A study of cremated human remains from an urn field dating to the final phase of the Bronze Age, found at “Le Caprine” (Guidonia, Rome, Italy 10th-9th century B.C.)

In this paper cremated human remains from an urn field dating from the final phase of the Bronze age (Guidonia, Rome, Central Italy) were studied. The aim of this study was to identify the minimal number of individuals for grave and cremation patterns. The results show as the ways in which the cremations were carried out were archaic in all the elements that made them up.     

EXTRAPAIR MATE CHOICE AND HONEST SIGNALING IN COOPERATIVELY BREEDING SUPERB FAIRY-WRENS

In many species of monogamous birds females copulate with males other than their social mates, resulting in extrapair fertilizations. Little is known about how females choose extrapair mates and whether the traits used to choose them are reliable indicators of male quality. Here we identify a novel male trait associated with extra-group mating success in the superb fairy-wren (Malurus cyaneus), a cooperatively breeding bird with one of the highest known frequencies of extra-group mating. Female fairy-wrens chose extra-group mates that molted earlier into breeding plumage. Males molted up to five months before the breeding season began, and only males that molted at least one month prior to its onset gained any extra-group fertilizations. This conclusion held after controlling statistically for the effect of age and social status on molt date. Once males acquired breeding plumage, they began courtship display to females on other territories. Thus, some males were displaying to females for several months before the breeding season began. This extraordinarily long period of advertisement by males may be facilitated by the long-term ownership of territories. We suggest that early acquisition of breeding plumage or the subsequent display behavior can be reliable cues for mate choice because they are costly to acquire or maintain.     

Growth strategies in the squid Loligo vulgaris from Portuguese waters

The growth of the European squid Loligo vulgaris in northwest Portuguese waters is described and the influences of gender and hatching season analysed, based on statolith readings from individuals of a wide range of sizes. Male and female growth follows different models, males attaining a higher length-at-age than females. Males display increasing growth rates irrespective of the hatching season, but the length-at-age is higher in animals hatched during the warm season. Females may exhibit asymptotic growth or not, depending upon the environmental conditions to which they are exposed through their life cycle. Although growth rates after hatching are lower in females hatched during the cold season, favourable feeding and temperature conditions during the following spring and summer months contribute not only to increase growth rates but also to delay sexual maturation. The higher length-at-age of squid hatching in the warm season, observed in both genders, provides evidence that the temperature close to hatching has a significant impact on the size of juveniles and subadults. However, there is also strong evidence that throughout their life, environmental conditions continue to play an important role in growth rates and in defining the shape of growth.     

Life span and reproductive cost explain interspecific variation in the optimal onset of reproduction

Fitness can be profoundly influenced by the age at first reproduction (AFR), but to date the AFR–fitness relationship only has been investigated intraspecifically. Here, we investigated the relationship between AFR and average lifetime reproductive success (LRS) across 34 bird species. We assessed differences in the deviation of the Optimal AFR (i.e., the species‐specific AFR associated with the highest LRS) from the age at sexual maturity, considering potential effects of life history as well as social and ecological factors. Most individuals adopted the species‐specific Optimal AFR and both the mean and Optimal AFR of species correlated positively with life span. Interspecific deviations of the Optimal AFR were associated with indices reflecting a change in LRS or survival as a function of AFR: a delayed AFR was beneficial in species where early AFR was associated with a decrease in subsequent survival or reproductive output. Overall, our results suggest that a delayed onset of reproduction beyond maturity is an optimal strategy explained by a long life span and costs of early reproduction. By providing the first empirical confirmations of key predictions of life‐history theory across species, this study contributes to a better understanding of life‐history evolution.     

Foraging for mates in the hyperparasitic wasp, Dendrocerus carpenteri: impact of unfavourable weather conditions and parasitoid age

Males of the aphid hyperparasitoid Dendrocerus carpenteri (Curtis) were attracted by a sex pheromone released by conspecific females. The intensity of this cue, and thus female attractiveness, depended both on the female's mating status and her age. Only virgin females younger than 2 h were consistently recognized as mates by foraging males. Male age did not influence foraging and mating success. Empty mummies, from which females had emerged within the previous 10 min were attractive to males and examined intensively. Rain reduced the searching success of males, although the host plant Vicia faba provided sheltered places. Wind did not reduce mating success but prevented both sexes from leaving the host plant. Since the time of female attractiveness seems to be very limited, wind may have an enormous effect on the mating success of D. carpenteri in the field and thus on the population dynamics of this species. Received: 5 October 1998 / Accepted: 16 December 1998     

