Biphasic growth in fish II: empirical assessment

In [Quince, et al., 2008. Biphasic growth in fish I: Theoretical foundations. J. Theor. Biol., doi:10.1016/j.jtbi.2008.05.029], we developed a set of biphasic somatic growth models, where maturation is accompanied by a deceleration of growth due to allocation of energy to reproduction. Here, we use growth data from both hatchery-raised and wild populations of a large freshwater fish (lake trout, Salvelinus namaycush) to test these models. We show that a generic biphasic model provides a better fit to these data than the von Bertalanffy model. We show that the observed deceleration of somatic growth in females varies directly with gonad weight at spawning, with observed egg volumes roughly 50% of the egg volumes predicted under the unrealistic assumption of perfectly efficient energy transfer from somatic lipids to egg lipids. We develop a Bayesian procedure to jointly fit a biphasic model to observed growth and maturity data. We show that two variants of the generic biphasic model, both of which assume that annual allocation to reproduction is adjusted to maximise lifetime reproductive output, provide complementary fits to wild population data: maturation time and early adult growth are best described by a model with no constraints on annual reproductive investment, while the growth of older fish is best described by a model that is constrained so that the ratio of gonad size to somatic weight (g) is fixed. This behaviour is consistent with the additional observation that g increases with size and age among younger, smaller breeding females but reaches a plateau among older, larger females. We then fit both of these optimal models to growth and maturation data from nineteen wild populations to generate population-specific estimates of ‘adapted mortality’ rate: the adult mortality consistent with observed growth and maturation schedules, given that both schedules are adapted to maximise lifetime reproductive output. We show that these estimates are strongly correlated with independent estimates of the adult mortality experienced by these populations.     

An assessment of the efficiency of protection status through determinations of biodiversity hotspots based on endemic bird species,Taiwan

Evaluations of species richness patterns have been performed at diverse scales, and biodiversity hotspots, especially endemism hotspots, have received much attention in conservation biology. We estimated the distributions of endemic bird species based on a 12-yr avian inventory project in Taiwan, identified biodiversity hotspots of endemism on a regional scale based on predictions from the ensemble forecasting framework and frequency histogram approach, and assessed the efficiency of protected areas. The results indicated that the predicted endemism hotspots were mostly located in mid- and high-elevation areas along the Central Mountain Range of Taiwan. An observed endemism hotspot was defined as one in which at least five of Taiwan's 17 endemic bird species were present. This criterion was used because the 5% of the sampled grid squares that were the richest in endemic bird species all had 5 endemic bird species or more. Seventy to seventy-one percent of the observed biodiversity hotspots matched the predicted biodiversity hotspots. This outcome was obtained whether the richness biodiversity in a grid square was based on summed predicted probability or summed predicted richness. The majority of the protected areas for these Taiwanese endemic bird species were national parks, protecting 24.1% of the predicted hotspot areas, whereas nature reserves and wildlife refuges protected less than 7%. Most of the predicted endemism hotspots were not adequately protected. We conclude that the ensemble forecasting framework and the frequency histogram approach are useful for selecting critical habitats and biodiversity hotspots for endemic species and for appraising the efficiency of the protection status provided by governments.     

Is the temperature-size rule mediated by oxygen in aquatic ectotherms?

Temperature is an important environmental factor that influences key traits like body size, growth rate and maturity. Ectotherms reared under high temperatures usually show faster growth, but reach a smaller final size, a phenomenon known as the temperature-size rule (TSR). Oxygen may become a limiting resource at high temperatures, when demand for oxygen is high, especially in water as oxygen uptake is far more challenging under water than in air. Therefore, in aquatic ectotherms, the TSR might very well be mediated by temperature effects on oxygen availability and oxygen demand. To distinguish between the direct effects of temperature and oxygen mediated effects, growth rate and final size were measured in the aquatic ectotherm Asellus aquaticus (Linnaeus, 1758) reared under different temperature and oxygen conditions in a factorial design. Growth could be best described by a modified Von Bertalanffy growth function. Both temperature and oxygen affected age at maturity and growth. Growth responses to temperature were dependent on oxygen conditions (interactive effect of temperature and oxygen). Only under hypoxic conditions, when oxygen was most limiting, did we find a classic TSR. Moreover, when comparing treatments differing in temperature, but where the balance between oxygen demand and supply was similar, high temperature increased both growth rate and final size. Thus effects of oxygen may resolve the life-history puzzle of the TSR in aquatic ectotherms.     

