New evidence on the systematic and phylogenetic position of Parides burchellanus (Lepidoptera: Papilionidae)

Parides burchellanus is considered a rare and threatened swallowtail species restricted to central Brazil. It shows considerable morphological similarity to Parides panthonus jaguarae, with which it shares both geographical range and larval host plant. At present, P. burchellanus and P. panthonus are believed to be distinct species, based on minor differences in male genitalia. In this study, the phylogenetic and systematic position of P. burchellanus in relation to three subspecies of P. panthonus (P. p. jaguarae, P. p. lysimachus and P. p. aglaope) was evaluated using molecular evidence: the complete sequence of the mtDNA genes COI and COII and of the nuclear gene EF‐1α (c. 3300 bp). In addition, the informativeness of the ‘barcode’ region next to the 5′ end of COI (c. 650 bp) was evaluated for delimiting these taxa. Individual analysis by neighbour‐joining, using Kimura 2‐parameter distance model, and by maximum parsimony showed that P. p. jaguarae + P. p. lysimachus + P. p. aglaope + P. burchellanus form a strongly supported monophyletic clade, and all molecular regions consistently recovered P. p. jaguarae and P. burchellanus as sister species. The genetic divergence among the subspecies of P. panthonus and P. burchellanus is equivalent to the divergence among conspecifics of other species of Parides, and smaller than the interspecific divergence among different sister species of this genus. The results support the proposal that P. p. jaguarae and P. burchellanus are likely to be synonymous, and suggest that P. burchellanus can be considered conspecific with P. panthonus. The taxonomic classification of P. burchellanus should be revised on the basis of the molecular data.     

A new species of subantarctic Plexechinus and its phylogenetic position within the Holasteroida (Echinodermata: Echinoidea)

A seventh species of Plexechinus, Plexechinus sulcatus sp. nov., is described from material collected at 585 m from an R/V “Marion Dufresne” station northwest of the Kerguelen Islands. It differs most markedly from its congeners in possessing a distinctive aboral sulcus in the anterior ambulacrum, which is unique in the Plexechinidae. There is strong phylogenetic evidence that P. sulcatus is the sister group to a clade containing P. cinctus and P. hirsutus. The implications of this placement are discussed in the light of previous work on the evolutionary biology of holasteroids. Accepted: 11 September 1999     

Cladistic analysis of Heliconius butterflies and relatives (Nymphalidae: Heliconiiti): a revised phylogenetic position for Eueides based on sequences from mtDNA and a nuclear gene

A new phylogenetic hypothesis for Heliconius and related genera is presented, based on DNA sequence data from mtDNA combined with a region of the wingless gene. This study also adds eight new taxa to a previous cladistic hypothesis based on the mtDNA alone. Simultaneous phylogenetic analysis of the two gene regions together supports a topology largely in agreement with traditional views of heliconiine relationships based on morphology and suggests that the mtDNA support for the sister relationship between Eueides and H. charithonia is due to convergent evolution of homoplasious mtDNA sites.     

Structure of the parasite communities of a coral reef fish assemblage (Labridae): testing ecological and phylogenetic host factors

The role of ecological and phylogenetic processes is fundamental to understanding how parasite communities are structured. However, for coral reef fishes, such information is almost nonexistent. In this study, we analyzed the structure of the parasite communities based on composition, richness, abundance, and biovolume of ecto- and endoparasites of 14 wrasse species (Labridae) from Lizard Island, Great Barrier Reef, Australia. We determine whether the structure of the parasite communities from these fishes was related to ecological characteristics (body size, abundance, swimming ability, and diet) and/or the phylogenetic relatedness of the hosts. We examined 264 fishes from which almost 37,000 individual parasites and 98 parasite categories (types and species) were recorded. Gnathiid and cestode larvae were the most prevalent and abundant parasites in most fishes. Mean richness, abundance, and biovolume of ectoparasites per fish species were positively correlated with host body size only after controlling for the host phylogeny, whereas no such correlation was found for endoparasites with any host variable. Because most ectoparasites have direct transmission, one possible explanation for this pattern is that increased space (host body size) may increase the colonization and recruitment of ectoparasites. However, endoparasites generally have indirect transmission that can be affected by many other variables, such as number of prey infected and rate of parasite transmission.     

