Experimental evidence of food-independent larval development in endemic Jamaican freshwater-breeding crabs

In an experimental study, we compared reproductive and developmental traits of endemic sesarmid crabs from Jamaica living in landlocked limnic or terrestrial habitats. Laboratory rearing and behavioral observations showed that the larval development of Sesarma windsor, Sesarma dolphinum (both from freshwater brooks), and Metopaulias depressus (the bromeliad crab) invariably consists of two nonfeeding zoeal stages and a facultatively lecithotrophic megalopa. In a quantitative study of life-history processes characterizing this developmental mode, we provide for S. windsor first data of biomass and elemental composition (dry mass, W; carbon, hydrogen, nitrogen, collectively, CHN) during development from the egg through successive larval stages. These data show that larval independence of food is based on an enhanced female energy allocation in reproduction, reflected in unusually large egg size (1.45-1.70 mm), as well as high contents of C and H (about 60% and 9%, respectively) and high C : N ratios (7.6-8.4) in eggs and early larvae. During zoeal development, about 6% of initial W and 9% of N but 13% each of C and H were lost; similar losses occurred during megalopal development in continued absence of food. These patterns reflect the metabolic utilization of stored organic matter, with preferential degradation of lipid reserves. Fed megalopae gained greater amounts of W and N as compared with C and H (increments of 37% and 38% vs. 25% and 19%, respectively), indicating preferential investment of nutritional energy in proteins required for the formation of new tissues and organs, while generally decreasing proportions of CHN within total W suggested an increasing mineralization of the exoskeleton. Although survival and molt cycle duration of the megalopa stage were not affected by absence of food, significant effects were found in the size of first-stage juvenile crabs, indicating a trade-off between nutritional flexibility in the last larval stage and postmetamorphic fitness. Similar patterns of development and biomass in M. depressus as well as preliminary data obtained for S. dolphinum and Sesarma fossarum suggest that reproductive and developmental traits may be similar in all endemic Jamaican sesarmids. These traits are interpreted as life-history adaptations to development in landlocked habitats, probably playing a key role during adaptive radiation.     

Ontogeny of osmoregulation and salinity tolerance in a mangrove crab, Sesarma curacaoense (Decapoda: Grapsidae)

The grapsid crab Sesarma curacaoense is believed to represent the closest saltwater relative to the ancestor which gave rise to an adaptive radiation of endemic freshwater and terrestrial species on the island of Jamaica. Living in mangrove swamps with variable salinity conditions and showing semiterrestrial behaviour, S. curacaoense exhibits ecological adaptations to non-marine conditions. In laboratory experiments, we studied the salinity tolerance during development from hatching to the end of the first juvenile stage. Successful development through metamorphosis occurred in the full salinity range tested (15-32 per thousand), although mortality was significantly enhanced and development delayed at 15 per thousand. In another series of experiments, we studied the ontogeny of the capability for osmoregulation, which is considered as the physiological basis of osmotic stress tolerance. Our results show that S. curacaoense is from hatching a fairly strong hyperosmoregulator in dilute media. This capability increased gradually from hatching throughout the larval and juvenile development. In seawater (32 per thousand) and at an enhanced salt concentration (44 per thousand), the zoeal stages remained hyperosmoconformers. The capability for hypoosmoregulation in concentrated media appeared first in the megalopa stage and increased thereafter. Adult crabs were observed to be strong hyper-hypo-osmoregulators in a salinity range from at least 1 per thousand to 44 per thousand. The unusually early appearance of strong regulatory capabilities, particularly in dilute media, is interpreted as a physiological preadaptation that should have facilitated the evolutionary process of adaptive radiation in non-marine environments on Jamaica.     

Earthworms (Clitellata, Acanthodrilidae) of the mountains of Eastern Jamaica

Fourteen species new to science are described from material collected at several sites in the Blue Mountains and the John Crow Mountains of eastern Jamaica, doubling the known endemic Jamaican earthworm fauna. New data on Dichogaster montecyanensis (Sims) are provided. All species are placed in the genus Dichogaster Beddard, which is here treated sensu lato, i.e. including Eutrigaster Cognetti. Eight of the new species have lost the posterior pair of prostates and the seminal grooves of the male field. These are D. bromeliocola, D. crossleyi, D. davidi, D. garciai, D. harperi, D. haruvi, D. hendrixi, and D. johnsoni. D. sydneyi n. sp. has independently lost the posterior prostates but not the seminal grooves. The new species D. altissima and D. manleyi have the conventional dichogastrine prostatic battery and male field characteristics. Three species described here, D. farri, D. garrawayi, and D. marleyi, all have a third pair of prostates in the 20th segment, no seminal grooves, dorsal paired intestinal caeca in segment lxv, and lack penial setae.     

