Relaxed purifying selection of rhodopsin gene within a Chinese endemic cavefish genus <Emphasis Type="Italic">Sinocyclocheilus</Emphasis> (Pisces: Cypriniformes)

The cyprinid fish genus Sinocyclocheilus, as the most cavefish rich genus, includes many species showing striking adaptation to caves and convergent reduction or even loss of eyes and pigmentation. RH1 is responsible for dim vision. In order to explore the evolution of RH1 gene in this genus, we sequenced the complete gene from 28 individuals of 16 representative species of Sinocyclocheilus, with cave and surface species included. Phylogenetic analyses supported the monophyly of Sinocyclocheilus and polyphyly of the cave species. Codon models implemented in PAML were used to infer the evolution of RH1. We found that Sinocyclocheilus had a significantly higher evolutionary rate for amino acids than other cyprinid fishes compared, which might be the result of relaxation of purifying selection and could be ascribed to cave habit of this genus. In contrast to previous hypotheses, both cave and surface lineages exhibited a similar rate of molecular evolution, so the RH1 of cave species may still be functional, although these species were highly adapted to cave environment. Two amino acid substitutions (D83G and E122V) that were not reported before were found, which may be useful for site-directed mutagenesis in the future. Handling editor: Christian Sturmbauer     

Identification of roots in lava tube caves using molecular techniques: implications for conservation of cave arthropod faunas

Lava tube cave ecosystems on the volcanic islands of Hawai‘i support communities of rare and highly specialized cave arthropods. In these cave ecosystems, plant roots, both living and dead, provide the main energy source for cave animals. Loss of deep-rooted plants over caves will affect populations of cave-adapted animals living below. Furthermore, the loss of native plant species will likely eliminate host specific cave animals. Thus, identification of plant roots currently found in caves is necessary for the development of effective management actions that encourage the growth of appropriate deep-rooted plant species, thereby protecting the underlying cave ecosystem. We used molecular techniques to identify plant roots found within cave ecosystems on the islands of Maui and Hawai‘i. Sequences of the internal transcribed spacer (ITS) regions and the 5.8S gene of nuclear ribosomal DNA from cave roots were compared to sequences of known plant species either collected on the surface over the footprint of each cave or to sequences accessioned in GenBank. Roots in the cave ecosystem studied on Maui belonged to two alien tree species: Eucalyptus tereticornis and Grevillea robusta. Within the Hawai‘i cave ecosystem, roots of two plant species were identified: the alien tree G. robusta and the native vine Cocculus orbiculatus. The Maui cave ecosystem supports populations of at least 28 species of arthropods, including eight that are blind obligate cave inhabitants. The Hawai‘i cave ecosystem supports 18 arthropod species, of which three are cave-adapted. Creating protected reserves around biologically significant caves, controlling, and preventing the introduction of harmful invasive plant species within the cave footprint, and encouraging the establishment of deep-rooted native plant species is essential for the continued survival of the unique ecosystems found within Hawaiian lava tube cave systems.     

Nontroglobitic Fishes in Bruffey-Hills Creek Cave, West Virginia, and other Caves Worldwide

Six species of fishes were tagged and released in September and November 1995 and on five dates between November 1998 and October 1999 inside Bruffey-Hills Creek Cave. Most of the tagged fishes were creek chub, Semotilus atromaculatus, and green sunfish, Lepomis cyanellus. The overall recapture rate was 2.6% as only three of 117 fishes were recaptured. Forty-nine days was the longest time of residence by two L. cyanellus and one S. atromaculatus, and movement of 83.4 m was observed only for the creek chub. Tag loss was confirmed as one factor in the low recapture rate. Nine species of fishes were collected in the cave, including Phoxinus oreas and Pimephales promelas, two species never collected in a cave. Most of the fishes were pigmented normally, but many creek chubs were depigmented and appeared white or pigmentless when first observed in the cave stream. Four species, Phoxinus oreas, Pimephales promelas, Ameiurus nebulosus, and Lepomis macrochirus, were collected for the first time in Bruffey-Hills Creek Cave and in the Bruffey and Hills creeks drainage. Although data from this study did not shed light on residence time of fishes in the cave, the consistent occurrence of epigean fishes in this cave was shown. A list of epigean fishes from caves worldwide was included along with a discussion of aspects of the ecology of epigean fishes in caves and of evolution of troglobitic fishes.     

