Seasonal dynamics of the component community structure of parasites of the minnow Phoxinus phoxinus (L.)

The material represented by 75 specimens of minnow of the age 2-2(+) was collected according to the standard technique in the Chovju River (tributary of the Vychegda River, a region of the settlement Nizniy Chov, district of Syktyvkar town) during the period June-September 2000. The quantitative estimation of the structure of the component parasite communities was performed by calculating errors of the equation of regression for each species group separately, with subsequent summarizing of means of errors by all parasite groups comprising the community (Dorovskikh, 2001 6; 2002 B). In order to have a possibility to get data complementing each other, the calculation of variety indexes and other indexes have been made for metazoan parasites only and for the whole community, including the protozoan parasites. In both cases, i.e. considering only metazoan parasites and the whole composition of parasite species, three states of the component parasite community have been recognised: the formed community (June), the community in destroying (July and August), the community in the process of formation (September). In the course of working on the total species composition we recorded the beginning of community destroying on 30th of June, and the beginning of community formation in August. Considering only the metazoan parasites, the community is defined (after: Pugachev, 1999) as the mature (balanced) one in June, while in July, August and September, it was unmature (off-balance) by its characteristics. Regarding the protozoan parasites, the community in June, August and September was characterized as the mature one based on indices of parasite biomass, and as unripe one based on the number of parasite individuals; however in July, both groups of indices allowed to refer it to the unripe state. However, these unripe states are essentially different. In July, it is the result of dieing out the parasites of the past generation; in August and September, it is the result of the appearances of new generations. Therefore we recognise three states of parasite community named above. Considering the whole species composition of parasites we noted the greater difference of index values based on the parasite specimen numbers and their conventional biomass, that was in the case of the metazoan parasites only. It is particularly noticeable in the middle of the June, in the period of the formed community. This fact, together with high errors of the equations of regression and the presence of the high number of Apiosoma, points to the disturbance in the structure of component parasite community in the minnow from the Chovju River. This is easily explicable, because the Chovju River is the polluted reservoir, and pollution comes from agricultural fields, Verhny-Chov settlement, pigsties and cow-sheds. The pollution is a seasonal factor here. The most powerful pollution was noted at May-June, and then it decreased along the beginning of rains in the end of August; in September it increased again. It is important to point out that the monitoring of the metazoan parasites only allows to reveal the general dynamics of the community during the period of observation, but does not allow to catch the beginning of its destroying and developing and to notice possible disturbances in the community structure caused by pollution of reservoirs, particularly, if this pollution is a seasonal factor as in the Chovju River. Three named states of the component community of the fish parasites take place in other periods of year than this observed in the intestional parasite communities of fish helminths of the temperate climate zone. The developing of parasite communities of the intestinal helminths of the Anguilla anguilla in England (Kennedy, 1997) and of Leuciscus idus from the Rybinsk reservoir (Zhohov, 2003) starts in the beginning of summer. In May, their species diversity is minimal and in August is maximal. In conditions of the middle stream of the Vychegda River, the species diversity of parasite community associated with the minnow is maximal in June and minimal in August, when it only begins developing.     

Component parasite communities in the minnow Phoxinus phoxinus (L.) from ecologically safe and polluted reservoirs

A comparative analysis of the structure of component parasite communities in the minnow from ecologically safe or polluted to variable extent reservoirs was made. The analysis showed that the increase of the reservoir pollution by everyday drains, washings of fertilizers from the fields around and the dacha sections causes the change of dominant parasite species in the minnow, alteration of the sum of errors in the regression equation characterizing the spread of values of biomasses of the species forming the parasite community, and change of the "graphic" structure of the community. It is proved, that the high concentration of biogens has a destructive effect on natural systems, and at the same time causes the process of self-organizing, leading to the alteration of the community structure. As soon as even a small part of biogens is stopped to come into the reservoir, and the quality of environment is restored, the community restores its structure.     