A search for the phylogenetic position of the seven-son flower (Heptacodium, Dipsacales): Combining molecular and morphological evidence

A first report on the problematic phylogenetic position ofHeptacodium (2 spp.; China) using molecular data from chloroplast DNA is presented. Amplification of ORF2280 homolog region was executed in a number of representative taxa in order to determine ifHeptacodium shows similar structural rearrangements as other Dipsacales. DNA sequences ofndhF were generated to clarify the phylogenetic position ofHeptacodium among Caprifoliaceae (s.l.). Six outgroup taxa and fifteen representatives of Dipsacales were sampled and more than 2100 basepairs ofndhF sequence were used in a cladistic analysis. Parsimony analysis produced two shortest trees and showedHeptacodium as sister to all members of Caprifoliaceae (s.str.), although weakly supported. Additionally, trees were constructed withndhF data supplemented with availablerbcL sequences and a morphological data set. Results of all analyses support an unresolved basal position forHeptacodium among Caprifoliaceae (s.l.), which in part explains the difficulty experienced previously in classifying the genus.     

Experimental evolution with a multicellular host causes diversification within and between microbial parasite populations—Differences in emerging phenotypes of two different parasite strains

Host‐parasite coevolution is predicted to have complex evolutionary consequences, potentially leading to the emergence of genetic and phenotypic diversity for both antagonists. However, little is known about variation in phenotypic responses to coevolution between different parasite strains exposed to the same experimental conditions. We infected Caenorhabditis elegans with one of two strains of Bacillus thuringiensis and either allowed the host and the parasite to experimentally coevolve (coevolution treatment) or allowed only the parasite to adapt to the host (one‐sided parasite adaptation). By isolating single parasite clones from evolved populations, we found phenotypic diversification of the ancestral strain into distinct clones, which varied in virulence toward ancestral hosts and competitive ability against other parasite genotypes. Parasite phenotypes differed remarkably not only between the two strains, but also between and within different replicate populations, indicating diversification of the clonal population caused by selection. This study highlights that the evolutionary selection pressure mediated by a multicellular host causes phenotypic diversification, but not necessarily with the same phenotypic outcome for different parasite strains.     

Cross‐continental comparison of parasite communities in a wide‐ranging carnivore suggests associations with prey diversity and host density

1. Parasites are integral to ecosystem functioning yet often overlooked. Improved understanding of host–parasite associations is important, particularly for wide‐ranging species for which host range shifts and climate change could alter host–parasite interactions and their effects on ecosystem function.
2. Among the most widely distributed mammals with diverse diets, gray wolves (Canis lupus) host parasites that are transmitted among canids and via prey species. Wolf–parasite associations may therefore influence the population dynamics and ecological functions of both wolves and their prey. Our goal was to identify large‐scale processes that shape host–parasite interactions across populations, with the wolf as a model organism.
3. By compiling data from various studies, we examined the fecal prevalence of gastrointestinal parasites in six wolf populations from two continents in relation to wolf density, diet diversity, and other ecological conditions.
4. As expected, we found that the fecal prevalence of parasites transmitted directly to wolves via contact with other canids or their excreta was positively associated with wolf density. Contrary to our expectations, the fecal prevalence of parasites transmitted via prey was negatively associated with prey diversity. We also found that parasite communities reflected landscape characteristics and specific prey items available to wolves.
5. Several parasite taxa identified in this study, including hookworms and coccidian protozoans, can cause morbidity and mortality in canids, especially in pups, or in combination with other stressors. The density–prevalence relationship for parasites with simple life cycles may reflect a regulatory role of gastrointestinal parasites on wolf populations. Our result that fecal prevalence of parasites was lower in wolves with more diverse diets could provide insight into the mechanisms by which biodiversity may regulate disease. A diverse suite of predator–prey interactions could regulate the effects of parasitism on prey populations and mitigate the transmission of infectious agents, including zoonoses, spread via trophic interactions.

     

Direct evidence for cyanide-insensitive quinol oxidase (alternative oxidase) in apicomplexan parasite Cryptosporidium parvum: phylogenetic and therapeutic implications

Cryptosporidium parvum is a parasitic protozoan that causes the diarrheal disease cryptosporidiosis, for which no satisfactory chemotherapy is currently available. Although the presence of mitochondria in this parasite has been suggested, its respiratory system is poorly understood due to difficulties in performing biochemical analyses. In order to better understand the respiratory chain of C. parvum, we surveyed its genomic DNA database in GenBank and identified a partial sequence encoding cyanide-insensitive alternative oxidase (AOX). Based on this sequence, we cloned C. parvum AOX (CpAOX) cDNA from the phylum apicomplexa for the first time. The deduced amino acid sequence (335 a.a.) of CpAOX contains diiron coordination motifs (-E-, -EXXH-) that are conserved among AOXs. Phylogenetic analysis suggested that CpAOX is a mitochondrial-type AOX, possibly derived from mitochondrial endosymbiont gene transfer. The recombinant enzyme expressed in Escherichia coli showed quinol oxidase activity. This activity was insensitive to cyanide and highly sensitive to ascofuranone, a specific inhibitor of trypanosome AOX.     

