in the inner side of the hide during the skinning of the animals. The study of the morphological features of eight larvae of different stages collected from two animals allowed the identification of Hypoderma actaeon Brauer. The small size (4–5 mm) of some of the first instars suggests that the internal lifecycle of H. actaeon may be exclusively subcutaneous. This is the first confirmation of H. actaeon in roe deer; however, further studies to assess the spread of the parasite and to follow the evolution of this myiasis in roe deer are needed.     

Experimental wood addition in streams: effects on organic matter storage and breakdown

1. Channel complexity affects the physical structure, biotic communities and functioning of stream ecosystems. Large wood (LW) is a key element in the creation and maintenance of physically complex stream channels in forested areas. 2. In an attempt to enhance stream habitat quality and ecosystem functioning and to reduce inputs of organic matter to a downstream reservoir, LW was experimentally introduced into four mountain streams in the Basque Country (northern Spain), ranging in channel width from 3 to 13 m. Following a before–after/control–impact (BACI) design, streams were monitored during 1 year prior to wood addition and during 2 years after addition in one control and one experimental reach per stream. 3. Areal cover of benthic organic matter in the entire channel was measured from regular transects and the mass of stored organic matter from random Surber samples. Breakdown of organic matter was assessed in litter bag experiments performed with black alder leaves. When 50% of the initial mass in the bags remained, invertebrates associated with leaf bags were collected. 4. Wood placement produced a 2‐ to 70‐fold increase in the storage of organic matter, especially in thick deposits upstream from wood jams, with values in excess of 2 kg AFDM per m² in the small streams. The accumulation of organic matter produced by wood introduction decreased with increasing stream size. 5. Despite the large increase in the availability of organic matter, litter breakdown rates were unaffected by the experimental reaches, suggesting large increases in the total amount of organic matter consumed at the reach scale. 6. Numbers of invertebrates and shredders per gram of leaf litter did not respond to wood addition. Average body mass of invertebrates associated with leaf litter showed a non‐significant decreasing trend, which might reflect increased recruitment. 7. Although the effects of wood addition can depend on wood stability and stream size, adding LW to restore channel complexity can improve environmental conditions for invertebrate communities and affect stream ecosystem functioning, enhancing the efficiency to use organic matter inputs on a reach scale.     

Do insect pests perform better on highly defended plants? Costs and benefits of induced detoxification defences in the aphid Sitobion avenae

Induced defences are a typical case of phenotypic plasticity, involving benefits for ‘plastic’ phenotypes under environments with variable degree of stress. Defence induction, in turn, could be energetically expensive incurring costs on growth and reproduction. In this study, we investigated the genetic variation and induction of detoxification enzymes mediated by wheat chemical defences (hydroxamic acids; Hx), and their metabolic and fitness costs using five multilocus genotypes of the grain aphid (Sitobion avenae). Cytochrome P450 monooxygenases and glutathione S‐transferases activities were seen to increase with Hx levels, whereas esterases activity and standard metabolic rate increased in wheat hosts with low Hx levels. Additionally, the intrinsic rate of increase (a fitness proxy) increased in highly defended hosts. However, we did not find significant genetic variation or genotype–host interaction for any studied trait. Therefore, aphids feeding on host plants with elevated chemical defences appeared to reduce their detoxification costs and to increase their reproductive performance, which we interpret as a novel adaptation to defended plants. In brief, this study supports the notion that aphids perform better on highly defended host plants, probably related to the selective pressures during the colonization of New World agroecosystems, characterized by highly defended host plants.     

Enhancement of root hydraulic conductivity by methyl jasmonate and the role of calcium and abscisic acid in this process

The role of jasmonic acid in the induction of stomatal closure is well known. However, its role in regulating root hydraulic conductivity (L) has not yet been explored. The objectives of the present research were to evaluate how JA regulates L and how calcium and abscisic acid (ABA) could be involved in such regulation. We found that exogenous methyl jasmonate (MeJA) increased L of Phaseolus vulgaris, Solanum lycopersicum and Arabidopsis thaliana roots. Tomato plants defective in JA biosynthesis had lower values of L than wild‐type plants, and that L was restored by addition of MeJA. The increase of L by MeJA was accompanied by an increase of the phosphorylation state of the aquaporin PIP2. We observed that MeJA addition increased the concentration of cytosolic calcium and that calcium channel blockers inhibited the rise of L caused by MeJA. Treatment with fluoridone, an inhibitor of ABA biosynthesis, partially inhibited the increase of L caused by MeJA, and tomato plants defective in ABA biosynthesis increased their L after application of MeJA. It is concluded that JA enhances L and that this enhancement is linked to calcium and ABA dependent and independent signalling pathways.     

