A re-examination of the age and growth of sand tiger sharks, Carcharias taurus, in the western North Atlantic: the importance of ageing protocols and use of multiple back-calculation techniques

Age and growth estimates for sand tiger sharks, Carcharias taurus, in the western North Atlantic were derived from 96 vertebral centra collected from sharks ranging from 94 to 277 cm total length (TL), and compared to previously published age and growth data. The oldest female and male sand tiger sharks aged in this study were 17 and 15 years of age, respectively. von Bertalanffy growth parameters derived from vertebral length-at-age data are L _∞ = 295.8 cm TL, k = 0.11 year⁻¹, and t ₀ = −4.2 years for females, and L _∞ = 249.5 cm TL, k = 0.16 year⁻¹, and t ₀ = −3.4 years for males. Sexual maturity is estimated to be 9–10 years for females and 6–7 years for males. Weight-to-length relationships determined for female and male sand tiger sharks in the western North Atlantic are; W = 1.3 × 10⁻⁴ × L ^2.4 (r ² = 0.84, n = 55) and W = 9.0 × 10⁻⁵ × L ^2.5 (r ² = 0.84, n = 47), respectively, and 7.9 × 10⁻⁵ × L ^2.5 (r ² = 0.84) for the sexes combined. Our results show sand tigers possess a slower rate of growth than previously thought. This information is crucial for accurately assessing this population’s ability to recover, and further justifies the need for this species to be fully protected.     

Mating system, multiple paternity and effective population size in the endemic flatback turtle (Natator depressus) in Australia

In recent years, genetic studies have been used to investigate mating systems of marine turtles, but to date no such research has been conducted on the flatback turtle (Natator depressus). This study investigates paternity of flatback turtle clutches at two rookeries in Queensland, Australia; Peak Island (Keppel Bay), and Mon Repos (Bundaberg). In the 2004–2005 nesting season, tissue samples were taken from either single or multiple clutches (n = 16) of nesting females (n = 8) representing a sampling effort ranging from 25% to 50% offspring per nest. Determination of the extent of multiple paternity was done using a comparative approach that included initial inferences based on observed alleles, Chi-square tests for deviations from Mendelian expectations, and three software programs (PARENTAGE1.0, GERUD2.0 and MER3.0). Results varied depending on the approach, but by calculating a consensus value of the output from these different methods, the null hypothesis of single paternity could be rejected in at least 11 of the 16 clutches (69%). Multiple paternity was thus observed in the clutches of six of nine females (67%), with two or three fathers being the most likely outcome. Analyses of successive clutches illustrated that paternal contribution to clutch fertilization can vary through time, as observed for two females. This first evidence regarding the mating system of flatback turtles indicates that multiple paternity is common in this species and that the observed frequency of multiple paternity is among the higher values reported in marine turtle species. Application of these results to estimates of effective population size (N _e) suggests that population size may have been relatively stable over long periods. Continued monitoring of population dynamics is recommended to ensure that future changes in the east coast can be detected.     

Assessing multiple paternity in three commercially exploited shark species: Mustelus mustelus,Carcharhinus obscurus and Sphyrna lewini

In this study, multiple paternity (MP) was investigated in three commercially important shark species, common smoothhound Mustelus mustelus, dusky shark Carcharhinus obscurus and scalloped hammerhead Sphyrna lewini occurring in southern Africa. Reduced marker panels of between five and six microsatellite loci were constructed for each species and used to genotype and assess the presence of MP in a total of 60 M. mustelus individuals from six litters, 90 C. obscurus individuals from 14 litters and 54 S. lewini individuals from 13 litters. Analysis in GERUD and COLONY revealed the presence of MP in all three species. Multiple paternities were observed in 67, 35 and 46% of the litters of M. mustelus, C. obscurus and S. lewini, with corresponding average sire size of 1·6, 1·4 and 2·0, respectively. The variation in the rate of MP among the three species is in accordance with previous studies whilst the comparatively high frequency of MP observed for M. mustelus, matches what has previously been reported for shark species demonstrating aggregation behaviour.     

