The social modes of men

Here we attempt to define a specifically human ecology within which male reproductive strategies are formulated. By treating the domestic and public spheres of social life as "ecological niches" that men have been forced to compete within or to avoid as best they can, we generate a typology of four "social modes" of human male behavior. We then attempt to explain the broad distribution of social modes within and between human groups based on the relative intensity of scramble and contest competition. This research was completed with the help of a Lowell M. Durham, Jr. Fellowship at the Tanner Humanities Center, University of Utah. Lars Rodseth (Ph.D., University of Michigan 1993) is Assistant Professor of Anthropology at the University of Utah. He has conducted fieldwork in Nepal and Micronesia and is the author of "Distributive Models of Culture: A Sapirian Alternative to Essentialism," American Anthropologist (1998) 100:55–69. Shannon A. Novak (Ph.D., University of Utah 1999) is Assistant Professor of Anthropology at Indiana State University. She has conducted fieldwork in Croatia and the United Kingdom and is the author of "Perimortem Processing of Human Remains among the Great Basin Fremont," International Journal of Osteoachaeology (2000) 10:65–75.     

Ecology of Some Ricefields in Japan as Exemplified by Some Benthic Fauna,with Notes on Management

The role of tubificids and mud snails in the ricefield ecosystem was elucidated using their ecology as a basis for highlighting problems in the strategy of recycling between agricultural and urban activities. Tubificid oligochaetes occur in high densities in ricefields where irrigation water is polluted with sewage, high organic matter content is present in the soil and when highly toxic insecticides are not used. High tubificid densities reduce and even eliminate weeds, change the composition and density of bacteria and increase the density of zooplankton. Also they serve as a high quality source of food for fish comparable to that of insects. Conditions that promote a healthy growth of tubificids obviate or reduce the need for weedicides and high levels of inorganic fertilizers. Mud snails which thrive in ricefields have been used as an important source of protein food for humans in rural Japan. The snails can consume a sludge-reed compost mixture used as a fertilizer in ricefields. However the high heavy metal content in the sludge is accumulated by the snails which are thus unfit for human consumption. Based on these results and the known ecology of tubificids and the snails, a possible recycling system comprising sewage sludge, reeds, fish, insects and egrets using these two kinds of benthic organisms is proposed.     

太白红杉种群的生殖对策研究Ⅱ．生殖力和生殖值

研究了太白红杉种群的年龄结构、生殖年龄结构、生殖力和生殖值,分析了太白红杉种群的生殖适合度和生殖对策.结果如下(1)北坡和南坡两个种群的低龄级个体数都非常少,种群间的生育力差异不显著(P>0.05),但北坡太白红杉的生殖年龄比南坡大,平均生殖时间比南坡长,平均寿命也比南坡长.(2)北坡各龄级的生殖值比南坡高,剩余生殖值随年龄下降的速度比南坡小,北坡的生殖适合度比南坡高.(3)北坡第Ⅰ～Ⅶ龄级的剩余生殖值比南坡高,第Ⅶ龄级后由于下降速度较快,其值要比南坡小.     

扁嘴海雀繁殖生态初报

据野外观察,对扁嘴海雀在青岛近海岛屿的居留期、繁殖过程和食性等作了记述。     

Effect of seasonal hypoxia on the benthic foraminiferal community of the Louisiana inner continental shelf: The 20th century record

A species census in sediment core samples reveals significant changes in the composition of the Louisiana-shelf benthic foraminiferal community in the past century; these changes can be explained by an increase in the severity of seasonal hypoxia in bottom waters. Agglutinated and porcelaneous orders living in water depths less than 60 m suffered a noticeable decline during this time. In particular, the genus Quinqueloculina was severely affected by the progression of hypoxia, and nearly disappeared from parts of the study area. In contrast, several hyaline taxa, especially Nonionella basiloba, Buliminella morgani, and Epistominella vitrea, tolerated the progressive oxygen depletion well. Results of cluster and principal components analyses of the foraminiferal assemblage data match the observed species distribution trends and indicate that seasonal hypoxia on the Louisiana shelf, related to eutrophication and water stratification, worsened in the past century, even near the outer edge of the present-day zone of spring and summer oxygen depletion. The temporal trends in the foraminiferal record correspond to that of fertilizer use in the U.S. and nitrogen loading in the Mississippi River, suggesting that the anthropogenic factor has been particularly strong in the development of coastal hypoxia since the early 1940s.     

Microbial diversity along a sediment detrital particle size gradient

We studied the structural organization of microbial decomposer communities by comparing patterns of genetic complexity over a template defined by site, season and detrital particle size. Epibenthic sediment samples were collected monthly from a Lake Erie coastal wetland and a small woodland stream, and sieved into five fine particulate organic matter (FPOM) size ranges: 1000–500 (500), 500–250 (250), 250–125 (125), 125–63 (63) and 63–38 (38) m. Whole community DNA-DNA hybridizations were used to compare the structural similarity of the microbial communities associated with each sample. Microbial community heterogeneity increased as particle size decreased, and declined from a summer maximum to a late winter minimum. Cluster analysis of hybridization scores partitioned the communities into two groups: one associated with the 500, 250 and 125 m fractions and a second with the 63 and 38 m fractions. The larger particles were easily recognized as comminuted plant detritus; the smaller particles were amorphous, presumably formed through the aggregation of dissolved organic carbon. This disjunction in particle morphology and microbial community diversity that occurs at about 100 m appears to delineate two trophic resources whose origin and fate may be largely independent.     

