Sexual selection in cane toads Rhinella marina： A male＇s body size affects his success and his tactics

Abstract Male body size can play an important role in the mating systems of anuran amphibians. We conducted labora- tory-based trials with cane toads Rhinella （Bufo） marina from an invasive population in the wet-dry tropics of northern Australia, to clarify the effects of a male＇s body size on his reproductive success and behavior （mate choice）. Males were stimulated with a synthetic hormone to induce reproductive readiness. Larger body size enhanced a male toad＇s ability to displace a smaller rival from amplexus, apparently because of physical strength： more force was required to dislodge a larger than a smaller amplectant male. A male＇s body size also affected his mate-choice criteria. Males of all body sizes were as likely to attempt amplexus with another male as with a female of the same size, and preferred larger rather than smaller sexual targets. However, this size prefe- rence was stronger in larger males and hence, amplexus was size-assortative. This pattern broke down when males were given access to already-amplectant male-female pairs： males of all body sizes readily attempted amplexus with the pair, with no size discrimination. An amplectant pair provides a larger visual stimulus, and prolonged amplexus provides a strong cue for sex iden- tification （one of the individuals involved is almost certainly a female）. Thus, a male cane toad＇s body size affects both his ability to defeat rivals in physical struggles over females, and the criteria he uses when selecting potential mates, but the impacts of that selectivity depend upon the context in which mating occurs     

动物求偶场交配制度及其发生机制

求偶场是动物在繁殖期的集群求偶交配的场所, 是动物求偶与繁殖行为的表达空间。为探索求偶场的发生及其进化机制, 研究者们在短短20 年中提出了近10 种关于求偶场发生与进化机制的假说与模型。在鸟类、哺乳类、两栖爬行类和鱼类中已广泛地展开有关求偶场的研究, 但目前国内却还鲜见相关研究报道。本文介绍了求偶场的特征、类型及其进化假说与模型。结合保护生物学理论, 简单阐述了求偶场研究的保护生物学及行为生态学意义。     

Invader danger: lizards faced with novel predators exhibit an altered behavioral response to stress

Animals respond to stressors by producing glucocorticoid stress hormones, such as corticosterone (CORT). CORT acts too slowly to trigger immediate behavioral responses to a threat, but can change longer-term behavior, facilitating an individual's survival to subsequent threats. To be adaptive, the nature of an animal's behavior following elevated CORT levels should be matched to the predominant threats that they face. Seeking refuge following a stressful encounter could be beneficial if the predominant predator is a visual hunter, but may prove detrimental when the predominant predator is able to enter these refuge sites. As a result, an individual's behavior when their CORT levels are high may differ among populations of a single species. Invasive species impose novel pressures on native populations, which may select for a shift in their behavior when CORT levels are high. We tested whether the presence of predatory invasive fire ants (Solenopsis invicta) at a site affects the behavioral response of native eastern fence lizards (Sceloporus undulatus) to elevated CORT levels. Lizards from an uninvaded site were more likely to hide when their CORT levels were experimentally elevated; a response that likely provides a survival advantage for lizards faced with native predatory threats (e.g. birds and snakes). Lizards from a fire ant invaded site showed the opposite response; spending more time moving and up on the basking log when their CORT levels were elevated. Use of the basking log likely reflects a refuge-seeking behavior, rather than thermoregulatory activity, as selected body temperatures were not affected by CORT. Fleeing off the ground may prove more effective than hiding for lizards that regularly encounter small, terrestrially-foraging fire ant predators. This study suggests that invasive species may alter the relationship between the physiological and behavioral stress response of native species.     

Extensive contiguous north–south range expansion of the original population of an invasive lizard in Florida

Florida has one of the two worst non-indigenous invasive species problems in the United States, and all such species are considered by statute to be a potential ecological problem. Unfortunately, little information is available about most of Florida's invasive species. Here, we provide information on range expansion of a population of one of the lesser-known species. The Palm Beach County, Florida, population of the northern curly-tailed lizard, Leiocephalus carinatus armouri, was examined for north–south expansion of its previously documented range. Observations were conducted as contiguous expansion outward from the previously known range. We found a substantial contiguous range expansion by a minimum of 46.3 km to the south and 34.1 km to the north. This species appears to be closely associated with coastal habitat degradation in the form of human infrastructure, especially ageing pavement, sea walls, buildings, and bridge bases.     

