Life Cycle of Himalopsyche japonica (Morton) (Trichoptera: Rhyacophilidae) in Two High Mountain Streams in Nagano, Central Japan

The life cycle of Himalopsyche japonica (Morton) was studied in two high mountain streams at about 1500 m a.s.l. from September 2000 to May 2002 in central Japan. The life cycles in both streams are univoltine. Larval development in upper streams with cooler water is slower than in lower streams with warmer water. The relationships between voltinism or larval size and water temperature are discussed.     

Life history variation between high and low elevation subspecies of horned larks Eremophila spp.

Environmental variation along elevational gradients can strongly influence life history strategies in vertebrates. We investigated variation in life history patterns between a horned lark subspecies nesting in high elevation alpine habitat Eremophila alpestris articola and a second subspecies in lower elevation grassland and sandy shoreline habitats E. a. strigata. Given the shorter breeding season and colder climate at the northern alpine site we expected E. a. articola to be larger, have lower fecundity and higher apparent survival than E. a. strigata. As predicted, E. a. articola was larger and the trend was toward higher apparent adult survival for E. a. articola than E. a. strigata (0.69 vs 0.51). Contrary to our predictions, however, there was a trend toward higher fecundity for E. a. articola (1.75 female fledglings/female/year vs 0.91). The larger clutch sizes, higher nest survival, and shorter renesting intervals have apparently allowed E. a. articola to compensate for the short breeding season. Estimates of population growth rate (λ) predicted a stable population for E. a. articola (λ=1.00) and a rapidly declining population for E. a. strigata (λ=0.62) this may provide an explanation for the deviations from our expectation of higher reproduction in E. a. strigata. We suggest that anthropogenic influences (e.g. habitat loss and degradation and increased nest predator abundance) to E. a. strigata nesting sites may be responsible for reducing annual fecundity to the point where it is almost half that of E. a. articola. This result suggests that human influenced habitat changes that, in turn, change demographic rates may result in vital rates that do not accurately reflect historically divergent life histories between the two groups. Our results underscore the importance of including estimates of multiple traits in life history studies to provide insight into compensatory interactions among components of demographic rates and to identify recent changes to demographic rates that might result in a mismatch between observed and predicted life history strategies.     

Male reproductive polymorphism and form-specific habitat utilization of the damselflyMnais pruinosa (Zygoptera: Calopterygidae)

Habitat utilization patterns were studied in damselfly males,Mnais pruinosa, which have two male forms with different reproductive behaviors. The ‘esakii’ (orange-winged males) were territorial around oviposition sites, while the ‘strigata’ (hyaline-winged males) were non-territorial, often sneaking into theesakii's territory or loitering on the foliage of vegetation along stream banks. The place in the stream in the study area where females frequently appeared was covered by reeds and had abundant oviposition sites. It was difficult for the territorialesakii to stay there because the crowded reeds prevented them from defending their territory and discovering the females. Furthermore, there was competition for the limited territorial space with another species,Mnais nawai. Strigata males concentrated in this place in direct proportion to the number of females. Females frequently mated withstrigata males and probably deposited eggs fertilized bystrigata sperm rather thanesakii sperm. The density ofstrigata was higher than that ofesakii in this study area. If the average reproductive success ofesakii andstrigata males is equal, this may indicate that the equilibrious point between the two male forms is biased towardstrigata.     

Life history and production of Caenis luctuosa (Burmeister) (Ephemeroptera, Caenidae) in two nearby reaches along a small stream

Population dynamics and production of C. luctuosa were compared in two reaches of the Agüera stream (northern Spain). This species showed univoltine winter life history in both sites. However, the start of the recruitment period, and the cohort production interval differed in 1 month between reaches. Secondary production of C. luctuosa ranged from 76 mg m^–2 year^–1 (upper site) to 93 mg m^–2 year^–1 (lower site). Although annual production seemed to be mainly influenced by the biomass found at each site, changes in life history may have also been important. The need to have accurate information about life history of the analysed species at the study sites when assessing secondary production is highlighted.     