珠江口底栖动物生态学研究

采泥样调查所获底栖动物一般为体形较小,活动能力较弱的种类,往往是一些底层鱼类和虾类等良好的天然饵料。珠江口海域渔业资源丰富,是中国南海区的主要渔场之一,因此,对该海域饵料底栖动物进行研究有重要意义。通过1999年9月和2000年4月分别对珠江口底栖生物进行的两个航次的采泥样调查,分别鉴定出底栖动物15衙睡21种,共计32种。底栖动物的优势种,秋季为光滑河篮蛤Potamocorbula laevis(Hinds)(Y=0.387),春季为光滑河篮蛤（Y＝0．464）和欧虫Owenia fusformis Delle Chiaje(Y=0.120)。平均个体数量和生物量,春季为591.7ind./m^2和26.7g/m^2,秋季为85.0ing./m^2和7.4g/m^2;而在各类群生物中,软体动物占绝大部分,其次为多毛类,其它各类群所占比例都不足5％。生物多样性,个体数量和生物量的分布均呈由北向南增加的趋势。另外,与近20a中的历史资料相比,珠江口底栖动物个体数量变化不大,除2000年春季较高为591.7ind./m^2外,其变化范围在72.4-128ing./m^2之间。春季生物量除1991年较高为27．0g/m^2外,变化不是很大,大约10g/m^2;但秋季生物量呈明显下降趋势,1980年为30.1g/m^2,1990年为27.8g/m^2,1999年秋季急剧下降至7.4g/m^2。此外,从底栖动物各大类群的百分组成变化情况来看,一般以软体动物个体数量（22．7％－83．2％）和生物量（57．9％－82．5％）都最高;多毛类的个体数量百分组成占第二倍,其范围是13．4％－52．3％;其它各类群的百分组成除个别时候所占比例较大外,一般都较小。     

Effects of sewage waste stabilization lagoon effluent on stream invertebrates

The ecological impact of discharge to streams of domestic sewage waste stabilization lagoon effluent was investigated. Benthic invertebrates were compared upstream and downstream of discharges to eight New Zealand streams where effluent dilution ranged from 6- to 484-fold. The percentage of common invertebrate taxa whose density changed significantly (ANOVA, P<0.05) downstream declined in proportion with the log of the effluent dilution (r=-0.87) and increased with downstream increase in benthic respiration (r=0.91) and several intercorrelated indicators of organic enrichment (log biochemical oxygen demand, r=0.91; log suspended solids (SS), r=0.84). However, these changes in invertebrate densities did not always reflect degraded community structure. The nature and direction of changes suggests a subsidy-stress gradient of responses. Increases in SS of > 4 g m^-3 were associated with significant changes in density of > 50 percent of the common taxa and > 50 percent reduction of the densities of the sensitive Ephemeroptera, Plecoptera, and Trichoptera (EPT). However, EPT densities increased by up to 50 percent at lower organic solids loadings. No general relationships were found between relative densities of functional feeding groups and metabolic or water quality variables. These findings confirm that early warning of enrichment stress is more easily seen at the species level than at the functional level.     

背角无齿蚌(Anodonta woodiana)对浅水系统底栖和浮游藻类竞争关系的影响

底栖藻类和浮游藻类之间的竞争关系对浅水生态系统的结构、功能具有重要的影响,双壳类可通过滤食控制浮游藻类,从而改变底栖藻类与浮游藻类之间的竞争结果。论文通过比较放养背角无齿蚌(Anodonta woodiana)(蚌处理组)与不放养背角无齿蚌(对照组)系统中底栖藻类、浮游藻类的生物量和优势种等的变化,研究了滤食性双壳类对底栖藻类和浮游藻类间竞争的影响。结果表明,背角无齿蚌可显著降低浮游藻类生物量,提高水体透明度和沉积物表面光照条件,从而显著提高底栖藻类的生物量;背角无齿蚌也改变了浮游藻类的优势种,使优势种由蓝藻转变成硅藻。因此,滤食性双壳类有利于促进浅水生态系统从混水态向清水态转变,本研究结果对富营养化浅水湖泊修复与管理具有一定的参考意义。     

Reproductive competition promotes the evolution of female weaponry

Secondary sexual traits in females are a relatively rare phenomenon. Empirical studies have focused on the role of male mate choice in their evolution; however, recently it has been suggested that secondary sexual traits in females are more likely to be under selection via reproductive competition. We investigated female competition and the influence of female phenotype on fitness in Onthophagus sagittarius, a species of dung beetle that exhibits female-specific horns. We compared reproductive fitness when females were breeding in competition versus breeding alone and found that competition for breeding resources reduced fitness for all females, but that smaller individuals suffered a greater fitness reduction than larger individuals. When females were matched for body size, those with the longest horns gained higher reproductive fitness. The fitness function was positive and linear, favouring increased horn expression. Thus, we present evidence that female body size and horn size in O. sagittarius are under directional selection via competition for reproductive resources. Our study is a rare example of female contest competition selecting for female weaponry.