Do reproductive characteristics of the species explain differences in the investment in weapon size present in males?

Sexually selected traits, such as male weapons, are highly variable in shape and size across species. However, little is known about the mechanisms that may govern this variation. Because males with greater investment in weapon size tend to win more fights, but also pay higher costs related to weapon development and maintenance, larger weapons should be expected only in species in which victory in male–male fights generate reproductive benefits that outweigh investment costs. Here, we hypothesized that the reproductive characteristics that increase the chances of winners to access females or to fertilize eggs will favor the evolution of larger weapons. To evaluate this hypothesis, we conducted a meta-analysis using arthropods as model organisms. To measure investment in weapon size, we gathered both Pearson correlation coefficient and the standardized (but non centralized) slope values for the relationship between weapon size and body size. We found that none of the reproductive characteristics we investigated was related to male weapon size. Thus, it seems that greater certainty of accessing a female or fertilizing female eggs with a victory does not modulate the investment in male weapon size. Perhaps the cost–benefit ratio between weapon size investment and reproductive success is not the main factor driving the variation in weapon size.     

小熊猫夏秋季的昼夜活动节律

2002年5~11月,在邛崃山系宝兴蜂桶寨自然保护区采用无线电遥测技术对6只野生小熊猫的昼夜活动节律进行了研究。结果表明,小熊猫具有晨昏活动的习性,5~11月的平均活动率为0.5286。小熊猫以白昼活动为主,兼夜间活动,白昼的活动率(0.5903±0.0538)高于夜晚活动率(0.4468±0.0413)。每昼夜有(52.86±9.8)%的时间处于活动状态,其中64.53%的活动时间在白昼,35.47%的活动时间在夜晚。每昼夜有两个活动高峰,分别出现在08∶00~10∶00和17∶30~18∶30。在休息时间的分配上,小熊猫每昼夜长休息平均2.07次,持续时间平均3.75小时;中等长度休息1.56次,持续1.59小时;短休息1.21次,持续0.84小时;长休息有44.06%在白昼,55.94%在夜晚。     

Plasticity of diel and circadian activity rhythms in fishes

In many fish species, some individuals arediurnal while others are nocturnal. Sometimes,the same individual can be diurnal at first andthen switch to nocturnalism, or vice-versa.This review examines the factors that areassociated with such plasticity. It covers thebreakdown of activity rhythms during migration,spawning, and the parental phase; reversals ofactivity patterns during ontogeny or from oneseason to the next; effects of light intensity,temperature, predation risk, shoal size, foodavailability, and intraspecific competition.Case studies featuring goldfish (Carassiusauratus), golden shiner (Notemigonuscrysoleucas), lake chub (Couesiusplumbeus), salmonids, sea bass (Dicentrarchus labrax), and parentalsticklebacks and cichlids illustrate some ofthese influences. It is argued that mostspecies have a circadian system but that havingsuch a system does not necessarily imply strictdiurnalism or nocturnalism. Rigidity ofactivity phase seems more common in species,mostly marine, that display behavioral sleep,and for these animals the circadian clock canhelp maintain the integrity of the sleepperiod and ensure that its occurrence takes place atthat time of day to which the animal's sensoryequipment is not as well adapted. However, inother fishes, mostly from freshwater habitats,the circadian clock seems to be used mainly foranticipation of daily events such as thearrival of day, night, or food, and possiblyfor other abilities such as time-place learningand sun compass orientation, rather than forstrict control of activity phase. In thesespecies, various considerations relating toforaging success and predation risk maydetermine whether the animal is diurnal ornocturnal at any particular time and place.     

Occurrence of Atlantic salmon parr in redds at spawning time

Several Atlantic salmon parr of different sizes were found alive in salmon redds under a 10–30 cm layer of stones at spawning time. Parr, both mature and immature, remain inactive in redds during daylight but show nocturnal activity.     

桓仁滑蜥室内饲养的初步观察

2005年7月～2006年7月,对12只采自桓仁县的桓仁滑蜥Schincella huanrensis进行室内饲养及观察.     

龟类野外活动节律的研究进展

龟类野外活动具有时间尺度上的差异性和周期性,温度、湿度、光照、天气、年龄和性别差异等各种因子对龟的野外活动有着不同程度的影响.从日活动、季节活动两个不同时间尺度对龟类野外活动节律的研究成果做了系统总结,将休眠作为一种特殊的季节活动进行了小结,并对影响龟类野外活动节律的相关因子进行了分析和探讨.     

松褐天牛的交配行为

采用室内试验和野外观察相结合的方法,对松材线虫病的主要媒介昆虫松褐天牛Monochamus alternatus Hope的交配行为进行了研究。结果表明： 松褐天牛一次完整的交配包括相遇抱对、插入输精和配后保护3个阶段,在交配过程中雄虫有多次插入输精现象发生。室内试验中共观察到松褐天牛的交配123次,松褐天牛一次完整的交配过程平均需时63.49 min,其中输精前的抱对时间平均为1.68 min,交配过程中每次输精插入时间平均为57.60 s,配后保护时间为15.18 min。松褐天牛在开始交配的4天内平均交配5.15次,不同雄性个体所获得的交配机会差异很大。松褐天牛的交配行为表现出强烈的雄性竞争现象,雄虫能根据雌虫或自身的交配经历调整交配投入,当雌虫或者雄虫是初次交配时,总输精时间和插入输精的次数显著大于与有交配经历的雌虫或雄虫交配时的输精时间和插入输精次数。田间松褐天牛的交配行为与室内观察结果基本一致。     

Different behavior of body temperature and total locomotor activity daily rhythms during light/dark cycle in stabled Oryctolagus cuniculus

In order to investigate the potential causal link between the rhythm of activity and body temperature, we simultaneously recorded rectal temperature and total locomotor activity in five clinically healthy female rabbits (blue Vienna breed), 12 week old and mean body weight 2.7 ± 0.3. Animals were housed in individual cages (90?×?50?×?35 cm) under natural 12/12 light/dark cycle. Total locomotor activity was monitored for 15 days by an activity data logger. On day 1, 5, 10, and 15 rectal temperature was recorded every 2 h for a 24-h period. Application of single cosinor method showed a nocturnal daily rhythm of rectal temperature with a range of oscillation of about 1 °C, acrophase after dusk and low robustness value. The daily rhythm of locomotor activity showed its acrophase in the middle of the scotophase and a high robustness value. This information improves the knowledge available on the circadian biology of rabbits useful in the evaluation of physiology of this species.     

黑腹果蝇昼夜活动节律及行为时间分配

采用试验室单管观察记录的方法,对3,4,5日龄野生型黑腹果蝇Drosophila melanogaster Meigenw1118成虫每日活动节律进行研究。试验将果蝇活动划分为强活动(飞行和爬行)、弱活动(梳理、觅食等原地发生的运动)和静息(身体不发生移动的休息)3种类型。强活动和弱活动之和为总运动。研究结果显示,野生型黑腹果蝇w1118的昼夜活动表现为明显的双峰模态,晨峰和晚峰分别处于开、关灯前后;雌、雄果蝇总体活动无差异,关灯(18:30)前后雌蝇活动稍强于雄蝇,开灯(6:30)前后则相反;果蝇强活动的节律与总运动基本一致,而弱活动节律不明显;静息节律为单峰模式,其高峰期位于夜间1:00~5:00;雌蝇的静息活动显著多于雄蝇(P<0·05)。