Interspecific Association and Substrate Specificity in Tardigrades from Florida, Southeastern United States

The distribution of terrestrial tardigrades in the Gulf Coast states of the United States is poorly known. Only one species has been reported in Florida. In this study moss, liverwort, lichen and fern samples (47 identified species) from trees and shrubs were collected from all 67 Florida counties. These samples contained 20 species of tardigrade. All possible pairs of tardigrade species and tardigrade and substrate were tested for interspecific association. Only three significant negative and one positive interspecific association between tardigrades were detected. Evidence for substrate specificity was weak. Although some tardigrade species were significantly associated with mosses or foliose lichens in general, no significant association between a tardigrade species and a substrate species was detected.     

Genetic and morphologic variation of the Pecos assiminea,an endangered mollusk of the Rio Grande region,United States and Mexico (Caenogastropoda: Rissooidea: Assimineidae)

Assiminea pecos is an endangered species of amphibious gastropod that occupies four widely separated portions of the Rio Grande region in the southwestern United States (Pecos River basin) and northeastern Mexico (Cuatro Cienegas basin). Our statistical and discriminant function analyses of shell variation among the disjunct populations of this species indicate that Mexican specimens differ in their morphometry from those of the United States and can be diagnosed by several characters. We also analyzed variation in the mitochondrial genome by sequencing 658 bp of mitochondrial COI from populations of A. pecos, representatives of the other three North American species of Assiminea, and several outgroups. Our results indicated substantial divergence of the Mexican population of A. pecos, which was consistently depicted as a monophyletic unit nested within or sister to the shallowly structured group comprised of American members of this species. Consistent with our findings, we describe the Mexican population as a new species, which is provisionally placed in the large, worldwide genus Assiminea pending further study of the phylogentic relationships of the North American assimineids. Our molecular data suggest that the Rio Grande region assimineids, which are among the few inland members of the otherwise estuarine subfamily Assimineinae, diverged from coastal progenitors in the late Miocene, with subsequent Pleistocene vicariance of Mexican and American species perhaps associated with development of the modern, lower course of the Rio Grande. Handling editor: K. Martens     

Biotic regionalization and climatic controls in western North America

New methods of weather analysis accompanied by microhabitat ‘bioassays’ have been applied in several case studies to demonstrate effects of atmospheric processes on patterns of community composition and structure and potential species evolution. Average spatial and seasonal airmass dynamics which determine regional and elevational patterns of relative microhabitat favorability, were found to vary between a recent global warming trend (ca 1900 to 1940) and the subsequent global cooling trend (ca 1940 to 1970). These apparently systematic spatial and temporal shifts in weather were related to plant establishment patterns and community composition and structure. The proposed causal mechanisms function, in part, through regional shifts in microhabitat size. These effects are similar to larger scale, longer term shifts deduced from the late Quaternary fossil record. By modifying the spatial approach, month-to-month and year-to-year variability of weather has been examined for the last 130 years at individual points in southwestern North America. Three climatic regimes (the end of the Little Ice Age, the recent warming trend and the recent cooling trend) exhibited distinct year-to-year patterns of weather that can be related to the establishment of different kinds of plants (e.g., C₄ grasses versus C₃ shrubs). Oscillations between different temporal climatic regimes appear to promote the episodic establishment of different life forms, but not necessarily their local extinction. The two methods of weather analysis have been combined in a regional assessment of climatic controls of different biomes in space and time with a primary focus on the Chihuahuan desert. Natural ecotones between the Chihuahuan desert and neighboring biomes are clearly related to large scale airmass dynamics associated with seasonal oscillations in jetstream position. The weather patterns controlling ecotonal positions result from seasonal topographic influences on the general circulation of the atmosphere. The apparent stability of these patterns allows causal hypotheses of biogeographic dynamics and the evolution of physiological traits and life history characteristics.     