Synchronization of reproductive period among the two male forms and female of the damselflyMnais pruinosa selys (Zygoptera: Calopterygidae)

Ecological parameters in a population ofMnais pruinosa were investigated in a mountain stream. In the study area, there were two forms of male with regard to wing color, the orange-winged male (esakii) and the hyaline-winged male (strigata), and only one female form with hyaline wings. Emergence of adults began in late April, and the flying season ended in late June. The time after emergence was spent in maturation, and the insects began to mate when they reached maturity. Longevity of adults was 17.6 days foresakii males, 18.4 days forstrigata males and 21.9 days for females. There was little difference in emergence time, maturation period, survivorship curve and longevity among the two male forms and female. In other words, the period for reproductive activities was perfectly coincident among them. The factors influencing the synchronization of emergence were discussed.     

Molecular phylogeny evidence of altitudinal distribution and habitat adaptation in Korean Ephemera species (Ephemeroptera: Ephemeridae)

Molecular phylogeny of the four Korean Ephemera species, Ephemera orientalis, E. sachalinensis, E. strigata, and E. separigata, was inferred from 630 bp sequences of the partial mitochondrial cytochrome c oxidase I (COI) gene. Results indicated that mean intraspecific sequence divergences were 0.70%, whereas mean interspecific divergences were 15.75%, and 17 samples were distinguished to four species correctly by COI sequences. The results also demonstrated that four species of Korean Ephemera assembled a monophyletic group with high support in maximum parsimony and maximum likelihood analyses. This Ephemera group was divided into two major clades of E. orientalis–E. sachalinensis and E. strigata–E. separigata. Furthermore, we demonstrated that this phylogeny explained altitudinal and habitat adaptations of Korean Ephemera species. The E. orientalis–E. sachalinensis clade, a widespread and lowland‐adapted mayfly group, retained plesiomorphic traits such as paired stripes on abdominal segments and was regarded as plesiotypic in terms of habitat adaptation, compared to the geographically more limited and upland‐adapted E. strigata–E. separigata clade.     

Competitive habitat utilization in the damselfly,Mnais nawai (Zygoptera: Calopterygidae) coexisting with a related species,Mnais pruinosa

Reproductive behaviors related to habitat utilization were studied in males of the damsefly,Mnais nawai, which has two male forms, territorial orange-winged males (nawai) and non-territorial pale-orange-winged males (sahoi), at the upper part of a mountain stream where they partiallycoexist with a related species,Mnais pruinosa, which also has two male forms, territorial orange-winged males (esakii) and non-territorial hyaline-winged males (strigata). These two species showed parapatric distribution; the lower part of the stream was occupied byM. nawai, and the upper part byM. pruinosa. In the present study, cross-matings occurred between bothMnais species, although normal intraspecific matings occurred more frequently than cross-matings. Territorial males of both species copulated with conspecific females that entered their territory and guarded the ovipositing females, probably to avoid sperm displacement resulting from subsequent copulations. Severe competition for oviposition sites by territorial males even occurred between the two species. On the other hand, non-territorial males of both species have alternative mating strategies (including several tactics such as sneaking, takeover and interception). The possible benefits from conflict among territorial males of both species is discussed.     

Life cycle of three stonefly species (Plecoptera) from an Apenninic stream (Italy) with the description of the nymph of Nemoura hesperiae

The life cycles of Isoperla grammatica, Amphinemura sulcicollis and Nemoura hesperiae are studied in a Northern Italy stream, sited in the Apennines. The three species show a univoltine life cycle and their development coincides approximately in the same period of the year, although the one of I. grammatica is longer. Possible egg dormancy could exist in the A. sulcicollis and N. hesperiae life cycles, but this needs to be proved. The three taxa show a spring flight period in the study area. Growth is almost constant through the life cycle, except in A. sulcicollis in which an increase is observed at the end of the development. N. hesperiae exhibits a faster growth than the other species. In addition, in this paper, the nymph of N. hesperiae is described and designed for the first time.     