The life history of the minnow Phoxinus phoxinus (L.) in a productive stream

SUMMARY. 1. In the River Frome, Dorset, this small cyprinid spawned from mid-April to early August and consequently some 0 group minnows did not develop scales until the following spring.
2. Most I group fish formed a summer hyaline band on their otoliths in a edition to the normal winter band.
3. Life-span was short with a winter age-structure of 67% 0 group, 32% I group and 1% II group fish with mean fork lengths of 29, 55 and 73 mm respectively.
4. In June, substantial numbers of I group fish reached reproductive size (50mm) and thereafter progressively replaced II group fish in the spawning shoals. Few II group males survived beyond June, few females beyond August.
5. Only half of I group minnows reached matutity. These were usually fish which had reached 30mm by the previous winter. Very few of these large I group fish survived to spawn the following year.
6. This differential mortality, together with the loss of condition and disappearance of II group fish during spawning, may indicate the cost of an extended high level of reproductive effort.
7. In this productive environment the life history of the minnow more closely resembles that of the small sympatric species Cottus gobio and Noemacheilus harhatulus than it does that of sympatric cyprinids.     

The genetic structure and microdistribution of shoals of Phoxinus phoxinus, the European minnow

Efficient foraging and a reduction in predation risk have been proposed as reasons for shoal formation. Some behaviours in cyprinid shoals are at first sight altruistic (e.g. predator inspection behaviour, reactions to alarm substance), such that kin selection may have been involved in their evolution. If shoaling behaviour does evolve through kin selection, then genetic differentiation is expected to be greater between shoals than within shoals. Such a hypothesis was tested here by examining shoal integrity and the relatedness of individuals within and between shoals in the European minnow, Phoxinus phoxinus , using nuclear and mitochondrial DNA markers. The breeding structure of 13 minnow shoals collected from Dorset and North Wales, U.K., was examined using allozymes. Genetic affinity within and between shoals was tested using mitochondrial DNA and multi-locus DNA fingerprinting. Shoals consisted of a random assortment of allozyme genotypes, shoal members did not share the same maternal mtDNA lineages and DNA fingerprint profiles were as varied within shoals as between them. The data indicate that it is unlikely that kin selection occurs in P. phoxinus and there is no apparent relationship between shoaling behaviour and genotype distribution in this species.     

三江平原农田土壤跳虫多尺度空间自相关性

土壤动物多尺度空间自相关性特征是土壤动物空间异质性和空间共存格局研究的重要基础。以土壤跳虫为研究对象,以中国科学院三江平原沼泽湿地生态实验站为研究区,于2011年8月和10月,选取具30 a以上耕作历史的旱地为实验样地,以5 m为步长设置一个50 m×50 m的实验样地,采用地统计中的全局Moran's I指数和局部Moran's I指数相结合的方法,研究土壤跳虫多尺度空间自相关性特征。全局空间自相关结果表明,土壤跳虫群落总密度和多数跳虫种类存在显著的多尺度空间自相关特征,多数为显著的正的空间自相关性,形成明显的空间集群。局部空间自相关结果表明,土壤跳虫群落总密度和所有跳虫种类均存在显著的局部空间自相关性,在局部地区形成"高—高"和/或"低—低"的空间集群,并和"高—低"和/或"低—高"的空间孤立区相伴发生,即形成"斑块"和"孔隙"相间分布的水平镶嵌格局;这种镶嵌格局具一定的时间动态特征,从夏季到秋季斑块大小和空间分布范围略有变化。研究表明,土壤跳虫具有明显的多尺度空间自相关性;空间集群是土壤跳虫的常见空间分布格局,在样地内形成"斑块"和"孔隙"相间分布的水平镶嵌格局,这种格局具年内时间变异性。     

物种多样性与植物群落的维持机制

物种多样性的形成与维持是生物多样性研究中的核心问题之一,形成了许多假说。剖析了群落物种多样性维持具有增加、减少和稳定共存三方面内容,着重阐明物种稳定共存的内因是物种的生物学与生态学特性差异,外因是生境具有小尺度的差异;群落生境异质性是其物种多样性维持的基础,并影响着群落的组织过程;群落的斑块镶嵌结构源于林隙形成的生境异质性,导致了物种多样性;群落斑块镶嵌结构是群落的基本属性,使群落的结构和功能得以长期维持等论点。最后,还以鼎湖山季风常绿阔叶林为例,对群落斑块镶嵌结构的形成及其对物种多样性维持和群落生产力构成与维持等方面的意义予以说明。     

