Discovery of the Quedius antipodum Sharp larva from New Zealand: phylogenetic test of larval morphology for Staphylinini at the intratribal level (Coleoptera: Staphylinidae)

Quedius antipodum Sharp is an endemic species from New Zealand. Here we describe its larva, the first of the species‐rich group of the south temperate ‘Quedius’ spp. This finding throws light on the controversy between the conventional systematics of Quedius Stephens and newer phylogenetic analyses, both of which are based on non‐larval characters only. We compare the larva of Q. antipodum with those of the north temperate Quedius (Quediina), where it was traditionally placed, and with the known larvae of Amblyopinina, a group where Q. antipodum was placed by recent phylogenetic studies. Sister‐group relationships of Q. antipodum within the tribe Staphylinini are explored based on larvae by means of parsimony analysis: 77 morphological characters scored for 20 species from 17 genera. Consistent with the adult morphology and DNA sequences, larvae‐based cladistic analysis confirms that Q. antipodum should not be placed in the north temperate genus Quedius. However, larval analysis alone remains dubious with respect to finding the exact sister relationships of that species.     

The influence of pre‐settlement and early post‐settlement processes on the adult distribution and relative dominance of two invasive mussel species

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Predictive modeling for allopatric Strix (Strigiformes: Strigidae) owls in South America: determinants of their distributions and ecological niche‐based processes

Strix (Strigidae) is a worldwide genus of 17 owl species typical of forested habitats, including Rusty‐barred Owls (S. hylophila), Chaco Owls (S. chacoensis), and Rufous‐legged Owls (S. rufipes) in South America. These species are distributed allopatrically, but the ecological traits that determine their distributions remain largely unknown and their phylogenetic relationships are unclear. We used species distribution models (SDMs) to identify variables explaining their distribution patterns and test hypotheses about ecological divergence and conservatism based on niche overlap analysis. For Rusty‐barred Owls and Chaco Owls, climatic factors related to temperature played a major role, whereas a rainfall variable was more important for Rufous‐legged Owls. When niche overlaps were compared, accounting for regional similarities in the habitat available to each species, an ecological niche divergence process was supported for Chaco Owl‐Rusty‐barred Owl and Chaco Owl‐Rufous‐legged Owl, whereas a niche conservatism process was supported for Rusty‐barred Owl‐Rufous‐legged Owl. Different ecological requirements support current species delimitation, but they are in disagreement with the two main hypotheses currently envisaged about their phylogenetic relationships (Chaco Owls as the sister taxa of either Rufous‐legged Owls or Rusty‐barred Owls) and support a new phylogenetic hypothesis (Rufous‐legged Owls as sister taxa of Rusty‐barred Owls). Our findings suggest that speciation of Rusty‐barred Owls and Rufous‐legged Owls was a vicariant event resulting from Atlantic marine transgressions in southern South America in the Miocene, but their niche was conserved because habitat changed little in their respective ranges. In contrast, Chaco Owls diverged ecologically from the other two species as a result of their adaptations to the habitat they currently occupy. Ecological and historical approaches in biogeography can be embedded to explain distribution patterns, and results provided by SDMs can be used to infer historical and ecological processes in an integrative way.     

Pollen feeding,resource allocation and the evolution of chemical defence in passion vine butterflies

Evolution of pollen feeding in Heliconius has allowed exploitation of rich amino acid sources and dramatically reorganized life‐history traits. In Heliconius, eggs are produced mainly from adult‐acquired resources, leaving somatic development and maintenance to larva effort. This innovation may also have spurred evolution of chemical defence via amino acid‐derived cyanogenic glycosides. In contrast, nonpollen‐feeding heliconiines must rely almost exclusively on larval‐acquired resources for both reproduction and defence. We tested whether adult amino acid intake has an immediate influence on cyanogenesis in Heliconius. Because Heliconius are more distasteful to bird predators than close relatives that do not utilize pollen, we also compared cyanogenesis due to larval input across Heliconius species and nonpollen‐feeding relatives. Except for one species, we found that varying the amino acid diet of an adult Heliconius has negligible effect on its cyanide concentration. Adults denied amino acids showed no decrease in cyanide and no adults showed cyanide increase when fed amino acids. Yet, pollen‐feeding butterflies were capable of producing more defence than nonpollen‐feeding relatives and differences were detectable in freshly emerged adults, before input of adult resources. Our data points to a larger role of larval input in adult chemical defence. This coupled with the compartmentalization of adult nutrition to reproduction and longevity suggests that one evolutionary consequence of pollen feeding, shifting the burden of reproduction to adults, is to allow the evolution of greater allocation of host plant amino acids to defensive compounds by larvae.     