The management of metabolic energy storage during the life cycle of mayflies: a comparative field investigation of the collector-gatherer <Emphasis Type="Italic">Ephemera danica</Emphasis> and the scraper <Emphasis Type="Italic">Rhithrogena semicolorata</Emphasis>

The concentration and seasonal dynamics of the major energy storage components, triglycerides and glycogen, were measured in two species of mayfly (Rhithrogena semicolorata and Ephemera danica) with contrasting life cycle strategies living in a small mountain stream. E. danica is a burrowing, semivoltine collector-gatherer; R. semicolorata is univoltine and scrapes periphyton from stones. This is the first publication which focuses on the role of metabolic energy sources during the larval life span of two mayfly species until the larvae emerge. Although triglycerides are the major energy reserve in both species (>84% of total energy storage) throughout the whole larval development their seasonal dynamic differed considerably. In R. semicolorata the triglyceride concentration declined during the last weeks prior to emergence in both sexes. The same pattern was found in female larvae of E. danica, but not in male E. danica. It is suggested that females use triglycerides in the last larval stages for egg maturation, which is completed in the last larval instar. In male E. danica the triglyceride concentrations remained high until emergence, presumably due to their high energy demands as adults for their swarming flights. Glycogen concentrations did not show such a difference between species and sexes. Its significance as a storage substrate for energy is rather low; however, concentrations decreased in both species and sexes prior to emergence.     

Reproductive behavior of females and its relation to the mating success of two male forms inMnais pruinosa (Zygoptera: Calopterygidae)

The behavior of females of the damselflyMnais pruinosa was observed in the breeding season. Males consisted of both territorial (esakii) and non-territorial (strigata) types in the study area. Females sometimes arrived at a stream for mating and oviposition. The staying time of females in the stream was 1–3 hours, while that of males was 5–8 hours. The proportion of the males that copulated with the females did not differ between the two male forms present in the stream. In the Calopterygidae, of which the females usually perform multiple copulation, oviposition without subsequent recopulation is considered to be advantageous for a mated male in order to avoid the risk of sperm displacement. From such a viewpoint, the time spent for oviposition was measured for females that arrived at the stream after copulation with different male forms. The ratio was 69.1: 11.5–30.9 betweenesakii andstrigata males. Assuming that the oviposition time is proportional to the number of fertilized eggs laid, this ratio would represent the relative reproductive success of the two male forms. In fact, the relative abundance of the two male forms was also biased in favor ofesakii males (61.7:38.3) in this population. The mechanism of coexistence of the two male forms is discussed in relation to their reproductive success.     

Potential for parthenogenesis of virgin females in a bisexual population of the geographically parthenogenetic mayfly Ephoron shigae (Insecta: Ephemeroptera,Polymitarcyidae)

The burrowing polymitarcyid mayfly Ephoron shigae is a geographically parthenogenetic species. Interestingly, the distributions of the bisexual and unisexual populations overlap broadly in their respective geographic ranges. In this mayfly, obligatory diploid thelytoky appears within unisexual populations. In the present study, we examined the potential for parthenogenesis or the parthenogenetic ability of females in a bisexual population aiming to understand the emergence of unisexual populations. The results obtained revealed that females in the examined bisexual populations showed a potential for diploid thelytoky as also seen in the unisexual populations, although, in females from bisexual populations, the development success rates of their unfertilized eggs were considerably lower than those of virgin females from unisexual populations. In the three bisexual reproducing species (Ephemera japonica, Ephemera strigata, and Ephemera orientalis) in the closely‐related family Ephemeridae, diploid thelytoky (i.e. tychoparthenogenesis; < 3%) was also observed. However, in this case, the parthenogenetic development success rates of unfertilized eggs were significantly lower than those of virgin females in the bisexual (Hino‐yosui Irrigation Canal) population of E. shigae. Accordingly, we suggest that parthenogenetic ability (i.e. tychoparthenogenesis or facultative parthenogenesis) in bisexual populations of E. shigae may facilitate the evolutionary transition to unisexual populations with fully obligatory parthenogenesis. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 326–334.     