基于COI基因分析的双齿蚋分子分类研究

为了确定COI基因序列分析在蚋科中的分类地位,本研究测定了双齿蚋(Simulium bidentatum) COI基因序列,分析该基因序列特征;下载与其同源性较高的12个蚋种的COI基因序列15条,进行同源性分析和分子系统发育研究。结果显示,双齿蚋COI基因序列(DQ534946)与S. notiale、S. snowi、S. nyssa等蚋种的COI基因序列同源性最高,在贝叶斯分析所构建的分子系统进化树中,不同蚋组的序列各自聚成一枝,双齿蚋序列(DQ534946)未与其他任何蚋种聚为一枝。研究结果表明,双齿蚋COI基因序列与蚋亚属序列同源性较高,COI基因序列分析能较好建立蚋亚属内组间关系,双齿蚋未与其他蚋组序列聚为一枝,分类至淡足蚋组并不合适,支持分类至阿根蚋组。本研究进一步明确了COI基因序列分析在蚋科分子系统发育研究中的意义,并在一定程度上解决了双齿蚋在蚋科的分类争议。     

Genetic Diversity and Species-Diagnostic Markers of Mud Crabs (Genus Scylla) in Eastern Thailand Determined by RAPD Analysis

Genetic diversity of three mud crab species, Scylla serrata (Forsk?l), S. oceanica (Dana), and S. tranquebarica (Fabricius), collected from two locations in eastern Thailand (Chanthaburi and Trat) was examined by randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). Ninety-one reproducible RAPD fragments, generated by UBC456, UBC457, and YNZ22, were polymorphic. The percentage of polymorphic bands within populations ranged from 47.92% to 77.59%. Species-specific RAPD markers were also observed and used to construct a molecular diagnostic key in these taxa. Large genetic differences between species were found (D(ij) = 0.425 to 0.751), whereas those between populations within each species were much lower (D(ij) = 0.171 to 0.199). The neighbor-joining tree based on genetic distances among pairs of individuals indicated three distinct groups, corresponding to S. serrata, S. oceanica, and S. tranquebarica. No genotypes were shared among these three species. This suggests the absence of genetic exchanges between sympatric mud crab species in eastern Thailand. Therefore, mud crabs in this area should be recognized as three different species rather than a single panmictic species exhibiting different morphs.     

A new species of Late Cretaceous crab (Brachyura: Carcineretidae) from Albion Island, Belize)

A new species of carcineretid crab, Carcineretes planetarius, is described from the Upper Cretaceous (lower Maastrichtian) Barton Creek Dolomite at Albion Island, Belize. The age is based on the stratigraphic range of associated nerineid gastropods and correlation with nannoplankton, benthic foraminifera, and the other known congeneric species of crab found in Jamaica. Confirmation of this age aids in constraining the timing of ejecta deposits of the Chicxulub impact found at the top of Barton Creek Dolomite exposed on Albion Island. Paleoenvironmental and paleoecological analyses suggest that these crabs were swimmers in lagoonal settings, capable of burrowing a few centimeters into the mud for protection.     

Molecular Characterization of Cacao (<Emphasis Type="Italic">Theobroma cacao</Emphasis>) Germplasm from Jamaica Using Single Nucleotide Polymorphism (SNP) Markers

Cacao is an economically important commodity in Jamaica. Knowledge of the genetic diversity of Jamaican cacao germplasm is essential for their conservation and management. In spite of cacao’s economic importance in Jamaica, the crop is under studied, therefore limiting sound decisions toward improving productivity. Assessment of germplasm and on-farm genetic diversity is required to assist selecting superior genotypes to propagate and distribute across the island, as well as to use them as parental clones in breeding programs. Using 94 single nucleotide polymorphism (SNP) markers, 140 Jamaican cacao samples from two germplasm collections and a farmer’s estate along with 150 reference samples were analyzed. The principal coordinate analysis demonstrated that the majority of the Jamaican cacao selections were hybrids derived from five original germplasm groups, including Criollo, Amelonado and three Upper Amazon Forastero groups. Among the Upper Amazon groups, the Bayesian clustering analysis revealed that the Parinari (PA) ancestral lineage contributed the most (29.9%) to the Jamaican cacao germplasm. The germplasm collections showed greater diversity in terms of ancestral contributions compared to the farmer’s estate. However, the genetic differentiation between the three collecting sites was small (Fst?=?0.036), indicating that samples collected from the three sites were derived from a common pool of germplasm. The current study supports the historical records and clarified the ancestry of Jamaican cacao. Although the majority of the cacao genetic groups were observed in the Jamaican cacao collections, several diversity gaps were found in both germplasm collections and in the farmer’s estate, especially germplasm with disease resistance to cacao frosty pod rot that was recently found in Jamaica.     