瓦氏黄颡鱼年龄与生长的研究

根据在长江中游嘉鱼至新滩口江段采集的瓦氏黄颡鱼标本,对其年龄与生长进行了研究。以脊椎骨为年龄鉴定材料,胸鳍棘和耳石作为对照材料。透射光下,脊椎骨上较宽的暗带和较窄的亮带相间排列成同心圆环,一个暗带和一个亮带构成一个年轮。2—7月形成新年轮,脊椎骨上不存在幼轮。雌、雄鱼的脊椎骨半径与体长呈显著的正相关,回归方程分别为:L_♀=6.95 131.46R-10.12R~2,L_♂=18.06 113.64R-1.70R~2。体长与体重的关系方程分别为:W_♀=1.85×10~(-5)L~(2.98),W_♂=1.69×10~(-5)L~(2.55)。雌鱼为等速生长,雄鱼为异速生长。雌、雄鱼的生长存在差异,1龄后雄鱼生长明显快于雌鱼。雌、雄鱼适宜的生长方程分别为:♀:L_t=300.88e~(-1.67e~(-0.42t)),W_t=511.77e~(-4.98e~(-0.38t)),♂:L_t=415.15e~(-1.96e~(-0.33t)),W_t=777.53e~(-4.92e~(-0.32t))。雌鱼体长、体重生长的拐点年龄分别为1.22龄和4.22龄,雄鱼分别为2.04龄和4.98龄。     

Stem demography and post-fire recruitment of a resprouting serotinous conifer

Abstract. The contribution of resprouts and seedling recruitment to post-fire regeneration of the South African fynbos conifer Widdringtonia nodiflora was compared eight months after wildfires in 1990. Stems on all trees were killed by fire but resprouting success was > 90 % at all but one site. A demographic study of burned skeletons revealed that prior to these fires, nearly all plants were multi-stemmed (4–9 stems/plant) and multi-aged, indicating continuous sprout production between fires. All stems were killed by these 1990 fires and at most sites > 90 % of the stems were burned to ground level. All diameter stems were susceptible to such incineration as, at most sites, there was no difference in average diameter of stems burned to ground level and those left standing. Individual genets usually had all ramets incinerated to ground level or all ramets charred, but intact, suggesting certain micro-sites burned hotter, whereas other sites were somewhat protected. Although not true of the 1990 fires, there was evidence that occasionally Widdring-tonia stems may survive fire. At one site, four of the 16 plants sampled had a burned stem twice as old as the oldest burned stem on the other 12 plants at the site, suggesting some stems had survived the previous fire (ca. 1970) and this conclusion was supported by fire-scars on these four stems that dated to ca. 1970. Based on the highly significant correlation between stem diameter and cone density left standing after the 1990 fires, we calculated that for most sites > 80 % of the initial cone crop was incinerated by fire. This is important because we observed a strong relationship between size of the canopy cone crop surviving fire and post-fire seedling recruitment. Under these conditions we hypothesize that sprouting confers a selective advantage to genets when fires cause heavy losses of seed. The infrequent occurrence of sprouting in the Cupressaceae suggests the hypothesis that resprouting is an apomorphic or derived trait in Widdringtonia. Data from this study suggests resprouting provides a selective advantage under severe fynbos fires, which are not only 'stand-replacing fires,’but also are intense enough to incinerate cone-bearing stems.     

Study on Age and Bunch Structure of Four Stipa Species in Inner Mongolia Plateau

The age status of four Stipa L. species, S. baicalensis Roshev., S. grandis P. Smim., S. krylovii Roshev., and S. klemenzii Roshev. in Inner Mongolia plateau was analyzed using a transect sampling method. The ontogeny of Stipa species was divided into five stages: the seedling, juvenile, reproductive, presenile, and senile. Dynamics of the population age speetra were determined mainly by the appearance of new individuals and their death rate. The survival rate of the seedlings was very low while that of file adults was high. The considerable longevity of bunch life allowed the old individuals to accumulate in the population. Both S. grandis and S. krylovii had higher proportion of seedlings than others. The proportion of the juveniles and the reproductives in the population decreased from S. baicalensis community to S. klemenzii community, but the old individuals including the preseniles and the seniles showed a reverse pattern. The aging process occurred in bunch level was characterized by the fragmentation of bunch and the within-bunch- self-thinning of the tillers. The process of within-bunch-self-thinning can be described by power equation Y: aXb. Meanwhile as a response to enviroument changes especially to the fluctuation of annual precipitation and its seasonal distribution both the numbers of reproductive shoots and vegetative shoot mass within a bunch were variable.