Behavior in the brachiopod Terebratulina septentrionalis (Couthouy)

The muscular contractions of the valves and the flow rate of inhalent currents in the brachiopod Terebratulina septentrionalis (Couthouy) have been directly and continuously monitored using a bead thermistor as the flow meter. Flow rate varied between individuals, with velocities reaching a maximum rate of 7 mm/sec. The flow rate of an individual was not constant: between adductions of the valves it increased gradually from zero to a peak velocity. A high average flow rate of up to 2 h duration alternated with low average velocities of longer duration. The variation in flow rate may be reflecting regulation of oxygen consumption. Intervals between adductions of the valves appeared to exhibit a fluctuating pattern of regularity. The sequence of adductions could not be correlated with elimination of feces, with tides, or with light factors. There was a ‘negative’ deflection of the flow curve resulting from heating of the thermistor bead in the initial flow in brachiopods which had been closed for 4 h or more: this type of deflection was also interspersed with normal inhalent flow in many specimens. Such negative deflections could be due to the erratic behavior of the thermistors or to metabolic activity.     

Low genetic diversity and contrasting patterns of differentiation in the two monotypic genera Halacsya and Paramoltkia (Boraginaceae) endemic to the Balkan serpentines

Halacsya and Paramoltkia are two monotypic genera of the Balkan ultramafic outcrops, both classified as paleoendemics. They show close phylogenetic relationship, similar ecology and partially sympatric range, but contrasting life-history traits, patterns of distribution and chromosomal features. We performed a study to compare their infraspecific genetic structure using AFLP fingerprinting. Within-population heterozygosity (H_S) and total heterozygosity (H_T) were lower in diploid H. sendtneri than in polyploid P. doerfleri (0.121 and 0.142 vs. 0.165 and 0.178, respectively). Number of polymorphic loci was also higher in the latter species. Halacsya showed significant levels of among-population variation (14.5%) and population differentiation (F_ST = 0.145), as well as a structuring in four main geographic groups connected by low gene flow. Combined with inability for long-distance dispersal, these data suggest that present-day range fragmentation in this species is the result of historical losses of intervening populations and support its status of paleoendemic surviving in refugial serpentine “islands”. Populations of P. doerfleri were instead genetically very close (F_ST = 0.049), and variation was partitioned almost exclusively among individuals (95.1%). Lack of population groupings and higher levels of gene flow suggested a single, panmictic group, fitting more a metapopulation than a “classical” paleoendemic model.     

Embryonic photoperiodic sensitivity in two species of fleshflies, Parasarcophaga similis and Boettcherisca septentrionalis

Embryonic photoperiodic sensitivity has been shown experimentally to exist in two species of larvipositing fleshflies, Parasarcophaga similis and Boettcherisca septentrionalis. The type of development of the puparia (with or without diapause) is determined by accumulated photoperiodic information which the larvae received during the final embryonic period of development and after emergence from the mother. The comparative importance of either of the two periods of ontogenesis differs with species, and depends on the sequence of alternate photoperiodic régimes. In the postembryonic period of development the first 10 days after the emergence of the larvae from the mother are the most important. The number of inductive photoperiodic cycles in different species of sarcophagids is compared.     

Early colonization of shallow subtidal boulders in two habitats

Intertidal and shallow subtidal boulder fields are relatively uncommon along the coast of New South Wales, Australia. Nevertheless, they provide habitat for a diverse suite of species, many of which are seldom found in other habitats. The types and abundances of animals found on or under boulders can be influenced by features of the boulders themselves, or by features of the substratum on which a boulder lies. Boulders can be colonized by larvae, or by adult or juvenile animals drifting in the water column or crawling up from the substratum. This experiment investigated the effect of an algal or sandy substratum on early stages of colonization of new boulders in two boulder fields by a suite of invertebrates, including gastropods, bivalves, chitons, polychaetes and insect larvae. Replicate times of three different periods (5, 18 and 38 days) tested for consistency of patterns of colonization at different times. Although the experiment was completed in a single season (within 2 months), there was considerable variation in patterns of abundances and diversity between replicate times. Thus, for each time in each period of a particular length, a different assemblage developed on the algal or sandy substratum in each boulder field. Despite this temporal variation, a few taxa showed some consistency of colonization among habitats, although most showed unpredictable patterns. The implications of these patterns of colonization for the creation or restoration of new intertidal and shallow subtidal boulder fields are discussed.     

