Zoogeography and life cycle patterns of Mediterranean hydromedusae (Gnidaria)

The distribution of the 346 hydromedusan species hitherto recorded from the Mediterranean is considered, dividing the species into zoogeographical groups. The consequences for dispersal due to possession or lack of a medusa stage in the life cycle are discussed, and related to actual known distributions. There is contradictory evidence for an influence of life cycle patterns on species distribution. The Mediterranean hydromedusan fauna is composed of 19.5% endemic species. Their origin is debatable. The majority of the remaining Mediterranean species is present in the Atlantic, with various world distributions, and could have entered the Mediterranean from Gibraltar after the Messinian crisis. Only 8.0% of the fauna is classified as Indo-Pacific, the species being mainly restricted to the eastern basin, some of which have presumably migrated from the Red Sea via the Suez Canal, being then classifiable as Lessepsian migrants. The importance of historical and climatic factors in determining the composition of the Mediterranean fauna of hydromedusae is discussed.     

2011年夏秋季南奥克尼群岛水域南极磷虾集群时空分布

基于2011年度夏秋季中国南极磷虾渔业科学观察员在大型拖网加工船“开欣轮”上收集的影像资料(作业水域为南奥克尼群岛周边海域,时间为2011年3月6日-4月21日),对该水域南极磷虾集群的时空分布特征进行了分析.结果表明:南极磷虾群在南奥克尼群岛西北部海域出现的次数较为集中,主要出现在60°00′S-60° 15′S,45 °30′W-46°30′W区域内;不同水层中,磷虾群主要呈块状分布,0～50 m和50 ～100 m水层集群类型极为相似(PSI=92.3),散点状、块状和带状磷虾群在0～50 m水层出现比例最高,且块状磷虾群和带状磷虾群在各水层中的分布极为相似(PSI=94.4);1:00-18:00南极磷虾群出现频率较高,随后比例开始下降,19:00-20:00出现频率最低.     

Flowering cycles of woody bamboos native to southern South America

Neotropical woody bamboos range from northern Mexico to southern Argentina and Chile. The most interesting aspect of bamboo biology is their flowering habit. The species that are the most intriguing are those that manifest a cyclic pattern of gregarious flowering after long vegetative periods. The flowering cycle has been described in very few species. The goal was to identify mass flowering events of woody bamboo species native to Argentina and neighboring areas, and to estimate the flowering cycle of each species. Sixteen species were surveyed: Chusquea culeou, C. deficiens, C. lorentziana, C. montana, C. quila, C. ramosissima, C. tenella, C. valdiviensis; Colanthelia rhizantha; Guadua chacoensis, G. paraguayana, G. trinii; Merostachys clausenii, M. multiramea, Rhipidocladum neumannii and R. racemiflorum. To reconstruct flowering dates, information from literature and herbarium collections was consulted and more than 990 records were gathered. Flowering cycles were estimated by recording the intervals between reported flowering events. Evidence of regular flowering cycles of ca. 30 years was found for most of the species considered. There is a remarkable concentration of flowering cycles about multiples of 15–16 years. Flowering synchrony among different species of woody bamboos was recorded for the first time in South America.     

Population dynamics, distribution patterns and life cycles of Neobisium muscorum and Chthonius orthodactylus (Pseudoscorpiones: Arachnida)

The population dynamics, life cycles and distribution patterns of Neobisium muscorum (Leach) and Chthonius orthodactylus (Leach) were studied over a two year period in a Chiltern beechwood site. The data obtained for the two species are compared, and the importance of pseudoscorpions in the beechwood community is discussed.     