上海市大莲湖池杉林三种优势植物枯落物分解动态

用枯落物分解网袋法,对上海市大莲湖湿地池杉林内3种优势植物池杉(Taxodium ascendens)、孔雀稗(Echinochloa cruspavonis)、日本看麦娘(Alopecurus japonicus)的枯落物进行了190 d的分解培养,测定了分解速率及其C、N、P养分元素释放动态.用收集器法对池杉林枯落物的数量进行了研究.结果表明,池杉林内池杉每年产生枯落物量为5.70t·hm-2,是该林地枯落物的主要来源.3种植物枯落物的分解速率(枯落物的干重量损失)依次为日本看麦娘＞孔雀稗＞池杉.C元素含量在3种植物枯落物中随时间显著下降;N、P元素在池杉枯落物中均有不同程度的富集,而在日本看麦娘和孔雀稗中则没有发生富集现象.     

High prevalence of multiple paternity in the invasive crayfish species,Procambarus clarkii

Reproductive strategy is a central feature of the ecology of invasive species as it determines the potential for population increase and range expansion. The red swamp crayfish, Procambarus clarkii, has invaded many countries and caused serious problems in freshwater ecosystems. However, little is known about the effects of environmental conditions on crayfish paternity and offspring traits in the wild. We studied these reproductive characteristics of P. clarkii in wild populations from two different habitats (ponds and ditches) in three locations with different environmental conditions in China. Genotyping of 1,436 offspring and 30 mothers of 30 broods was conducted by using four microsatellites. An analysis of genotyping results revealed that gravid females were the exclusive mother of the progeny they tended. Twenty-nine of 30 mothers had mated with multiple (2-4) males, each of which contributed differently to the number of offspring in a brood. The average number of fathers per brood and the number of offspring per brood were similar (P > 0.05) among six sampling sites, indicating that in P. clarkii multiple paternity and offspring number per brood are independent of environmental conditions studied. Indirect benefits from increasing the genetic diversity of broods, male and sperm competition, and cryptic female choice are a possible explanation for the high level multiple paternity and different contribution of fathers to offspring in this species.     

Frequency of multiple paternity in Myrmica scabrinodis from southern Poland

In haplodiploid insects that create social systems, more than one male may contribute to the progeny of a single female (polyandry). Little is known about the possible evolutionary benefits of multiple mating or the occurrence of this phenomenon across different species of Hymenoptera. Here we present our observations of polyandry in a Myrmica scabrinodis Nylander population from southern Poland. The estimated proportion of multiply mated queens was 0.71 and the average pedigree‐effective mate number was 1.45.     

三个亚热带森林优势种凋落物非结构性碳水化合物含量的季节动态

非结构性碳水化合物(NSC)是凋落物中的易分解组分,在凋落物分解早期快速释放进入土壤并被微生物利用,参与森林土壤生物地球化学循环,因此新鲜凋落物中NSC变化规律是认识森林土壤碳和养分循环的关键之一。选取亚热带常绿阔叶林优势树种米槠(Castanopsis carlesii)和主要造林树种杉木(Cunninghamia lanceolata)、马尾松(Pinus massoniana)为研究对象,分析其新鲜凋落叶和凋落枝中NSC(可溶性糖和淀粉)含量的动态变化规律。结果表明：凋落物中NSC含量在不同月份表现出明显的时间动态,米槠、杉木和马尾松凋落叶和凋落枝中NSC含量总体上在11—12月呈上升趋势,而在2—6月呈缓慢下降趋势。不同类型的凋落物NSC含量存在显著差异,米槠、杉木和马尾松凋落叶中NSC含量分别为3.03%—3.56%、2.18%—4.37%、3.38%—4.89%,凋落枝中NSC含量分别为1.87%—4.22%、2.88%—4.28%、2.75%—5.27%,米槠和马尾松凋落叶中NSC含量高于凋落枝,而杉木凋落枝中NSC含量高于凋落叶。不同树种凋落物NSC含量差异显著,米槠和...     