Pupal colour dimorphism in a desert swallowtail (Lepidoptera: Papilionidae) is driven by changes in food availability,not photoperiod

1. The swallowtail butterfly Battus polydamas archidamas Boisduval, 1936, exhibits polyphenism for pupal coloration (green and brown). It is distributed across arid regions with winter rains and is monophagous on Aristolochia plants, which emerge after the winter rains and dry out the during summer. Thus, day length does not covary positively with host plant productivity. It was hypothesised that pupal colour was driven by food availability, not photoperiod. The benefits of pupal coloration matching the colour of pupation sites in terms of field survival were also investigated to evaluate the adaptive value of pupa colour. 2. Larvae were reared under a factorial array of two photoperiods (LD 10:14 h and LD 14:10 h) and two food availability regimes (leaves ad libitum and available every other day) to assess the frequency of green and brown pupae. Field survival of green and brown pupae was quantified in three commonly used habitats that differ in background coloration (cacti, rocks and shrubs). 3. Food availability determined pupal colour. Larvae in the ad libitum regime resulted mostly in green pupae, while those with restricted food were mostly brown. In contrast, photoperiod did not influence pupal colour. Survival probability of pupae placed on cacti was higher than those placed on rocks and shrubs, and the lowest predation risk across habitats was for green pupae on cacti. 4. Food availability plays a major role in the seasonal polyphenism for pupal colour of specialist butterflies inhabiting arid environments with winter rains.     

Evidence of predation in Early Cretaceous unionoid bivalves from freshwater sediments in the Cameros Basin,Spain

Here, we present evidence of possible vertebrate predation on freshwater bivalves from the Lower Cretaceous strata of the Cameros Basin (Spain). The described collection contains the largest number of vertebrate‐inflicted shell injuries in freshwater bivalve shells yet reported in the Mesozoic continental record. Several types of shell damage on fossil shells of Protopleurobema numantina (Bivalvia: Unionoida) are described and their respective modes of formation interpreted in the context of morphological attributes of the shell injuries and the inferred tooth morphology of predators that could have inflicted such injuries. Detailed study of these bite marks shows similarities with the well‐documented injuries in the shells of marine molluscs, namely ammonoids, that have likewise been attributed to reptilian predators. The most parsimonious interpretation suggests crocodiles as the vertebrates interacting with the bivalves in the Cameros Basin. □Barremian–Aptian; bite marks; freshwater bivalves; predation; reptile; Unionoida.     

FLOW PATTERN AROUND THE RIGID CEPHALIC SHIELD OF THE DEVONIAN AGNATHAN ERRIVASPIS WAYNENSIS (PTERASPIDIFORMES: HETEROSTRACI)

Abstract: Palaeozoic armoured agnathans (or ostracoderms) are characterised by having an external, bone shield enclosing the anterior part of their bodies, which demonstrate great diversity of both forms and sizes. The functional significance of these cephalic shields remains unclear (they may have been a functional analogue of the vertebral column, or merely afforded protection). Here we assess the importance of the cephalic shield in terms of locomotion. In order to do this, we have studied flow patterns of the Devonian heterostracan Errivaspis waynensis ( White, 1935 ), using an anatomically correct model of E. waynensis positioned at different pitching angles. The fluid flow was visualised in a wind tunnel, using planar light sheet techniques, adding vaporised propylene glycol to the fluid. The flow pattern over the cephalic shield of Errivaspis is dominated by the formation of leading‐edge vortices (LEVs). When the model was positioned at angles of attack of ‐2 degrees or higher a pair of nearly symmetrical, counter‐rotating primary vortices were produced, which flowed downstream over the upper surface of the cephalic shield. At moderate angles of attack, LEVs remained attached to the dorsal surface, but, as the angle of attack increased above 7 degrees, vortices began to separate from the surface at posterior locations. At a high angles of attack (around 12 degrees or 13 degrees), vortex breakdown (or vortex burst) occured. The body‐induced vortical flow around the cephalic shield is very similar to the that described over delta wing aircraft. This strategy generates lift forces through vortex generation (vortex lift). Based on this analogue and knowing that Errivaspis lacked pectoral fins or any other obvious control surfaces, vortex lift forces added through this mechanism may have played a major role in the locomotion of these primitive fishes, not only to counteract the negative buoyancy of the fish, but also as a means of manoeuvring.