鄱阳湖丰水期水位波动对浮游动物群落演替的影响

为了解鄱阳湖夏季丰水期水位剧烈波动过程中浮游动物的群落演替特征,2012年夏季鄱阳湖水位剧烈波动期间,于6月24日、7月7日和8月27日当水位下降且接近17.6 m时,在江西鄱阳湖国家级自然保护区内的1个浅水碟形湖泊设置4个采样点进行采样调查。共发现浮游动物65种,其中轮虫52种,枝角类7种,桡足类6种,多为营浮游生活的广温性和嗜温性种类。单因子方差分析(one-way ANOVA)显示3个月之间浮游动物的密度和生物量均具有显著差异(P0.05),7月份浮游动物密度(1030.17±68.18个/L)显著高于6月份(325.16±41.60个/L)和8月份(203.79±24.91个/L);6月份浮游动物的生物量(0.56±0.04 mg/L)显著低于7月份(1.22±0.11 mg/L)和8月份(0.99±0.11 mg/L)。基于浮游动物多度的聚类分析和自组织映射神经网络图均揭示夏季3个月份的浮游动物可区分为明显的3个群落:6月群落、7月群落和8月群落。蒙特卡罗检验发现水温、电导率、浊度和溶氧与浮游动物群落结构变化显著相关(P0.05)。典型相关分析显示,6月份浮游动物群落与叶绿素a含量呈显著正相关关系,7月份浮游动物群落与水体温度呈显著正相关关系,8月份浮游动物群落与水深和电导率、浊度和溶氧呈显著正相关关系(P0.05)。在3个月均为优势物种的盖氏精囊轮虫与叶绿素a含量呈正相关关系(P0.05),与水温、pH、溶氧呈负相关(P0.05)。夏季水位波动过程中浮游动物的群落结构在时间上(月份之间)发生明显演替,呈现轮虫密度逐渐降低,枝角类和桡足类密度逐渐增加的变化规律。水位波动引起环境因子的改变,从而对浮游动物的群落演替产生了重要影响。     

李园节肢动物群落时间动态的聚类分析

为了了解李园节肢动物群落的结构、特征,发挥生态系统中自然因素对害虫的生态调控作用,采用系统调查方法,在分析李园节肢动物群落结构和组织水平的基础上,对李园节肢动物群落的时间动态进行聚类分析,结果表明,对不同时期的总群落、亚群落进行模糊聚类得出结果,总群落的12次调查结果可以聚为5类,D=0.2000,3、11、7和6月初各自归为一类,其余归为一类.天敌亚群落调查结果也聚为5类,D=0.2000,3、7、8月各自归为一类,9月和10月归为一类,其余归为一类.非天敌亚群落调查结果同样聚为5类,D=0.1000,4、7、6、11月各自归为一类,其余归为一类.聚类结果部分反映了群落状况的季节差异,聚类交替现象反映了群落结构复杂性.最优分割结果将总群落、各亚群落均分割为5个阶段,即4月6日为第一阶段,4月27日～6月8日为第二阶段,6月27日～8月27日为第三阶段,9月21日～10月19日为第四阶段,11月22日为第5阶段.反映了各阶段物种种类、数量等其他指标在发生时间上存在的差异.     