Ultrastructural characterization and comparative phylogenetic analysis of new microsporidia from Siberian mosquitoes: evidence for coevolution and host switching

A survey of mosquito larvae infected with microsporidia was conducted from 2005 to 2008 in the Tomsk, Kemerovo and Novosibirsk regions of western Siberia, Russia. Twenty-one morphologically and genetically unique species of microsporidia were isolated from nine species of Anopheles, Aedes, Culex and Ochlerotatus mosquitoes including: (1) 14 proposed new species of Amblyospora (A. bakcharia, A. baritia, A. bogashovia, A. chulymia, A. hristinia, A. jurginia, A. kazankia, A. mavlukevia, A. mocrushinia, A. modestium, A. salairia, A. severinia, A. shegaria, and A. timirasia); (2) a newly proposed genus and species, Novothelohaniaovalae and; (3) six species of Amblyospora (A. flavescens, A. kolarovi, A. rugosa), Parathelohania (P. divulgata and P. tomski) and Trichoctosporea (T. pygopellita) from which gene sequences had not been previously obtained. Detailed ultrastructure of meiospores revealed unique cytological features associated with the length, arrangement and ratio of broad to narrow coils of the polar filament, comparative thickness of the exospore and endospore, and overall size of each species reaffirming their value in distinguishing taxonomic relationships. SSU rDNA sequences obtained from each species of microsporidia were unique when compared with GenBank entries. Phylogenetic trees constructed by Maximum Parsimony, Maximum Likelihood and Neighbor Joining analyses yielded similar topologies with a high degree of congruence between parasite and host at the generic level. Species that parasitize Aedes/Ochlerotatus and Culex mosquitoes segregate into distinct monophyletic groupings mirroring their host phylogeny, while species from Anopheles mosquitoes group as a sister clade basal to the entire group of mosquito-parasitic microsporidia as their Anopheles hosts cluster as a sister clade to the entire group of culicine mosquitoes. This provides strong evidence for host-parasite coevolution by descent at the generic level and limited host lineage switching between unrelated taxa. Among parasites of Aedes/Ochlerotatus and Anopheles mosquitoes, we found several instances where a single mosquito species serves as a host for two or more related species of microsporidia, an observation consistent with host switching and independent parasite speciation. Among the microsporidian parasites of Culex mosquitoes, we found only one parasite per host indicating a higher degree of host specificity and less host switching among parasites of this genus. Findings suggest a degree of host-parasite co-speciation with host switching occurring occasionally when the "normal" host is unavailable in the aquatic ecosystem. Frequency of host switching seems to be occurring in proportion to host relatedness and does not cross generic boundaries in this system.     

Evolutionarily stable infection by a male-killing endosymbiont in Drosophila innubila: molecular evidence from the host and parasite genomes

Maternally inherited microbes that spread via male-killing are common pathogens of insects, yet very little is known about the evolutionary duration of these associations. The few examples to date indicate very recent, and thus potentially transient, infections. A male-killing strain of Wolbachia has recently been discovered in natural populations of Drosophila innubila. The population-level effects of this infection are significant: approximately 35% of females are infected, infected females produce very strongly female-biased sex ratios, and the resulting population-level sex ratio is significantly female biased. Using data on infection prevalence and Wolbachia transmission rates, infected cytoplasmic lineages are estimated to experience a approximately 5% selective advantage relative to uninfected lineages. The evolutionary history of this infection was explored by surveying patterns of polymorphism in both the host and parasite genomes, comparing the Wolbachia wsp gene and the host mtDNA COI gene to five host nuclear genes. Molecular data suggest that this male-killing infection is evolutionarily old, a conclusion supported with a simple model of parasite and mtDNA transmission dynamics. Despite a large effective population size of the host species and strong selection to evolve resistance, the D. innubila-Wolbachia association is likely at a stable equilibrium that is maintained by imperfect maternal transmission of the bacteria rather than partial resistance in the host species.     