Characterization and utilization of microsatellite loci in the New World screwworm fly, Cochliomyia hominivorax

Abstract.  New World screwworm populations in North and Central America have been the targets of virtually continuous eradication attempts by sterile insect technique (SIT) since the 1950s. Nevertheless, in some areas, such as Jamaica, SIT control programmes have failed. Reasons for the failure of SIT-based control programmes in some locations are unknown, but it has been hypothesized that failure may be related to mating incompatibility between sterile and wild fly populations or to the existence of sexually incompatible cryptic species. This paper outlines the development of a suite of four new microsatellite loci which can be used to study intra-specific relationships between populations of Cochliomyia hominivorax from the Caribbean and South America, which represent those populations involved in, or earmarked for, forthcoming SIT control. Cross-amplification with the secondary screwworm, Cochliomyia macellaria , was also successful with three of the new loci. We present results which suggest that populations from Trinidad and Jamaica form distinct groupings of flies and that C. hominivorax from Trinidad appears particularly distinct.     

Molecular phylogeny of Eastern Pacific porcelain crabs, genera Petrolisthes and Pachycheles, based on the mtDNA 16S rDNA sequence: phylogeographic and systematic implications

Porcelain crabs, genera Petrolisthes and Pachycheles, are diverse and abundant members of the eastern Pacific near-shore decapod crustacean community. Morphology-based taxonomic analyses of these crabs have determined groupings of affiliated species, but phylogenetic relationships remain unknown. We used sequence data from the mitochondrial 16S rRNA gene of 46 species of eastern Pacific porcelain crabs to perform phylogenetic analyses by distance and parsimony methods. Our results are used to compare the taxonomic significance of morphological and molecular characters, to examine sequence divergence rates of crab 16S rRNA genes, and to analyze the phylogeographic history of these crabs. Our phylogenetic trees indicate that the genus Petrolisthes is divided into two main clades, reflecting morphological features. One clade contains primarily tropical species, and the other contains species from throughout the eastern Pacific, as well as species in the genera Allopetrolisthes and Liopetrolisthes. Phylogenetic trees of Pachycheles suggest an antitropical distribution; north and south temperate species form one clade and tropical species form a second clade. Sequence divergence rates of the 16S rRNA gene from three pairs of geminate species can be used to date divergence times, and we discuss porcelain crab phylogeographic patterns in relation to paleogeographic events.     

Genetic Variability in the Yellow-Necked Field Mouse (<Emphasis Type="Italic">Sylvaemus flavicollis</Emphasis> Melch., 1834, Muridae,Rodentia) at the Eastern Border of the Range

The first characterization of the genetic variability in populations of S. flavicollis on the eastern border of the range is presented. Seven individuals from the most northeastern habitat of the species (Middle Urals) were karotyped. No deviations from the standard chromosome set, either by the chromosome number or morphology, were revealed. Analysis of the mtDNA cytochrome b gene sequences (1133 bp) in 44 individuals from five populations on the eastern border of the species range (Middle and Southern Urals) resulted in identification of 17 haplotypes. All haplotypes were new and not found earlier in other parts of the species range. The genetic diversity indices and analysis of the demographic and genetic structure indicate a relatively recent origin of the populations under study as a result of rapid expansion. Phylogenetic analysis (97 haplotypes, including the GenBank data) showed that all haplotypes described at the eastern border of the range belonged to the same phylogroup distributed in the Balkan region, Northern and Eastern Europe, and Russia (Samara oblast). Close relationships between the examined populations and the populations from the northern part of the species range in Eastern Europe was demonstrated.     

Infective larvae of five Onchocerca species from experimentally infected Simulium species in an area of zoonotic onchocerciasis in Japan