The peculiar nemertean larva pilidium recurvatum belongs to Riserius sp., a basal heteronemertean that eats Carcinonemertes errans,a hoplonemertean parasite of Dungeness crab

A typical nemertean pilidium larva resembles a hat with ear flaps. But one type, called pilidium recurvatum, looks more like a sock, swimming heel first. This distinctive larva was discovered in 1883 off the coast of Rhode Island and subsequently found in plankton samples from other parts of the world. Despite the long time since discovery, and its significance in discussions of larval evolution, this larva remained unidentified even to the family level. We collected pilidium recurvatum larvae from plankton samples in Coos Bay, OR, and identified them as belonging to the heteronemertean genus Riserius based on juvenile morphology and DNA sequence data. Phylogenetic analysis suggests that two distinct types of pilidium recurvatum from Oregon represent two new species within this currently monotypic genus. We describe the morphology of pilidium recurvatum using confocal microscopy and compare it to that of the typical pilidium, discussing possible implications for larval feeding. We also report our surprising discovery that juveniles of Riserius sp. from Oregon prey on another nemertean, Carcinonemertes errans, an egg predator of Cancer magister (Dungeness crab), a commercially important species. We speculate that the species‐level diversity and geographic distribution of Riserius may be much greater than currently appreciated.     

Irradiation effect on the structure of bacterial communities associated with the oriental fruit fly,Bactrocera dorsalis

The role of symbiotic microbes in insects, especially the beneficial character of this interaction for insects, has received much attention in recent years as it has been related to important aspects of the host insects' biology such as development, reproduction, survival, and fitness. Among insect hosts, tephritid fruit flies are well known to form beneficial associations with their symbionts. To control these destructive agricultural pests, environmentally friendly approaches, like the sterile insect technique as a component of integrated pest management strategies, remain most effective. In this study, changes in the bacterial profile of mass‐reared oriental fruit flies, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), were examined in both larval and adult stages and also after irradiation by employing a 16S rRNA gene‐based Illumina sequencing approach. Proteobacteria was the prevalent bacterial phylum in non‐irradiated adults and larvae. Alphaproteobacteria was the most abundant class in larvae but almost absent in adults, which was dominated by Gammaproteobacteria. Firmicutes were present in both developmental stages but at lower relative abundance. At genus level, Acetobacter prevailed in the larval stage and members of the Enterobacteriaceae family in adults. Irradiated samples exhibited higher diversity and richness indices compared to the non‐irradiated oriental fruit flies, whereas no significant changes were observed between the two developmental stages of the non‐irradiated samples. Lactobacillus, members of the Orbacecae family, and Morganella were detected but to a lesser degree upon irradiation, whereas the relative abundance of Lactococcus and Orbus increased. The bacterial profile of larvae appeared to be different compared to that of adult B. dorsalis flies. The subsequent application of irradiation at the pupal stage led to the development of different microbiota between treated and untreated samples, affecting diversity and operational taxonomic unit composition. Irradiated samples of oriental fruit flies were characterized by higher species diversity and richness.     

Altitude and life‐history shape the evolution of Heliconius wings

Phenotypic divergence between closely related species has long interested biologists. Taxa that inhabit a range of environments and have diverse natural histories can help understand how selection drives phenotypic divergence. In butterflies, wing color patterns have been extensively studied but diversity in wing shape and size is less well understood. Here, we assess the relative importance of phylogenetic relatedness, natural history, and habitat on shaping wing morphology in a large dataset of over 3500 individuals, representing 13 Heliconius species from across the Neotropics. We find that both larval and adult behavioral ecology correlate with patterns of wing sexual dimorphism and adult size. Species with solitary larvae have larger adult males, in contrast to gregarious Heliconius species, and indeed most Lepidoptera, where females are larger. Species in the pupal‐mating clade are smaller than those in the adult‐mating clade. Interestingly, we find that high‐altitude species tend to have rounder wings and, in one of the two major Heliconius clades, are also bigger than their lowland relatives. Furthermore, within two widespread species, we find that high‐altitude populations also have rounder wings. Thus, we reveal novel adaptive wing morphological divergence among Heliconius species beyond that imposed by natural selection on aposematic wing coloration.     

