花姬蛙蝌蚪对藻类的捕食效应

对花姬蛙(Microhyla pulchra)蝌蚪捕食藻类的效应进行了初步研究。结果表明,随着蝌蚪密度的增加,对蓝藻的总捕食量显著增加,但每只蝌蚪的平均捕食量随蝌蚪密度的增加而下降。文中讨论了蝌蚪在水资源环境保护中控制蓝藻暴发的意义。     

温度对饰纹姬蛙蝌蚪生长的影响

为揭示温度对饰纹姬蛙(Microhyla fissipes)蝌蚪生长的影响,将同一家系发育至28期的45只蝌蚪随机均分为3组,每组15只,分别置于水温25、28、30℃条件下饲养,测定其全长、体宽、眼距、吻长及头体长5项形态指标,分析不同温度下各项形态指标的变化。结果显示,5项形态特征有基本一致的变化趋势,其中全长最易表征蝌蚪的生长状况。从全长看,25℃组蝌蚪生长发育缓慢,但在12 d后有加快的趋势;30℃组在饲养第3~12 d,生长最迅速(增长率β=50.05%),但在12 d后生长明显变缓(β=9.42%),而到28 d时,已有较多蝌蚪死亡(5/15);28℃组的蝌蚪生长发育态势最好,且在饲养第28 d均超过30℃组,其在3 d后加快的生长趋势也强于25℃组。其他4项指标与全长有类似的结果。综合结果分析表明,30℃下蝌蚪在后期(21 d后)的成活率明显降低,而25℃下其生长缓慢,提示28℃是饰纹姬蛙蝌蚪比较适合的饲养温度。     

Eight novel tetranucleotide and five cross-species dinucleotide microsatellite loci for the ornate chorus frog (Pseudacris ornata)

We describe the cloning and characterization of eight novel tetranucleotide microsatellite loci in the ornate chorus frog (Pseudacris ornata). We also screened 26 loci from GenBank that were isolated from other Pseudacris species and obtained consistent product from five of these dinucleotide loci. All loci are polymorphic. In our sample of 26 frogs from a natural population, polymorphism ranged from 1 to 22 alleles per locus with expected heterozygosities ranging from 0 to 0.958. These loci enable high-resolution studies of P. ornata. Moreover, cross-species amplification success suggests they will also be useful for other chorus frog species.     

杀虫剂敌敌畏和除草剂丁草胺对饰纹姬蛙蝌蚪的急性毒性实验

采用静态换水法研究了杀虫剂敌敌畏、除草剂丁草胺对饰纹姬蛙(Microhyla ornata)蝌蚪的急性毒性影响。结果表明,杀虫剂敌敌畏对饰纹姬蛙蝌蚪的24-h、48-h的半致死浓度(LC50)分别为3．91μl／l和1．97μ/l;除草剂丁草胺对饰纹姬蛙蝌蚪的24-h LC50和48-h LC50分别为3．37μl／1和1．88μl／1,饰纹姬蛙蝌蚪对丁草胺的敏感性稍大于敌敌畏。     

<Emphasis Type="Italic">Turbinaria ornata</Emphasis> invasion in the Tuamotu Archipelago,French Polynesia: ocean drift connectivity

This paper focuses on the invasion by Turbinaria ornata (a brown algae) in the Tuamotu archipelago, French Polynesia [(5–35°S)/(200–230°E)]. Prior to 1980, this alga existed only in the Society and Austral archipelagoes. Between 1985 and 1990, it began to appear in the southern and northern parts of the Tuamotu archipelago. Genetic analyses have been shown not to be appropriate in determining the origin of this algae population. This study investigated the possible ocean drift of floating aggregates of algae. Ocean currents were calculated from satellite data from 1993 to 2001. Their spatial variations as well as their seasonal and interannual variations are described along with calculated drift trajectories. While it was found that mean currents cannot directly transport algae from the Society and Austral archipelagoes to the Tuamotu, the large interannual changes during the El Niño-Southern Oscillation phenomenon produce current reversals that are strong enough to create a transport pathway in a short enough time to allow their survival.     

Ontogenetic Variation in Blade Toughness May Contribute to the Spread of Turbinaria ornata Across the South Pacific

Coral reefs are shifting from coral to algal-dominated ecosystems worldwide. Recently, Turbinaria ornata, a marine alga native to coral reefs of the South Pacific, has spread in both range and habitat usage. Given dense stands of T. ornata can function as an alternative stable state on coral reefs, it is imperative to understand the factors that underlie its success. We tested the hypothesis that T. ornata demonstrates ontogenetic variation in allocation to anti-herbivore defense, specifically that blade toughness varied nonlinearly with thallus size. We quantified the relationship between T. ornata blade toughness and thallus size for individual thalli within algal stands (N = 345) on seven fringing reefs along the north shore of Moorea, French Polynesia. We found that blade toughness was greatest at intermediate sizes that typically form canopies, with overall reduced toughness in both smaller individuals that refuge within the understory and older reproductive individuals that ultimately detach and form floating rafts. We posit this variation in blade toughness reduces herbivory on the thalli that are most exposed to herbivores and may facilitate reproduction in dispersing stages, both of which may aid the proliferation of T. ornata.     