A narrow hybrid zone between two crayfish species from a Mexican cave

In Northern Chiapas (Mexico), two newly discovered species of Procambarus crayfish inhabit a subterranean stream. These species can be morphologically distinguished only by comparing extreme phenotypes (dark, thick-eyed, surface dwelling-like individuals vs light, elongated, microphtalmic, cave dwelling-like individuals). Individuals with intermediate phenotypes co-occur with those exhibiting extreme phenotypes. Crayfish were assayed electrophoretically and individual patterns at 23 gene loci were obtained. Unusually high levels of heterozygosity in both species and a clear discrimination between the two gene pools were revealed. The relationships between individuals were investigated by means of multivariate analysis on individual multilocus genotype profiles. Results showed the occurrence of individuals genetically intermediate between the two major clusters, which shared allozymic variants with both species. Due to the occurrence of alternative alleles in the two gene pools, we could quantify patterns of introgression, which revealed asymmetric gene flow between the two species. Moreover, differential levels of introgression in subsamples within the surface-like species were found: most introgressed individuals came from the inner section of the cave, where the two species were greatly mixed. These results are also discussed in reference to the morphometric results from a companion paper. A possible evolutionary pathway, leading to the situation in this cave, and possibly in neighbouring cave systems, is outlined. The hypothesis of a past history of allopatric divergence from a common ancestor and a subsequent secondary contact between these two Procambarus species is supported by geological studies. Crayfish sympatry and competitive exclusion are also discussed.     

Phylogenetic relationships of the Chinese cyprinid genus <Emphasis Type="Italic">Rhinogobio </Emphasis>Bleeker (Teleostei: Cyprinidae) based on sequences of the mitochondrial DNA control region,with comments on character adaptations

Rhinogobio is a cyprinid genus restricted to the river drainages of China. Sequences of the mitochondrial DNA control region were determined for four Rhinogobio species and one outgroup species, Coreius heterodon, to investigate the phylogenetic relationships within the genus. The control region of the Rhinogobiospecies ranges from 922 to 930 base pairs and comprises 930 base pairs in Coreius. Our phylogenetic analysis indicates two distinct lineages in the genus Rhinogobio. The first includes only R R. ventralis. In the second lineage there are three species, two closely related species R.cylindricus andR.hunanensis, and their sister speciesR. typus. An analysis of character adaptations suggests an evolutionary trend in this genus towards a relatively lower body and caudal peduncle depth, a shorter dorsal fin, and a more anterior anus. In addition, there is a trend towards shorter barbels and relatively larger eyes. Some or all of these traits may be associated with a habitat shift from fast-flowing turbid rivers to slower-flowing clear river habitats.     

Speciation with gene flow in a narrow endemic West Virginia cave salamander (Gyrinophilus subterraneus)