Variability of ecological and autotrophic host specificity in a mycoheterotrophic system: Pterospora andromedea and associated fungal and conifer hosts

Few studies of tripartite mycoheterotrophic systems have examined ecological specificity across broad geographic ranges or addressed autotrophic host specificity. Pterospora andromedea was selected as an ideal candidate to examine ecological specificity of a mycoheterotrophic system as it is widely distributed, has been shown to have high levels of symbiont specificity with Rhizopogon subgenus Amylopogon, and is found with several autotrophic hosts. Pairs of P. andromedea + Rhizopogon spp. samples were co-collected across North America and were sequenced using trnL and ITS, respectively. Bayesian phylogenetic reconstructions between the co-collected taxa were used to examine ecological specificity, and for subsequent tests for autotroph specificity. P. andromedea lineages exhibited both high specificity and relaxed specificity for fungal symbionts and autotrophic hosts across the geographic landscape under allopatric and sympatric conditions. This strong evidence for geographic mosaics of specificity in mycoheterotrophic systems is an important future consideration in determining the evolutionary ecology of mycoheterotrophs.     

A hierarchical classification of freshwater mussel diversity in North America

Aim North America harbours the most diverse freshwater mussel fauna on Earth. This fauna has high endemism at the continental scale and within individual river systems. Previous faunal classifications for North America were based on intuitive, subjective assessments of species distributions, primarily the occurrence of endemic species, and do not portray continent‐wide patterns of faunal similarity. The aim of this study is to provide an analytical portrayal of patterns of mussel diversity in a hierarchical framework that informs the biogeographical history of the fauna. Location The study considered the mussel fauna of North America from the Rio Grande system northwards. Methods Patterns of mussel faunal similarity in 126 river systems or lake watersheds across North America were examined. The dataset was developed from the literature and consisted of recent species presence/absence (282 species) in each drainage unit; subspecies were not included. Patterns of mussel diversity were examined with hierarchical cluster analysis, based on a pairwise distance matrix between all drainage units. Results Cluster analysis revealed 17 faunal provinces within four major faunal regions: Mississippian, Atlantic, Eastern Gulf and Pacific. The Mississippian Region dominates the North American fauna with 11 provinces, including five not recognized by previous classifications: Mississippi Embayment, Upper Mississippi, Great Plains, Ohioan and Pontchartrain–Pearl–Pascagoula. Within the Eastern Gulf Region (containing three provinces), the Escambia–Choctawhatchee Province is distinctive from the Apalachicolan Province, under which it was previously subsumed. Patterns of diversity in the Atlantic Region (two provinces) and Pacific Region (one province) were similar to previous classifications. Main conclusions The classification proposed in this study largely corroborates earlier schemes based on the occurrence of endemic species but identifies additional heterogeneity that reflects unique assemblages of widely distributed species. The study proposes a hierarchical structure that illustrates relationships among these provinces. Although some provinces in the Mississippian Region have high endemism, all Mississippian provinces share a group of widely distributed species. The Atlantic and Eastern Gulf regions have distinctive, endemic faunas suggesting limited past connectivity with the Mississippian Region. The Pacific Region is the most distinct fauna in North America and bears close affinity to the Eurasian mussel fauna.     

Non-native fishes and native species diversity in freshwater fish assemblages across the United States

The proliferation of non-native species in North American freshwater ecosystems is considered a primary threat to the integrity of native community structure. However, a general understanding of consistent and predictable impacts of non-native species on native freshwater diversity is limited, in part, because of a lack of broad-scale studies including data from numerous localities across multiple drainages. This study uses data from 751 localities collected during the United States Geological Survey (USGS) National Water Quality Assessment (NAWQA) program to examine the influence of non-native fish species on native freshwater fish assemblages across the United States. In general, no significant differences in native fish richness and diversity measures were detected between sites with only native species and sites containing non-native species. However, at sites with non-native species, the number of non-native species present was negatively correlated with native species richness and Shannon diversity and positively correlated with native evenness. Non-native piscivores were negatively correlated with native species richness and Shannon diversity and positively correlated with native evenness. Native piscivores were positively correlated with native richness and diversity and negatively correlated with native evenness at sites with only native species. Our results suggest that from a superficial perspective, native species richness and diversity are not different among sites with and without non-native species. However, when patterns of native species richness and diversity are examined at sites containing non-native species, correlations between non-native and native species richness and diversity imply the expected negative effect of invasive taxa. Additionally, non-native piscivores appear to have a significant negative effect on native taxa and possibly represent a novel selective force on naive native prey.     