Seed germination and seedling growth of two Pseudobombax species (Malvaceae) with contrasting habitats from Brazilian Cerrado

Pseudobombax tomentosum and P. longiflorum are common trees in the Cerrado region, but the former species is more common in forest edges while the later is present in open cerrado areas. This work aimed to investigate differences in seed germination and seedling growth in these species, from seed collected from Cerrado areas in Central Brazil. For this, a seed germination experiment was designed and included four replicates with 25 seeds per species; seeds were randomly distributed in the germination chamber. To evaluate initial seedling growth, seedlings height was measured up to 67 days after seedling emergence; besides, some of these seedlings were grown for biomass evaluation during nine months. Results showed that seeds of the two species had the same germinability (near 100%) and mean germination time (ca. 12 days). However, P. longiflorum showed a more spread seed germination through time, with higher values of coefficient of variation in germination time and uncertainty index; and lower values of synchronization than P. tomentosum. The two species showed basically the same growth pattern, but lower values for height of apical meristem, diameter of underground structures (mostly roots), dry mass of shoots, underground structure and total mass of seedlings in P. tomentosum were obtained, compared to P. longiflorum. Both species allocated more dry mass to underground structures in detriment of shoot. This probably allows resprouting behavior which prevents hydric stress and detrimental fire action typical of the open Cerrado areas.     

Tree species diversity and structure characters in the habitats of black-crested gibbons (Nomascus concolor)

Via the survey of 250 plots, tree species diversity and community structure were discussed in the habitats of black- crested gibbons, Wuliang Mountain, Yunnan, China. The research showed that (1) 111 tree species from 33 families and 23 lianas from 18 families were recorded in all, in which dominant families included Lauraceae, Magnoliaceae, Fagaceae, Theaceae and Ericaceae; (2) two forest vegetation types existed in the study area: the semi-humid evergreen broad-leaved forest and mid-mountain humid evergreen broad-leaved forest; (3) the diversity index declined with the rising of elevation in each forest vegetation; however, the evenness index showed degressive trend only in semi-humid evergreen broad-leaved vegetation; (4) the age structure of six dominant species revealed that the tree layer in the study area would increase stably.     

Zooplankton spatial patterns in two lakes with contrasting fish community structure

Horizontal and temporal patterns in crustacean zooplankton communities were analyzed in two small, oligotrophic lakes which were morphologically and chemically similar, but had contrasting fish communities. Ranger Lake was dominated by two bass species and the planktivores numbered < 25 ind. ha^–1. Mouse Lake had no large piscivores and planktivores numbered > 1200 ind. ha^–1. There were significant differences in the distribution of zooplankton taxa and size classes between sampling stations. In Ranger Lake, the smallest size classes were more abundant at the deeper stations and the larger individuals were more abundant at the shallower stations. In Mouse Lake, the smaller individuals were more common at the shallow stations and the larger individuals were more common at the deeper stations. These differences suggest medium scale patterns induced by vectorial forces, but modified by species specific migration patterns. We tested the hypothesis that horizontal heterogeneity should be influenced by planktivore density and found that none of the taxa showed significant between-lake differences in the variance-mean regressions. We also tested the hypothesis that larger taxa should be more heterogeneous and we found that cladocerans were more heterogeneous than copepods and nauplii. In terms of sampling methodology our data suggest that the between-station variability was so high that a single mid-lake sample would certainly lead to completely unacceptable errors in the estimation of population densities and biomasses.     