Due to their limited geographic distributions and specialized ecologies, cave species are often highly endemic and can be especially vulnerable to habitat degradation within and surrounding the cave systems they inhabit. We investigated the evolutionary history of the West Virginia Spring Salamander (Gyrinophilus subterraneus), estimated the population trend from historic and current survey data, and assessed the current potential for water quality threats to the cave habitat. Our genomic data (mtDNA sequence and ddRADseq-derived SNPs) reveal two, distinct evolutionary lineages within General Davis Cave corresponding to G. subterraneus and its widely distributed sister species, Gyrinophilus porphyriticus, that are also differentiable based on morphological traits. Genomic models of evolutionary history strongly support asymmetric and continuous gene flow between the two lineages, and hybrid classification analyses identify only parental and first generation cross (F1) progeny. Collectively, these results point to a rare case of sympatric speciation occurring within the cave, leading to strong support for continuing to recognize G. subterraneus as a distinct and unique species. Due to its specialized habitat requirements, the complete distribution of G. subterraneus is unresolved, but using survey data in its type locality (and currently the only known occupied site), we find that the population within General Davis Cave has possibly declined over the last 45 years. Finally, our measures of cave and surface stream water quality did not reveal evidence of water quality impairment and provide important baselines for future monitoring. In addition, our unexpected finding of a hybrid zone and partial reproductive isolation between G. subterraneus and G. porphyriticus warrants further attention to better understand the evolutionary and conservation implications of occasional hybridization between the species.

     

Morphological differentiation within the Ranunculus cassubicus group compared to variation of isozymes, ploidy levels, and reproductive systems: implications for taxonomy

 In the partly apomictic Ranunculus cassubicus group, a subgroup of the R. auricomus complex, two species were studied by morphometric analyses: R. cassubicifolius W. Koch (with three diploid and two autotetraploid sexual populations), and R. carpaticola Soó (with three diploid sexual populations and a hexaploid apomictic one). Multidimensional scaling analyses (MDS) of individuals, boxplots and cluster analyses of populations revealed a differentiation of R. cassubicifolius and R. carpaticola, whereby in MDS the hexaploid apomictic individuals are partly intermediate between R. cassubicifolius and R. carpaticola. The cytodemes of R. cassubicifolius showed no morphological and only a weak genetic differentiation. A comparison of morphology, isozymes, reproductive system and ploidy levels showed only partly congruence of data sets in respect of grouping populations, thus illustrating the problem to find criteria for a taxonomic concept. A treatment of the apomictic population as a separate group is indicated by all data sets, afterwards R. cassubicifolius and diploid R. carpaticola represent two other well-defined groups. Canonical variate analysis including all characters confirmed the three suggested groups as significantly different and showed that a total of 89.3% of individuals are correctly classified; number of teeth of stem leaf segments and number of petals are the most discriminating characters. Herbarium studies confirm the morphological differentiation yielded from population samples. The three population groups are even better separated in a canonical variate analysis of isozyme data (presence/absence of 25 alleles) of the same material, here 92.6% of individuals are correctly classified. Morphology and isozyme data suggest that the hexaploid apomict originated from hybrids of R. cassubicifolius and diploid R. carpaticola and must be excluded from the sexual taxa; the final classification and naming of the apomicts must be left for further studies on a larger material. The sexual taxa should be classified as separate species. Herbarium studies indicate that R. carpaticola s.str. is widespread over the Carpathians and might include other populations hitherto ascribed to other microspecies as well. Received November 20, 2001; accepted May 10, 2002 Published online: September 13, 2002     

Parallel evolution leads to reduced shoaling behavior in two cave dwelling populations of Atlantic mollies (<Emphasis Type="Italic">Poecilia mexicana</Emphasis>, Poeciliidae,Teleostei)

Shoaling behavior protects fishes from avian and piscine predation, but at the same time costs of group living arise due to several mechanisms including increased food competition. Most cave fishes live in an environment in which avian and piscine predators are lacking, and cave environments are often characterized by low food availability, leading to increased food competition. Altogether, this should favor the reduction of shoaling in cave fishes. We compared shoaling behavior (i.e. the tendency to associate with a stimulus shoal) among surface dwelling populations of the Atlantic molly, Poecilia mexicana, and two cave forms of that species. The first cave population of P. mexicana originated from the Cueva del Azufre and was previously recognized as the only cave form of a poeciliid fish. The second cave population examined came from a cave that was discovered only recently (Cueva Luna Azufre). In both cave forms shoaling behavior was reduced compared with surface dwelling mollies.     