Microfilariae of five Onchocerca species, O. dewittei japonica (the causative agent of zoonotic onchocerciasis in Oita, Kyushu, Japan) from wild boar (Sus scrofa), O. skrjabini and O. eberhardi from sika deer (Cenus nippon), O. tienalis from cattle, and an as yet unnamed Onchocerca sp. from wild boar, were injected intrathoracically into newly-emerged black flies of several species from Oita to search the potential vector(s) of these parasites and identify their infective larvae. Development of O. dewittei japonica microfilariae to the infective larvae occurred in Simulium aokii, S. arakowae, S. bidentatum, S. japonicum, S. quinquestriatum, and S. rufibasis while development of infective larvae of O. skrjabini, O. eberhardi, and the unnamed Onchocerca sp. was observed in S. aokii, S. arakawae, and S. bidentatum. Development of O. lienalis microfilaria to infective larvae occurred in S. arakawae. Based on the morphology of infective larvae obtained, we proposed a key of identification of Onchocerca infective larvae found in Oita. We also reconsider the identification of three types of infective larvae previously recovered from Simulium species captured at cattle sheds: the large type I larvae that may be an undescribed species; the small type III identified as O. lienalis may include O. skrjabini too; the intermediary type II that may be O. gutturosa, or O. dewittei japonica, or the unnamed Onchocerca sp. of wild boar.     

Phylogeography of the Chinese endemic freshwater crab Sinopotamon acutum (Brachyura,Potamidae)

Phylogeographical inferences based on multiple molecular markers from different modes of inheritance (i.e. mtDNA and nucDNA) can help to explore drivers of current species divergence over different timescales and allow a deeper understanding of evolutionary processes. River systems and mountains, owing to their drainage networks and complex topography, are often a high priority when inferring external causes of phylogeographical patterns. Here, we selected the Chinese endemic freshwater crab Sinopotamon acutum inhabiting drainage networks across the Qinling–Daba Mountains, a watershed that divides northern from southern fauna in China, as a model species (1) to investigate whether river networks and mountain systems act as barriers in shaping the phylogeography of freshwater crabs and (2) to test the impact of historic environments and ecological habitats on crab distribution. Phylogenetic tree and network analyses based on mtDNA revealed divergence between eastern and western populations, but microsatellite DNA did not recover this. Frequent and male‐biased gene flow is evident. The adjacent tributaries, such as Weihe River 1 and Hanjiang River 1, although isolated by Qinling Mts, have low genetic variation in mtDNA. In addition, microsatellite DNA showed low variation between all rivers. Frequent gene flow, genetic variation and mitochondrial genetic structure in S. acutum indicated that the Qinling–Daba Mountains have had no effect on divergence in this species; instead, hydrological networks across these mountains serve as a continuous migration corridor for these crabs. Glacial refugia are probably responsible for the initial isolation of the eastern and western clades, and local adaptations after dispersal have further driven divergence. Cytonuclear discordance in phylogeographical patterns may be attributable to ongoing male‐biased gene flow.     

Origin(s), evolution,and systematics ofCucurbita pepo (Cucurbitaceae)

Numerical studies of morphological data and starch gel electrophoresis have provided a new perspective on important issues pertinent to the origin(s) and subsequent evolution of domesticatedCucurbita pepo. Wild C.texana and/orC. fraterna appear to be the most likely candidates for progenitor(s) of the domesticate. Populations of texana-like plants from beyond Texas share various attributes with Texas populations, suggesting that C. texana once had a more widespread distribution to the northeast. The possibility exists thatC. pepo was domesticated independently in eastern U.S., as well as in Mexico, which is in line with recent archeological findings. Multiple domestications are also supported by allozyme data indicating a substantial divergence within the species. A new classification consisting of C.pepo ssp.pepo (origins in Mexico),C. pepo ssp.ovifera var. ovifera (origins in eastern U.S.), and C.pepo ssp.ovifera var. texana (spontaneous populations in eastern U.S.) is proposed.     

Shell preference and utilization patterns in littoral hermit crabs of the bay of Panama

Shell utilization patterns of three sympatric hermit crab species from the Bay of Panama are examined. Shell preferences, as shown by laboratory choice experiments and the selective use of empty shells experimentally added to hermit crab populations, are shown to be important determinants of shell utilization under natural conditions.Factors which influence the types and sizes of shells occupied by hermit crabs in separate populations include: (1) the presence and relative abundance of different gastropod species; (2) the specific shell preferences of different hermit crab species; and (3) the presence and relative abundance of sympatric hermit crab competitors for the limited supply of empty shells. Since the size and type of shell occupied by a hermit crab influences its growth rate and reproductive output, these factors appear to have a direct effect on hermit crab fitness and the demographic structure of separate hermit crab populations.     