Inversion and allozyme polymorphism show contrasting patterns of microgeographical population structure in a natural population of Drosophila buzzatii from Argentina

Second chromosome inversions and genotypic frequencies at seven allozyme loci were determined in a natural population of the cactophilic species Drosophila buzzatii that uses as breeding sites the necrotic cladodes of the prickly pear Opuntia quimilo and the rotting stems of cardón, Trichocereus terschekii. Different processes govern the evolutionary fate of inversion and allozyme polymorphisms. A pattern of heterotic balance for inversions seems to be acting uniformly in each breeding site and could depend on different regimes of density‐dependent selection within cactus hosts. Patterns of variation of allozymes revealed significant heterogeneity in allele frequencies for Esterase‐1 (Est‐1) among O. quimilo rots and Aldehyde oxidase (Aldox) and Xanthine dehydrogenase (Xdh) among T. terschekii substrates and showed gene‐cactus effects only for Esterase‐2 (Est‐2). Consistent and significant excesses of homozygotes were detected at both the within‐rot and in the total population levels that could be accounted for by diversifying selection among individual breeding sites.     

Nectar production and carbohydrate composition across floral sexual phases: contrasting patterns in two protandrous Aconitum species (Delphinieae,Ranunculaceae)

In dichogamous species, it is necessary that pollinators are attracted both to male- and female-phase flowers in order to achieve effective cross-pollination. We investigated, over a two-year period, how nectar production and composition differs in protandrous flowers of Aconitum lycoctonum L. and Aconitum carmichaelii Debeaux, two species originating from different geographical regions. Flowers of A. carmichaelii secreted approx. 2.5-fold more nectar than flowers of A. lycoctonum. The nectar of A. carmichaelii was sucrose-dominant (87.6:9.5:2.9, sucrose:fructose:glucose), whereas sucrose-rich nectar, lacking glucose, occurred in A. lycoctonum (39.9:60.1, sucrose:fructose). Total sugar concentration was similar (53%, on average) in both species. These species also showed contrasting patterns in nectar production and composition between the floral sexual phases. On average, in A. carmichaelii, male-phase flowers produced 2.4-fold more nectar than female-phase flowers in the two years of study, and nectar was sucrose-dominant, irrespective of sexual phase. By contrast, nectar production in A. lycoctonum was biased towards the male phase in one year of study and towards the female phase in the other, and whereas nectar was sucrose-dominant during the male-phase, it was fructose-rich during the female phase, indicating sucrose re-absorption. Although the characteristics of nectar in these Aconitum species indicate pollination by bumblebees, it is possible that their biogeographical history, and not pollinator selection alone, is important in understanding the lack of glucose in A. lycoctonum nectar. Variability in nectar production and/or carbohydrate composition between sexual phases suggests indirectly that nectar traits complement each of the latter. Nevertheless, further research is required if we are to understand the significance of these disparities in pollination ecology, i.e. for promoting pollinator movements between flowers and plants in order to achieve cross-pollination and avoid inbreeding.     

Photosynthesis and photoinhibition of two green macroalgae with contrasting habitats

We evaluated light-related traits ofUlva pertusa Kjellman from the intertidal and upper subtidal zones, and ofUmbraulva japonica (Holmes) Bae & Lee (formerlyUlva japonica) within its upper growth limit of 10 m, in Korean coastal regions.U. pertusa showed significantly higher maximum photosynthetic rates, photosynthetic efficiency, saturating irradiances, and total pigment contents. However, green light-use efficiency at limiting irradiances was notably higher inU. japonica, possibly due to the presence of green light absorbing pigments like siphonaxanthin and siphonein. Non-enzymatic antioxidation capacity as determined by DPPH (α,α-diphenyl-β-picrylhydrazyl) radical scavenging rate was markedly higher inU. pertusa (50.49%) than inU. japonica (8.85%). Both species showed a substantial decrease in optimal photosystem (PS) II efficiency (F_v/ F_m) with increasing PAR doses despite the degree of photoinhibition being more marked inU. japonica. After 24 h in dim light,U. pertusa rapidly and almost fully recovered F_v/ F_m within an hour whileU. japonica exhibited slow and incomplete PSII recovery over the full recovery period. A significant depression in photosynthetic activity with monochromatic UV-B radiation was observed inU. japonica only, followed by slight recovery in dim light. Light use efficiency and high irradiance tolerance may be important ecological axes along which the niche separation of green foliose algae occurs in Korean coastal waters.     