The parasitic communities of the minnow (Phoxinus phoxinus L>)

Phoxinus phoxinus being a widely distributed through Palaearctic and ecologically specialised species is a good model to study parasite communities. 72 specimens of P. phoxinus from 5 localities of the Siberia and Mongolia has been studied by the author and 651 specimens--from 5 localities in Kola Peninsula by the other researches. 595 specimens were studied by B. S. Shulman (1983) year around. To describe infra- and component parasite communities the Brillouin, Shannon, Berger-Parker indexes were used. Communities within individual fish were compared within, and between localities with quantitative percentage similarity index (Esch e. a., 1988). The Brillouin, Shannon and Berger-Parker indexes can be calculated based on abundance or total number of parasites of each species for component or compound communities. Intensity cannot be used. Significant negative correlation was observed between the Brillouin and Berger-Parker dominance indexes (r = -0.984, p < 0.01, n = 66) in infracommunities. The Brillouin index was significant positive correlated with the number of parasites in infracommunity (r = 0.407, p < 0.01, n = 66) and with the number of species in infracommunity (r = 0.92, p < 0.01, n = 66). Berger-Parker dominance index was significant negative correlated with the number of parasite in infacommunity (r = -0.815, p < 0.01, n = 66) and with the number of species in infracommunity (r = -0.268, p < 0.05). Total number of parasites and the number of species in infracommunity was positive correlated significantly (r = 0.565, p < 0.01, n = 66). These correlations remain the same at the component community level for the Shannon/Berger-Parker indexes (r = -0.965, p < 0.01, n = 10) and total number of parasites/number of species (r = 0.789, p < 0.01, n = 10) only. Similarity index was not correlate with any other indexes and parameters. No significant correlation was found between the Brillouin, Berger-Parker indexes and geographical characters of localities (longitude, latitude, altitude above sea-level). Weak correlation (r = 0.551, p < 0.098, n = 10) was observed only between the Berger-Parker dominance index and the latitude. 37 metazoan parasites have been found in all localities (specialists--40%, allogenic species--22%, rare species--40%). Allogenic generalist species of the genus Diplostomum (D. phoxini in most cases) were dominant in 60% of the component communities and 36% of infracommunities on average. 20% of the component communities were dominant by autogenic specialists Gyrodactylus magnificus and only 12% of the infracommunities were dominated by this species. Trematode and nematode larvae were core species in most localities. Frequency distribution of infracommunity richness varied from locality to locality being overdispersed in combine sample. Parasite communities at least on the infracommunity level demonstrate high variability of all parameters. Some tendency to decrease the diversity seems to be present depending on remoteness from prospective centre of origin of the genus Phoxinus.     

Host age and structure of the component communities of parasites in river minnow Phoxinus phoxinus (L.)

Species composition and structure of the communities of fish parasites in river minnow Phoxinus phoxinus (L.) from the Pechora river were investigated in two of the Pechora-Ilychsky Biosphere Nature Reserve, Komi Republic. The component communities of the parasites in river minnow are shown to have a one-year cycle including the states of development, completion, and destruction. Communities in the state of development are characterized by a low variety of species, low values of Shannon index, often high values of domination index, presence of only two groups of parasites in the structure described by variational curved of the conditional biomasses of species, deviation of the conditional biomasses of species from the linear regression, and sum of errors of the regression equations lower a threshold value. The communities consist of young individual parasites and their larval stages. Completed community is characterized by the following properties. There are three groups of parasites, differing in allometric index, in the structure, discerned by the ratio of conditional biomasses of the species included. Conditional biomasses of species in ecologically safe reservoirs lie on the segments of straight lines. Species variety reaches its maximum. Species are presented mainly by mature specimens and larval stages of the parasites using fish as intermediate host. Community in the state of destruction shows low values of domination index and relatively small variety pf species. Such community is consist of one or two groups of species, which are represented by mature, oviparous, and dying individuals. There are larval stages of parasites using fish as intermediate hosts. Dominant species or species groups, as well as values of indexes describing the component communities of parasites, can be different in mature river minnow from different geographical regions. However, the number of groups of parasites, formed by the ratio of conditional biomasses, remains constant, and sum of errors of the regression equations characterizing the communities is always below 0.25. Component communities of parasites in young river minnows differ from the communities in mature fishes by lower variety of species. Lower biomass, and lower number of individual parasites. The communities of parasites in 0+ old fishes are often characterized by lesser number of groups of parasites, classified by the ratio of their biomasses, and presence of two dominate species. It is often impossible to count the sum of errors of the regression equations describing spread in values of biomasses of the species forming the community.     