中国北方地区蜜环菌生物种的初步研究

对采自北京东灵山地区、黑龙江带岭地区、以及帽儿山地区不同寄主上的１５个蜜环菌子实体进行了极性测试和生物种测定。配对培养结果表明１５个子实体中共存在着四个生物种,分别命名为ＣｈＢＳＩ、ＣｈＢＳＩ、ＣｈＢＳⅢ和ＣｈＢＳⅣ。除生物种ＣｈＢＳⅢ的极性不清楚外,其它生物种都是四极性异宗配合的真菌。东灵山菌株中的两个生物种是ＣｈＢＳⅡ和ＣｈＢＳⅣ,带岭菌株中的两个生物种是ＣｈＢＳＩ和ＣｈＢＳⅢ,帽儿山菌株是生物种ＣｈＢＳⅠ。经过中国生物种与欧洲生物种的配对培养,发现生物种ＣｈＢＳⅣ与Ａｒｍｉｌａｒｉａｇａｌｉｃａ融合。     

Facultative monogamy in obligate coral-dwelling hawkfishes (Cirrh tidae)

Synopsis Obligate coral-dwelling hawkfishes have been hypothesized to be monogamous. This hypothesized mating system is at odds with what is known of those of other cirrhitids. Neocirrhites armatus, which inhabits Pocillopora spp. corals, and Oxycirrhites typus, which inhabits gorgonians and antipatharian corals, were examined for evidence of a monogamous mating system. Life history criteria that favor monogamy in reef fishes (Barlow 1986) were examined for these two species. Facultative monogamy was found in both. In this mating system, males are limited in their ability to acquire and maintain females, and thus have only a single mate, but may acquire additional females if conditions for doing so are favorable.     

圈养大熊猫受配后的行为研究

1999～2002年,对成都大熊猫繁育研究基地的8只健康大熊猫20只次受配后行为进行了观察,以了解大熊猫配种后的行为变化,结果发现有以下4种情况：1)妊娠反应明显;2)妊娠反应不明显;3)假妊娠;4)无任何反应。并对这4种情况从行为上进行了探讨,明显的妊娠反应是怀孕产仔大熊猫的普遍规律,在产前27d左右明显减食、拒食,静卧安静休息时间在91％以上,有明显的临产反应,外阴、乳房发生明显的变化;不明显的妊娠反应是怀孕产仔大熊猫的特殊情况,有所减食,静卧安静休息时间无明显变化,也无明显的临产反应,有的外阴变化不大;假妊娠反应类似于明显的妊娠反应,出现在部分受配和未受配的大熊猫中,食欲变化有波动,到一定时间后食欲、活动量及外阴逐渐恢复;无任何反应是受配后一直无任何与妊娠有关的行为表现,食欲、活动情况如常。     

驱除痢疾杆菌侵袭大质粒的新方法

用质粒不相容性原理驱除痢疾杆菌福氏 2a 2 4 5 7T和宋内S7的侵袭大质粒 ,先从福氏2a侵袭大质粒分别扩增ori和inc基因 ,将它们克隆至 pMD18 T载体 ,得重组质粒pMDori和 pMDinc ,然后转化 2 4 5 7T和S7,不管是pMDori还是 pMDinc都能竞争驱除痢疾杆菌福氏 2a 2 4 5 7T和宋内S7的侵袭大质粒。     

Location of a contact zone between Mus musculus domesticus and M. m. domesticus with M. m. castaneus mtDNA in southern New Zealand

The house mouse, Mus musculus, was first introduced into New Zealand in significant numbers in the early to mid nineteenth century, with genomic components from different sources of the three subspecies M. m. domesticus, M. m. musculus and M. m. castaneus. M. m. domesticus is now widely distributed in New Zealand, with genomic and morphological evidence of M. m. musculus in a few scattered locations. M. m. domesticus/M. m. castaneus hybrids are dominant in the southern third of the South Island. We anticipated that there should be a definable southern contact zone between pure M. m. domesticus and M. m. domesticus/M. m. castaneus hybrids. We tested this hypothesis by screening 170 DNA samples from mice collected in the southern South Island, using a PCR technique which rapidly distinguishes the mitochondrial genomes of the three subspecies.All mice sampled from in or north of Lincoln (43.63° S) had only M. m. domesticus mtDNA, whereas all those from or further south than Hook (44.68° S) had M. m. castaneus mtDNA. Between the two sites, mice carrying mtDNA of both subspecies were found, sometimes in the same building. On present data, this contact zone extends approximately 50 km north to south and some 30 km inland. Classical tests with three nuclear DNA markers confirmed earlier work showing that the nuclear genomes of all mice appeared to be predominantly domesticus-like.We conclude that if purebred M. m. castaneus mice did originally reach New Zealand, extensive backcrossing with M. m. domesticus has made the castaneus nuclear genome virtually undetectable with the tests that we employ.     