Microsatellite markers for the roman, Chrysoblephus laticeps (Teleostei: Sparidae), an overexploited seabream from South Africa

Eleven polymorphic microsatellite loci were developed from an enrichment library of the roman, Chrysoblephus laticeps, and characterized for 40 individuals collected in Africa's largest and oldest Marine Protected Area (MPA), the Tsitsikamma National Park. The number of alleles per locus ranged from three to 19, and heterozygosities ranged from 0.20 to 0.85. A significant departure from Hardy-Weinberg equilibrium was detected for one locus, and linkage disequilibrium was identified among three pairs of loci. The markers will be useful to detect whether populations resident in MPAs along the South African coast are genetically connected, and whether there is spillover of recruits into adjacent exploited areas.     

Ungulate browsing in winter reduces the growth of <Emphasis Type="Italic">Fraxinus</Emphasis> and <Emphasis Type="Italic">Acer</Emphasis> saplings in subsequent unbrowsed years

Browsing by ungulates has become a hotly debated issue in many European mountain forests in the past century. Acer pseudoplatanus L. and Fraxinus excelsior L. are broadleaved tree species that are preferentially browsed by roe deer (Capreolus capreolus) in central Europe. We analyzed growth data from shaded saplings of both tree species to quantify the extent to which height growth after game browsing is reduced in subsequent, unbrowsed years in forest stands. Sixty saplings of F. excelsior and A. pseudoplatanus from forest stands at Albisriederberg (Switzerland) were available to us that had been dissected into pieces that then were split in the middle for counting tree rings and assessing ungulate damage. We fitted the von Bertalanffy growth equation to these height growth data and included a reduction factor for winter browsing. Both tree species showed significantly reduced height growth in unbrowsed years after one to several browsing events in winter, and this effect increased with the number of browsing events. Saplings with a high growth rate showed a higher growth reduction. After winter browsing, height growth of A. pseudoplatanus saplings was less affected in unbrowsed years than that of F. excelsior saplings. We conclude that browsed saplings of these species in forest stands are not able to compensate browsing-induced height loss, but that height differences between browsed and unbrowsed saplings probably increase over time. A comparison between our analysis and the parameters estimated using equations published by Eiberle for predicting age at 130 cm height suggests that our parameter values are rather conservative estimates of the growth reduction effect after winter browsing. Neither F. excelsior nor A. pseudoplatanus show a distinct pattern in browsing-induced growth reduction with respect to soil moisture, nutrient level, and altitude. We thus conclude that our results are likely to be valid for a wide range of forested sites.     

A skeletochronological study of age, growth and longevity in a population of the frog Rana ridibunda from southern Europe

Age at sexual maturity and longevity in a population of Rana ridibunda from north-eastern Greece were studied by skeletochronology performed on the phalanges. Analysis of the age structure was based on counting the lines of arrested growth (LAGs). Sexual maturity for both sexes arises during the first year or after the first hibernation. Ages ranged from 1 to 5 years (mean=2.96) among 52 males and from 1 to 5 years (mean=3.73) among 56 females. The mean snout-vent length was 69.03+/-12.6mm in males and 82.38+/-13.27 mm in females. The difference between the sexes in age and size was significant. Growth of individuals was fitted on? The von Bertalanffy model. The growth coefficient (K) was 0.57 in males and 0.54 in females, mainly due to faster male growth between metamorphosis and maturation.     

A unified approach to the Richards-model family for use in growth analyses: Why we need only two model forms

