Abstract: In this paper the feeding index (FI), Gastro somatic index (GaSI) and Food Prevalence Index (FPI) of freshwater prawn M. assamense peninsulare were evaluated to assess the quantity and kind of food which this prawn consumes in the Rawasan stream. A total of 401 prawns were collected for an interval of two years form five selected site in Rawasan stream of Garhwal in Central Himalaya, India from August 2013 to July 2015. Collected prawn was in the size range of 20-75 mm in male and 24-65 mm in female in total length during the study period. The stomach contents of 10 collected specimens were examined monthly and observed that 35% of the stomach was full or semi-full and 15% stomach were empty. Highest Gastro somatic value (Mean±SE) was obtained 2.95±0.80 during June in the male and 3.25±0.44 during May in the female. After that, it gradually decreased in both the sex and this repeated in cyclic pattern each year. More or less a similar trend was reported in the feeding index value during the study indicate a significant relationship between feeding intensity and Gastro somatic index. Highest Food Prevalence Index (FPI) was seen in fragment of animals in both sex, which was (88.48) in male and (58.26) in female prawn and lowest FPI value in sand debris 7.9 and 5.7 in male & female prawn respectively. Main food items were fragment of plants & animal, diatoms, algae, and sand. In overall, the results show that this prawn is selectively abstemious
1. Gummosis on Acacia decurrens, an invasive tree species, that got established in Merapi Volcano National Park (MVNP) after the eruption of Mount Merapi in 2010 was studied to i) identify the causal organism of the disease, ii) analyze disease symptoms, iii) understand the spatio-temporal distribution of gummosis in the tree population and iv) examine how the disease affects the anatomy of tree wood. 2. Pathological, morphological and molecular studies were used in this studies. 3. Ceratocystis fimbriata was proved to be the causal organism of the disease. The disease spread was probably aided by the ambrosia beetle (Euwallacea sp.) which bores holes on the stem. 4. The disease is noted to spread from the base of the trees, where the ambrosia beetle bores holes first, to the upper part. 5. The number of parenchyma cells in the infected stem was significantly more than in the healthy stem which apparently facilitated water and nutrition transport within the tree helping it to grow normally despite serious gummosis. 6. The management of invasion by A. decurrens in the MVNP area poses a serious challenge due its success as an invader in the volcano impacted area and the threat of the gummosis pathogen spreading to other species both of which will affect the regeneration and establishment of native species and recuperation of the ecosystem.
1. The abundance of UV-B absorbing compounds (for example p-Coumaric acid, pCA) within pollen-grain sporopollenin has been proposed as a proxy for reconstructing past changes in surface solar radiation, but drivers of the variation of these compounds in pollen grains remains poorly understood. 2. One important consideration is that the physiological response that results in the production and timing of pCA in pollen remains poorly understood. This calls for studies that explicitly tests the temporal resolution and plasticity of the response of pCA in pollen under field conditions. 3. To address this, we conducted two parallel experiments. First, we measured pCA in four Pinus spp. from Geneva in two consecutive years to investigate the impact of natural variation in ambient solar radiation, and differences in responses between species. Second, we covered pollen cones on Pinus sylvestris trees in Bergen with 90% shading cloth one month before dehiscence and compared the amount of pCA in pollen from shaded and sun-exposed cones from the same tree. 4. Between years, in Geneva, Pinus spp. produced 31% more pCA in 2014 than in 2013, with higher levels of solar radiation also observed in 2014. pCA content also showed strong species-level variation, largely reflecting differences in pollen size between species. Experimentally shaded Pinus sylvestris pollen produced 21% less pCA than fully exposed pollen. 5. Our work demonstrates a plastic response in the production of UV absorbing compounds (pCA) to inter-annual and experimentally induced variation in ambient solar radiation in Pinus spp. pollen. This supports pCA as a highly responsive proxy for early-season solar radiation. We also find strong species-level variation in pCA content in pine pollen, likely related to pollen grain size, which should be accounted for in reconstructions from sites with multiple Pinus species present.
Plant negative density dependence is the result of interactions between plants themselves and between plants and the environment. We selected a succession series comprising early successional, mid-successional and late successional stages (Artemisia ordosica, Sophora alopecuroides and Stipa bungeana communities, respectively) in a semi-arid area. We investigated plant density and biomass and determined the nitrogen (N) and phosphorus (P) contents of each plant species in each of 225 quadrats, and we calculated the N and P contents of vegetation using biomass as a weighted coefficient. We found that the total plant density of the A. ordosica community increased with the increase in vegetation N:P ratio while the total plant density of the S. bungeana community decreased with the increase in vegetation N:P ratio, with the latter (late successional stage) community exhibiting negative density dependence. In the communities representing the early successional and mid-successional stages, the vertex coordinate of the quadratic function relationship between plant total density and vegetation N/P ratio was (16.6, 353.3); that is, if the N:P ratio of the vegetation was greater than 16.6, the community was characterized by negative density dependence. The analysis showed that the negative density dependence was due to P limitation. These findings reveal that the vegetation N:P ratio in a semi-arid region is the driver of negative density dependence.