Long‐term monitoring of the life history of a riverine mayfly Ephemera orientalis (Ephemeroptera: Ephemeridae) in the Han River in Seoul,Korea

Climatic change often affects life history aspects of aquatic insects. Long‐term monitoring was conducted to understand the life history variability of the riverine mayfly Ephemera orientalis in the Han river, where habitat is largely disturbed by summer floods. Water level of the study site, Godeok‐dong area in Seoul, is regulated by the Paldang Dam located approximately 14 km above the study site. E. orientalis often emerged in large numbers around the study area. Larvae were sampled monthly from April 2006 to July 2010 using a Surber sampler (50 × 50 cm, mesh 0.25 mm, two replicates). Additional qualitative sampling was conducted using a hand net. As a result, based on the larval body size distribution, E. orientalis had a univoltine life cycle with two distinct slow growing cohort groups: the S1group emerged during May–June and the S2 group emerged during August–September. Our previous study conducted in Gapyeong stream in Gyeonggi‐do showed that E. orientalis normally had three cohort groups, S‐1 and S‐2 groups and the F‐group (a fast growing cohort developed during May–August). However, the Han River population of E. orientalis lacked such a fast growing cohort. It is most probable that habitat disturbances caused by high water level during the rainy season negatively affected the development of the fast growing cohort (F‐group) in the Han River area. The relationships between monthly E. orientalis population data and water level in the Han River are presented.     

Machine‐learning‐based detection of adaptive divergence of the stream mayfly Ephemera strigata populations

Adaptive divergence is a key mechanism shaping the genetic variation of natural populations. A central question linking ecology with evolutionary biology is how spatial environmental heterogeneity can lead to adaptive divergence among local populations within a species. In this study, using a genome scan approach to detect candidate loci under selection, we examined adaptive divergence of the stream mayfly Ephemera strigata in the Natori River Basin in northeastern Japan. We applied a new machine‐learning method (i.e., random forest) besides traditional distance‐based redundancy analysis (dbRDA) to examine relationships between environmental factors and adaptive divergence at non‐neutral loci. Spatial autocorrelation analysis based on neutral loci was employed to examine the dispersal ability of this species. We conclude the following: (a) E. strigata show altitudinal adaptive divergence among the populations in the Natori River Basin; (b) random forest showed higher resolution for detecting adaptive divergence than traditional statistical analysis; and (c) separating all markers into neutral and non‐neutral loci could provide full insight into parameters such as genetic diversity, local adaptation, and dispersal ability.     

Instar sizes,life cycles,and food habits of five Rhyacophila (Trichoptera: Rhyacophilidae) species from the Appalachian Mountains of South Carolina,U.S.A.

The larval head widths at each instar, life cycles, and food habits of late instars were determined for five species of Rhyacophila from two Appalachian mountain streams in South Carolina, U.S.A. Rhyacophila acutiloba Morse & Ross was univoltine with two cohorts, one emerging in the spring and another presumably emerging in early autumn. Rhyacophila fuscula (Walker), R. nigrita Banks, and R. carolina Banks were apparently multicohort, univoltine species with extended flight periods. Rhyacophila minor Banks was univoltine with a spring emergence. All species were predaceous and consumed mainly Plecoptera nymphs and Trichoptera larvae.     

The Euscaphis japonica genome and the evolution of malvids

Malvids is one of the largest clades of rosids, includes 58 families and exhibits remarkable morphological and ecological diversity. Here, we report a high-quality chromosome-level genome assembly for Euscaphis japonica, an early-diverging species within malvids. Genome-based phylogenetic analysis suggests that the unstable phylogenetic position of E. japonica may result from incomplete lineage sorting and hybridization event during the diversification of the ancestral population of malvids. Euscaphis japonica experienced two polyploidization events: the ancient whole genome triplication event shared with most eudicots (commonly known as the γ event) and a more recent whole genome duplication event, unique to E. japonica. By resequencing 101 samples from 11 populations, we speculate that the temperature has led to the differentiation of the evergreen and deciduous of E. japonica and the completely different population histories of these two groups. In total, 1012 candidate positively selected genes in the evergreen were detected, some of which are involved in flower and fruit development. We found that reddening and dehiscence of the E. japonica pericarp and long fruit-hanging time promoted the reproduction of E. japonica populations, and revealed the expression patterns of genes related to fruit reddening, dehiscence and abscission. The key genes involved in pentacyclic triterpene synthesis in E. japonica were identified, and different expression patterns of these genes may contribute to pentacyclic triterpene diversification. Our work sheds light on the evolution of E. japonica and malvids, particularly on the diversification of E. japonica and the genetic basis for their fruit dehiscence and abscission.     