Craniological differentiation between European wildcats (Felis silvestris silvestris), African wildcats (F. s. lybica) and Asian wildcats (F. s. ornata): implications for their evolution and conservation

Intraspecific diversification of the wildcat (Felis silvestris), including the European wildcat (F. s. silvestris), the Asian wildcat (F. s. ornata) and the African wildcat (F. s. lybica), was examined based on 39 cranial morphology variables. The samples of free‐ranging cats originated from Britain, Europe, Central Asia and southern Africa, consisting of both nominal wildcat specimens (referred to henceforth as ‘wildcats’) and nominal non‐wildcat specimens (‘non‐wildcats’) based on museum labels. The skull morphology of ‘wildcats’ from Britain and Europe is clearly different from that of ‘wildcats’ of Central Asia and southern Africa. The latter are characterized especially by their proportionately larger cheek teeth. On the basis of principal component, discriminant function and canonical variate analyses, the skull morphology of British ‘non‐wildcats’ is less distinct than is that of British ‘wildcats’ from the skull morphologies of ‘wildcats’ of Central Asia and southern Africa. On the other hand, the skull morphology of southern African ‘non‐wildcats’ is as distinct from those of ‘wildcats’ of Britain and Europe as is that of southern African ‘wildcats’. We suggest that the evolution of the modern wildcat probably consisted of at least three different distribution expansions punctuated by two differentiation events: the exodus from Europe during the late Pleistocene, coinciding with the emergence of the steppe wildcat lineage (phenotype of Asian–African wildcat), followed by its rapid range expansion in the Old World. The second differentiation event was the emergence of the domestic cat followed by its subsequent colonization of the entire world with human assistance. Considering the recent evolutionary history of, and morphological divergence in, the wildcat, preventing hybridization between the European wildcat and the domestic cat is a high conservation priority. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 83 , 47–63.     

ONTOGENETIC CHANGES IN BUOYANCY,BREAKING STRENGTH,EXTENSIBILITY, AND REPRODUCTIVE INVESTMENT IN A DRIFTING MACROALGA TURBINARIA ORNATA (PHAEOPHYTA)1

Turbinaria ornata (Turner) J. Agardh is a tropical alga that disperses by detached, reproductively mature floating fronds. Material properties (breaking stress, breaking extension), buoyancy, and the proportion of reproductive tissue per frond were measured for juvenile, adult, and old fronds of T. ornata. Correlations between these factors indicate that as fronds age and become more reproductively mature, the tissue in their stipes (where they break) becomes weaker, more brittle, and the overall buoyancy of the frond increases. Measurement of drag force experienced by fronds from each ontogenetic stage allowed calculation of the environmental stress factor (ESF), which indicates the likelihood of detachment of a frond in the flow environment of its habitat. The ESF for fronds of each ontogenetic stage predicted that reproductively mature fronds (adult and old) break more readily than immature (juvenile) fronds. Increased proportions of reproductively mature fronds in floating rafts following storms compared with the proportion of mature fronds attached to the substratum support the ESF predictions. This combination of ontogenetic changes in material properties, buoyancy, and reproductive maturity in combination with the life history of T. ornata may contribute to the dispersal of this alga throughout French Polynesia.     

Anodic asymmetry of leaves and flowers and its relationship to phyllotaxis

BACKGROUND AND AIMS: New approaches are needed to evaluate the various hypotheses of phyllotaxis, and an examination of anodic leaf asymmetry may be one such approach. METHODS: Data were collected on the direction of midrib curvature and leaf coil in Syngonium podophyllum, the location of floral buds in Acalypha virginica, the position of secondary leaves of Croton variegatus 'Banana' and the relative size of half-lamina in Aglaonema crispum and Calathea ornata. KEY RESULTS: All five features were exclusively anodic with respect to the direction of the genetic spiral regardless of whether the spiral was clockwise or counterclockwise. CONCLUSIONS: Any phyllotactic mechanism must include some asymmetric component which cannot be explained by the prevalent hypotheses of contact parastichies, inhibitory fields, available space, pressure waves and auxin transport. The most favourable hypothesis is the primary vasculature explanation as it includes an asymmetric feature.     

Shit Happens (to be Useful)! Use of Elephant Dung as Habitat by Amphibians

Although elephants are commonly cited as an example of ecosystem engineering, cases involving Asian elephants are missing in the literature. In a dry environment of southeastern Sri Lanka, I examined 290 elephant dung piles and found a total of six frogs from three different species in 1.7 percent ( N =5) of the dung piles. This suggests a facilitative role of elephants by providing habitat for amphibians.