Winds under the Rain Forest Canopy: The Aerodynamic Environment of Gliding Tree Frogs

Movement of air under the canopy of a forest affects the gliding of animals such as frogs, snakes, geckos, and squirrels; the dispersal of pollen, seeds, and spores; as well as convective transport of heat and carbon dioxide. Wind speed profiles were measured under the canopy of a lowland rain forest during the morning, afternoon, and night at three sites in Costa Rica to determine the aerodynamic environment in which tree frogs maneuver while gliding. During the course of a day, average and maximum wind speeds were highest in the morning and midday, and lowest at night. Wind speeds under the canopy were highest near the top of the canopy and were lowest near the canopy floor in the morning and afternoon, and exhibited little variation with respect to height at night. Turbulence intensity (a common measure of gustiness) was constant (ca 1) for all times of day, heights in the canopy, and sites, but the absolute magnitudes of wind gust speeds were higher during the day than at night. Power spectral densities revealed that most of the variation in wind speeds occurred at frequencies that could potentially affect the gliding of tree frogs. Tree frogs (and many other gliding animals), however, glide at night and thereby avoid the higher wind speeds that occur by day. Computer simulations of the dynamic motions of frogs while gliding revealed that the night levels of wind gusts have little effect on the direction of gliding of tree frogs.     

Age and Long-term Growth of Trees in an Old-growth Tropical Rain Forest, Based on Analyses of Tree Rings and 14C1

In an old‐growth tropical wet forest at La Selva, Costa Rica, we combined radiocarbon (¹⁴C) dating and tree‐ring analysis to estimate the ages of large trees of canopy and emergent species spanning a broad range of wood densities and growth rates. We collected samples from the trunks of 29 fallen, dead individuals. We found that all eight sampled species formed visible growth rings, which varied considerably in distinctiveness. For five of the six species for which we combined wood anatomical studies with ¹⁴C‐dates (ring ages), the analyses demonstrated that growth rings were of annual formation. The oldest tree we found by direct ring counting was a Hymenolobium mesoamericanum Lima (Papilionaceae) specimen, with an age of ca. 530 years at the time of death. All other sampled individuals, including very large trees of slow‐growing species, had died at ages between 200 and 300 years. These results show that, even in an everwet tropical rain forest, tree growth of many species can be rhythmic, with an annual periodicity. This study thus raises the possibility of extending tree‐ring analyses throughout the tropical forest types lacking a strong dry season or annual flooding. Our findings and similar measurements from other tropical forests indicate that the maximum ages of tropical emergent trees are unlikely to be much greater than 600 years, and that these trees often die earlier from various natural causes.     

The role of environment and mid-domain effect on moth species richness along a tropical elevational gradient

Aim The biodiversity of geometrid moths (Lepidoptera) along a complete tropical elevational gradient was studied for the first time. The patterns are described, and the role of geometric constraints and environmental factors is explored. Location The study was carried out along the Barva Transect (10° N, 84° W), a complete elevational gradient ranging from 40 to 2730 m a.s.l. in Braulio Carrillo National Park, Costa Rica, and adjacent areas. Methods Moths were sampled manually in 2003 and 2004 at 12 rain forest sites using light ‘towers’, each with two 15 W ultraviolet fluorescent tubes. We used abundance‐based rarefaction, statistical estimation of true richness (Chao 1), geographically interpolated observed richness and Fisher's alpha as measures of local diversity. Results A total of 13,765 specimens representing 739 species were analysed. All four measures showed a hump‐shaped pattern with maxima between 500 and 2100 m elevation. The two subfamilies showed richness and diversity maxima at either lower (Ennominae) or higher (Larentiinae) elevation than Geometridae as a whole. Among the four environmental factors tested, relative humidity yielded the highest correlation over the transect with the rarefaction‐based richness estimates as well as with estimated true species richness of Geometridae as a whole and of Larentiinae, while rainfall explained the greatest variation of Ennominae richness. The elevational pattern of moth richness was discordant with both temperature and with tree species richness. A combination of all environmental factors in a stepwise multiple regression produced high values of r² in Geometridae. The potential effects of geometric constraints (mid‐domain effect, MDE) were investigated by comparing them with observed, interpolated richness. Overall, models fitted very well for Geometridae as a whole and for Ennominae, but less well for Larentiinae. Small‐ranged species showed stronger deviations from model predictions than large‐ranged species, and differed strikingly between the two subfamilies, suggesting that environmental factors play a more pronounced role for small‐ranged species. We hypothesize that small‐ranged species (at least of the Ennominae) may tend to be host specialists, whereas large‐ranged species tend to be polyphagous. Based on interpolated ranges, mean elevational range for these moths was larger with increasing elevation, in accordance with Rapoport's elevational rule, although sampling effects may have exaggerated this pattern. The underlying mechanism remains unknown because Rapoport's ‘rescue’ hypothesis could not explain the observed pattern. Conclusions The results clearly show that moth diversity shows a hump‐shaped pattern. However, remarkable variation exists with regard to taxon and range size. Both environmental and geometric factors are likely to contribute to the observed patterns.     