Standing genetic variation as a potential mechanism of novel cave phenotype evolution in the freshwater isopod,Asellus aquaticus

Novel phenotypes can come about through a variety of mechanisms including standing genetic variation from a founding population. Cave animals are an excellent system in which to study the evolution of novel phenotypes such as loss of pigmentation and eyes. Asellus aquaticus is a freshwater isopod crustacean found in Europe and has both a surface and a cave ecomorph which vary in multiple phenotypic traits. An orange eye phenotype was previously revealed by F₂ crosses and backcrosses to the cave parent within two examined Slovenian cave populations. Complete loss of pigmentation, both in eye and body, is epistatic to the orange eye phenotype and therefore the orange eye phenotype is hidden within the cave populations. Our goal was to investigate the origin of the orange eye alleles within the Slovenian cave populations by examining A. aquaticus individuals from Slovenian and Romanian surface populations and Asellus aquaticus infernus individuals from a Romanian cave population. We found orange eye individuals present in lab raised surface populations of A. aquaticus from both Slovenia and Romania. Using a mapping approach with crosses between individuals of two surface populations, we found that the region known to be responsible for the orange eye phenotype within the two previously examined Slovenian cave populations was also responsible within both the Slovenian and the Romanian surface populations. Complementation crosses between orange eye Slovenian and orange eye Romanian surface individuals suggest that the same gene is responsible for the orange eye phenotype in both surface populations. Additionally, we observed a low frequency phenotype of eye loss in crosses generated between the two surface populations and also in the Romanian surface population. Finally, in a cave population from Romania, A. aquaticus infernus, we found that the same region is also responsible for the orange eye phenotype as the Slovenian cave populations and the Slovenian and Romanian surface populations. Therefore, we present evidence that variation present in the cave populations could originate from standing variation present in the surface populations and/or transgressive hybridization of different surface phylogenetic lineages rather than de novo mutations.     

Isolation and characterization of five microsatellite loci in Dolichopoda cave crickets (Orthoptera Rhaphidophoridae)

Five microsatellite loci are described for the cave cricket genus Dolichopoda. Preliminary data on allelic variation of these loci are presented for one population of D. schiavazzii and one population of D. laetitiae to test their usefulness in fine‐scale studies of the genetic aspect of cave colonization. Cross‐species amplifications were carried out in four other Dolichopoda species and in two species belonging to another cave cricket genus (Troglophilus) to test the potential use of these microsatellite markers in studies of both congeneric species and species belonging to the same family.     

Increased cave dwelling reduces the ability of cave crickets to resist dehydration

Differential strategies for maintaining water balance are reported for female adults of three cave crickets Hadenoecus cumberlandicus, H. opilionoides and H. jonesi, a species replacement series along the Cumberland Plateau in the southeastern United States. The distribution of H. cumberlandicus is much broader than the range of H. opilionoides, which is much smaller in body size, and that of H. jonesi, which possesses enhanced troglomorphic (cave dwelling) characteristics. Due to high net transpiration (water loss) rates and increased activation energies, H. jonesi and H. opilionoides are more susceptible to dehydration than H. cumberlandicus. To avoid dehydration, H. opilionoides and H. jonesi require more moisture than H. cumberlandicus to counter their higher rates of water loss. The heightened reliance on moisture likely indicates that the more troglomorphic H. jonesi and smaller H. opilionoides are required to spend more time in the moist cave region. Reliance on the cave for H. cumberlandicus is presumably less, allowing them to function in epigean habitats for longer periods and disperse to nearby caves, likely accounting for the more expansive distribution of this cricket. While in the cave habitat, cave crickets are exposed to water-saturated conditions, reducing the pressure of dehydration stress the longer a species remains in this wet environment. This reduced pressure leads to higher water loss rates as cave confinement increases. We conclude that increasing water loss rates associated with increasing troglomorphic adaptation in cave crickets is a side effect of extended residence in stable moist cave environments.     