This paper advances a unified approach to the modeling of sigmoid organismal growth. There are numerous studies on growth, and there have been several proposals and applications of candidate models. Still, a lack of interpretation of the parameter values persists and, consequently, differences in growth patterns have riddled this field. A candidate regression model as a tool should be able to assess and compare growth-curve shapes, systematically and precisely. The Richards models constitute a useful family of growth models that amongst a multitude of parameterizations, re-parameterizations and special cases, include familiar models such as the negative exponential, the logistic, the Bertalanffy and the Gompertz. We have reviewed and systemized this family of models. We demonstrate that two specific parameterizations (or re-parameterizations) of the Richards model are able to substitute, and thus to unify all other forms and models. This unified-Richards model (with its two forms) constitutes a powerful tool for an interpretation of important characteristics of observed growth patterns, namely, [I] maximum (relative) growth rate (i.e., slope at inflection), [II] age at maximum growth rate (i.e., time at inflection), [III] relative mass or length at maximum growth rate (i.e., relative value at an inflection), [IV] value at age zero (i.e., birth, hatching or germination), and [V] asymptotic value (i.e., adult weight or length). These five parameters can characterize uniquely any sigmoid-growth data. To date most studies only compare what is referred to as the “growth-rate constant” or simply “growth rate” (k). This parameter can be interpreted as neither relative nor actual growth rate, but only as a parameter that affects the slope at inflection. We fitted the unified-Richards and five other candidate models to six artificial data sets, generated from the same models, and made a comparison based on the corrected Akaike’s Information Criterion (AICc). The outcome may in part be the result of the random generation of data points. Still, in conclusion, the unified-Richards model performed consistently well for all data sets, despite the penalty imposed by the AICc.     

雷州半岛15个阔叶树种混交幼林的生长分析*

通过15个阔叶树种2.5a生幼林在雷州半岛的生长比较,结果表明,树高、胸径和冠幅生长超过所有树种平均值的有水翁(Cleistocalyx operculatus)、盘架子(Winchia catophyua)、麻楝(Chukrasia tabularis)和秋枫(Bischofia javanica);按生长过程变化15个树种可分为3个类型:一是水翁、盘架子、秋枫和阴香(Cinnamomum burmanni),二是山楝(Aphanamixis polystachya)、麻楝、樟树(Cinnamomum camphora)、黎蒴栲(Castanopsis fissa)、火力楠(Michelia macdurei)、人面子(Dracontomelon duperreanum)、扁桃(Mangifera persiciformis)和榄仁树(Temninalia catappa),三是见血封喉(Antiaris toxicaria)、木棉(Bombax malabaricum)和无忧树(Saraca dives),不同类型的树种对生态位有不同要求,营造混交林应注意选择搭配。月平均温度、降雨量和相对湿度与多数种类的早期树高生长量与有较好的相关性,而与胸径和冠幅生长量的相关性则不明显。     

三峡库区地方特有维管植物研究

三峡库区位于我国中亚热带北部 ,既是我国植物种类丰富的地区之一 ,又是我国第三纪古老植物的残遗分布中心之一。从中国特有属的分布来看 ,该区被认为是中国三大特有植物分布中心之一的“川东 -鄂西”的分布中心〔1〕。该区的特有植物是在长期的自然历史发展过程中形成的 ,它们的存在与分布在科研上具有重要价值 ,而且较多的种类又是重要的资源植物 ,在开发利用上亦至关重要。因此 ,作者根据近年来在三峡库区实地调查的结果 ,结合有关文献 ,对三峡库区的地方特有维管植物的种类及分布特点进行了分析与探讨 ,为有效地保护三峡库区特有植物资…     

Biomass duration in growth models

To gain a better understanding of growth curve, biomass duration in several growth models, such as the exponential, linear, Gompertz, Mitscherlich, logistic, Richards and Bertalanffy, is formulated. Generally, biomass duration in these models can be given in two ways; thet- andw-representations. The latter representation, which can be defined as the summed value of reciprocal of relative growth rate with respect to biomass, gives a new significance to biomass duration. The utility of both representations is exemplified by the observed data of a fir. The idea of biomass duration is extended to get total amounts of anabolism and catabolism in the Bertalanffy model.     

Micropropagation from inflorescence stems of the Spanish endemic plant Centaurea paui Loscos ex Willk. (Compositae)

Tissue culture techniques have been established as a useful approach for ex situ conservation of rare, endemic or threatened plant species. This report describes the micropropagation of Centaurea paui Loscos ex Willk (Compositae), an extremely endangered plant species endemic to the Valencia Community (eastern Spain), as a conservation measure which does not cause damage to the wild plants used as explant source. Inflorescence nodal segments of C. paui were selected as explants for in vitro establishment. The best rate of shoot proliferation was obtained on Murashige and Skoog (MS) mineral medium supplemented with 0.5 mg/l 6-benzyladenine or with 2 mg/l kinetin. Maximum shoot elongation was achieved without growth regulators, and the addition of cytokinins significantly decreased their size. In vitro rooting of shoots was difficult after 6 weeks on rooting media. The combination of 2 mg/l indole-3-acetic acid plus 2 mg/l indole-3-butyric acid on MS medium yielded the best results. In this medium, 40% of shoots rooted before 30 days of culture. About 70% of the rooted plants were successfully transferred to pots and acclimatized to ex vitro conditions. Received: 12 January 1998 / Revision received: 10 October 1998 / Accepted: 28 October 1998     

