Species diversity and habitat complexity: does vegetation organize vertebrate communites in the Great Basin?

In this study, we have examined the effect of vegetation structure on the three major vertebrate taxa in Great Basin habitats of southwestern Utah. The effect of increasing vegetation heterogeneity, both horizontally and vertically, on the diversities of lizards, rodents, and postbreeding birds was investigated. We found no statistically significant relationship between diversity of all animal taxa and horizontal vegetation heterogeneity, although lizard diversity tended to decrease with increasing heterogeneity and rodent diversity tended to increase. Bird species diversity was positively correlated with vertical habitat heterogeneity. Abundances were highest for rodents in pinyon/juniper habitat and highest for lizards and birds in areas with the highest grass cover. Species richness was highest in sagebrush habitat for rodents but highest for lizards and birds in pinyon/juniper. Evenness values were relatively similar and high for birds and rodents and were relatively high for lizards in all habitats except for pinyon/juniper, which had an evenness value of 0.38. For rodents and lizards, abundance was significantly correlated with the index for horizontal habitat heterogeneity. After logarithmic transformation, abundance of lizards was positively correlated with increasing vegetation complexity. Combined abundance of lizards and rodents was also positively correlated with vegetation complexity. Rodent and lizard abundances, however, were affected by different aspects of the habitat. After logarithmic transformation, lizard abundances increased significantly with increasing grass cover, whereas rodent abundances increased significantly with increasing shrub cover.     

The stream–lake ecotone: potential habitat for juvenile endangered June suckers ( Chasmistes liorus )

Potamodromous fish are poorly studied even though they are threatened often by human activities. The June sucker ( Chasmistes liorus ) is an endangered potamodromous species endemic to Utah Lake. Larval June suckers have not been collected from Utah Lake for at least 3 decades. Recruitment appears to be limited by low temperatures and scarce food, resulting in mass starvation of larval June suckers in the stream environment. We compared water temperature, zooplankton food availability, and small fish abundance in the stream and in 3 habitats along the stream&;ndash;lake ecotone (dense emergent vegetation, sparse emergent vegetation, and open lake) to test the hypothesis that all 3 factors would reach a maximum in the dense emergent vegetation of the stream&;ndash;lake ecotone. We used the abundance of fathead minnows in each habitat type as a surrogate for small fish like juvenile June suckers. We found that temperature, food, and fathead minnows reached their maximums in the open lake rather than in vegetated habitats of the stream&;ndash;lake ecotone. The stream had the lowest average temperatures (15.1 &;deg;C) and the lowest zooplankton concentrations (61 ? L &;ndash;1 ) over the growing season. Contrary to expectations, low temperatures (16.9 &;deg;C) and low food abundance (505 ? L &;ndash;1 ) also characterized the densely vegetated habitat, whereas the open lake had the highest temperatures (20.4&;deg; C) and highest concentrations of zooplankton (2353 ? L &;ndash;1 ). Restoration should include a mechanism to transport larval fish through the densely vegetated portion of the stream&;ndash;lake ecotone, which can be hundreds of meters wide, to the warm productive waters of the open lake. The braided planform of the terminal reaches of Hobble Creek should be replaced with shallow riffles to increase mean stream velocity and decrease the transport time of larval June suckers. Los peces potamodromos se han estudiado poco a pesar de que a menudo los amenazan las actividades humanas. El matalote junio ( Chasmistes liorus ) es una especie potamodroma en peligro de extinci&;oacute;n que es end&;eacute;mica del Lago Utah. Hace al menos tres d&;eacute;cadas que no se colectan matalotes larvales del Lago Utah. El reclutamiento parece estar limitado tanto por las temperaturas bajas como por la escasez de alimento, la cual causa una inanici&;oacute;n masiva de matalotes junio larvales en el h&;aacute;bitat fluvial. Comparamos la temperatura del agua, disponibilidad de zooplancton y abundancia de peces peque&;ntilde;os en el arroyo y en tres h&;aacute;bitats a lo largo del ecotono arroyo&;ndash;lago (vegetaci&;oacute;n semisumergida tupida, vegetaci&;oacute;n semisumergida escasa y el lago abierto) para comprobar la hip&;oacute;tesis de que los tres factores alcanzar&;iacute;an su m&;aacute;ximo en la vegetaci&;oacute;n semisumergida tupida del ecotono arroyo&;ndash;lago. Utilizamos la abundancia de la carpita cabezona en cada clase de h&;aacute;bitat como indicador indirecto de peces peque&;ntilde;os como los matalotes junio juveniles. Descubrimos que la temperatura, el alimento y las carpitas cabezonas alcanzaron sus niveles m&;aacute;ximos en el lago abierto y no en los h&;aacute;bitats con vegetaci&;oacute;n del ecotono arroyo&;ndash;lago. El arroyo tuvo las temperaturas promedio m&;aacute;s bajas durante la temporada de crecimiento (15.1 &;deg;C) y concentraciones bajas de zooplancton (61 ? L &;ndash;1 ). Al contrario de lo esperado, el h&;aacute;bitat de vegetaci&;oacute;n tupida tuvo temperaturas bajas (16.9 &;deg;C) y concentraciones bajas de alimento (505 ? L &;ndash;1 ), mientras que el lago abierto tuvo la temperatura m&;aacute;s alta (20.4 &;deg;C) y la mayor concentraci&;oacute;n de zooplancton (2353 ?&;nbsp; L &;ndash;1 ). La restauraci&;oacute;n de esta especie debe incluir alg&;uacute;n mecanismo para transportar los peces larvales a trav&;eacute;s de la parte de vegetaci&;oacute;n tupida del ecotono arroyo&;ndash;lago, la cual puede tener cientos de metros de ancho, a las aguas c&;aacute;lidas y m&;aacute;s productivas del lago abierto. Se debe reemplazar la forma trenzada de los tramos terminales de Hobble Creek con encalladeros para aumentar la velocidad promedio del arroyo y agilizar la traves&;iacute;a de los matalotes junio larvales.     