Distribution and phylogenetic relationships of Australian glow-worms Arachnocampa (Diptera, Keroplatidae)

Glow-worms are bioluminescent fly larvae (Order Diptera, genus Arachnocampa) found only in Australia and New Zealand. Their core habitat is rainforest gullies and wet caves. Eight species are present in Australia; five of them have been recently described. The geographic distribution of species in Australia encompasses the montane regions of the eastern Australian coastline from the Wet Tropics region of northern Queensland to the cool temperate and montane rainforests of southern Australia and Tasmania. Phylogenetic trees based upon partial sequences of the mitochondrial genes cytochrome oxidase II and 16S mtDNA show that populations tend to be clustered into allopatric geographic groups showing overall concordance with the known species distributions. The deepest division is between the cool-adapted southern subgenus, Lucifera, and the more widespread subgenus, Campara. Lucifera comprises the sister groups, A. tasmaniensis, from Tasmania and the newly described species, A. buffaloensis, found in a high-altitude cave at Mt Buffalo in the Australian Alps in Victoria. The remaining Australian glow-worms in subgenus Campara are distributed in a swathe of geographic clusters that extend from the Wet Tropics in northern Queensland to the temperate forests of southern Victoria. Samples from caves and rainforests within any one geographic location tended to cluster together within a clade. We suggest that the morphological differences between hypogean (cave) and epigean (surface) glow-worm larvae are facultative adaptations to local microclimatic conditions rather than due to the presence of cryptic species in caves.     

Evolution of cave living in Hawaiian Schrankia (Lepidoptera: Noctuidae) with description of a remarkable new cave species

Although temperate cave‐adapted fauna may evolve as a result of climatic change, tropical cave dwellers probably colonize caves through adaptive shifts to exploit new resources. The founding populations may have traits that make colonization of underground spaces even more likely. To investigate the process of cave adaptation and the number of times that flightlessness has evolved in a group of reportedly flightless Hawaiian cave moths, we tested the flight ability of 54 Schrankia individuals from seven caves on two islands. Several caves on one island were sampled because separate caves could have been colonized by underground connections after flightlessness had already evolved. A phylogeny based on approximately 1500 bp of mtDNA and nDNA showed that Schrankia howarthi sp. nov. invaded caves on two islands, Maui and Hawaii. Cave‐adapted adults are not consistently flightless but instead are polymorphic for flight ability. Although the new species appears well suited to underground living, some individuals were found living above ground as well. These individuals, which are capable of flight, suggest that this normally cave‐limited species is able to colonize other, geographically separated caves via above‐ground dispersal. This is the first example of an apparently cave‐adapted species that occurs in caves on two separate Hawaiian islands. A revision of the other Hawaiian Schrankia is presented, revealing that Schrankia simplex, Schrankia oxygramma, Schrankia sarothrura, and Schrankia arrhecta are all junior synonyms of Schrankia altivolans. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 114–139.     

Ruminococcal cellulosome systems from rumen to human

A cellulolytic fiber‐degrading bacterium, Ruminococcus champanellensis, was isolated from human faecal samples, and its genome was recently sequenced. Bioinformatic analysis of the R. champanellensis genome revealed numerous cohesin and dockerin modules, the basic elements of the cellulosome, and manual sequencing of partially sequenced genomic segments revealed two large tandem scaffoldin‐coding genes that form part of a gene cluster. Representative R. champanellensis dockerins were tested against putative cohesins, and the results revealed three different cohesin–dockerin binding profiles which implied two major types of cellulosome architectures: (i) an intricate cell‐bound system and (ii) a simplistic cell‐free system composed of a single cohesin‐containing scaffoldin. The cell‐bound system can adopt various enzymatic architectures, ranging from a single enzyme to a large enzymatic complex comprising up to 11 enzymes. The variety of cellulosomal components together with adaptor proteins may infer a very tight regulation of its components. The cellulosome system of the human gut bacterium R. champanellensis closely resembles that of the bovine rumen bacterium Ruminococcus flavefaciens. The two species contain orthologous gene clusters comprising fundamental components of cellulosome architecture. Since R. champanellensis is the only human colonic bacterium known to degrade crystalline cellulose, it may thus represent a keystone species in the human gut.     