Review of the species of Paratenetus Spinola inhabiting America,north of Mexico (Coleoptera,Tenebrionidae)

The North American (north of Mexico) species of the tenebrionid genus Paratenetus Spinola are reviewed and a key is presented for their identification. Five species are recognized, P. gibbipennis Motschulsky, P. fuscus LeConte, P. punctatus Spinola and two sp. n., P. exutus [type locality: Tabusintac, Nova Scotia] and P. texanus [type locality: Port Isabel, Cameron County, Texas]. Two syn. n. are proposed: P. cribratus Motschulsky, 1868 with P. gibbipennis Motschulsky, 1868 and P. crinitus Fall, 1907 with P. fuscus LeConte, 1850. A lectotype is selected for Paratenetus punctatus Spinola. A type species is designated for Storthephora Mäklin, 1875 (Storthephora denticollis Mäklin, 1875).     

Scolecophidia (Serpentes) of the Late Oligocene and Early Miocene,North America,and a fossil history overview

An abundant fossil record of the snake clade Scolecophidia exists in Europe; however, the minute snake is noticeably absent in reports about the North American Paleogene and Neogene. Presented here are four localities from Florida, USA, that contain scolecophidian remains older than the Pleistocene: Thomas Farm (late Early Miocene, Hemingfordian Land Mammal Age, LMA), Live Oak (Oligocene-Miocene transition, latest Arikareean LMA), White Springs 3B (late Arikareean LMA), and Brooksville 2 (Late Oligocene, middle Arikareean LMA). These remains extend their known existence by about 26 m.y. and are now the oldest reported scolecophidian remains in North America. Molecular evidence on extant scolecophidians concludes that these tiny snakes have a Gondwanan origin. Interestingly, the oldest record of a scolecophidian is from Europe (Belgium) and dates back to the middle Paleocene (MP 1–5). The earliest African record of the snake clade comes from the Paleocene-Eocene boundary in Morocco. The clade is apparently absent from Europe and Middle East deposits dating from the latest Eocene through to the latest Oligocene (MP 19–30) and to the Early Miocene (MN 4). A portion of this time is known as the booid ‘Dark Period’ which represents an apparent response to global aridization and cooling. Scolecophidians appear to re-emerge into the southern Eurasian record in the Early Miocene (MN 4) and become widely dispersed throughout Europe and Middle East. The fossil record of these minute snakes is largely absent in southern Asia and South America. It is possible that the current lack of a decent fossil scolecophidian record outside of Europe and Middle East is due mainly to a bias in the methodology to recover fossils; wet sieving sediments through < 1.0 mm mesh is needed to recover the minuscule vertebrae.     

Late Quaternary biomes of Canada and the eastern United States

Pollen data have been used to construct biome maps for today, 6000 ¹⁴C yr bp and 18,000 ¹⁴C yr bp for Canada and the eastern United States. The inferred modern biome distributions agree well with independent reconstructions of North American vegetation prior to European settlement. Some discrepancies between the pollen data and the modern potential vegetation are caused by post‐settlement clearing of the landscape and the consequent increase of herbaceous types in the recent pollen record. Biome distributions at 6000 ¹⁴C yr bp reflected the warmer and drier conditions then prevalent in the continental interior, but the overall position of biomes was similar to that of today. The boreal treeline in North America was not significantly north of its present position, in contrast to the 100–200 km shift reported for Siberia. At the last glacial maximum (18,000 ¹⁴C yr bp ), steppe and tundra were prevalent in the Midwest and north‐western Canada, and coniferous forests and woodlands grew in eastern North America. The open vegetation at 18,000 ¹⁴C yr bp was probably due to drier conditions and/or lower concentrations of atmospheric CO₂. The composition and physical structure of biomes is not constant over time. Mid‐Holocene biomes were similar in structure to those of today, but shifts in the relative importance of individual plant functional types are large enough that the physical properties of biomes, such as albedo, canopy conductance and surface roughness, are likely to have varied even during the Holocene. Last glacial maximum biomes were structurally different from their modern counterparts. The biome maps therefore may obscure significant vegetational changes in space and time during the late Quaternary. The difference between the highest and next highest affinity scores for each sample measures how strongly affinity scores discriminate among biomes. For many biomes, the difference is not large, and affinity score ties are not uncommon, highlighting the importance of tie‐break procedures when using the biomization method.     