Further perspectives on the breeding distribution of migratory birds: South American austral migrant flycatchers

1. Patterns of distribution of breeding austral migrant tyrant-flycatchers in temperate South America were quantified and analysed in conjunction with a variety of ecological, biogeographical and climatic variables.
2. The pattern of proportion of migratory to total breeding tyrannids was most strongly associated with latitude and two temperature variables, mean temperature of the coldest month and relative annual range of temperature.
3. The strong associations of latitude and temperature with percentage of migrants are consistent with the results of most similar investigations of the breeding distributions of migratory birds, both for migrants breeding in North America and in Europe, but contradict the hypothesis that habitat complexity plays a major role in structuring the proportion of migrants in communities of breeding birds.
4. The consistency of results among studies of migrants on different continents suggests that temperature and latitude, presumably a surrogate for one or more climatic variables, are globally significant factors in the breeding distributions of migratory birds.
5. The results for austral migrant flycatchers are consistent with the hypothesis that the prevalence of migration at any particular locality is ultimately dependent on the abundance of resources in the breeding season and the severity of the winter season, or on the difference in resource levels between summer and winter.     

Floristic distributional patterns in a diverse ecotonal area in South America

The Paraguayan territory and region, in the centre of South America, is a huge transition area with a succession of various vegetation types. However, this area has received little attention from researchers, with few works published on its flora and its delimitations. We aimed to identify the most important environmental driving forces and delimit floristic patterns in this region, since understanding the forces that drive floristic variations in this ecotonal region could help comprehend the distribution of vegetation not only in this region but throughout South America. We obtained 1234 tree species occurrence records, 205 geographic coordinates and 23 environmental variables and altitude from the ‘NeoTropTree’ database and verified the influence and contribution of environmental factors through variance partition. We tested the floristic consistency of the different vegetation types using dendrogram, indicator species and ordination analyses. We also constructed multiple linear models to check the correlation between species distribution and environmental variables. We found eight consistent vegetation types. The spatial variables coupled with environmental variables were more important than individual environmental or spatial variables. Among the environmental variables, the aridity index was the most important. Despite the importance of spatial factors, due to environmental heterogeneity, we found a gradient related to climate and edaphic variables related to tree flora. The results confirm that the Paraguayan territory and region can be considered to be a diversified and important ecotone area in South America with respect to tree flora.     

Biosystematics and distribution of simuliid vectors of human onchocerciasis in South America

A brief review is given of the taxonomic status, biology and medical importance, and distribution of the vectors of human onchocerciasis in Latin America. Key reference works are cited and distribution maps of each vector species in relation to the known onchocerciasis foci are given.     

Vertical migration and diel activity patterns of hydromedusae: studies in a large tank

Vertical distributions and swimming behaviors of 7 species ofhydromedusae (Aequorea victoria, Bougainvillia principis, Gonionemusvertens, Mitrocoma cellularia, Phialidium gregarium, Polyorchispenicillatus, and Stomotoca atra) were observed over 24-h periodsin a 2 m high, 1500 1 transparent tank. In this tank, most speciesperformed well-marked diel vertical migrations that were mediatedby swimming. Manipulation of the light regime showed the didswimming behaviors to be light-dependent rather than intrinsic,even in species that do not possess recognized photoreceptors.Correlations between vertical migration and spawning times forseveral species of medusae suggest that in cases when verticalmigration reduces the distances between individuals (e.g., inmass movements to the surface) just prior to spawning, enhancedfertilization success may result from such movements. ¹Present address: Friday Harbor Laboratories, Friday Harbor,WA 98250, USA.     

Potential geographical distribution of the red palm mite in South America

Among pests that have recently been introduced into the Americas, the red palm mite, Raoiella indica Hirst (Prostigmata: Tenuipalpidae), is the most invasive. This mite has spread rapidly to several Caribbean countries, United States of America, Mexico, Venezuela, Colombia and Brazil. The potential dispersion of R. indica to other regions of South America could seriously impact the cultivation of coconuts, bananas, exotic and native palms and tropical flowers such as the Heliconiaceae. To facilitate the development of efficacious R. indica management techniques such as the adoption of phytosanitary measures to prevent or delay the dispersion of this pest, the objective of this paper was to estimate the potential geographical distribution of R. indica in South America using a maximum entropy model. The R. indica occurrence data used in this model were obtained from extant literature, online databases and field sampling data. The model predicted potential suitable areas for R. indica in northern Colombia, central and northern Venezuela, Guyana, Suriname, east French Guiana and many parts of Brazil, including Roraima, the eastern Amazonas, northern Pará, Amapá and the coastal zones, from Pará to north of Rio de Janeiro. These results indicate the potential for significant R. indica related economic and social impacts in all of these countries, particularly in Brazil, because the suitable habitat regions overlap with agricultural areas for R. indica host plants such as coconuts and bananas.     