Cyanobacteria and cyanolichens: Can they enhance availability of essential minerals for higher plants?

In both field and greenhouse studies, cyanobacterial and cyanolichens of cold-temperature deserts often enhance growth and essential uptake by associated herbs. That effect is associated with better seedling establishment and larger seedlings. The following are possible mechanisms for these effects: (1) the microbiota concentrate essential elements in available forms in soil surface layers, (2) the microbial surface covers are usually darker colored than the soil itself and produce warmer soils during cool seasons when soil water is most available, (3) the gelatinous sheaths of several cyanobacterial genera common on alkaline deserts contain chelating compounds, and (4) conditions that favor persistent microbial growths on soil surfaces also favor maintenance of larger populations of microorganisms that form mycorrhizal and/or rhizosheath associations with seed plants. There is evidence that associated animals may be nutritionally benefited by the enhanced mineral content of forage plants growing in well-developed cyanobacterial crusts.     

New distribution records for the Querétero dusky rattlesnake Crotalus aquilus (Viperidae), with comments on morphology and habitat use

We provide the 1st documented accounts of the Mexican endemic rattlesnake Crotalus aquilus from the state of México. The new records extend the known distribution of the species into a region where it may be sympatric with the superficially similar C. triseriatus . Because these taxa have previously been subject to some taxonomic confusion, we performed a preliminary morphological comparison using individuals of both species obtained from proximal localities. Our analyses support the supposition that these taxa are morphologically distinct. The new localities for C. aquilus are situated in high valleys that have been extensively modified by human settlement and agriculture.     

The Eucerotinae: a Gondwanan origin for a cosmopolitan group of Ichneumonidae?

A new genus and species of the formerly monobasic and predominantly amphitropical, ichneumonid subfamily, Eucerotinae, is described from Chile. A phylogenetic analysis of the redefined Eucerotinae is undertaken. Barronia araucaria gen. et sp. n. has a sister-group relationship with Euceros. The southern hemisphere species of the latter genus were found to comprise a monophyletic clade, the sister group to all other Euceros species. Similarly all north temperate Euceros species form a monophyletic clade, the sister group of which occurs in Madagascar. Within the former clade, the North American species form a monophyletic group, the sister species of which is Palaearctic. Several other groups of Palaearctic taxa have a sister-group relationship to this lineage. These results suggest the Eucerotinae had an ancient origin on Gondwanaland in the lower Cretaceous, prior to the separation of the Indo-Madagascar terrane from the Australian-Antarctic-South American tectonic plate. We hypothesize the Palaearctic fauna colonized Eurasia following the impaction of India on to its southern margin, and that the North American fauna is derived from a single circum-polar dispersal from Eurasia. Our results do not support an earlier hypothesis that the Eucerotinae arose as hyperparasitoids of Symphyta. Evidence suggests the group arose as parasitoids of ophioniform ichneumonids attacking lepidopterous larvae feeding on gymnosperms or anemophilous angiosperm trees.     

Observations of water-flea Daphnia magna and avian fecalia in rock pools: is traditional natural history reporting still relevant for science?

Unexpected observation of freshwater invertebrate Daphnia magna in temporary rock pools on a small island off the Norwegian Atlantic coast confirms colonising ability, mediated through avian dispersal. Robust diapausal eggs of D. magna pass the gut of migrating geese and subsequently hatch in environments where such waterfowl forage and rest along migrating routes. The incubation experiment demonstrates that decomposing fecalia of geese constitute sufficient feed to support developing populations of D. magna in experimental oligotrophic conditions. The findings also show that D. magna is highly adapted for colonisation of temporary pools north of the Arctic Polar Circle, with excellent tolerance to low temperatures. Discussion part I relates the findings to published evidence on avian transport of invertebrate propagules, such as correlations between migration patterns of waterfowl and geographical patterns of aquatic invertebrate diversity. Discussion part II reflects on academic cultures, epistemological aspects of natural history reporting, the presence of a whale cadaver as an ecological indicator and the relevance of simple observation as a starting point for further discourse.     