Detection and variability of the lethal yellowing group (16Sr IV) phytoplasmas in the Cedusa sp. (Hemiptera: Auchenorrhyncha: Derbidae) in Jamaica

Lethal yellowing (LY) group phytoplasma was detected in members of the Cedusa species of Derbids from Jamaica by nested PCR assay employing the rRNA primer pairs P1/P7 and LY16Sf/LY16Sr. A 1400‐bp product was obtained from 13/43 Derbids that were analysed. Restriction fragment length polymorphism analysis of the nested PCR product revealed variations in 6/13 Derbids analysed, suggesting that the planthoppers could be infected with different strains of the LY group phytoplasma. Sequence analysis of the 16S rDNA gene determined that the percentage of similarity of the phytoplasma strains in the Derbids ranged from 97–98% to the phytoplasma strain found in coconuts in Florida (LYFL‐C2) and Jamaica (LYJ‐C8). The phytoplasma strains in the Derbids clustered together with the Jamaican and Florida coconut LY phytoplasma, as well as other characterised strains composing the LY phytoplasma (16Sr IV) group.     

The population biology and ecology of the Homerus swallowtail, <Emphasis Type="Italic">Papilio (Pterourus) homerus</Emphasis>, in the Cockpit Country,Jamaica

The Homerus swallowtail, Papilio (Pterourus) homerus (Lepidoptera: Papilionidae), is an endangered species of butterfly endemic to Jamaica. As the largest species of the genus Papilio in the world and the largest butterfly in the Western Hemisphere, this rare butterfly once inhabited most of Jamaica but has now dwindled into two tiny populations: an eastern population, found where the Blue Mountains and John Crow Mountains merge, and a western population in the Cockpit Country. The present research focused on the previously unstudied Cockpit Country population of P. homerus; most previous information about this species is derived from studies of the eastern population. The purpose was to estimate the size of the remaining population in the Cockpit Country using MRR protocols, while making observations to better understand its ecology. Sampling consisted of carefully netting the butterfly, marking a permanent ink number on the wing (metallic Sharpie® marker), and recording winglength, wing condition, time, and sex. The population was found to be very small, estimated at fewer than 50 flying individuals. Many observations were made about the ecology of the species. These new data suggest a conservation plan is strongly needed, coupled with a breeding program to increase numbers of this extraordinary butterfly.     

Homing Experiments in the Tree-climbing Crab Sesarma leptosoma (Decapoda,Grapsidae)

Sesarma leptosoma an East African mangrove-dwelling crab, migrates twice a day from a system of known dens among the roots to well-defined feeding areas in the branches of trees, reaching 15 m high. Field experiments were performed to test whether chemical or visual cues are involved in the orientation and homing of this species to reach their feeding areas. Manipulation of the substratum at branch junctions, in order to alter possible chemical cues, did not affect homing ability in S. leptosoma. Moreover, crabs trained to cross an asymmetrical artificial wooden fork could still follow their preferred directions after (1) the fork branches had been switched, (2) the whole fork had been rotated around the trunk, resulting in a right-left inversion, and (3) the inversion of two wide black and white screens hiding most of the canopy from view of the climbing crabs. These results suggest that S. leptosoma may not rely on reference systems such as chemical trail-following and chemical or visual cues from the substratum, but probably depend on complex visual information from the surroundings trunks and/or from the sun's position integrated with junction sequence memory.     

生态因子对红螯相手蟹捕食毛蚶苗种的影响

敌害生物的捕食在控制海洋底栖生物群落的丰度和组成中起着关键性的作用。以红螯相手蟹(Sesarma haematocheir)和毛蚶(Scapharca subcrenata)为试验对象,研究了红螯相手蟹的密度、规格、性别,以及毛蚶的密度、规格、海水温度和底质条件对毛蚶苗种存活的影响。结果表明,蟹表现出了第二种类型的功能反应,高密度底播毛蚶苗种可以显著提高成活率;当毛蚶苗种壳长达到20mm以上时,蟹的摄食速率显著下降;随着蟹个体的增大,其摄食速率显著增加,毛蚶的存活率下降;当蟹的密度逐渐增加的时候,同种个体之间的干扰竞争显著提高了毛蚶存活率;雄蟹凭借强有力的螯导致了更多毛蚶苗种的死亡;海水温度较低的春季和秋季底播毛蚶苗种可以显著提高成活率;底质条件的复杂性和异质性为毛蚶的存活提供了"庇护空间",从而减少了敌害生物捕食所带来的损失。     

Phosphoglucose isomerase polymorphism in the freshwater crab Sesarma boulengeri

Three phenotypes of phosphoglucose isomerase (PGI) were detected in abdominal muscle extracts from freshwater crab (Sesarma boulengeri) by starch-gel electrophoresis. The observed phenotypes were assumed to be under the control of two allelic genes. This assumption was supported by the observed distribution of phenotypes. There were no significant differences in PGI phenotype distribution among samples of crab taken from Karmat Ali, and Abu Al-Khasib locations along Shatt Al-Arab River. The three PGI alleles observed in S. boulengeri appear to be the same in specimens from the two locations.