New intermediate hosts in the life cycle of Zygocotyle lunata in South America

Biomphalaria peregrina was found to be naturally infected with cercariae of Zygocotyle lunata in a pond of the Zoological Garden of Buenos Aires. Mice and chicks were fed metacercariae and gravid adults recovered. Eggs recovered from mice feces were used for experimental infections. Laboratory-reared B. peregrina and 4 other Biomphaluria spp. were successfully infected with Z. lunata miracidia. Biomphaleria glabrata was refractory. Species of Helisoma, the only intermediate hosts of Z. lunata so far reported, have never been found in Argentina. Species of Biomphalaria may be intermediate hosts of Z lunata in the southern region of the Parana River Basin.     

The pest termites of South America: taxonomy, distribution and status

Abstract: A total of 77 species of termites have been reported as structural or agricultural pests in South America. These records are reviewed, with indication of the damage they cause, their pest status, distribution and sources of information. Among these, 40 species are reported as structural pests, 53 species as agricultural pests and 15 species as both. However, only 18 species are considered major pests and the status of most of the others is uncertain. Uncertainty about status is much higher among agricultural pests. Specific taxonomic problems are discussed and distribution maps of the main pest genera and species are presented. The most important structural pests are the introduced Coptotermes havilandi and Cryptotermes brevis and the native Nasutitermes corniger. Reticulitermes was introduced into Uruguay and Chile, where it is the only serious pest. The main agricultural pests are Heterotermes spp., Nasutitermes spp., Cornitermes spp., Procornitermes spp. and Syntermes spp., and the most affected crops are sugarcane, upland rice and eucalyptus.     

Variation of thymidine incorporation patterns in the alternating vegetative and sexual life cycles of Chlamydomonas reinhardtii

The cellular distribution of thymidine kinase activities in Chlamydomonas reinhardtii, as manifested by the in vivo incorporation of exogenous thymidine and 5-bromodeoxyuridine into different DNA species, appeared to be organelle specific and varied with different developmental stages in the life cycle of this organism. During vegetative growth and gametogenic differentiation, thymidine and 5-bromodeoxyuridine were shown to be selectively incorporated into chloroplast but not nuclear DNA. On the other hand, during zygotic germination in which meiosis occurs and the ensuing vegetative divisions of meiotic products, thymidine as well as 5-bromodeoxyuridine were incorporated into both nuclear and chloroplast DNA. These results suggest that, in addition to the thymidine kinase activity that is constantly present in the chloroplast, a cytoplasmic thymidine kinase is derepressed only during the sexual reproductive cycle of C. reinhardtii.     

Observations on the distribution patterns,behaviour, diets and reproductive cycles of sand-dwelling clinids (Perciformes: Clinidae) from South Africa