Biological reasons for the unsuitability of growth parameters and indices for comparing fish growth

Parameters k and L in the Von Bertalanffy equation and their derivatives =kL, = logk + 2logL; as well as slopes b_L/t of the regression L=at^b (t, years), relative increments (CI=[L₂–L₁]/L₁), specific growth rates (C_v=InL₂–InL₁), growth characteristics (Clh = CvxL₁) and growth constants (Clt=Cvx[t₂ + t₁]/2) were analyzed. A total of 121 bream Abramis brama stocks in the first 10 years of life were studied. At the same real growth rate (the average absolute linear annual increments, mm year^–1) the values of k, L, , , b_L/t, CI, Cv and Clt in different stocks vary within almost the whole range. The main reason is the natural process of growth self-regulation: the relation between the average body lengths in the first year (L₁) and the relative growth rates (slopes b_L/t) is negative (b_L/t = exp[0.1183–0.0053L₁], r=0.76). The above relation defines 4 principal types of the Ford-Walford lines. Thirty four percent of the stocks have rather steep slopes of the lines and even parallel the absolute slope of 45°, so the L values of these stocks have no biological significance. The authors recommend a simple and more precise, from a biological point of view, approach for comparing fish population growth rates.     

论我国大中型湖泊鱼类资源繁殖保护的生物学及其渔业意义

2022—2023年在长江上游干流江段开展圆筒吻鮈(Rhinogobio cylindricus Günther)生长特征和自然死亡系数的调查, 与长江十年禁渔前对比, 分析禁渔后的变化, 评估禁渔效果。结果显示, 2022—2023年在长江上游合江和木洞江段采集圆筒吻鮈417尾, 体长为200—250 mm的个体占总尾数的45.56%, 体重为100—200 g的个体占总尾数的49.88%。体长与体重关系式为W=8.02×10^–6L^3.08, 呈正异速生长。其中, 285尾个体取鳞片进行年龄鉴定, 年龄范围为1—7龄, 3龄个体最多, 占总尾数的50.18%。对生长特征进行拟合分析, 结果显示, L_t= 379.9[1–e^{–0.19(t+1.59)}]和W_t=720.4[1–e^{–0.19(t+1.59)}]^3.08(R²=0.87; n=285), 表观生长指数为4.44, 自然死亡系数平均值为0.30。与禁渔前对比分析结果表明, 在禁捕后, 长江上游干流江段圆筒吻鮈各年龄组的个体规格增大, 生长状况明显改善, 自然死亡系数减小, 说明禁渔对鱼类生长和种群资源恢复有显著的作用。为进一步保护圆筒吻鮈种群资源, 建议加强圆筒吻鮈生活史过程及产卵场和栖息地环境条件的监测和研究, 开展河漫滩等重要栖息地的保护和修复, 以及在长江十年禁渔之后仍继续禁渔政策。

     

The Diversity and Distribution of the Fruit Bat Fauna (Mammalia, Chiroptera, Megachiroptera) of Danjugan Island, Cauayan, Negros Occidental, Philippines (with Notes on the Microchiroptera)

Bats are the most diverse mammalian order in the Philippines and whilst many endemic and threatened species have been documented, they are also probably the least well-known order. Negros Island (central Visayas, Philippines) represents one of the ten highest-ranking sites globally for megachiropteran diversity, and is listed as a priority area for the establishment of protected areas for megachiropteran conservation. It is also listed as a priority site for survey work. The current study undertook mist-netting, roost and observation surveys of the bat fauna of Danjugan Island, off the west coast of Negros Occidental, to inventory the bat species present and to provide baseline ecological information to identify key areas of conservation concern. Eight species – five megachiropterans and three microchiropterans – were recorded over the course of the study, representing over 10% of the total Philippine bat fauna. Four of the species are new records for the island, and three are IUCN Red Listed. The results show that the island provides important cave- and tree-roosting areas for the local populations of several endemic and globally endangered species and sub-species. Already designated with reserve status, and with an environmental education programme established within the local communities, the island may be considered of national and global importance for bat conservation. Recommendations are given for future management.