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1.
The host suitability of five zucchini and three cucumber genotypes to Meloidogyne incognita (MiPM26) and M. javanica (Mj05) was determined in pot experiments in a greenhouse. The number of egg masses (EM) did not differ among the genotypes of zucchini or cucumber, but the eggs/plant and reproduction factor (Rf) did slightly. M. incognita MiPM26 showed lower EM, eggs/plant, and Rf than M. javanica Mj05. Examination of the zucchini galls for nematode postinfection development revealed unsuitable conditions for M. incognita MiPM26 as only 22% of the females produced EM compared to 95% of the M. javanica females. As far as cucumber was concerned, 86% of the M. incognita and 99% of the M. javanica females produced EM, respectively. In a second type of experiments, several populations of M. arenaria, M. incognita, and M. javanica were tested on zucchini cv. Amalthee and cucumber cv. Dasher II to assess the parasitic variation among species and populations of Meloidogyne. A greater parasitic variation was observed in zucchini than cucumber. Zucchini responded as a poor host for M. incognita MiPM26, MiAL09, and MiAL48, but as a good host for MiAL10 and MiAL15. Intraspecific variation was not observed among the M. javanica or M. arenaria populations. Cucumber was a good host for all the tested populations. Overall, both cucurbits were suitable hosts for Meloidogyne but zucchini was a poorer host than the cucumber.  相似文献   
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Historically, marine ecologists have lacked efficient tools that are capable of capturing detailed species distribution data over large areas. Emerging technologies such as high‐resolution imaging and associated machine‐learning image‐scoring software are providing new tools to map species over large areas in the ocean. Here, we combine a novel diver propulsion vehicle (DPV) imaging system with free‐to‐use machine‐learning software to semi‐automatically generate dense and widespread abundance records of a habitat‐forming algae over ~5,000 m2 of temperate reef. We employ replicable spatial techniques to test the effectiveness of traditional diver‐based sampling, and better understand the distribution and spatial arrangement of one key algal species. We found that the effectiveness of a traditional survey depended on the level of spatial structuring, and generally 10–20 transects (50 × 1 m) were required to obtain reliable results. This represents 2–20 times greater replication than have been collected in previous studies. Furthermore, we demonstrate the usefulness of fine‐resolution distribution modeling for understanding patterns in canopy algae cover at multiple spatial scales, and discuss applications to other marine habitats. Our analyses demonstrate that semi‐automated methods of data gathering and processing provide more accurate results than traditional methods for describing habitat structure at seascape scales, and therefore represent vastly improved techniques for understanding and managing marine seascapes.  相似文献   
4.
Genetic and morphological structure of tub gurnard Chelidonichthys lucerna populations in Turkish marine waters were investigated with mtDNA sequencing of 16S rRNA and morphological characters. C. lucerna samples were collected from the Black Sea, Marmara, Aegean and northeastern Mediterranean coasts of Turkey. The lowest genetic diversity was found in the northeastern Mediterranean (Iskenderun Bay) population, while the highest was in the Marmara population with overall average value of genetic diversity within populations. A total of 14 haplotypes was found, and the highest haplotype diversity was in the Black Sea whereas the lowest was in the northeastern Mediterranean population (Iskenderun Bay). The Black Sea and Iskenderun Bay populations showed the least genetic divergence (0.001081), while the highest was between the Marmara Sea and northeastern Mediterranean (Antalya Bay) populations (0.002067). Pairwise comparisons of genetic distance revealed statistically significant differences (P < 0.05) between the Marmara and both the Aegean and northeastern Mediterranean (Antalya Bay) samples. Neighbour joining tree analyses clustered the northeastern Mediterranean populations (Antalya Bay and Iskenderun Bay) as genetically more interrelated populations, whereas the Aegean Sea population was clustered as most isolated one. Discriminant function analysis of morphological characters showed that only the Black Sea population is differentiated from the other populations.  相似文献   
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Sensory organs in Annelida are very diverse and may be useful for assessments of morphological adaptation and character evolution. We used several methods to provide new insights into processes underlying the evolutionary radiation of anterior sensory organs in Sabellariidae. The presence and morphological diversity of the median organ (MO) found in the group was reviewed in order to test its phylogenetic significance and possible relationships to the distribution and ecological traits of the lineages. To test the intraspecific phenotypic plasticity of the MO, molecular analyses were conducted that focused on mitochondrial and nuclear genes from populations of Idanthyrsus australiensis exhibiting variation in the morphology of the MO. We used an integrative microscopical study of the ontogeny of Sabellaria alveolata to describe the anterior sensory structures present in the larvae and the morphological changes occurring before, during, and after settlement. In larval stages, the palps and the dorsal hump (DH) exhibit distinct innervation. The larval DH organ, which is likely to play a major role in chemoreception for settlement, is interpreted as being the incipient form of the adult MO. These results suggest that annelid sensory organs including the MO may be useful for phylogenetic and developmental investigations.  相似文献   
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  1. Top‐down population regulation can influence the success of biological control agents when they are released into the field. Entomopathogenic nematodes (EPNs) are used commonly in biological control programmes, but their efficacy suffers from poor persistence. Although abiotic soil conditions have been shown to reduce EPN persistence, consumption of infected insects by scavengers and of infective juvenile (IJ) nematodes by predators may also regulate these populations. In the present study, the effects of different soil arthropods on EPNs in laboratory conditions were measured. It was hypothesised that arthropods commonly found in soil communities where EPNs are applied would consume cadavers of insects parasitised by the nematodes and the IJs themselves.