北美洲药用植物

简介北美洲药用植物的总体情况,30种重要种类的产地、药用部位、活性成分、功效,以及常用种类的简要情况。     

New material of Pleistocene cats (Carnivora, Felidae) from Southern South America, with comments on biogeography and the fossil record

In this paper the systematic position and age of several Pleistocene cat remains found in southern South American are studied, in an attempt to more fully document the scarce record of the group and clear up their obscure Quaternary history. The fossils are compared with a large sample of recent specimens by means of qualitative and quantitative characters, as well as multivariate methods (discriminant analysis). The age of previous records is restricted using recent chronostratigraphic and biostratigraphic studies. Ly. colocolo is recorded in the late Ensenadan (0.78-0.5 Ma BP) and Bonaerian/Lujanian (0.5 Ma-8.5 Ka BP) ages of the Pampean Region (Argentina) and in the late Pleistocene or Holocene of Tierra del Fuego (Chile). An incomplete hemimandible found in the Bonaerian of the Pampean Region is referred to cf. Herpailurus and could be the earliest record of this lineage. Two other remains could belong to On. geoffroyi, but their incompleteness and some differences prevent their assignation to this recent species. The age of “Felis” vorohuensis is restricted to the late Ensenadan. The fossil record of the Ocelot Lineage is very fragmentary, but it is at least as old as late Ensenadan. Taphonomic biases are responsible for this poor fossil record and this fact could partially explain the hiatus with respect to the timing estimated by molecular divergence. The combination of data suggests that Ly. colocolo, On. guigna, On. geoffroyi and Oreailurus jacobita speciated in South America, supporting previous opinions. If the molecular divergence dates are right the recent diversity of this group could be explained by a minimum of five to six immigrations.     

Pseudaptinus (Thalpius) nobilis Liebke, new to the United States, and a key to the species of subgenus Thalpius LeConte in North America, including Mexico (Coleoptera, Carabidae, Zuphiini)

The Mexican carabid species Pseudaptinus (Thalpius) nobilis Liebke is documented from the United States for the first time based on two specimens captured in southeastern Texas. A new taxonomic key distinguishes the 10 members of subgenus Thalpius known in North America, including Mexico. Pseudaptinus (Thalpius) dorsalis, which is found to be highly variable in its dorsal coloration, is compared to similar Pseudaptinus (Thalpius) hoegei. Geographic ranges are extended for several species.     

Geographical patterns for relict and young species of birds in Africa and South America and implications for conservation priorities

By comparing geographical patterns of old and new species with historical and ecological processes, interpretations can be made about time patterns of diversification. Such interpretations can form a basis for developing rationales for ranking biodiversity conservation priorities. The results of the comprehensive study of avian DNA were used to compare geographical distributions in Africa and South America of species of strong Plio-Pleistocene radiations and species representing older monophyletic branches. Striking patterns, some of them overlooked so far, were found. Most old species are widespread across a physiognomic and climatic domain, such as lowland rainforests, and therefore, are not specific conservation targets. In contrast, new species have evolved in well defined places with a special local environment, in particular in ecologically equable places inside geologically complex ecotonal regions. High species richness and taxonomic diversity, where maintained over wide areas by steady habitat alteration through patch dynamics, may be easiest to protect by general reforms that integrate regional development and protection of ecosystem services, rather than by strictly site-oriented projects. Areas of active speciation, although small, may have important regulatory functions and a critical role for maintaining evolutionary fronts'. The Tropical Andes Region includes a dozen such places. There is a congruence between the occurrence of old species which have relictual distributions and aggregates of limited-range component species of recent vicariance patterns, indicating that vicariance events take place mainly by isolation in extremely ecologically stable areas. Although these places do not necessarily have the highest taxic diversity, they should be top priorities for rapid and concentrated conservation action.     

New species of Halicyclops (Copepoda Cyclopidae) from the United States of America

Two new species of Halicyclops, H. reidae and H. maculatus, are described from the groundwater and marsh sediment of Wye Island, Maryland. Halicyclops maculatus is the rst species of the genus to show sexual dimorphism in the males consisting of digitiform setae on the endopodite of swimming legs 1 and 2. Halicyclops reidae is the only American species of the genus having the inner distal seta of the leg 4 endopodite 3 plumose and the proximal seta spiniform.A key for identification of the Halicyclops species from North America is provided.     