A new species of Astyanax (Characiformes: Characidae) from Dolina Água Milagrosa,Rio Paraguai basin,Mato Grosso,Brazil

A new species of Astyanax is described from the upper Rio Paraguai basin, Mato Grosso State, Brazil. The new species can be distinguished from congeners by having the body intensely yellowish in life (v. silvery, reddish or lightly yellow) and by morphometric and meristics traits. Astyanax dolinae n. sp. cannot be assigned to any of the Astyanax species complex currently recognized for the genus. It is only known from the Dolina Água Milagrosa, a karstic sinkhole lake, entirely fed by groundwater, surrounded by Cerrado, the savannah‐like vegetation of central South America.     

镧对烟草愈伤组织和油菜幼根钙含量的影响

ＭＳ培养基中添加镧（Ｌａ）（０ ．０１ ～０ ．１０ｍ ｍｏｌ·Ｌ－ １） 培养烟草愈伤组织,其总Ｃａ２ ＋ 及原生质体Ｃａ２ ＋ 含量明显比对照（ 不加Ｌａ） 低;长时间（ 继代培养３０ｄ） 较短时间培养（ 悬浮培养２４ｈ） 低．低浓度（０ ．０１ ～０ ．０５１ｍｏｌ·Ｌ－ １）Ｌａ３ ＋ 使细胞壁中Ｃａ２ ＋ 含量高于对照并随浓度提高而增加,高浓度（０ ．１０１ｍｏｌ·Ｌ－ １） 则减少．与Ｃｅ２ ＋ 相比较,Ｌａ３ ＋ 的排Ｃａ２ ＋ 作用稍弱于Ｃｅ３ ＋ ．以不同浓度Ｌａ（ＮＯ３）３ 溶液浸种,油菜幼根总Ｃａ２ ＋ 及原生质体中Ｃａ２ ＋ 含量变化与上述类似．Ｌａ３ ＋ 使烟草愈伤组织褐化明显,生长量比对照低．     

Functional morphology of the postcranium and locomotor behavior of Neosaimiri fieldsi,a Saimiri-like Middle Miocene platyrrhine

A number of postcranial specimens of Neosaimiri fieldsi, a Middle Miocene platyrrhine, were discovered in 1988, 1989, and 1990 at La Venta, Colombia. Until recently only three postcranial specimens of this species had been discovered and the present material adds further information about this taxon's postcranial morphology. In overall skeletal dimensions and in postcranial features, Neosaimiri is most similar to Saimiri among extant medium-sized platyrrhines, but differs from Saimiri in having more rugose surface markings, a longer olecranon, a smaller anterior process of the distal tibia, an absence of a distal surface extension on the anterior tibial shaft, an absence of an anterior midtrochlear depression of the talus, and a shorter distal calcaneus relative to the calcaneal tuberosity. These differences suggest that Neosaimiri was relatively heavily built, possessed a more dominant forelimb in quadrupedal progression, and utilized a less stabilized upper ankle joint, and a shorter power arm for plantarflexion. Neosaimiri is interpreted as an arboreal quadruped with frequent leaping across arboreal gaps, as in extant Saimiri, with perhaps less frequent running and leaping than in Saimiri. As with the dentition, the postcranial specimens suggest the close relationship between Neosaimiri and extant Saimiri. Am J Phys Anthropol 102:515–544, 1997. © 1997 Wiley-Liss, Inc.     