Detecting ancient codispersals and host shifts by double dating of host and parasite phylogenies: Application in proctophyllodid feather mites associated with passerine birds

Inferring cophylogeographic events requires matching the timing of these events on both host and symbiont (e.g., parasites) phylogenies because divergences of hosts and their symbionts may not temporally coincide, and host switches may occur. We investigate a large radiation of birds (Passeriformes) and their permanent symbionts, the proctophyllodid feather mites (117 species from 116 bird species; six genes, 11,468 nt aligned) using two time‐calibration strategies for mites: fossils only and host phylogeography only. Out of 10 putative cophylogeographic events 4 agree in timing for both symbiont and host events being synchronous co‐origins or codispersals; three were based on host shifts, but agree in timing being very close to the origin of modern hosts; two disagree; and one large basal mite split was seemingly independent from host phylogeography. Among these events was an ancient (21–25.3 Mya), synchronous codispersal from the Old World leading to the origin and diversifications of New World emberizoid passerids and their mites, the thraupis + quadratus species groups of Proctophyllodes. Our framework offers a more robust detection of host and symbiont cophylogeographic events (as compared to host‐symbiont reconciliation analysis and using host phylogeography for time‐calibration) and provides independent data for testing alternative hypotheses on timing of host diversification and dispersal.     

Resolving the systematic and phylogenetic position of isolated ovules: a case study on a new genus from the Permian of China

Isolated ovules occur in many fossil plant assemblages, where they provide important insights into seed‐plant diversity and evolution. However, in many cases, the ovules cannot be attributed to individual groups of seed plants, restricting systematic and evolutionary assessments that can be made from otherwise well‐characterized fossil taxa. In the present paper, we describe a new kind of ovule discovered in tuffaceous sediments from the Permian‐aged Xuanwei Formation in Guizhou Province, China. This ovule has 180° rotational symmetry and an integument comprising a variably thick sarcotesta, a uniformly thick sclerotesta and a uniformly thin endotesta. The nucellus is attached to the integument at least basally and contains a collapsed seed megaspore; a nucellar apex is absent. Both the integument and nucellus are vascularized by paired bundles in the major plane of the ovule; the integumentary bundles are considerably larger than the nucellar bundles and the nucellar bundles emerge from a conical vascular pad. Generation of a three‐dimensional reconstruction based on serial peels revealed the gross morphology and organization of the ovule and highlighted the presence of features consistent with cardiocarpalean‐type ovules (ovule shape, histological features of the integument) and also features more typical of lagenostomalean‐ and trigonocarpalean‐type ovules (large integumentary bundles, presence of nucellar bundles). To assess the affinity and evolutionary significance of the ovule, it has been included in a cladistic matrix of cardiocarpalean‐, lagenostomalean‐ and trigonocarpalean‐type ovules. Results place the ovule within the cardiocarpalean group of ovules known to have been produced by several plant groups, including cordaitean coniferophytes, pteridosperms and Palaeozoic conifers. The cladistic topology supports generic level distinction of the present species, requiring the establishment of Muricosperma guizhouensis Seyfullah & J.Hilton gen. & sp. nov . Lagenostomalean ovules produced by hydrasperman pteridosperms form a basal paraphyletic grade, whereas trigonocarpalean ovules produced by medullosan pteridosperms form a monophyletic group in which Stephanospermum is paraphyletic with respect to Rhynchosperma and Pachytesta. The results also place the Mississippian ovule Mitrospermum bulbosum apart from all of the Pennsylvanian species of Mitrospermum that form a strongly supported clade. Consequently, M. bulbosum is transferred to the new genus Whitaddera Seyfullah & J.Hilton as W. bulbosa (Long) Seyfullah & J.Hilton. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 84–108.     

A phylogeny of four mitochondrial gene regions suggests a revised taxonomy for Asian pitvipers (Trimeresurus and Ovophis)

We present a phylogeny of the Asian pitvipers, based on 2403 bp of four mitochondrial gene regions. All but six known species of Trimeresurus sensu stricto (s.s.) as currently defined, as well as multiple populations of widespread species, which may yet be described as full species, and representatives of all other Asian pitviper genera, are included. Both the greater sampling and larger dataset provide improved resolution over previous studies and support the existence of distinct species groups within Trimeresurus s.s. Although all but two species currently referred to this genus form a monophyletic group, morphological and molecular analyses identify four subgroups that warrant recognition at the generic level. We propose a new generic arrangement to reflect these findings. We also highlight the non-monophyly of Ovophis, and propose a new genus to accommodate a species formerly assigned to Ovophis.     

