Territorial strategies in ants

Several features in social insects, particularly in ants, make the behavioral organization of territoriality considerably more complex than that of solitary animals. The establishment and maintenance of territories are based on a division of labor and a complex communication system. The analyses of territorial strategies in ants comprise the study of the design and spatiotemporal structure of the territory, as well as the social mechanisms through which the insect society pursues its territorial strategy. The geometric and behavioral organization of the absolute territories of the African weaver ants (Oecophylla longinoda) and harvester ants (Pogonomyrmex), and of the "spatiotemporal territories" of honey ants (Myrmecocystus mimicus) are described, and simple cost-benefit models are developed to illustrate the economic defensibility of each type of territory.     

Courtship disruption modifies mate choice in a lek-breeding bird

The aggregation of displaying males in lek-breeding birds is often associated with disruption of courtship and mating but effects of this disruption on mate choice have not been shown. In a 4-year study of Rupicola rupicola in Suriname, interference among territorial adult males disrupted 31 percent of all female courtship visits and terminated 32 percent of all matings at a lek where there were an average of 55 territorial males. Disruption in this rain forest species caused females to modify their courtship and mating patterns, and males that used intense and persistent disruption received a disproportionate share of this redirected mate choice.     

Evolution of clutch size in birds: adaptive variation in relation to territory quality

Reproductive output from enlarged or reduced magpie broods showed that each female generally lays a clutch of optimal size. This size varies considerably between females. Approximately 85 percent of the within-years variation in clutch size was associated with differences between territories. Colonial bird species, lacking individual foraging territories, have a smaller clutch size variation than territorial species.     

Barking, dominance, and territoriality in male sea lions

Experiments in which male sea lions (Zalophus californianus) were removed and reintroduced into a social group demonstrate that barking by larger males restricts movement and barking by other smaller males. Barking and aggression were primarily directed toward animals of most nearly equal size. Two 6-year-olds seeking to establish and maintain territorial status used aggressive tactics similar to those observed in breeding males in the field.     

Extended male growth in a fossil hominin species

In primates that are highly sexually dimorphic, males often reach maturity later than females, and young adult males do not show the size, morphology, and coloration of mature males. Here we describe extended male development in a hominin species, Paranthropus robustus. Ranking a large sample of facial remains on the basis of dental wear stages reveals a difference in size and robusticity between young adult and old adult males. Combined with estimates of sexual dimorphism, this pattern suggests that male reproductive strategy focused on monopolizing groups of females, in a manner similar to that of silverback gorillas. However, males appear to have borne a substantial cost in the form of high rates of predation.     

性别、季节和体型大小对吐鲁番沙虎巢域的影响

2008年6月份至2009年5月份对吐鲁番沙虎的巢域进行调查:2008年6月份至2008年8月份为繁殖季节(RS),2008年9月份至2009年5月份(冬眠期除外)为非繁殖季节(NRS).利用截趾标志重捕法研究吐鲁番沙虎的巢域,共标记283只吐鲁番沙虎,累计繁殖季节24只,非繁殖季节43只重捕超过3次(其中13只个体在繁殖季节和非繁殖季节均够3次以上捕捉次数,为重复个体),可以用于计算个体巢域面积数据.利用软件MapGis计算最小凸多边形法(MCP)巢域面积,并分析性别、体型大小、季节等因素对巢域的影响.结果表明:吐鲁番沙虎非繁殖季节雄性、雌性与幼体各组间的巢域面积差异均显著,繁殖季节巢域面积差异不显著;雌雄个体不同季节或全年合并比较巢域面积差异性均不显著;非繁殖季节面积与吻肛长(SVL)显著相关、全年成体组的巢域面积与吻肛长显著相关;成体巢域面积季节差异显著(U=41,P=0.046),幼体则没有季节差异(U=159,P=0.537).因而,吐鲁番沙虎的巢域大小受性别因素影响不大,体型大小对巢域面积有显著影响,由于繁殖、食物资源等的季节变化是影响吐鲁番沙虎巢域最重要的因素.     