Testing the phylogenetic position of Cambrian pancrustacean larval fossils by coding ontogenetic stages

The study of ontogeny as an integral part of understanding the pattern of evolution dates back over 200 years, but only recently have ontogenetic data been explicitly incorporated into phylogenetic analyses. Pancrustaceans undergo radical ontogenetic changes. The spectacular upper Cambrian “Orsten” fauna preserves phosphatized fossil larvae, including putative crown‐group pancrustaceans with amazingly complete developmental sequences. The putative presence and nature of adult stages remains a source of debate, causing spurious placements in a traditional morphological analysis. We introduce a new coding method where each semaphoront (discrete larval or adult stage) is considered an operational taxonomic unit. This avoids a priori assumptions of heterochrony. Characters and their states are defined to identify changes in morphology throughout ontogeny. Phylogenetic analyses of semaphoronts produced possible relationships of each Orsten fossil to the crown‐group clade expected from morphology shared with extant larvae. Bredocaris is a member of the stem lineage of Thecostraca or (Thecostraca + Copepoda), and Yicaris and Rehbachiella are probably members of the stem lineage of Cephalocarida. These placements rely directly on comparisons between extant and fossil larval character states. The position of Phosphatocopina remains unresolved. This method may have broader applications to other phylogenetic problems which may rely on ontogenetically variable homology statements.     

Regulation of drosophila folylpolyglutamates during development

The polyglutamate status of reduced folates during the larval, pupal and adult stages of Drosophila melanogaster development was investigated. The chain length distribution is very similar and is predominantly pentaglutamate. Half-life estimates of the hydrolytic degradation to the monoglutamate showed larva < pupa < adult. This raises the possibility that polyglutamate hydrolase may have a role in regulating the total intracellular reduced folate content of the different developmental stages.     

UCP4C mediates uncoupled respiration in larvae of Drosophila melanogaster

Larvae of Drosophila melanogaster reared at 23°C and switched to 14°C for 1 h are 0.5°C warmer than the surrounding medium. In keeping with dissipation of energy, respiration of Drosophila melanogaster larvae cannot be decreased by the F‐ATPase inhibitor oligomycin or stimulated by protonophore. Silencing of Ucp4C conferred sensitivity of respiration to oligomycin and uncoupler, and prevented larva‐to‐adult progression at 15°C but not 23°C. Uncoupled respiration of larval mitochondria required palmitate, was dependent on Ucp4C and was inhibited by guanosine diphosphate. UCP4C is required for development through the prepupal stages at low temperatures and may be an uncoupling protein.     

Development and immature survival of two aphidophagous ladybirds, Coelophora biplagiata and Micraspis discolor

The developmental parameters, namely developmental periods, larval survival, adult emergence, growth index, developmental rate and sex ratio in terms of female proportion in a population of two aphidophagous ladybirds, namely, Coelophora biplagiata （Swartz） and Micraspis discolor （Fabricius） were investigated, using three aphid species as prey. The immature stages of C. biplagiata were significantly affected by prey quality and developed fastest when fed on Aphis craccivora followed by Aphis gossypii and Rhopalosiphum maidis. The order of prey suitability in terms of developmental rate of immature stages of M. discolor was just reversed. The adult females were heavier than males, while pre-pupae were heavier than pupae in both ladybirds. The sex ratio of adult emergence, though female-biased in both ladybird species, was not significantly affected by prey quality.     