祁连山北坡退化林地植被群落的自然恢复过程及土壤特征变化

采用长期定位观测的方法,研究了祁连山北坡退化林地人工抚育下2001-2008年间植被群落的自然恢复过程和土壤特征变化。结果表明:人为干扰消除后,退化林地群落环境逐渐优化,群落的科、属、种均明显增加,物种成员更替频繁;灌木和乔木物种出现后,群落垂直高度增大,群落结构出现成层现象;群落总体多样性指数呈不断增大的趋势,在空间结构上,Patrick丰富度指数、Shannon-Wiener多样性指数和Simpson优势度指数表现出:草本层>灌木层>乔木层的规律,而Pielou均匀度指数变化相反;土壤含水量、土壤有机碳和全氮含量随植被恢复均不断增加。在实施封育禁牧措施后,退化林地实现了由草本群落-灌木群落-乔木群落方向的快速演替,当恢复到早期的先锋乔灌混交阶段时,群落的物种组成、结构和多样性趋于复杂化,土壤性状也得到一定改善,显示出相对较好的适应性和恢复效果。     

长江口邻近海域丰水季大型底栖动物群落特征

为了研究长江口丰水季邻近海域大型底栖动物群落特征, 我们根据2012年6、8和10月长江口邻近海域大型底栖动物的调查资料, 应用双因素方差分析(Two-Way ANOVA)、聚类分析(Cluster)、非参数多维标度排序(Non-metric Multidimensional Scaling, NMDS)以及丰度生物量比较曲线(Abundance-Biomass Comparison Curves, ABC Curves)对数据资料进行分析。本研究共记录大型底栖动物181种, 其中多毛类动物82种, 甲壳动物46种, 软体动物31种, 棘皮动物11种, 其他类群11种。大型底栖动物丰度、生物量、种类丰富度和多样性指数月份间差异和空间差异均不显著。均匀度指数月份间差异不显著, 而空间上远海显著高于近海。6、8和10月大型底栖动物在20%的相似性水平上划分为3-4个群聚, 不同站位相似性水平较低。ABC曲线表明远海大型底栖动物群落受扰动的程度小于近海。受人类活动的持续影响, 长江口邻近海域大型底栖动物种类变化剧烈, 空间分布不均匀。     

不同群落类型柔毛淫羊藿总黄酮和淫羊藿苷含量及其与土壤因子的关系

2009年8月,采用高效液相色谱法和紫外分光光度法测定了唐家河自然保护区次生落叶阔叶林红桦群落(群落Ⅰ)、常绿落叶阔叶混交林细叶青冈群落(群落Ⅱ)和常绿阔叶林油樟群落(群落Ⅲ)下生长的柔毛淫羊藿各器官的总黄酮和淫羊藿苷含量,分析其与土壤因子的关系结果表明：柔毛淫羊藿叶片中总黄酮和淫羊藿苷含量最高、茎中最低;群落Ⅰ的柔毛淫羊藿总黄酮和淫羊藿苷含量［(5.32±0.23)%和(0.47±0.05)%］均显著高于群落Ⅱ［(4.06±0.03)%和(0.32±0.01)%］和群落Ⅲ［(4.15±0.07)%和(0.28±0.09)%］;土壤氮含量和pH值对柔毛淫羊藿的总黄酮和淫羊藿苷含量影响较大,柔毛淫羊藿总黄酮和淫羊藿苷含量与土壤全氮和碱解氮呈显著负相关(P<0.05),与土壤pH值呈极显著正相关(P<0.01).土壤较低的氮供应水平和较高的土壤酸度可能使群落Ⅰ柔毛淫羊藿的总黄酮和淫羊藿苷含量增加.     