Morphology of the blood cells from three species of wobbegong sharks (Orectolobus species) on the east coast of New South Wales

This study is the first study to describe blood cell morphology, using light microscopy, for three species of wild‐caught wobbegong shark. Blood cell morphology was similar to that described previously in fish. Wobbegong sharks possess erythrocytes, at least three different morphological types of thrombocytes, lymphocytes, eosinophils, neutrophils, granuloblasts and monocytes. No basophils were observed in this study. Similarities and differences in morphological appearance of wobbegong shark blood cells compared to Chondrichthyes, teleosts and mammalian blood cells are discussed. Zoo Biol 0:1–10, 2005. © 2005 Wiley‐Liss, Inc.     

Development and characterization of 13 novel microsatellite loci from the flat-headed bat (Tylonycteris pachypus) with cross-species amplification in closely related taxa

13 novel microsatellite loci was isolated using the enriched library method from genomic DNA of the flat-headed bat (Tylonycteris pachypus). These loci showed high levels of genetic polymorphism testing on 54 individuals sampled from Guangxi province, China. The number of observed alleles per locus ranged from 2 to 15. The expected and observed heterozygosity values ranged from 0.170 to 0.900 and from 0.185 to 0.944, respectively. One loci departed significantly from Hardy-Weinberg equilibrium (HWE) after Bonferroni correction and no Linkage disequilibrium was found between any pairs of loci. In addition, these loci were tested in the sister species, Tylonycteris robustula, seven loci amplified successfully and were also polymorphic.     

Clues to the cause of the Tsushima leopard cat (Prionailurus bengalensis euptilura) decline from isotopic measurements in three species of Carnivora

The estimated population of the Tsushima leopard cat Prionailurus bengalensis euptilura is only 80–110 individuals. However, the cause of the population decline is not clear. We investigated temporal changes in the food habits of the cat and two other species of Carnivora (marten and weasel) inhabiting the Tsushima Islands by measuring δ¹³C and δ¹⁵N values in hair samples. Hair samples of the cat were collected not only from specimens and furs, but also from feces. The gathering of hair from cat feces was most efficient when the feces were collected in the spring. The food habit of male cats seemed to be more diverse and tended to comprise prey of higher trophic levels than the food habits of the females. The δ¹³C and δ¹⁵N measurements suggested that the trophic level of the food sources has been decreasing over the last several decades for the cat and weasel, but not for the marten. Increased consumption of prey from lower trophic levels in the food habit of the cat seems to be related to the decline of the cat population because these phenomena occurred simultaneously.     

非损伤采样提取DNA技术在猫科动物调查中的应用

<正>猫科动物广泛分布于世界各地(Johnson et al.,2006),全球现存37种猫科动物,其中25种已被国际自然保护联盟(IUCN)列为濒危和易危,86%以上的种群数量处于下降或未知状态(IUCN Red List,2011)。我国有13种猫科动物,占世界种类的35%(王应祥,2003),其中属于国家一级保护的有4种,二级保护的有8种,然而,对这些珍稀物种的生态学研究并不充分(高耀亭,     

Assessment of rabbit hemorrhagic disease in controlling the population of red fox: A measure to preserve endangered species in Australia

Predator's management requires a detailed understanding of the ecological circumstances associated with predation. Predation by foxes has been a significant contributor to the Australian native animal reduction. This paper mainly focuses on the dissemination of rabbit hemorrhagic disease in the rabbit population and its subsequences on red fox (Vulpes vulpes) population, by qualitative and quantitative analyses of a designed eco-epidemiological model with simple law of mass action and sigmoid functional response.Existence of solution has been analyzed and shown to be uniformly bounded. The basic reproduction number (R₀) is obtained and the occurrence of a backward bifurcation at R₀ = 1 is shown to be possible using central manifold theory. Global stability of endemic equilibrium is established by geometric approach. Criteria for diffusion-driven ecological instability caused by local random movements of European rabbits and red fox are obtained. Detailed analyses of Turing patterns formation selected by reaction-diffusion system under zero flux boundary conditions are presented. We found that transmission rate, self and cross-diffusion coefficients have appreciable influence on spatial spread of epidemics. Numerical simulation results confirm the analytical finding and generate patterns which indicate that population of red foxes might be controlled if rabbit hemorrhagic disease (RHD) is introduced into the rabbit population and thus ecological balance can be maintained.     