The shifting defence hypothesis attributes the invasion success of many plant species to the species’ post- introduction evolution of traits that confer high fitness including reduced allocation to physiologically and ecologically costly chemical defence compounds against herbivores. However, to date, most of the studies that compared invasive and conspecific native plants for differences in defence compounds focused only on one or a few compounds. Thus, it remains unclear whether invasive plants may evolve a lower diversity of defence compounds in response to a simplified herbivore community assemblages in the introduced range. Therefore, the present study used B. nigra plants from 11 invasive- and 14 native range populations to test whether invasive B. nigra plants: i) express a lower diversity of glucosinolate compounds and higher concentration of a single dominant glucosinolate compound owing to a reduced diversity of herbivores in the introduced range; ii) are less preferred by generalist herbivores and attract more specialist herbivore species than B. nigra from the native range when grown in a common garden in the native range; iii) are less preferred by generalist herbivores than native-range B. nigra in no- choice feeding bioassays. In support of the shifting defence hypothesis, invasive B. nigra plants expressed a lower diversity of glucosinolates and a higher concentration of sinigrin (a major glucosinolate compound in B. nigra) than native-range B. nigra plants. Moreover, the invasive B. nigra plants were more deterrent to two generalist herbivore species in no-choice feeding bioassays than native B. nigra plants. Brassica nigra plants that expressed higher concentrations and diversities of glucosinolate compounds were visited by a more diverse specialist herbivore community than B. nigra plants with low concentrations and diversities of glucosinolates. The biogeographical differences in glucosinolate profiles observed here may be the result of differential herbivore selection pressures in the respective invaded and native ranges.
Non-native fish invasions are among the greatest threats to freshwater ecosystems worldwide. In South China, the same climatic conditions that facilitate the culture of some non-native fishes may also support their invasive potential. We conducted systematic collections of fish in eight main rivers of South China, from 2016 to 2018, to investigate and analysis species composition and the distribution of non-native fishes. The data reveal that non-native fishes are widespread in the sampled rivers: of the 98,887 fish collected, 11,832 individuals representing 20 species were not native. Of the non-native fish species, 17 are used in aquaculture and 19 are native to the tropics; 13 are omnivores while other seven are predators. Based on dissimilarity of the non-native fish species distributions across the eight rivers, the different rivers could be divided into four assemblages. Geographical isolation and temperature were identified as affecting the distribution patterns of non-native fishes, thereby influencing fish species composition, species number, dominant species, and distribution variations in the South China rivers. Species composition of the non-native fishes in the rivers in this region are related to their introduction vector, compatibility with their native habitat, and trophic position. And their distribution pattern was mainly influenced by the geographical location and temperature.
Maize and teosintes are excellent systems for study of population and ecological genomics, as well as teosintes provide excellent germplasm resources for forage maize breeding. However, genetic relationship, evolution, hybridization and introgression among the genus Zea species have not been completely resolved and effective methods for Zea species classification and identification are scarce. In current study, nuclear (ITS), mitochondrial DNA (atp6, cob and nad1) and chloroplast DNA sequences (matK, psbA-trnH and rbcL) were used to explore as a simple and efficient DNA barcode for identification and genetic study of the Zea species. Phylogenetic incongruence between nuclear and cytoplasmic sequences detected in present study. The lowest divergence value from pairwise comparisons were found between Z. mexicana and Z. parviglumis based on combined six cytoplasmic sequences and Z. mexicana and maize showed lowest divergence value based on ITS sequences. It is suggested that single-gene data sets and combined data sets of six cytoplasmic sequences failed to identify and classify every species at inter-species level, however, the combined data set containing ITS and atp6 can identify and classify Zea species perfectly. Moreover, the tetraploid Z. perennis was confirmed an autotetraploid of diploid Z. diploperennis reflecting from phylogenetic tree based on combined six cytoplasmic sequences.
1. Global warming is rapidly emerging as a universal threat that could alter the distribution of many animal species and change their morphology, physiology, behavior and life history. The heat dissipation limitation (HDL) hypothesis proposes that females’ reproductive performance is limited by their capacity to dissipate heat. Although exposure to wind is known to increase heat exchange, its effect on reproductive performance is unknown. 2. In this study, the effect of simulated wind on the energy budget and milk energy output of female striped hamsters (Cricetulus barabensis) was measured under cool (21°C) and hot (32.5°C) ambient temperatures and the preference of hamsters for windy conditions in lactating females was tested both in the laboratory and the wild. 3. Females lactating at 32.5°C significantly decreased their energy intake and milk output, and raised lighter offspring than those lactating at 21°C. Exposure to wind significantly increased both energy intake during lactation and heat loss at both temperatures. Females lactating at 32.5°C considerably increased their reproductive output when exposed to wind. Moreover, females kept at an ambient temperature of 21°C preferred sheltered conditions whereas those kept at 32.5°C preferred exposure to simulated wind. We captured significantly more lactating female hamsters on windy days in summer and on calm days in spring. Wrapping a glass vessel in the fresh pelt of a striped hamster significantly reduced the rate of both water loss and cooling. 4. These findings support the HDL hypothesis; high ambient temperatures do appear to limit the energy intake and reproductive output of lactating hamsters. Small mammals lactating under hot conditions may be able to utilize the cooling properties of wind to increase their energy intake and milk production, and thereby their reproductive output and fitness.