Synopsis Twenty-two samples of sand-dwelling fishes were collected from sublittoral sandy substrata off the Cape Peninsula, South Africa using a novel quantitative technique in which the ichthyocide, rotenone, was introduced beneath 6.25 m² plastic sheets weighted around the perimeter with chain. A total of 94 fish of eight species and four families were recorded. Of these, four species of the family Clinidae made up 92% of the material. Fish densities varied from 0.10–2.96 fish m^–2 (0.17–1.14 g m^–2). Distribution patterns amongst the Clinidae were explained by sediment particle size, with all of the newly discovered species, Cancelloxus longior, inhabiting fine sand (median grain size 0.25–0.50 mm), and all Xenopoclinus leprosus, C. elongatus and Pavoclinus smalei occurring in gravel (> 1 mm). Xenopoclinus kochi was found in all sediment types, but was most abundant in coarse substrata. Diets of all four species were similar, consisting chiefly of amphipods and isopods. However, small differences in prey preference were evident. All four species reached sexual maturity at 25–30 mm standard length, were viviparous, exhibited superembryonation and gave birth to live young of approximately 14 mm. Breeding seasonality occurred in all species except P. smalei.     

Mesozooplankton distribution patterns and grazing impacts of copepods and Euphausia crystallorophias in the Amundsen Sea, West Antarctica, during austral summer

The rapid melting of glaciers as well as the loss of sea ice in the Amundsen Sea makes it an ideal environmental setting for the investigation of the impacts of climate change in the Antarctic on the distribution and production of mesozooplankton. We examined the latitudinal distribution of mesozooplankton and their grazing impacts on phytoplankton in the Amundsen Sea during the early austral summer from December 27, 2010 to January 13, 2011. Mesozooplankton followed a latitudinal distribution in relation to hydrographic and environmental features, with copepods dominating in the oceanic area and euphausiids dominating in the polynya. Greater Euphausia crystallorophias biomass in the polynya was associated with lower salinity and higher food concentration (chlorophyll a, choanoflagellates, and heterotrophic dinoflagellates). The grazing impact of three copepods (Rhincalanus gigas, Calanoides acutus, and Metridia gerlachei) on phytoplankton was low, with the consumption of 3 % of phytoplankton standing stock and about 4 % of daily primary production. Estimated daily carbon rations for each of the three copepods were also relatively low (<10 %), barely enough to cover metabolic demands. This suggests that copepods may rely on food other than phytoplankton and that much of the primary production is channeled through microzooplankton. Daily carbon rations for E. crystallorophias were high (up to 49 %) with the grazing impact accounting for 17 % of the phytoplankton biomass and 84 % of primary production. The presence of E. crystallorophias appears to be a critical factor regulating phytoplankton blooms and determining the fate of fixed carbon in the coastal polynyas of the Amundsen Sea.     

Mapping the observed and modelled intracontinental distribution of non-marine ostracods from South America

Ecological niche modelling (ENM) has been used to quantify the potential occurrence of species, by identifying the main environmental factors that determine the presence of species across geographical space. We provide a large-scale survey of the distribution of ostracod species in South America, by using the domains of 25 river basins. From 221 known ostracod species, we estimate the potential distribution of 61 species, using ENM. Ten clusters of potential distribution patterns were found. Clusters 8 and 9 grouped most of the species, which presented high similarity of niche between them. Heterocypris paningi Brehm, 1934 (group 1) obtained higher niche variability. The minimum temperatures of the coldest month and the mean elevation of the river basin were most important to predict the potential distribution of ostracods of most groups. South America has a complex pattern of elevation, which affects species distributions indirectly through changes in local factors. For instance, the Andes mountains might impose a barrier for ostracod distribution in the southern part of South America because of the low temperatures and precipitation. The ENM indicated that some regions and/or basins of South America might be susceptible to the entry of several ostracod species, presently absent, including non-native species.

     

Morphoprocess and life cycles of organisms

In developing the ideas of V.N. Beklemishev about an organism as a form, existing in a process of determined transformation and matter/energy exchange, we consider different aspects of the term "morphoprocess" and introduce corresponding additional terms. Momentary morphoprocess characterizes an organism in the given moment of time. This term reflects a constancy of the form ("momentary form"), where the existence of an organism can be imagined as a sequence of "momentary forms". "First derivative" of this momentary characteristic is particular morphoprocess--an organism from its origin to fission/division or death. Compound particular morphoprocess is a determined and reiterating sequence of different particular morphoprocesses. And, at last, general morphoprocess--a "second derivative" of momentary morphoprocess--is rhythmical reiteration of a particular morphoprocess on the long-term scale, an ancestors/descendants lineage. To describe consecutive changes in this material system, the terms ontogenesis and life cycle are used. Ontogenesis characterizes a sequence of the morpho-functional changes of an individual organism during its life, whereas life cycle reflects a sequence of changes during one complete segment of the general morphoprocess represented by a single or several particular morphoprocesses. We also discuss morphoprocess uniformity along with the phase nature of morphoprocesses, both particular and compound particular ones.     