中亚热带主要树种凋落叶在杉木人工林中分解及氮磷释放过程

采用分解网袋法研究了马尾松(Pinus massoniana)、桤木(Alnus cremastogyne)、木荷(Schima superba)、青冈(Cycloblanopsis glauca)等树种凋落叶在21年生杉木人工林内的分解速率和养分释放过程。经过13个月的分解实验,4种供试凋落叶以青冈分解最快,质量失重率为33.5%,其次为桤木和木荷,马尾松分解最慢,其质量失重率仅为29.9%。4种凋落叶分解50%和95%所需要的时间分别为21～26个月和94～112个月。在凋落叶分解过程中,除桤木凋落叶中氮含量下降外,其他3种凋落叶的氮含量均增加,但凋落叶的C/N均降低;在凋落叶分解的前3个月,凋落物中磷含量快速下降,此后变化很小,C/P呈增加趋势。在凋落叶分解过程中,马尾松凋落叶对氮素表现为固持作用,而其他3种凋落叶对氮素表现为净释放,4种凋落叶的磷素均表现为净释放。4种供试材料中桤木较适合与杉木混交种植。     

Plasticity in above‐ and belowground resource acquisition traits in response to single and multiple environmental factors in three tree species

Functional trait plasticity is a major component of plant adjustment to environmental stresses. Here, we explore how multiple local environmental gradients in resources required by plants (light, water, and nutrients) and soil disturbance together influence the direction and amplitude of intraspecific changes in leaf and fine root traits that facilitate capture of these resources. We measured population‐level analogous above‐ and belowground traits related to resource acquisition, i.e. “specific leaf area”–“specific root length” (SLA–SRL), and leaf and root N, P, and dry matter content (DMC), on three dominant understory tree species with contrasting carbon and nutrient economics across 15 plots in a temperate forest influenced by burrowing seabirds. We observed similar responses of the three species to the same single environmental influences, but partially species‐specific responses to combinations of influences. The strength of intraspecific above‐ and belowground trait responses appeared unrelated to species resource acquisition strategy. Finally, most analogous leaf and root traits (SLA vs. SRL, and leaf versus root P and DMC) were controlled by contrasting environmental influences. The decoupled responses of above‐ and belowground traits to these multiple environmental factors together with partially species‐specific adjustments suggest complex responses of plant communities to environmental changes, and potentially contrasting feedbacks of plant traits with ecosystem properties. We demonstrate that despite the growing evidence for broadly consistent resource‐acquisition strategies at the whole plant level among species, plants also show partially decoupled, finely tuned strategies between above‐ and belowground parts at the intraspecific level in response to their environment. This decoupling within species suggests a need for many species‐centred ecological theories on how plants respond to their environments (e.g. competitive/stress‐tolerant/ruderal and response‐effect trait frameworks) to be adapted to account for distinct plant‐environment interactions among distinct individuals of the same species and parts of the same individual.     

Determinants of species richness patterns in the Netherlands across multiple taxonomic groups

We examined the species richness patterns of five different species groups (mosses, reptiles and amphibians, grasshoppers and crickets, dragonflies, and hoverflies) in the Netherlands (41,500 km²) using sampling units of 5 × 5 km. We compared the spatial patterns of species richness of the five groups using Spearman’s rank correlation and used a stepwise multiple regression generalized linear modelling (GLM) approach to assess their relation with a set of 36 environmental variables, selected because they can be related to the several hypotheses on biodiversity patterns. Species richness patterns of the five groups were to a certain extent congruent. Our data suggest that environmental heterogeneity (in particular habitat heterogeneity) is one of the major determinants of variation in species richness within these five groups. We found that for taxonomic groups comprising a low number of species, our regression model explained more of the variability in species richness than for taxonomic groups with a large number of species.     

