Habitat Characteristics of Lowland Leopard Frogs in Mountain Canyons of Southeastern Arizona

Abstract: Many aquatic species in the arid southwestern United States are imperiled, persisting primarily in isolated, low-order streams that are increasingly vulnerable to stochastic disturbances. During 2003 and 2004, we surveyed 39 mountain canyons in southeastern Arizona, USA, for lowland leopard frogs (Rana yavapaiensis), a species that has declined in abundance and distribution across its range in the United States. We quantified habitat features at 2 spatial scales, canyon and pool, to identify features that distinguished sites inhabited by frogs from those uninhabited by frogs. Canyons inhabited by frogs had watersheds that averaged 8.1 km² larger (SE = 2.52), pools that averaged 37.8 m³ greater (9.30) in volume, gradients that averaged 4.1% (1.40%) less steep, and locations that averaged 3.2 km closer (1.06) to the nearest valley stream than did uninhabited canyons. Plunge pools inhabited by frogs averaged 13.5% (5.66%) more perimeter vegetation, 11.2% (5.34%) more canopy cover, and 1.9 (0.60) more refuges than uninhabited pools. In general, canyons that provided more perennial water during dry summer months and plunge pools that provided more bank heterogeneity were more likely to be inhabited by frogs. Conservation of lowland leopard frogs and other aquatic species that inhabit xeric systems in the southwestern United States depends principally on maintaining riparian ecosystems that provide habitat for these species and the adjacent uplands that influence the structure and function of these systems. Therefore, both riparian areas and their adjacent uplands must be managed to maintain habitat for organisms that inhabit these rare and diverse ecosystems.     

Mobility is related to species traits in noctuid moths

1. Mobility is important for the understanding of how species survive in fragmented landscapes and cope with increasing rates of habitat and climate change. However, mobility is a difficult trait to explore and is poorly known in most taxa. Species traits have been studied in relation to range shifts, extinction risks, and responses to habitat area and isolation, and have also been suggested as good estimators of mobility. Here we explore the relation between mobility and species traits in noctuid moths. 2. We sampled noctuid moths by an automatic light‐trap on an island far out in the Baltic Sea. We compared traits of the non‐resident species on the island with traits of a species pool of assumed potential migrants from the Swedish mainland. 3. Mobility was significantly related to adult activity period, length of flight period, and the interaction between host‐plant specificity and distribution area. Widely distributed host‐plant generalists were more mobile than host‐plant specialists with more restricted distribution, and species with an adult activity period in August to September moved to the island to a higher extent than species with an adult activity period in May to July. Our results remained qualitatively robust in additional analyses, after controlling for phylogeny and including all species recorded on the island, except for the trait ‘length of flight period’. 4. Our results highlight the importance of the relation between mobility and species traits. Noctuid moths with certain traits move over longer distances than earlier known. This finding is important to include when predicting range dynamics in fragmented and changing landscapes, and when conservation measures of species are devised.     

A new species of Acynodon (Crocodylia) from the upper cretaceous (Santonian–Campanian) of Villaggio del Pescatore,Italy

Abstract: The new species Acynodon  adriaticus is described on the basis of remains from the Santonian–Campanian of Villaggio del Pescatore (Trieste, NE Italy). This species differs in several cranial features from Acynodon  iberoccitanus, the only other Acynodon species whose cranial osteology is known in detail. The absence of maxillary and dentary caniniform teeth coupled with the presence of enlarged molariform teeth suggests that Acynodon probably fed on slowly moving hard‐shelled prey. Moreover, the new materials reveal for the first time the morphology of some postcranial elements of Acynodon: in particular, medial‐most paravertebral osteoderms that are characterized by two keels. A new cladistic phylogenetic analysis resolves the previously reported polytomy among the basal Globidonta: Acynodon is recognized as the most primitive globidontan. This genus may represent the geologically oldest known globidontan. The fact that Acynodon has been found only in Europe and that the outgroup of Globidonta, the Diplocynodontinae, is mainly known from Europe, suggests that globidontans may have originated in Europe and not in North America as previously supposed.     

Phylogenetic position of the trichomonad parasite of turkeys, Histomonas meleagridis (Smith) Tyzzer, inferred from small subunit rRNA sequence.