Morphological parallelism of sympatric cave-dwelling microsnails of the genus Georissa at Mount Silabur,Borneo (Gastropoda,Neritimorpha, Hydrocenidae)

Parallel evolution in phenotype may result when closely related taxa are adapting in the face of similar ecological pressures. Here, we discuss possible parallelism in shell morphology in the context of the microgeographic phylogeography of two conchologically distinct sympatric hydrocenid snails inhabiting a limestone outcrop and its cave system, Georissa pyrrhoderma and Georissa silaburensis, respectively, at Mount Silabur in Sarawak, Malaysian Borneo. Our results show a certain degree of morphological parallelism of a third, possibly new, cryptic Georissa species within the same cave that strongly diverged from its above-ground sister species, G. pyrrhoderma. We found that both sympatric cave species have shifted from a more sculptured, conical shell toward a broader, less sculptured form.     

Un nuovo ascomicete entomogeno rinvenuto in grotta: Cordyceps riverae

Abstract

A new entomogenous Ascomycete found in cave: Cordyceps riverae.—A new species of entomogenous Cordyceps, belonging to Subgenus Racemella (Ces.) Sacc., found on an adult Lepidotteron in a cave near L'Aquila (Abruzzo, Italy) is described. The characters of this species, named Cordyceps riverae, are compared with those of other similar species of Cordyceps.     

Phylogeny and historical biogeography of the cave-adapted shrimp genus Typhlatya (Atyidae) in the Caribbean Sea and western Atlantic

Aim To infer phylogenetic relationships among five species of the cave‐adapted shrimp genus Typhlatya in order to test competing hypotheses of dispersal and colonization of the disjunct cave localities occupied by these five species. Location Typhlatya species are found in caves and anchialine ponds across the northern margin of the Caribbean Sea, along the Mediterranean and Adriatic coasts and on oceanic islands in the Atlantic and eastern Pacific oceans. This study focuses on five species, one from Bermuda, one from the Caicos Islands and three from the Yucatan Peninsula of Mexico. Methods Partial sequences (c. 1400 bp) from the mitochondrial cytochrome b, 16S rDNA and COI genes were obtained from representative samples of the five species. Phylogenetic inference was carried out with maximum parsimony and maximum likelihood analyses. Parsimony networks were constructed for the Bermudian species Typhlatya iliffei and one Yucatan species Typhlatya mitchelli, to determine the degree of connectivity among populations inhabiting different cave systems. Results All three land masses were recovered as monophyletic. The two insular marine species from Bermuda and the Caicos Islands formed a clade, while the three continental freshwater species from the Yucatan Peninsula formed another. Within both Bermuda and the Yucatan, shared haplotypes were found in different cave systems, suggesting recent or ongoing gene flow among populations in both locales. Main conclusions The two insular marine Typhlatya species originated from an ancestral marine population, possibly already cave‐adapted, that is suggested to have colonized the Caicos Islands and subsequently dispersed to Bermuda via the Gulf Stream. Divergence estimates suggest that colonization occurred before the formation of present‐day anchialine cave habitat, which did not form on either island until the late Pliocene to early Pleistocene. Divergence estimates also indicate that the Yucatan freshwater species split before the formation of freshwater cave habitat in the Yucatan. These species could have inhabited crevicular marine habitats before the late Pliocene/early Pleistocene in the Yucatan or elsewhere in the Caribbean, and subsequently migrated to freshwater caves once they formed.     