Life cycles of 17 riffle-dwelling mayfly species (Baetidae,Heptageniidae, and Ephemerellidae) in central Japan

We described the life cycles of 17 riffle-dwelling mayfly species in a central Japanese stream. Both species of Baetidae (Alainites yoshinensis Gose and Baetis thermicus Uéno) and two of nine species of Heptageniidae (Ecdyonurus scalaris Kluge and Epeorus latifolium Uéno/l-nigrus Matsumura) in this stream were multivoltine (more than one generation per year). Seven other heptageniid species (two unidentified species of Cinygmula, Epeorus aesculus Imanishi, E. curvatulus Matsumura, E. ikanonis Takahashi, E. napaeus Imanishi, and Rhithrogena japonica Uéno) and all six species of Ephemerellidae [Cincticostella elongatula (McLachlan), C. nigra (Uéno), Drunella basalis (Imanishi), D. ishiyamana Matsumura, D. sachalinensis (Matsumura), and D. trispina (Uéno)] were essentially univoltine.     

Identification of specific proteins from seed embryos by two-dimensional gel electrophoresis for the discrimination between indica and japonica rice

Summary Proteins extracted from seed embryos of 29 different cultivated rice (Oryza sativa L.) and one wild rice (O. rufipogon Griff.) were compared by two-dimensional gel electrophoresis analysis. Among more than 300 protein spots on the gel we found some interesting variations in ten spots which were individually designated as proteins A-J. Protein E was observed in all indica cultivars but was not found in those of the subspecies japonica. In contrast, protein F was only detected in japonica cultivars. Protein A existed in all japonica cultivars but, with the exception of IR-36, could not be found in other indica cultivars. Therefore, proteins A, E and F can be used as markers for the identification of indica and japonica. Some so-called Javanica cultivars showed the characteristics of japonica subspecies with regard to proteins A and F, while one other cultivar of Javanica expressed a type intermediate between indica and japonica interms of proteins A and E. One feature discriminating between Javanica and japonica cultivars was found in the D, G, and J proteins which were expressed strongly in Javanica cultivars but were scarcely expressed in those of japonica. Expression of subspecies-specific proteins E and F in f₁ hybrids was also investigated.     

Calcium concentration in leaf litter affects the abundance and survival of crustaceans in streams draining warm–temperate forests

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Life cycle and nymphal feeding of Rhabdiopteryx christinae Theischinger 1975 (Plecoptera: Taeniopterygidae)

In the present paper some aspects of the nymphal biology of Rhabdiopteryx christinae, an endemic species from the Iberian Peninsula, are studied in a temporary stream from Southern Spain. R. christinae has an univoltine life cycle, with very short, fast and constant nymphal development, only having four months (December-March), related with the seasonality of the stream. In order to resist the period in which the stream has no water, an egg diapause probably occurs. The study of nymphal gut contents showed that R. christinae acts mainly as collector (detritus) and scraper (epiphytic and epilitic diatoms), as it is generally accepted for the family Taeniopterygidae.     

Life cycles and nymphal feeding of Isoperla morenica Tierno de Figueroa and Luzón-Ortega, 2011 and Brachyptera vera cordubensis Berthélemy and Baena, 1984 (Plecoptera: Perlodidae and Taeniopterygidae) in a Mediterranean stream (Spain)

Some aspects of the biology of two endemic Iberian stonefly species, Isoperla morenica Tierno de Figueroa and Luzón-Ortega, 2011 and Brachyptera vera cordubensis Berthélemy and Baena, 1984, were studied in a temporary stream from Sierra Morena (Southern Spain). Isoperla morenica shows a univoltine fast seasonal life cycle, with nymphs growing from November to April. After oviposition, eggs remain in a dormant state in the riverbed until the following autumn when the river water flows again. Nymphal diet is mainly composed of detritus in small individuals (they behave as gatherer–collectors) but when larger, they become predators. Brachyptera vera cordubensis also shows a univoltine fast seasonal life cycle, from November to March. Nymphs behave mainly as gatherer–collector and no significant ontogenetic changes in diet were detected. Male and female nymphs do not show differences in feeding in this species. Data obtained were compared with the previously known information on both species in another stream from the same mountain range as well as for other related species, and some differences in both aspects, mainly on feeding habits, could be detected.