Reptiles as principal prey? Adaptations for durophagy and prey selection by jaguar (Panthera onca)

We examined the evidence supporting the hypothesis that jaguars (Panthera onca) have morphological and behavioural adaptations to facilitate reptile predation. Jaguars’ head and bite features show adaptations to durophagy (consumption of hard-integumented prey) that are very unusual within the genus Panthera. These include: thick canines, well-developed head muscles and a fatal bite directed to braincase or nape. These characteristics have been previously considered an adaptation for the consumption of reptilian prey, whose thick integument poses a challenge to predation. Although causation of any trait as result of natural selection is hard to demonstrate with ecological evidence, its consequences can be suggested and predictions made. Here, through a review of the literature on jaguar predatory habits, we tallied the evidence for saurophagy against environmental characteristics correlated with jaguar predation on reptiles. We offer a new explanation for the presence of those traits, based on the selection patterns, prey abundances and main predation habits over the geographic range of the jaguar. We believe that these features allow jaguars to overcome dangerous and/or armoured prey by dispatching them rapidly through a bite to the head or nape. Reptile consumption is restricted to areas of high reptile abundance while dangerous or armoured prey is consistently preyed upon throughout the jaguar’s distribution, and selected even when their abundance is low. This questions the validity of the saurophagy hypothesis. We believe that these results are relevant to jaguar conservation and management, because some of the main prey species are severely threatened over their range, and because threatened reptiles are also consumed as prey.     

Biotic components of dung beetles (Insecta: Coleoptera: Scarabaeidae: Scarabaeinae) from Pantanal – Cerrado Border and its implications for Chaco regionalization

We use a panbiogeographical approach to determine the distribution pattern of dung beetles from a border region between Cerrado and Rondônia biogeographical provinces in Brazil. We constructed 54 individual tracks and 12 generalized tracks. The generalized tracks infer historical events that have happened in the past, highlighting the significant role of vicariant processes and their influence on the current distribution pattern of dung beetles from the Pantanal–Cerrado Border. The study region is a biogeographical node, including representatives from different biogeographic origins. Contrary to previous suggestions, the Scarabaeinae fauna of southern Rondônia province is not related to Amazonian fauna. Rather, it shows stronger connections with Chaco. Hence we suggest the inclusion of the southern part of the province of Rondônia, representing the Pantanal depression itself, as a new biogeographical district within Chaco province.     

Nearctic–Palaearctic relationships of black flies (Diptera: Simuliidae): chromosomal and morphological evidence for the Prosimulium magnum species group in Japan

The banding patterns of the polytene chromosomes of Prosimulium yezoense Shiraki from Japan are resolved relative to the standard map for the genus Prosimulium, revealing two unique fixed inversions and novel autosomal and sex-linked rearrangements. Diagnostic chromosomal and morphological criteria demonstrate that P. yezoense is a member of the Prosimulium magnum group. The species is transferred, with three additional species – P. apoina Ono, P. karibaense Ono, and P. sarurense Ono – from the Prosimulium hirtipes group to the P. magnum group, representing the first geographic record of the group outside North America. The P. magnum group is one of only a few insect taxa, and one of only two simuliid taxa, distributed exclusively in Japan and the Nearctic region.     

Diet comparison between rainforest and cave populations of Craugastor alfredi (Anura: Craugastoridae): does diet vary in contrasting habitats?

Information about interpopulational variation of diet is important for thoroughly understanding the ecological niche of a species, the possible attributes that have allowed it to live in different habitats and ecosystems (if it is the case) and the degree of dietary specialization. This study compared dietary composition and diversity, size of prey consumed and feeding intensity between two geographically proximate populations of Craugastor alfredi, inhabiting contrasting habitats: one located in a remnant tropical rainforest and the other population located within a cave entrance, in eastern Mexico. A total of 118 frogs (50 from rainforest and 68 from cave) were stomach-flushed and, from those, 86 had at least one prey item (42 from rainforest and 44 from cave). Consumption proportions of orthopterans differed between habitats, with frogs from the cave having higher importance values of this prey than frogs from the rainforest. Additionally, both dietary diversity and feeding intensity were higher in the rainforest population. It was concluded that the generalized diet of C. alfredi, besides the high consumption of orthopterans by the cave population, may have contributed to its success in cave entrances. Nonetheless, other non-feeding attributes like small body size, direct development and semiarboreality may also facilitate the use of rock crevices in caves for foraging and reproduction.     

Contrasting modes of handling moss for feeding and case‐building by the caddisfly Scelotrichia willcairnsi (Insecta: Trichoptera)

Final‐instar larvae of the microcaddisfly, Scelotrichia willcairnsi sp. nov. (Trichoptera: Hydroptilidae) were discovered feeding on a moss, Platyhypnidium muelleri in north‐eastern Queensland. Not only do the larvae feed on the moss, but their cases are constructed from fragments of moss leaves. Microscopic examination of larval guts and cases showed a total contrast in the angle at which the moss leaves are cut for each purpose: for cases the moss leaves are cut longitudinally, in parallel with the length of the cells, whereas for feeding the leaves are cut perpendicular to the leaf margin, across the cells, presumably an adaptation that releases the cell contents for digestion. The new caddisfly species is described based on the adult males. Scelotrichia willcairnsi represents the first Australian record of the South‐east Asian‐New Guinean Stactobiini genus Scelotrichia.     

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