The ontogeny of the olfactory system in ceratophryid frogs (Anura,Ceratophryidae)

The aquatic‐to‐terrestrial shift in the life cycle of most anurans suggests that the differences between the larval and adult morphology of the nose are required for sensory function in two media with different physical characteristics. However, a better controlled test of specialization to medium is to compare adult stages of terrestrial frogs with those that remain fully aquatic as adults. The Ceratophryidae is a monophyletic group of neotropical frogs whose diversification from a common terrestrial ancestor gave rise to both terrestrial (Ceratophrys, Chacophrys) and aquatic (Lepidobatrachus) adults. So, ceratophryids represent an excellent model to analyze the morphology and possible changes related to a secondary aquatic life. We describe the histomorphology of the nose during the ontogeny of the Ceratophryidae, paying particular attention to the condition in adult stages of the recessus olfactorius (a small area of olfactory epithelium that appears to be used for aquatic olfaction) and the eminentia olfactoria (a raised ridge on the floor of the principal cavity correlated with terrestrial olfaction). The species examined (Ceratophrys cranwelli, Chacophrys pierottii, Lepidobatrachus laevis, and L. llanensis) share a common larval olfactory organ composed by the principal cavity, the vomeronasal organ and the lateral appendix. At postmetamorphic stages, ceratophryids present a common morphology of the nose with the principal, middle, and inferior cavities with characteristics similar to other neobatrachians at the end of metamorphosis. However, in advanced adult stages, Lepidobatrachus laevis presents a recessus olfactorius with a heightened (peramorphic) development and a rudimentary (paedomorphic) eminentia olfactoria. Thus, the adult nose in Lepidobatrachus laevis arises from a common developmental ‘terrestrial’ pathway up to postmetamorphic stages, when its ontogeny leads to a distinctive morphology related to the evolutionarily derived, secondarily aquatic life of adults of this lineage.     

Myogenesis in Aplysia californica (Cooper, 1863) (Mollusca,Gastropoda, Opisthobranchia) with special focus on muscular remodeling during metamorphosis

To date only few comparative approaches tried to reconstruct the ontogeny of the musculature in invertebrates. This may be due to the difficulties involved in reconstructing three dimensionally arranged muscle systems by means of classical histological techniques combined with light or transmission electron microscopy. Within the scope of the present study we investigated the myogenesis of premetamorphic, metamorphic, and juvenile developmental stages of the anaspidean opisthobranch Aplysia californica using fluorescence F‐actin‐labeling in conjunction with modern confocal laser scanning microscopy. We categorized muscles with respect to their differentiation and degeneration and found three true larval muscles that differentiate during the embryonic and veliger phase and degenerate during or slightly after metamorphosis. These are the larval retractor, the accessory larval retractor, and the metapodial retractor muscle. While the pedal retractor muscle, some transversal mantle fibers and major portions of the cephalopedal musculature are continued and elaborated during juvenile and adult life, the buccal musculature and the anterior retractor muscle constitute juvenile/adult muscles which differentiate during or after metamorphosis. The metapodial retractor muscle has never been reported for any other gastropod taxon. Our findings indicate that the late veliger larva of A. californica shares some common traits with veligers of other gastropods, such as a larval retractor muscle. However, the postmetamorphic stages exhibit only few congruencies with other gastropod taxa investigated to date, which is probably due to common larval but different adult life styles within gastropods. Accordingly, this study provides further evidence for morphological plasticity in gastropod myogenesis and stresses the importance of ontogenetic approaches to understand adult conditions and life history patterns. J. Morphol., 2008. © 2007 Wiley‐Liss, Inc.     

Lecithotrophic development and metamorphosis in the Indo-West Pacific brittle star Ophiomastix venosa (Echinodermata: Ophiuroidea)

Summary

The larval development of the ophiocomid ophiuroid Ophiomastix venosais described using SEM. The gastrula transforms into a uniformly ciliated early larva which progressively changes into a lecithotrophic late premetamorphic larva with a continuous bilateral ciliated band. This stage is short-lived and equivalent to a highly reduced ophiopluteus. Comparisons between O. venosa and other ophiuroid species whose development has been investigated suggest that, whatever the developmental mode (lecithotrophic or planktotrophic), a pluteus stage always occurs in ophiuroids with planktonic development. Two metamorphic stages were identified, the late metamorphic larva differing from the early one by the closure of the larval mouth. The appearance of the permanent mouth marks the end of the metamorphosis. The postlarva still possesses remnants of larval features. The transformation of the reduced ophiopluteus into a barrel-shaped metamorphic larva with transverse ciliated bands, a vitellaria larva, is followed. The possible occurrence of a unique type of metamorphic larva in non-brooding ophiuroids is discussed. Verification of this, however, needs further SEM investigations on metamorphic larva from species having “regular” planktotrophic development.     