Phenotypic plasticity to light of two congeneric trees from contrasting habitats: Brazilian Atlantic Forest versus cerrado (savanna)

The Brazilian Atlantic Forest is a typically multi-layer tropical forest, while cerrado (savanna) is a patchy habitat with different physiognomy. Despite these differences, both habitats have high light heterogeneity. Functional traits of Dalbergia nigra and D. miscolobium from the Atlantic Forest and cerrado, respectively, were evaluated under shade (25% of full sunlight) and full sunlight in a nursery experiment. We hypothesised that both species should benefit from high phenotypic plasticity in relation to light. Plasticity was estimated using the relative distance phenotypic index (RDPI). D. miscolobium had lower shoot growth under both light conditions, suggesting it has low competitive capacity in the forest environment, which could explain its limited ability to expand over areas of Atlantic Forest. The studied species exhibited photoprotection strategies under high light and improved light capture under low light. Stomatal conductance, ETR(max) (maximum electron transport rate), PPFD(sat) (saturating photosynthetically active photon flux density), chlorophyll and carotenoid content had higher RDPI than stem morphological traits. Although both species showed considerable phenotypic plasticity, D. miscolobium had higher RDPI for eight of 11 evaluated traits. This high plasticity could be one of the factors that explain the occurrence of this species in a wide range of environmental conditions, from open grassland to dense woodlands, and it could also reflect its adaptation to high light. D. nigra also had considerable plasticity and good growth performance in both shade and full sunlight, but its absence in areas of cerrado suggests that factors other than light limit its occurrence in these habitats.     

不同生境条件下四合木（Tetraena mongolicaMaxim.）种群结构特征

对天然分布区及不同生境内四合木种群的径级结构、年龄结构、冠幅结构、高度结构及空间结构特征进行了比较分析,运用静态生命表描述了四合木种群年龄结构动态变化规律,应用Clark-Evans的 R值法计算出四合木个体空间分布格局指标.结果表明:四合木种群径级、龄级与高度级结构均基本呈正态分布,冠幅级结构呈现出近乎指数型的衰减趋势;但不同生境的四合木种群因所处微环境各异,在径级、龄级、高度级、冠幅级结构上表现出一定差异.四合木种群的存活率随龄级的增大而降低,死亡率和消失率随龄级的增大而升高,其存活曲线接近于DeeveyⅠ型,表明该种群为下降种群.不同生境的四合木种群个体分布均不均匀,其空间分布为随机型.     

Phylogeography of the pantropical sea urchin Tripneustes: contrasting patterns of population structure between oceans