Life on the edge: hydrogen sulfide and the fish communities of a Mexican cave and surrounding waters

Most eucaryotic organisms classified as living in an extreme habitat are invertebrates. Here we report of a fish living in a Mexican cave (Cueva del Azufre) that is rich in highly toxic H₂S. We compared the water chemistry and fish communities of the cave and several nearby surface streams. Our study revealed high concentrations of H₂S in the cave and its outflow (El Azufre). The concentrations of H₂S reach more than 300 μM inside the cave, which are acutely toxic for most fishes. In both sulfidic habitats, the diversity of fishes was heavily reduced, and Poecilia mexicana was the dominant species indicating that the presence of H₂S has an all-or-none effect, permitting only few species to survive in sulfidic habitats. Compared to habitats without H₂S, P. mexicana from the cave and the outflow have a significantly lower body condition. Although there are microhabitats with varying concentrations of H₂S within the cave, we could not find a higher fish density in areas with lower concentrations of H₂S. We discuss that P. mexicana is one of the few extremophile vertebrates. Our study supports the idea that extreme habitats lead to an impoverished species diversity.     

Evidence for speciation underground in diving beetles (Dytiscidae) from a subterranean archipelago

Most subterranean animals are assumed to have evolved from surface ancestors following colonization of a cave system; however, very few studies have raised the possibility of “subterranean speciation” in underground habitats (i.e., obligate cave‐dwelling organisms [troglobionts] descended from troglobiotic ancestors). Numerous endemic subterranean diving beetle species from spatially discrete calcrete aquifers in Western Australia (stygobionts) have evolved independently from surface ancestors; however, several cases of sympatric sister species raise the possibility of subterranean speciation. We tested this hypothesis using vision (phototransduction) genes that are evolving under neutral processes in subterranean species and purifying selection in surface species. Using sequence data from 32 subterranean and five surface species in the genus Paroster (Dytiscidae), we identified deleterious mutations in long wavelength opsin (lwop), arrestin 1 (arr1), and arrestin 2 (arr2) shared by a sympatric sister‐species triplet, arr1 shared by a sympatric sister‐species pair, and lwop and arr2 shared among closely related species in adjacent calcrete aquifers. In all cases, a common ancestor possessed the function‐altering mutations, implying they were already adapted to aphotic environments. Our study represents one of the first confirmed cases of subterranean speciation in cave insects. The assessment of genes undergoing pseudogenization provides a novel way of testing modes of speciation and the history of diversification in blind cave animals.     

Structure and dynamics of the parasitoid community shared by two herbivore species on different host plants

The structure of the parasitoid community on phytophagous insects can be affected by host plant properties, such as chemical compounds, trichomes, and glandular hairs. To clarify effects of host plants on herbivores and the parasitoid community, I examined the structure and dynamics of the parasitoid community associated with two species of Caloptilia moths (Lepidoptera: Gracillariidae) that feed on different Rhododendron species (Ericaceae) for 3 years in a temperate secondary forest in central Japan. Caloptilia azaleella had overlapping generations in summer and overwintered as larvae on leaves of R. macrosepalum. Caloptilia leucothoes also had overlapping generations in summer, but it did not overwinter on the deciduous shrub R. reticulatum. The parasitoid community of C. azaleella larvae and pupae was composed of 18 species, whereas that of C. leucothoes was composed of seven species. Five species of parasitoids attacked both Caloptilia species. The most abundant parasitoid, Apanteles cf. xanthostigma (Hymenoptera: Braconidae), more frequently attacked C. azaleella than C. leucothoes larvae. In contrast, another abundant parasitoid, Acrysocharoides sp. (Hymenoptera: Eulophidae), more frequently attacked C. leucothoes than C. azaleella larvae. This differential parasitism by the most abundant parasitoid species may be responsible for the differential structure and dynamics of the parasitoid community between the Caloptilia species. The host plant of C. azaleella, R. macrosepalum, more frequently trapped and killed parasitoids (of similar size to Acrysocharoides sp.) on the glandular hairs of leaves than did R. reticulatum. The differential effect of host plants on abundant parasitoids may be related to the differential parasitism by the two abundant parasitoids shared by the herbivore hosts.