珍珠菜属三种植物的核型研究

对国产三种珍珠菜属 (Lysimachia)植物进行了核型研究 ,其中点腺过路黄 (LysimachiahemsleyanaMaxim .)染色体核型 2n =2 2 =2m +4sm +8st+8t,聚花过路黄 (L .congestifloraHesmsl.)核型 2n =2 4=2m +2sm +1 0st+1 0t及山萝过路黄 (L .melampyroidesR .Knuth)染色体数目 2n =2 2 ,核型 2n =2 2 =4m +6sm +4st+8t,为首次报道。本文还分析了黄连花亚属 (subgen.Lysimachia) 2组 8种植物的核型 ,结果表明黄连花组(sect.Lysimachia)核型类型 1A ,过路黄组 (sect.Nummularia)核型类型 3A或 3B。     

Attractiveness of single and multiple species flower patches to beneficial insects in agroecosystems

The provision of floral resources for the enhancement of beneficial insect populations has shown promise as a strategy to enhance biological control and pollination in agroecosystems. One approach involves the provision of a single flower species while a second involves the multiple flower species, but the two have never been compared experimentally. Here we examine the influence of single and multiple species flower treatments on the abundance and foraging behaviour of key beneficial insects in two agricultural agroecosystems (broccoli and lucerne crops). The five flower treatments comprised buckwheat only, phacelia only, a simple mixture of buckwheat and phacelia, a complex mixture of buckwheat, phacelia and a commercial seed blend or the existing crop as a control. The abundance of bumble‐bees (Bombus hortorum) and honey bees (Apis mellifera) was highest in the three treatments that contained phacelia, while hoverfly (Melanostoma fasciatum) numbers were high in all four flower treatments. Bumble‐bees and honey bees probed almost exclusively phacelia flowers, even when provided with a choice of other flower species in the simple and complex mixture treatments. In contrast, hoverflies probed the flowers of all plant species in single and multiple species treatments, with no apparent difference in acceptance. However, in mixture treatments, the majority of individual bumble‐bees, honey bees and hoverflies probed the flowers from only one species, despite the presence of alternative flower species. Our results illustrate how an appreciation of insect floral attractiveness can be used to customise the species composition of floral patches to potentially maximise biological control and pollination in targeted agroecosystems.     

Ovarian cycles and microhabitat use in two species of topminnow, Fundulus olivaceus and F. euryzonus, from the southeastern United States

Synopsis Differences in spawning seasonality, inferred from ovarian cycles, and microhabitat use for two closely related Fundulus species were not effective as potential reproductive isolating mechanisms. Seasonal spawning periodicity of F. olivaceus and F. euryzonus as shown by changes in mean egg diameter and mean number of mature eggs recovered from ovaries showed nearly identical temporal patterns in reproductive activity. Peak egg development was between April and May and was lowest by the end of August. Univariate comparisons of 11 environmental variables associated with aggregations of Fundulus spp. revealed highly significant differences in several of these variables. However, individuals of both species were frequently collected together, and microhabitat differences did not remove the potential for mismating.     

Haplotype-specific single-locus multiplex PCR assay for molecular identification of sea-bob shrimp,Xiphopenaeus kroyeri (Heller, 1862), cryptic species from the Southwest Atlantic using a DNA pooling strategy for simultaneous identification of multiple samples

This work describes a single-locus multiplex PCR assay based on partial COI mitochondrial gene polymorphisms for identification of two Atlantic cryptic species of the sea-bob shrimp, Xiphopenaeus kroyeri (Heller, 1862) that were recently identified using molecular approaches. Reliable identification of cryptic species of Xiphopenaeus spp. has fundamental implications for management and conservation of the sea-bob shrimp fishery stocks. The assay was developed based on sequence polymorphisms of 130 specimens of both species, comprising samples from Venezuela to the southern coast of Brazil, validated by the amplification of 368 adult shrimp samples from nine different locations and confirmed by direct sequencing. The methodology has been optimized to enable the identification of equi-molar mixtures of DNA from up to 10 individuals by PCR reaction, allowing the fast and cheap identification of many specimens for large scale studies on fisheries biology and population genetics. The DNA pooling strategy enabled the identification of a new locality of occurrence of Xiphopenaeus sp. II in the Brazilian coast, Caravelas, indicating that the species distribution may be continuous on the coast, and not disjoint as observed so far.