地形因素对外来入侵种紫茎泽兰的影响

 在紫茎泽兰(Eupatorium adenophorum)的分布区内设置171块临时样地,研究它的盖度和多度与经纬度、海拔、坡向、坡度、风向坡等地形因素的关系。结果表明,紫茎泽兰入侵最严重地区位于102° E左右,随着纬度增加入侵能力逐渐下降,但不显著(p>0.05);紫茎泽兰在中国的分布以云贵高原,尤其是云南高原为主体,通过云贵高原与原产地墨西哥、哥斯达黎加的气候条件对比,推断紫茎泽兰将来在中国的分布区主体还将局限在云贵高原,但不排除在某些局域气候条件下,形成斑块的可能;该次调查的海拔范围为75 m～2 330 m,以200 m为一个海拔梯度,多项式回归分析显示：紫茎泽兰的盖度与多度随着海拔升高而增加（p<0.05）,但在2 000 m左右已趋平缓,表明紫茎泽兰适宜生长在海拔2 000 m左右; ANOVA的结果显示：坡向对紫茎泽兰的入侵影响显著（p<0.05）,通过多重比较发现,北坡和南坡的盖度比东坡大（p<0.05）;北坡的多度比东坡大（p<0.05）,说明东坡不易被紫茎泽兰入侵,而北坡和南坡紫茎泽兰的盖度和多度差异并不显著（p>0.05）,说明温度与湿度可能不是造成不同坡向紫茎泽兰入侵差异的主导因素;坡度对紫茎泽兰入侵的影响并不显著（p>0.05）;风向坡对紫茎泽兰的盖度影响不显著（p>0.05）,而对多度的影响显著（p<0.05）,背风坡的多度显著大于侧风坡。     

Spread of Microcosmus squamiger (Ascidiacea: Pyuridae) in the Mediterranean Sea and adjacent waters

The Mediterranean Sea is subject to an ever-increasing arrival of non-indigenous marine organisms. Microcosmus squamiger is a solitary ascidian that inhabits shallow rocky littoral habitats. It probably originated in Australia and it has shown great invasive potential in other parts of the world. In the Mediterranean, M. squamiger has only been reported at a few sites in Spain and Italy. However, the closely related species Microcosmus exasperatus has been reported in several areas of the western Mediterranean. As these species can be easily confused, we re-examined most of the material from previous studies and our personal collections. In addition, sampling was done at several sites along the western Mediterranean and Atlantic coasts. The results showed that the majority of the M. exasperatus reports correspond to M. squamiger, and that M. squamiger is common on the Atlantic shores. This suggests that M. squamiger has entered the Mediterranean through the Gibraltar Strait, while the restricted distribution in the eastern Mediterranean of M. exasperatus suggests that this species is probably a Lessepsian migrant. In the Mediterranean Sea, M. squamiger has the ability to occupy extensive areas of hard substrata and to outcompete native species. Further studies are necessary to assess what impacts this invasive species have on native communities.     

Invasive alien plants in China: diversity and ecological insights

China’s current invasive alien plant species were analyzed with regard to their floristic status, biological attributes and invasion status elsewhere. Most of the 270 species identified were annuals, followed by perennial herbs. Woody perennials made only about 10% of the species. The invasives were comprised of 59 families, the largest being Asteraceae, Poaceae, and Brassicaceae. The genera with most invasive species were Amaranthus, Ipomoea, and Solanum. Most of the species originated from the New World, notably from South America. About one-third of the species were serious invaders of natural habitats in countries other than China. The proportion of invasive alien plants in province floras ranged from 0.5 to 3.8%, absolute numbers from nine to 117 species per province. Density of invasive species was correlated positively with native species density at provincial scale. The results demonstrate that in China invasive plants are present throughout the country, with a particularly high species richness in the Southeast. The ecological diversity of invasive plants suggests wide ranging impacts which need to be assessed.