Geographic and phylogenetic evidence for dispersed nuclear introgression in a daphniid with sexual propagules

The role of among-species gene flow in eukaryotic evolution remains controversial. Putative hybrid lineages are common in water fleas, but their ecological success is often associated with polyploidy and the production of asexual propagules. Advanced hybrid lineages with sexual propagules are expected to be geographically restricted because their successful dispersal is contingent on overcoming fertility complications, assimilation by parent taxa, and competition with parent taxa. Here we provide evidence that a diploid lineage of Daphnia has been formed by introgression between distantly related species and attained a broad distribution (Nearctic) despite its requirement for sexual propagules. The evidence is based on geographical discordance, phylogenetic discordance, recombinant genotypes and additive genotypes of the nuclear internal transcribed spacer regions (ITS) and mitochondrial DNA. Additive genotypes also provided evidence of hybridization between introduced European Daphnia and North American Daphnia. We argue that the unique biology of Holarctic lacustrine water fleas and the spatial separation of lineages during Pleistocene glaciation have promoted hybridization and its evolutionary consequences.     

Isolation of plasma membrane from amphibian epidermis: evidence for a basal-to-apical charge and activity gradient

Aqueous two-phase partition and preparative free-flow electrophoresis were used in series to isolate the plasma membranes of amphibian epidermis. Fractions obtained by two-phase partition were 40-fold enriched in a K+-stimulated, ouabain-inhibited, p-nitrophenylphosphatase relative to the total homogenate and based on morphology were representative isolates of all epidermal cells together. Small mucosal granules and mucin aggregates were the primary contaminants. Based on activities of marker enzymes, contents of mitochondria, Golgi apparatus and endoplasmic reticulum were low (0.15 that of total homogenate) or absent. When plasma membranes isolated by aqueous two-phase partition were subjected to preparative free-flow electrophoresis, they were distributed toward the anode in a series of fractions of increasing net negative charge, sialic acid content and specific activity of the K+-stimulated, ouabain-inhibited, p-nitrophenylphosphatase reminiscent of the activity gradient from base to apex for frog epidermis observed from cytochemical investigations. The most electronegative fractions nearest the anode and to the left of the main protein peak were enriched in both sulfate groups and thick membranes of the stratum corneum. A fraction migrating less toward the anode and to the right of the main protein peak contained hemidesmosomes together with the lowest enrichments of sialic acid, sulfate and the phosphatase. The results suggest that the plasma membranes isolated from mixed cell populations, such as those encountered in epidermal homogenates, may be resolved by free-flow electrophoresis according to cell type of origin following activity gradients present in the original tissue. Additionally, the findings provide independent biochemical confirmation of a base-to-apex gradient of transport (ATPase) activity associated with the plasma membranes of cells of the different strata of the amphibian epidermis.     

Vermetid gastropods as key intermediate hosts for a lineage of marine turtle blood flukes (Digenea: Spirorchiidae), with evidence of transmission at a turtle rookery

Blood flukes of the family Spirorchiidae Stunkard, 1921 are significant pathogens of marine turtles, both in the wild and in captivity. Despite causing considerable disease and mortality, little is known about the life cycles of marine species, with just four reports globally. No complete life cycle has been elucidated for any named species of marine spirorchiid, but the group is reported to use vermetid and fissurellid gastropods, and terebelliform polychaetes as intermediate hosts. Here we report molecular evidence that nine related spirorchiid species infect vermetid gastropods as first intermediate hosts from four localities along the coast of Queensland, Australia. ITS2 rDNA and cox1 mtDNA sequence data generated from vermetid infections provides the first definitive identifications for the intermediate hosts for the four species of Hapalotrema Looss, 1899 and Learedius learedi Price, 1934. Additionally, we provide a new locality report for larval stages of Amphiorchis sp., and evidence of three additional unidentified spirorchiid species in Australian waters. Based on the wealth of infections from vermetids during this study, we conclude that the previous preliminary report of a fissurellid limpet as the intermediate host for L. learedi was likely mistaken. The nine species found infecting vermetids during this study form a strongly supported clade exclusive of species of the other two marine spirorchiid genera for which sequence data are available; Carettacola Manter & Larson, 1950 which falls sister to the vermetid-infecting clade + a small clade of freshwater spirorchiids, and Neospirorchis Price, 1934 which is distantly related to the vermetid-infecting clade. We provide further evidence that spirorchiid transmission can occur in closed system aquaria and show that spirorchiid transmission occurs at both an important turtle rookery (Heron Island, southern Great Barrier Reef, Australia) and foraging ground (Moreton Bay, Australia). We discuss the implications of our findings for the epidemiology of the disease, control in captivity, and the evolution of vermetid exploitation by the Spirorchiidae.