The phylogenetic position of the trichomonad, Histomonas meleagridis was determined by analysis of small subunit rRNAs. Molecular trees including all identified parabasalid sequences available in data bases were inferred by distance, parsimony, and likelihood methods. All reveal a close relationship between H. meleagridis, and Dientamoeba fragilis. Moreover, small subunit rRNAs of both amoeboid species have a reduced G + C content and increased chain length relative to other parabasalids. Finally, the rRNA genes from H. meleagridis and D. fragilis share a recent common ancestor with Tritrichomonasfoetus, which exhibits a more developed cytoskeleton. This indicates that Histomonas and Dientamoeba secondarily lost most of the typical trichomonad cytoskeletal structures and hence, do not represent primitive morphologies. A global phylogeny of parabasalids revealed significant discrepancies with morphology-based classifications, such as the polyphyly of most of the parabasalid families and classes included in our study.     

A CYAMODONTID PLACODONT (REPTILIA: SAUROPTERYGIA) FROM THE TRIASSIC OF SLOVENIA

Abstract: An isolated dentary bone from the Triassic of To?ko ?elo, near Ljubljana (Slovenia) is referred to the genus Cyamodus. It is the first record of a placodont from Slovenia. The specimen is late Ladinian or early Carnian in age, and is thus among the latest known representatives of the genus Cyamodus. The late survival of Cyamodus in the southern Alpine domain, while it disappeared from the Germanic Basin in the early Ladinian, is probably linked to the persistence of fully marine conditions in the southern part of its range, after environments had become less favourable to placodonts in the Germanic Basin with the advent of the Keuper facies.     

Morphological convergence during pregnancy among predator and nonpredator populations of the livebearing fish Brachyrhaphis rhabdophora (Teleostei: Poeciliidae)

Predation can drive morphological divergence in prey populations, although examples of divergent selection are typically limited to nonreproductive individuals. In livebearing females, shape often changes drastically during pregnancy, reducing speed and mobility and enhancing susceptibility to predation. In the present study, we document morphological divergence among populations of nonreproductive female livebearing fish (Brachyrhaphis rhabdophora) in predator and nonpredator environments. We then test the hypothesis that shape differences among nonreproductive females are maintained among reproductive females between predator and nonpredator environments. Nonreproductive females in predator environments had larger caudal regions and more fusiform bodies than females in nonpredator environments; traits that are associated with burst speed in fish. Shape differences were maintained in reproductive females, although the magnitude of this difference declined relative to nonreproductive females, suggesting morphological convergence during pregnancy. Phenotypic change vector analysis revealed that females in predator environments became more similar to females in nonpredator environments in the transition from nonreproductive to reproductive. Furthermore, the level of reproductive allocation affected shape similarly between predator environments. These results suggest a life‐history constraint on morphology, in which predator‐driven morphological divergence among nonreproductive B. rhabdophora is not maintained at the same level during pregnancy. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 104 , 386–392.     

Influence of aquatic macrophyte habitat complexity on invertebrate abundance and richness in tropical lagoons

1. Aquatic plants are a key component of spatial heterogeneity in a waterscape, contributing to habitat complexity and helping determine diversity at various spatial scales. Theoretically, the more complex a habitat, the higher the number of species present. 2. Few empirical data are available to test the hypothesis that complexity increases diversity in aquatic communities (e.g. Jeffries, 1993 ). Fractal dimension has become widely applied in ecology as a tool to quantify the degree of complexity at different scales. 3. We investigated the hypothesis that complexity in vegetated habitat in two tropical lagoons mediates littoral invertebrate number of taxa (S) and density (N). Aquatic macrophyte habitat complexity was defined using a fractal dimension and a gradient of natural plant complexities. We also considered plant area, plant identity and, only for S, invertebrate density as additional explanatory variables. 4. Our results indicate that habitat complexity provided by the different architectures of aquatic plants, significantly affects both S and total N. However, number of individuals (as a result of passive sampling) also helps to account for S and, together with plant identity and area, contributes to the determination of N. We suggest that measurements of structural complexity, measured through fractal geometry, should be included in studies aimed at explaining attributes of attached invertebrates at small (e.g. plant or leaf) scales.     

Gill Structure in Zebra Mussels: Bacterial-Sized Particle Filtration

SYNOPSIS. The filtration mechanics of the gill of the zebramussel, Dreissena polymorpha, allow this organism to captureparticles less than 1 µm. The organization of gill cirriand the architecture of the cirri appear to be important inproviding the organism with the ability to filter small particles.Bacteria may provide a useful nutrient source for these animalsas bacterial proteins can be digested and assimilated into musselproteins. Laboratory experiments indicate that D. polymorphais capable of filtering and assimilating a wide range of bacteriaranging in size from 1–4 µm. Unionid species appearto be at least an order of magnitude less efficient at filteringbacteria than D. polymorpha. Because of its relatively smallergill size, C. fluminea also filters bacteria less efficientlythan D. polymorpha. We suggest that bacterial utilization byfreshwater mussel species has important population and evolutionaryimplications.