Comparative morphology of the first instar of three species of Metopia Meigen (Diptera: Sarcophagidae, Miltogramminae)

The first instar larva is described for three species of the kleptoparasitic miltogrammine genus Metopia Meigen: M. campestris (Fallén), M. argentata Macquart and M. argyrocephala (Meigen). Using a combination of light microscopy and scanning electron microscopy, the morphology of the cephaloskeleton as well as the general external morphology are extensively documented, and the phylogenetic implications are discussed. Like other species of Miltogramminae, the first instar of species of Metopia possesses a strong labrum and well‐developed mouth‐hooks. Some other features found in Metopia spp. are rare in the Miltogramminae, such as a serrated ventral surface of the tip of the mouth‐hook and the lack of a posterior spiracular cavity. A few larval features apparently unique for species of Metopia have so far been documented: base of mouth‐hook with a lateral arm‐like extension and abdominal segments with transverse furrow ventrally. The body is equipped with longitudinal cuticular ridges on all segments, which may be a subfamily ground‐plan autapomorphy. Marked morphological and behavioural differences are documented between the first instar of M. argentata and that of M. argyrocephala, the adult females of which are otherwise difficult to separate.     

Influence of thermal conditions on habitat use by a rare spring‐emerging butterfly Euphydryas editha taylori

We may expect butterflies as ectotherms to have particularly active life‐history stages that occur in the warmest and lightest times of the year; however, there are temperate species that are active when climatic conditions seem unfavourable and photoperiod short, such as the Taylor's checkerspot (Euphydryas editha taylori). For such species, studies suggest that even subtle changes to microclimate can potentially impact populations. Thus, understanding how in situ variations in microclimate influence the Taylor's checkerspot butterfly could provide much needed insights into more effective management. We conducted a series of surveys that explored (i) adult habitat use, (ii) final instar larval distribution and (iii) adult movement up to and across site boundaries at two sites in Oregon, USA, in 2010 and 2011. We found that in situ habitat use by the Taylor's checkerspot butterfly was strongly influenced by microclimate. Both adult activities and final instar larvae distribution were clustered within the warmest areas of the sites. Moreover, adults did not use up to 59% and larva up to 90% of their sites, despite vegetation structure and composition being uniform. More specifically, butterfly habitat use increased with increasing ground temperatures, and we found that areas with the highest ground temperatures were more exposed to direct sunlight. Similarly, we found that butterflies tended to only move through sunlit site boundaries. We conclude that the Taylor's checkerspot is sensitive to changes in its thermal environment at fine spatial scales. Our results highlight the importance of microclimate as an indicator of habitat quality, and establishing the thermal criteria in which species of concern exists may provide valuable insights into the implications of climate change.     

Postembryonic development of the sea spider Ammothella biunguiculata (Pycnogonida,Ammotheidae) endoparasitic to an actinian Entacmaea quadricolor (Anthozoa,Stichodactylidae) in Izu Peninsula,Japan

Postembryonic developmental stages of an endoparasitic pycnogonid, Ammothella biunguiculata in Izu Peninsula, Japan are described. Eleven stages were identified beginning with a protonymphon larva attached to the male oviger. We found endoparasitic individuals in the host actinian from the second to tenth instar, and forms in the ninth stage to adult were found free-living. This indicates a transition from being endoparasitic to free-living during the ninth to tenth instar stages. The first instar protonymphon attached to the adult male oviger has a gland duct on the anterior margin of each chelifore scape which completely disappears with the second instar. The disappearance of the chelifore gland duct coincides with the beginning of an endoparasitic stage in the development of this species. Although the larval morphology and the postembryonic development of pycnogonids have been summarized by several authors, the present study concludes that much remains to be learnt.