Female-Female Pairing in Western Gulls (Larus occidentalis) in Southern California

Pairs of females that remain together from one year to the next are associated with the presence of supernormal clutches in western gull nests. Intervals between laying of eggs in supernormal clutches are less than those found in normal clutches, a result indicating both females in a pair contribute to the clutch. Most eggs in supernormal clutches are infertile. The pairs of females occupy territories that are not shared with a resident male. In three homosexual pairs one of the females exhibited behaviors normally ascribed only to males.     

Categorical perception of a natural stimulus continuum: birdsong

A fundamental issue in perception and communication is how continuously varying stimuli are partitioned into discrete categories. In swamp sparrow songs, note duration is a critical feature distinguishing two note categories with different roles in song construction. Pairs of songs with initial notes from different categories contrast more in their effects on territorial males than song pairs with initial notes differing by the same amount but taken from within one note category. The results indicate categorical perception by wild swamp sparrows.     

Microgeographic prediction of polygyny in the lark bunting

Field experiments on breeding populations of lark buntings (Calamospiza melanocorys) in South Dakota support the hypothesis that polygyny is promoted by a high variance in quality among male territories. Among these birds protection of the nest site from solar radiation is the major indicator of quality: nestling survival was significantly correlated with nest-site cover, and experimental increase of shading resulted in higher reproductive success. Males with superior territories attracted two mates, whereas those with poor territories failed to attract any. Secondary females had fledging success at least equal to that of contemporaneous monogamous pairs. On the sole basis of a shading score for each territory, the mating status of males (polygynous, monogamous, or bachelor) was predicted accurately in new areas of Colorado and North Dakota before females arrived.     

Sexual behavior in rhesus monkeys after vasectomy

Vasectomy had no statistically significant effect on the sexual behavior of vigorous adult rhesus monkeys. Of two groups of males matched for level of sexual performance, one was vasectomized and the other underwent sham vasectomy. In sex tests administered within the month after surgery, the groups showed no difference (P .05) in rate of mounting, intromission, or ejaculation, or in any other measure of sexual or sex-related behaviors.     

Influence of the lethal yellow (Ay) gene on estrous synchrony in mice

Introduction of an adult male induces partially synchronous estrus in female laboratory mice that have been caged in groups. In the inbred YS/ChWf strain, this effect was observed only when the male was nonyellow (aa), while males heterozygous for the lethal yellow allele (A(y)a) failed to induce synchrony.     

Lekking behavior in kafue lechwe

The Kafue lechwe (Kobus leche kafuensis) exhibits lekking behavior in which a number of males occupy small territories clustered together in discrete areas where females go for mating. Similar behavior in antelope is known only in the Uganda kob (Kobus kob thomasi). Lechwe lekking occurs only during a main rutting season although some breeding occurs throughout the year.     

Prenatal alcohol exposure alters adult expression of sexually dimorphic behavior in the rat

Saccharin preference and performance in a Lashley III maze were found to be altered in adult male and female rats that had been exposed to alcohol during gestation. Specifically, the sexual dimorphism normally observed in both behaviors was absent in fetal alcohol-exposed animals. The lack of sexual dimorphism appeared to result from a masculinization of the exposed females and a feminization of the exposed males.     

Rhesus monkeys: mating season mobility of adult males

Groups of rhesus monkeys, heretofore described as closed social units, experience a seasonal exchange of a portion of the adult males. Male shifting corresponds with the season of mating, and results in copulation with females of newly joined groups. This pattern is socially disruptive, but provides opportunity for exchange of genetic material between groups of a region.     