Resolution of Trp near UV CD spectra of calmodulin-domain peptide complexes into the 1La and 1Lb component spectra

Near uv CD spectra of Trp residues in proteins frequently show a complex line shape deriving from the overlap of ¹L_a and ¹L_b electronic transitions. This study presents an original empirical method of resolving these components, based on the near uv CD spectra of well-defined complexes of calmodulin domains with target peptides containing a single Trp residue and derived from the skeletal muscle myosin light chain kinase target sequence. Spectra of 4 complexes were used to obtain the ¹L_a and ¹L_b component spectra that were then used to analyze further complexes. The broad and featureless ¹L_a spectrum is centered at 279 nm, the ¹L_b spectrum shows vibrational fine structure with maxima at 274.9, 281.5, and 289.8 nm. The CD spectrum of most complexes could successfully be fitted with one ¹L_a and one ¹L_b spectrum, the ¹L_b spectrum being negative for all complexes but the ¹L_a spectrum showing either positive or negative sign. Spectra of some complexes, however, failed to be adequately represented by only one ¹L_a and one ¹L_b spectrum. Instead, they could be fitted with one ¹L_b spectrum and two ¹L_a spectra with different sign and position. The method is successful in identifying and quantitating the relative intensities of a two-component system, consistent with a single conformation for tryptophan in a protein, and provides a simple indication of cases where a more complicated explanation is required. © 1998 John Wiley & Sons, Inc. Biopoly 45: 493–501, 1998     

La（NO3）3浸种对NaCl胁迫下红小豆幼苗生长的影响

采用向1／2Hoagland营养液中按一定比例添加中性盐（NaCl）模拟盐胁迫的方式,研究了h（NO3）,浸种对盐胁迫下红小豆（Phaseolus angularis）幼苗生长的影响。结果表明：（1）与对照组相比,盐胁迫不同程度地降低了红小豆幼苗的株高、叶面积、地上部分鲜重、总根数及根系活力、根苗SOD、POD、CAT活性等,明显增加了根苗MDA含量水平。（2）使用适当浓度的La（NO3）3浸种可以提高对照组和盐处理组红小豆的株高、叶面积、总根长、总根数、叶绿素、根活力及SOD、POD和CAT活性,也可以显著降低根苗MDA含量水平,且大多表现出在盐胁迫下变化幅度高于正常处理。La（NO3）3浸种有利于缓解盐胁迫带来的不良影响。（3）低浓度的La（NO3）3浸种处理能够提高红小豆幼苗的耐盐性,缓解盐胁迫伤害,而高浓度处理则加剧了盐胁迫伤害。30mg／L La（NO3）3浸种对提高红小豆幼苗耐盐性的效果最好。     

Tadpole Xenopus laevis hemoglobin. Correlation between structure and functional properties

Perutz & Brunori (1982) proposed that the COOH-terminal His and Ser F9 of the beta-chains of fish and amphibian hemoglobins are responsible for their Root effect and part of their alkaline Bohr effect. Analysis of the kinetics of carbon monoxide binding by hemoglobin from the tadpole of Xenopus laevis supports that model and suggests an explanation for the absence of an alkaline Bohr effect in many aquatic Anura and Urodela.     

NaHCO3胁迫下硝酸镧对黑麦草幼苗光合机构的保护作用

研究了150 mmol·L^-1NaHCO₃胁迫下,不同浓度硝酸镧对黑麦草幼苗光合作用、叶绿素荧光参数、Mehler反应,以及叶黄素循环的影响.结果表明：低浓度硝酸镧(0.05 mmol·L^-1)叶面喷施处理能显著减小NaHCO₃胁迫下黑麦草叶片净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、气孔限制值(L_s)的下降幅度和胞间CO₂浓度(C_i) 的上升幅度,有效缓解NaHCO₃胁迫对叶片PSⅡ光化学猝灭(q_P)、实际光化学效率(Φ_PSⅡ)、依赖光合碳同化电子传递(ETR_p)和依赖Mehler反应电子传递(ETR_m) 的抑制,增强黑麦草叶片中超氧化物歧化酶、过氧化物酶和抗坏血酸过氧化物酶的活性,提高非光化学能量耗散(NPQ)、叶黄素循环库(V+A+Z)和脱环氧化程度(A+Z)/(V+A+Z),从而减轻NaHCO₃胁迫对光合机构的伤害;但高浓度硝酸镧(0.5 mmol·L^-1)对NaHCO₃胁迫伤害的缓解效果不明显.表明适宜浓度的硝酸镧能够缓解NaHCO₃胁迫下非气孔因素引起的黑麦草叶片光合速率下降以及对光化学效率的抑制,并通过促进Mehler反应直接耗散过剩激发能和激活依赖叶黄素循环的热耗散,保护NaHCO₃胁迫引起的过剩光能对光合机构造成的伤害,而Mehler反应加强所产生的活性氧可被抗氧化酶活性的提高所清除.