Polychaete zonation and its relation to algal distribution down a vertical cliff in the western Mediterranean (Italy): a structural analysis

The zonation of polychaetes down a vertical cliff (0–5 m in depth) at Cape Romito, Leghorn, Italy, was investigated. The structural organization of the community changed with depth. A community typical of photophilic environments was found in the superficial zone (0–2 m), while in the deeper zone (3–5 m), a more diversified community characterized by species typical of sciaphilic environments was present. At the surface (0 m) the community was very poor in species and individuals and thus probably corresponds to the midlittoral fringe. In fact, some species typical of the midlittoral zone were found. This distribution pattern was constant for samples taken in February and August 1985. The distribution of polychaetes was closely related to that found for macroalgae. It is hypothesized that algae condition the substratum and that this is the main factor responsible for the zonation of polychaetes.     

Temporal distribution of the archaeal community in the Changjiang Estuary hypoxia area and the adjacent East China Sea as determined by denaturing gradient gel electrophoresis and multivariate analysis

The archaeal community and the effects of environmental factors on microbial community distribution were investigated at five sampling sites in the Changjiang Estuary hypoxia area and the adjacent East China Sea in June, August, and October 2006. Profiles of the archaeal communities were generated by denaturing gradient gel electrophoresis of 16S rRNA genes followed by DNA sequence analysis, and the results were analyzed by multivariate statistical analysis. Denaturing gradient gel electrophoresis band patterns were analyzed by cluster analysis to assess temporal changes in the genetic diversity of the archaeal communities. Most of the October samples grouped together separately from those of June and August. Analysis of DNA sequences revealed that the dominant archaeal groups in the Changjiang Estuary hypoxia area and the adjacent East China Sea were affiliated with Euryarchaeota (mainly marine group II) and Crenarchaeota. The effects of environmental factors on the archaeal community distribution were analyzed by the ordination technique of canonical correspondence analysis. Salinity had a significant effect on the archaeal community composition.     

长江口东滩湿地芦苇生境大型底栖无脊椎动物群落结构的月动态

2015年5月至2016年4月对长江口东滩湿地芦苇生境的大型底栖无脊椎动物群落结构进行监测,分析了该生境下底栖动物群落物种组成和多样性的月变化.结果表明: 芦苇株高和盖度均在3—8月逐渐增大,9月后逐渐降低;芦苇密度和地上生物量(干质量)均在7月达到最大值.调查期间,共发现大型无脊椎底栖动物20种(包括2种鉴定到属,2种鉴定到科).其中,腹足纲种类最多,有11种(包括1种鉴定到属);软甲纲有5种;昆虫纲和多毛纲均只有2种.以緋拟沼螺、堇拟沼螺和尖锥似蟹守螺等为主要优势种.从生活型来看,底上附着型种类数最多(11种),其次为穴居型(5种)和底内型(4种).大型底栖动物密度和生物量存在明显的季节或月变化,夏季(8月)出现全年最高值.Margalef物种丰富度指数(D)和Shannon指数(H)月份间差异显著,Pielou均匀度指数(J)月份间差异不显著(除11月).大型底栖动物群落在42%相似性水平上划分为3个群聚.从非度量多维标序(nMDS)排序图可知,5月、10—11月与其他月份差异较大.水温、芦苇地下生物量和盐度等环境因子对于底栖动物密度变化具有一定影响,但未达到显著水平(P>0.05).受人类活动的持续影响,长江口东滩湿地芦苇生境底栖动物群落物种多样性有所下降,芦苇生境价值急需重视.     