To understand how allopatric speciation proceeds, we need information on barriers to gene flow, their antiquity, and their efficacy. For marine organisms with planktonic larvae, much of this information can only be obtained through the determination of divergence between populations. We evaluated the importance of ocean barriers by studying the mitochondrial DNA phylogeography of Tripneustes, a pantropical genus of shallow water sea urchin. A region of cytochrome oxidase I (COI) was sequenced in 187 individuals from locations around the globe. The COI phylogeny agreed with a previously published phylogeny of bindin that barriers important to the evolution of Tripneustes are: (1) the cold water upwelling close to the tip of South Africa, (2) the Isthmus of Panama, (3) the long stretch of deep water separating the eastern from the western Atlantic, and (4) the freshwater plume of the Orinoco and the Amazon rivers between the Caribbean and the coast of Brazil. These barriers have previously been shown to be important in at least a subset of the shallow water marine organisms in which phylogeography has been studied. In contrast, the Eastern Pacific Barrier, 5000 km of deep water between the central and the eastern Pacific that has caused the deepest splits in other genera of sea urchins, is remarkably unimportant as a cause of genetic subdivision in Tripneustes. There is also no discernible subdivision between the Pacific and Indian Ocean populations of this genus. The most common COI haplotype is found in the eastern, central, and western Pacific as well as the Indian Ocean. Morphology, COI, and bindin data agree that T. depressus from the eastern Pacific and T. gratilla from the western Pacific are, in fact, the same species. The distribution of haplotype differences in the Indo-Pacific exhibits characteristics expected from a sea urchin genus with ephemeral local populations, but with high fecundity, dispersal, and growth: there is little phylogenetic structure, and mismatch distributions conform to models of recent population expansion on a nearly global scale. Yet, comparisons between local populations produce large and significant F(ST) values, indicating nonrandom haplotype distribution. This apparent local differentiation is only weakly reflected in regional divergence, and there is no evidence of isolation by distance in correlations between F(ST) values and either geographical or current distance. Thus, Tripneustes in the Indo-Pacific (but not in the Atlantic) seems to be one large metapopulation spanning two oceans and containing chaotic, nonequilibrium local variation, produced by the haphazard arrival of larvae or by unpredictable local extinction.     

Foraging behaviour of dormice Muscardinus avellanarius in two contrasting habitats.

Anatomical evidence suggests that the dormourse is a specialist feeder. Radio-tracking and direct observation confirm this, highly selective, arboreal feeding behaviour. Dormice choose flowers and fruits from a series of trees and shrubs as each becomes seasonally available. Deferred breeding and a high incidence of diurnal torper suggest that dormice experience food shortage in spring. In early summer, when flowering has ended, but fruits are not yet ripe, dormice may again suffer food shortage. At this time they appear to supplement their diet by taking insects, another high-quality food with cyclic availability. Although some tree species are particularly valuable to dormice, they may not be essential if alternatives exist. A spectrum of species which will ensure a continuum of differeing food supplies, within a small area, is essential. This im;plies a need for heterogeneous woodland structure. The implications for conversation management are discussed.     

北草蜥的交配行为

在围栏条件下,观测北草蜥(Takydromus septentrionalis)的交配过程,分析其行为模式,旨在建立北草蜥交配行为谱,探讨雄性交配成功率与个体特征的关系。北草蜥交配行为的一般模式为:雌雄接近→咬尾→咬腹→交媾。该行为过程的持续时间分别为0.53m、1.77m、0.47m和141.3m。所观察到的51对成功交配中,70%的配对为雄体>雌体,且雄体平均体长和体重显著大于配对雌体。雄体的交配成功率与其体长成正相关,但与头长、头宽、尾长、体重及体色均无显著相关性。     

Morphological integration and developmental progress during fish ontogeny in two contrasting habitats

SUMMARY Morphological integration can respond to environmental conditions, a response that may be dynamic through ontogeny. Among fishes, brook charrs ( Salvelinus fontinalis ) display a trophic polymorphism that makes it a good species for analyzing the ontogeny of morphological integration. To better understand the processes regulating variation and integration, we assess the ontogenetic dynamics of covariances and developmental progress for populations of S. fontinalis from two habitats that differ in water velocity; lake and stream. Geometric morphometrics and developmental progress were evaluated on 751 and 198 specimens, respectively. In both habitats, most ossification events occur before the transition from alevin to juvenile. This threshold defines two distinct periods. During the first period representing free-embryos and alevins, there are important shape changes and rapid ossification, integration tends to be relatively low and decreasing and the variance of shape drastically decreases. During the juvenile period, the rate of shape change decreases and the onset of ossification is nearly complete, plus integration increases and shape variance stabilizes. While we find two distinct developmental periods, we nonetheless find a notable stability underlying the ontogenetic dynamics of variability as well as gradual change in the structure of covariation within each habitat. Our results imply that the variability of juvenile body shape does not seem to retain signals of variability determined early in ontogeny and warrants caution in using juvenile as guides to the earlier causes of variability. Overall, this study highlights the difficulty of inferring causes of integration from studies of static covariance.