沙棘木蠹蛾成虫行为学特征及性诱效果研究

为沙棘木蠹蛾性引诱剂的开发和利用作准备 ,在内蒙古鄂尔多斯地区 ,就与沙棘木蠹蛾性引诱有关的几个生物生态学特性进行了研究 .结果表明 ,沙棘木蠹蛾 7月中旬进入羽化高峰期 ,1 5 :0 0— 1 8:0 0羽化量占日羽化总量的 90 % .雌蛾的求偶行为主要发生在 2 0 :0 0— 0 :0 0 .未观察到雌蛾多次交尾现象 ,偶尔可见雌蛾未交尾即产卵 .雌蛾寿命一般 2～ 7d ,平均 4d ;雄蛾寿命 3～ 8d ,平均 6d .处女雌蛾在林缘上风方向 30～ 1 0 0 0m都能诱到一定数量的雄蛾 .雌蛾的求偶行为表现出很强的时间节律 ,通过悬挂 7个处女雌蛾诱捕器连续观察发现 ,2 0 :0 0— 0 :0 0诱蛾量占日诱总量的 94 2 % ,1日龄处女雌蛾诱蛾量最多 ,随着处女雌蛾日龄的增加 ,诱蛾数量下降 .雌蛾腹部性腺体粗提物具有引诱雄蛾活力 ,交配雌蛾不再具有引诱雄蛾能力 .雌蛾的求偶暗期为 1～ 2h .沙棘木蠹蛾性诱特性符合蛾类的一般规律     

Effects of lead stress on Vg expression in the beet armyworm over five successive generations

Heavy metals have been found to be endocrine disruptors in invertebrates.Lead is one of the most widespread elements of contamination,but there has been no research about the effects of lead stress on vitellogenin(Vg) gene expression in insects exposed to lead over multiple generations.In this paper,the effects of different concentrations of lead(0,0.3,4.8 and 76.8 mg kg~(–1)) on the expression of Vg in the beet armyworm over five successive generations were studied.The results showed that lead stress had significant effects on Vg expression in a dose-dependent manner.For females at the larval and adult stages,as lead concentration increased,Vg expression was significantly inhibited; for males at these two developmental stages,Vg expression was induced and increased as lead concentration increased.In addition,with the increase over stressed generations,inhibited effects for females and induced effects for males at the larval and adult stages became increasingly more obvious.However,at the pupal stage,Vg expression in the two genders was different from that at the larval and adult stages.The results indicate that lead stress can upregulate Vg expression in males which should be a useful indicator for environmental risk assessment.     

Aggression in adult mice: modification by neonatal injections of gonadal hormones

Incidence of spontaneous aggression in adult male mice given a single injection of estradiol benzoate (0.4 milligram) when they were 3 days old was less than that of controls injected with oil. Aggressiveness was increased among adult females injected with either estradiol or testosterone propionate (1 milligram) at the same age. The increased aggressiveness noted among females given androgen was further documented during subsequent mating tests, when these females often attacked, wounded, and, in one case, killed naive males.     

栗山天牛触角感受器超微结构观察

作为探讨栗山天牛成虫的寄主选择、配偶定位等行为机制的一部分,利用扫描电镜对栗山天牛触角的形态、 感受器的类型及分布特点等进行观察。结果表明:栗山天牛触角上有锥形感受器7 个亚型、刺形感受器4 个亚型、 毛形感受器2 个亚型、齿形感受器2 个亚型、芽形感受器1 个亚型、钟形感受器1 个亚型;锥形感受器郁、刺形感受 器郁为雌虫特有的感受器,锥形感受器吁、锥形感受器遇、锥形感受器喻、毛形感受器玉和钟形感受器为雄虫特有 的感受器;触角感受器数量上雌虫多于雄虫,雌虫触角腹面感受器数量略多于背面,但都差异不显著。栗山天牛雌 雄成虫触角上感受器的数量、类型和分布等的差异表明,雌雄虫可能对环境中的物理、化学信息的反应存在一定 差异。      

Variance of gender and age structure of populations of moose and wild boars under the effect of winter feeding

Winter feeding of moose and wild boars altered the gender and age structure of the population. In the reproductive group and among adult females of these animals, during embryonic and postembryonic periods, females prevailed mainly, and in case of an absence of feeding the males prevailed. In connection to this, winter feeding heightened the reproductive capacity of the animal population.     

Hormone-induced esterase in mouse kidney

Starch-gel electrophoresis of an extract of mouse kidney disclosed that an esterase is present in mature males but absent in females and immature males. When testosterone was injected for 7 days the enzyme could be detected in kidney extracts obtained from both female and young animals. Hence the enzyme may be a hormone-induced one.