豚草发生地土壤昆虫群落结构及动态

采用分层取样法、大类群分类法和数理统计方法,研究了普通豚草Ambrosia artemisiifolia和三裂叶豚草A．trifida发生地土壤昆虫的群落结构及动态。共采集土壤昆虫46个科（成虫与幼虫分开单列）,隶属于12个目,其中弹尾目个体数占绝对优势（占土壤昆虫总个体数的80.879%）,其次是膜翅目（8.765%）、鞘翅目幼虫（3.951%）和双翅目虫（3.093%）,其余合计占3.312%。在46个科中,优势类群有3科：棘跳虫科（Onychiuridae）（占土壤昆虫总个体数的32.756%）、鳞跳虫科（Tomoceridae）（18.869%）和节跳虫科（Isotomidae）（18.178%）。土壤昆虫个体数和类群数,随着豚草生长季的推进而增加,8月达到最高值。豚草降低了土壤昆虫的个体数量和群落多样性,根据逐月方差分析和多重比较,8月和9月对照样地土壤昆虫个体数量和多样性指数均显著高于豚草样地。豚草表现出对某些土壤昆虫类群的驱避作用,步甲科（Carabidae）成虫、拟花萤科（Dasytidae）幼虫、叶蝉科（Jassidae）、阎甲科（Histeridae）和管蓟马科（Phloeothripidae）在豚草整个生长季从未在豚草样地中出现。豚草对于土壤昆虫的抑制作用在豚草纯群落和植物生长旺季更为明显。土壤昆虫的垂直分布具有明显的表聚性。     

Male Ornamentation in the European Minnow (Phoxinus phoxinus) Signals Swimming Performance

The association between male secondary sexual ornamentation and male quality has been under intensive study for decades. It has been shown that male ornaments in fish indicate a variety of physical and genetic qualities. However, only few studies have investigated whether male ornaments signal locomotor performance, a trait that is expected to be vital for individual fitness in the nature. In this study, we sampled two populations of European minnow (Phoxinus phoxinus), a cyprinid fish species with spectacular and colourful male breeding ornamentation, and examined the association between male ornaments (tubercle number, lateral darkness and abdominal redness), swimming performance, and three fitness‐related traits, body length (L_T), condition factor (K) and gonadosomatic index (GI). We found that male tubercle number and abdominal redness were positively correlated with their swimming performance. In addition, these two ornaments were correlated with male fitness‐related traits, which in turn were also directly associated with the swimming performance. In general, these results suggest that in the European minnow male ornamentation may act as an honest signal of several fitness‐related traits and locomotor performance in the nature.     

Sexual process in eight-spored ascus-forming yeast, Schizosaccharomyces japonicus II. Dependency of the sexual process on the carbon source

The carbon-source dependency of the sexual process in Schizosaccharomycesjaponicus was studied. Schiz. japonicus grew well in vegetativemedia containing glucose, sucrose, fructose or raffinose, anddid poorly in one containing mannose. On the other hand, itssexual process proceeded well in sporulation media containingglucose, sucrose or mannose, and was markedly delayed in thosecontaining fructose or raffinose. Neither vegetative growthnor sexual process occurred when non-fermentable carbon sources,such as glycerol, were used. The amount of glucose in the sporulationmedium sufficient for completion of the sexual process varieddepending on the cell-population density. Glucose was requiredfor both zygote and ascus formation but not for spore liberation.Cells were committed to sporulation shortly after the stageof zygote formation. (Received August 3, 1978; )     

Identification of extraretinal photoreceptors in the teleost Phoxinus phoxinus

The existence of cells capable of detecting changes of the photoperiod within the deep brain, the so-called deep brain photoreceptors, was proposed in the early years of the twentieth century. By using immunocytochemistry with antisera against phototransductory proteins on paraffin and vibratome sections, we have localized several positive areas in the brain of the teleost Phoxinus phoxinus. These areas were restricted to two encephalic regions: the epithalamus and the hypothalamus. Immunopositive (rod-opsin- and a-transducin-like) pinealocytes and parapinealocytes, as well as some sparse neurons in the habenula, were seen in the epithalamus. The immunoreaction of the hypothalamus was represented by a-transducin-like positive (magnocellular and parvicellular) neurons of the Nucleus Preopticus, as well as by a-transducin- and arrestin-like positive fibers corresponding to the hypothalamic-hypophyseal tract and a few fibers running towards the basal telencephalon. These findings corroborate the data published on other teleost fish and fully support the hypothesis of the presence of photosensitive cells in the encephalon of lower vertebrates. The labelling with antisera against different components of the phototransductory cascade also strengthens the idea that such cells employ a biochemical mechanism similar to that in the retinal visual photoreceptor cells, rods and cones. Although the function is still unclear, the detection of the photoperiod seems to be the most likely role for these extraretinal photoreceptors.