  2. Some species of scavengers consume EPN‐infected insects. Crickets (Gryllus bimaculatus De Geer), American cockroaches [Periplaneta Americana (Linnaeus)], ants [Tetramorium chefketi Forel and Pheidole pallidula (Nylander)], earwigs (Labidura riparia Pallas), mites (Sancassania polyphyllae Zachvatkin), and springtails (Sinella curviseta Brook and Folsomia candida Willem) have different responses to nematode‐killed insects. Results suggested that ants (T. chefketi), cockroaches, mites, and earwigs fed on Steinernema‐killed insects whereas neither crickets nor springtails consumed them.
  3. In the second part of the study, experiments were conducted to determine whether mites and springtails consumed IJ EPNs. Results showed that S. polyphyllae mites do not consume infective juveniles in soil, whereas both springtail species consumed significant numbers of the IJs.
  4. Top‐down regulatory processes can be a limiting factor for EPN populations under laboratory conditions. Both host cadavers and IJs are consumed (albeit by different arthropods), so these results may help explain the difficulties associated with the persistence of EPN application to soil.
  相似文献   
8.
We studied the effects of two common chemical extraction techniques on bottlenose dolphin (Tursiops truncatus) skin tissues with the intent to develop a mathematical lipid correction for dolphin skin δ13C. One method employs a hot solvent mixture (chloroform and methanol) while the other method requires washing the samples with cold solvent followed by water. The water wash method resulted in significant alteration of tissue δ15N. We found no correlation between change in sample mass and C/N or between change in sample mass and the change in δ13C (Δδ13C) following lipid extraction. Although Δδ13C was positive following lipid extraction (mean = 1.6‰ and 1.2‰, for the two methods), there was no correlation between C/N and Δδ13C for either method. Cumulatively, these results prevented us from applying a mathematical lipid normalization. Based on our findings and consideration of previously reported results, we suggest that applying these extraction techniques to dolphin skin with C/N < 4.5 introduces greater uncertainty than is warranted. We recommend against lipid correction for dolphin skins with C/N < 4.5, but stress that the resulting uncertainty in δ13C needs to be accounted for when implementing isotope mixing models to assess diet or organic matter sources.  相似文献   
9.
Animals must balance a series of costs and benefits while trying to maximize their fitness. For example, an individual may need to choose how much energy to allocate to reproduction versus growth, or how much time to spend on vigilance versus foraging. Their decisions depend on complex interactions between environmental conditions, behavioral plasticity, reproductive biology, and energetic demands. As animals respond to novel environmental conditions caused by climate change, the optimal decisions may shift. Stochastic dynamic programming provides a flexible modeling framework with which to explore these trade‐offs, but this method has not yet been used to study possible changes in optimal trade‐offs caused by climate change. We created a stochastic dynamic programming model capturing trade‐off decisions required by an individual adult female polar bear (Ursus maritimus) as well as the fitness consequences of her decisions. We predicted optimal foraging decisions throughout her lifetime as well as the energetic thresholds below which it is optimal for her to abandon a reproductive attempt. To explore the effects of climate change, we shortened the spring feeding period by up to 3 weeks, which led to predictions of riskier foraging behavior and higher reproductive thresholds. The resulting changes in fitness may be interpreted as a best‐case scenario, where bears adapt instantaneously and optimally to new environmental conditions. If the spring feeding period was reduced by 1 week, her expected fitness declined by 15%, and if reduced by 3 weeks, expected fitness declined by 68%. This demonstrates an effective way to explore a species' optimal response to a changing landscape of costs and benefits and highlights the fact that small annual effects can result in large cumulative changes in expected lifetime fitness.  相似文献   
10.
Unmanned aerial vehicles (UAVs) are increasingly used for wildlife research and monitoring, but little information exists on their potential effect on marine mammals. We assessed the effects of a UAV on the behavior of southern right whales (Eubalaena australis) in Australia. Focal follows of ten right whale mother-calf pairs were conducted using a theodolite. Control data were recorded for 30 min, and then a DJI Inspire 1 Pro was flown above the whales for 10 min at 5 m altitude. Potential changes to horizontal behavior (swim speed and turning angle) and surfacing pattern (interbreath intervals) were investigated by comparing mother-calf behavior before and during UAV approaches. Changes in respiration rate were used to quantify energetic effects. We also explored acoustic cue perceptibility of the UAV at 5, 10, and 30 m altitude, by measuring the received UAV underwater noise level on whales equipped with acoustic tags (DTAGs). The received noise levels were 86.0 ± 3.9 dB re 1 μPa, while the measured ambient noise was 80.7 ± 7.3 dB re 1 μPa in the same frequency band (100–1,500 Hz). No behavioral response to the UAV was observed. This provides support for UAVs as a noninvasive tool to study baleen whale behavior and ecophysiology.  相似文献   
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