The geographic ranges of mammalian species in South America: spatial patterns in environmental resistance and anisotropy

We analyse the geographical distribution of South American mammalian species using two biogeographic indices: environmental resistance (R ₅₀) and anisotropy (A₅₀). R₅₀ quantifies the loss of biotic resemblance occurring from any point in the map to the rest of the continent. A ₅₀ quantifies the extent to which the perimeter: area ratio of the geographical ranges of all species whose distributions overlap at any particular location depart from the perimeter: area ratio of a circle. We test for the latitudinal Rapoport effect that predicts an increase in the range-sizes of mammalian species, and hence a decrease in the values of R ₅₀, towards the south. We test for the effect of mountains on species’ ranges, given that Janzen's argument that ‘mountain passes are higher in the tropics’ implicitly predicts greater anisotropy in the tropics. Continental spatial patterns of variation in R ₅₀ and A₅₀ suggest a biogeographic division of South America consistent with most classical zoogeographical classifications proposed for the continent. Rapid change in mammalian range-sizes and shapes occurs at the limit between the Guayano-Brazilian and Andean-Patagonean subregions. R ₅₀ data do not support the latitudinal Rapoport effect: the most widespread species locate in the eastern portions of Brazil, the most restricted ones are in association with the Andes. A ₅₀ data support Janzen's prediction: the effect of mountains on species’ distributions is greater in equatorial and central regions of the Andes rather than in the south. R ₅₀-and A₅₀-contour maps reveal that, mainly due to the effects of the lie of the land and likely differences in the history of the fauna, the continent has a biogeographic texture which must have major constraints on local ecological patterns and processes. This stresses the importance of considering the role of biogeographic structure in the analyses of geographical gradients in species’ distributions.     

Out in the cold: genetic variation of Nothofagus pumilio (Nothofagaceae) provides evidence for latitudinally distinct evolutionary histories in austral South America

Nothofagus pumilio is the dominant and almost ubiquitous tree species in mountainous environments of temperate South America. We used two types of molecular markers (cpDNA and isozymes) to evaluate the effects of the Paleogene paleogeography of Patagonia and more recent climatic oscillations of the Neogene on such cold‐tolerant species’ genetic makeup. Phylogeographic analysis on sequences of three cpDNA non‐coding regions at 85 populations yielded two latitudinally disjunct monophyletic clades north and south of c. 42°S containing 11 and three haplotypes, respectively. This indicates a long‐lasting vicariant event due to the presence of an extended open paleobasin at mid latitudes of Patagonia. Also distribution patterns of cpDNA haplotypes suggest regional spread following stepping‐stone models using pre‐Cenozoic mountains as corridors. Comparable genetic diversity measured along 41 sampled populations using seven polymorphic isozyme loci provides evidence of local persistence and spread from multiple ice‐free locations. In addition, significantly higher heterozygosity and allelic richness at high latitudes, i.e. in areas of larger glacial extent, suggest survival in large and isolated refugia. While, higher cpDNA diversity in lower latitudes reflects the complex orogeny that historically isolated northern populations, lower isozyme diversity and reduced F_ST values provide evidence of local glacial survival in numerous small locales. Therefore, current genetic structure of N. pumilio is the result of regional processes which took place during the Tertiary that were enhanced by contemporary local effects of drift and isolation in response to Quaternary climatic cycles.