北美地区一新外来入侵种——花曲柳窄吉丁

介绍了原产亚洲的北美地区的一种新的入侵种——花曲柳窄吉丁AgrilusplanipennisFairmaire的国内外研究进展,对该虫的分类地位、形态特征、分布与起源、寄主、生物学特性等进行了综述,提出了作为入侵种需要进一步研究的方向。     

中国与北美苔藓植物区系关系的探讨

关于中国和北美间苔藓植物区系关系的研究是在20世纪90年代开始的。研究表明中国和北美苔类和藓类的种间关系疏远,这一事实说明两个大陆在第三纪后期分离后,由于地质、地理、气候等因素的差异致使苔藓植物区系成分也产生明显分异。虽然它们在科、属方面差异较小,但两个大陆已各自形成地区特有的苔类和藓类的属。已知的中国特有及东亚特有的苔类属有5个,藓类属有22个;而已知北美地区特有的苔类属有4个、藓类属有5个。北美东部和西部形成于不同地质时期,在苔藓植物方面与中国共同分布的科、属和种存在一定差异。从神农架藓类植物研究表明,从共同分布的种来看,北美东部与中国比北美西部与中国的相似性系数高约6％。从两地区间苔类和藓类植物的雌雄同株或雌雄异株及孢子直径大小而论,这两个因素似乎并不是影响苔藓植物在两大地区间分布的主要原因,但对苔藓植物的分布仍然十分重要。本文作者认为结合中国和北美的地史、地理条件及苔藓植物自身的特点,可以认为白令海峡不是阻碍中国和北美苔藓植物交流的绝对自然屏障;中国和北美苔藓植物区系关系目前的状况,是长期多次交流融合和分异的结果。     

Tardigrades of South America: Machu Picchu and Ollantaytambo, Peru

During July 1999, a study group from the University of Kansas visited the ancient Inca ruins in and around Machu Picchu and Ollantaytambo, Peru. They collected lichens and mosses from the rock walls around the ruins. The samples contained four genera and six species of tardigrades. No associational patterns and relationships were detected. A new species, Echiniscus ollantaytamboensis nov. sp. is described.     

7. Tundra stream macroalgae of North America: composition, distribution and physiological adaptations

Eighty-three infrageneric taxa of stream macroalgae have been reported from tundra regions of North America, composed of 32 cyanobacteria, 35 Chlorophyta, 10 Chrysophyta and 6 Rhodophyta. There are few if any endemics represented in this flora. The most widespread species are the cyanobacteria Rivularia minutula, Nostoc commune and Tolypothrix tenuis as well as asexual populations of the chlorophyte genus Zygnema. The relative contribution of cyanobacteria compared to that of the Chlorophyta increases from the low to high arctic. Number of species per segment ranges from 0 to 7, with a mean of 2.8, and varies little between the low and high arctic. The percentage of stream bottom covered by macroalgae ranges from 0 to ca. 75%; mean cover values for low and high arctic streams are ca. 12 and 8%, respectively. Tundra macroalgae tend to be more abundant and diverse in less rigorously flowing stream sections. Most species tolerate prolonged freezing by forming resistant vegetative cells with thick walls, plentiful reserves and low molecular weight solutes to lower the freezing point. Many tundra stream macroalgae also produce ‘sunscreen’ pigments to reduce exposure to damaging radiation in the blue and ultraviolet regions. Nutrients tend to be low and phosphorus is often limiting in these systems. Arctic streams appear to differ from those of Antarctica in having potential grazers of macroalgae, such as the chironomid Diamesa, the mayfly Baetis and the caddisfly Brachycentrus.     

Holocene Human Footprints in North America

Reports of human footprints from North American archaeological sites are summarized and described. Although some human footprints have been claimed to be of Pleistocene and earlier ages, the earliest authenticated prints in America north of Mexico, as distinct from Central or South America, date to the Holocene. The earliest of these prints is at least 5,070 years old, and the youngest are late prehistoric period, only about 400 years old. Footprint sites are reported in the U.S. Southeast, Southwest, and California. Activities indicated by ancient North American human footprints include the mundane, such as daily tasks in a riparian zone and domestic behaviors inside a habitation. Footprints were also left by prehistoric peoples undertaking more esoteric activities deep in cave interiors, including exploration, mineral extraction, and ritual.