Mycorrhizal fungi alter their host plant’s resistance to herbivores and their competitive ability. However, most studies on how mycorrhizae alter resistance have been conducted in single plant studies, and so the interacting effects of mycorrhizae and competition on constitutive and induced plant resistance is largely unexplored. We tested whether mycorrhizal colonization with Rhizophagus intraradice would alter herbivore performance and the expression of chemical resistance traits in tomato plants with and without intraspecific competition. We treated the plants with jasmonic acid to measure their induced chemical resistance traits which we evaluated by measuring leaf consumption by Trichoplusia ni caterpillars and two traits that affect herbivore performance: protease inhibitors, an antinutritive protein, and carbon/nitrogen ratio, a metric of plant nutritional quality. Mycorrhizae decreased resistance (increased leaf consumption) to herbivores when the plants were not in competition but had no effect in competition. While mycorrhizae reduced protease inhibitors, independent of competition or treatment with jasmonic acid, this did not increase caterpillar feeding. However, mycorrhizae, competition and induction with jasmonic acid interacted to decrease plant nutrition, measured as C/N ratio, which was correlated with caterpillar feeding. Here, we show that mycorrhizae induced decreases in plant nutritional quality; a novel mechanism by which mycorrhizae affect resistance to herbivores. Mycorrhizae and competition interact to decrease plant nutritional quality and alter resistance to herbivores.
1. Wild animal populations typically harbour multiple parasite species, which can interact in various ways depending on the species involved and the state of the host upon infection. While many pairwise parasite interactions and within-guild parasite communities have been characterised, understanding how an interaction network spanning multiple parasite groups might be mediated has been less commonly explored. 2. We aimed to characterise parasites associations across guilds in a wild population of a model species, allowing for comparisons with existing laboratory-based research, and better understanding of how any observed associations might manifest within the host. 3. We used cross-sectional data from an island population of the house mouse, Mus musculus domesticus, to identify associations between a broad range of parasite species, including blood-borne microparasites, arthropod ectoparasites, and gastrointestinal and hepatic helminths. 4. Every recorded species was found to exist within a framework of positive and negative associations, involving multiple between-guild associations, and with the under-studied helminth species Calodium hepaticum playing a central role. 5. This study highlights the need to account for as many infections as possible when studying naturally infected populations, due to the prevalence of inter-species associations. Various potential mechanisms, including immunological and ecological, are suggested to explain how these associations might occur. Comparisons with analogous laboratory research from the same species are explored. A need for longitudinal study to determine causality of interactions is highlighted.
Vulnerability assessment has become a critical issue and an important approach for regional sustainable development. The Qinghai Province, located in the northeastern part of the Qinghai-Tibet Plateau, suffers a severe grassland degradation caused by climate change and human activities. The degradation constrains the development of local animal husbandry and further affects the vulnerability of social system. In this study, based on the vulnerability assessment framework of exposure-sensitivity-adaptability, two index systems were established including ecological and social aspects. The entropy weight method was used to determine the index weight. The dynamic changes of the ecological vulnerability and social vulnerability of Qinghai province were assessed from 1995 to 2015. Results indicated that ecological vulnerability in Qinghai province increased from eastern part to the west, and decreased from northern to southern part, while social vulnerability showed an opposite trend. Key ecologically fragile areas were mainly located in the Qaidam Basin and western Three-River Headwaters Region (TRHR), while key social vulnerability areas were mainly distributed in the Qilian Mountains and eastern Qinghai province. The overall ecological vulnerability showed a decreasing trend through time, but increased in several local areas. Social vulnerability dropped significantly, especially in the eastern part of Qinghai province. The results will help to identify key vulnerable areas of Qinghai province and provide references for the ecological protection and restoration and the formulation of ecosystem management policies.
Turtles have been prominent subjects of analyses of sexual size dimorphism (SSD) owing to their mating system and habitat diversity. In prior studies, marine turtles were grouped with non-marine aquatic turtles (NMAT). This is odd because it is well-established that the marine environment imposes a distinct selective milieu on body form of vagile vertebrates, driven by convergent adaptations for energy-efficient propulsion and drag reduction. We generated a comprehensive database of adult marine turtle body size (38,569 observations across all species), which we then used to evaluate both the magnitude of SSD in marine turtles and how it compares to SSD in NMAT. We find that marine turtles are not sexually size dimorphic, whereas NMAT typically exhibit female-biased SSD. We argue that the reason for this difference is the sustained long-distance swimming that characterises marine turtle ecology, which entails significant energetic costs incurred by both sexes. Hence, the ability of either sex to allocate proportionately more to growth than the other is likely constrained, meaning that sexual differences in growth and resultant body size are not possible. Consequently, lumping marine turtles with NMAT dilutes the statistical signature of different kinds of selection on SSD and should be avoided in future studies.