oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Egocentric Path Integration Models and their Application to Desert Arthropods  [PDF]
Tobias Merkle,Martin Rost,Wolfgang Alt
Quantitative Biology , 2005,
Abstract: Path integration enables desert arthropods to find back to their nest on the shortest track from any position. To perform path integration successfully, speeds and turning angles along the preceding outbound path have to be measured continuously and combined to determine an internal {\em global vector} leading back home at any time. A number of experiments have given an idea how arthropods might use allothetic or idiothetic signals to perceive their orientation and moving speed. We systematically review the four possible model descriptions of mathematically precise path integration, whereby we favour and elaborate the hitherto not used variant of egocentric cartesian coordinates. Its simple and intuitive structure is demonstrated in comparison to the other models. Measuring two speeds, the forward moving speed and the angular turning rate, and implementing them into a linear system of differential equations provides the necessary information during outbound route, reorientation process and return path. In addition, we propose several possible types of systematic errors that can cause deviations from the correct homeward course. Deviations have been observed for several species of desert arthropods in different experiments, but their origin is still under debate. Using our egocentric path integration model we propose simple error indices depending on path geometry that will allow future experiments to rule out or corroborate certain error types.
Ecophysiology
Lüttge, Ulrich;Scarano, Fabio R.;
Brazilian Journal of Botany , 2004, DOI: 10.1590/S0100-84042004000100001
Abstract: an attempt to delineate rather than to precisely define what we mean by "ecophysiology" is based on a brief historical overview of what eventually led to development of instrumentation and sampling strategies for analyses that allow description of physiological performance in the field. these techniques are surveyed. ecophysiology originally is aut-ecology dedicated to the behaviour of individual plants, species or higher taxa, viz. "physiotypes", in particular habitats. examples of ecophysiological diversity are developed, which illustrate gradual merging with more integrative considerations of functions and dynamics of habitats or ecosystems, i.e. a trend of research towards physiological syn-ecology. the latter is exemplified by studies with comparisons of a variety of morphotypes and physiotypes within a given habitat or ecosystem and across a range of habitats or ecosystems. the high demand and complexity as well as the excitement of ecology and ecophysiology arise from the quest to cover all conditions of the existence of organisms according to ernst haeckel's original definition of "ecology".
Phylogeography of the Cactophilic Drosophila and Other Arthropods Associated with Cactus Necroses in the Sonoran Desert  [PDF]
Edward Pfeiler,Therese A. Markow
Insects , 2011, DOI: 10.3390/insects2020218
Abstract: Studies on the population genetics, phylogenetic relationships, systematics and evolution of arthropods that inhabit necrotic tissue of cacti in the Sonoran Desert of North America are reviewed. These studies have focused upon several species of insects (orders Diptera and Coleoptera) and arachnids (order Pseudoscorpiones). For most taxa studied, little genetic structure and high dispersal ability are found in populations inhabiting the mainland and Baja California peninsula regions of the Sonoran Desert, consistent with the availability of the rotting cactus microhabitat which is patchily distributed and ephemeral. There is evidence, however, that the Gulf of California, which bisects the Sonoran Desert, has played a role in limiting gene flow and promoting speciation in several taxa, including histerid beetles, whereas other taxa, especially Drosophila nigrospiracula and D. mettleri, apparently are able to freely cross the Gulf, probably by taking advantage of the Midriff Islands in the northern Gulf as dispersal “stepping stones”. Genetic evidence has also been found for historical population expansions dating to the Pleistocene and late Pliocene in several taxa. Overall, these studies have provided important insights into how arthropods with different life history traits, but generally restricted to a necrotic cactus microhabitat, have evolved in an environmentally harsh and tectonically active region. In addition, they suggest some taxa for further, and more detailed, hypothesis driven studies of speciation.
The Importance of Acacia Trees for Insectivorous Bats and Arthropods in the Arava Desert  [PDF]
Talya D. Hackett, Carmi Korine, Marc W. Holderied
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0052999
Abstract: Anthropogenic habitat modification often has a profound negative impact on the flora and fauna of an ecosystem. In parts of the Middle East, ephemeral rivers (wadis) are characterised by stands of acacia trees. Green, flourishing assemblages of these trees are in decline in several countries, most likely due to human-induced water stress and habitat changes. We examined the importance of healthy acacia stands for bats and their arthropod prey in comparison to other natural and artificial habitats available in the Arava desert of Israel. We assessed bat activity and species richness through acoustic monitoring for entire nights and concurrently collected arthropods using light and pit traps. Dense green stands of acacia trees were the most important natural desert habitat for insectivorous bats. Irrigated gardens and parks in villages and fields of date palms had high arthropod levels but only village sites rivalled acacia trees in bat activity level. We confirmed up to 13 bat species around a single patch of acacia trees; one of the richest sites in any natural desert habitat in Israel. Some bat species utilised artificial sites; others were found almost exclusively in natural habitats. Two rare species (Barbastella leucomelas and Nycteris thebaica) were identified solely around acacia trees. We provide strong evidence that acacia trees are of unique importance to the community of insectivorous desert-dwelling bats, and that the health of the trees is crucial to their value as a foraging resource. Consequently, conservation efforts for acacia habitats, and in particular for the green more densely packed stands of trees, need to increase to protect this vital habitat for an entire community of protected bats.
Ecophysiology of tropical tree crops: an introduction
DaMatta, Fábio M.;
Brazilian Journal of Plant Physiology , 2007, DOI: 10.1590/S1677-04202007000400001
Abstract: in this special issue, ecophysiology of major tropical tree crops, considered here on a broader sense and including species such as banana, cashew, cassava, citrus, cocoa, coconut, coffee, mango, papaya, rubber, and tea, are examined. for most of these crops, photosynthesis is treated as a central process affecting growth and crop performance. the crop physiological responses to environmental factors such as water availability and temperature are highlighted. several gaps in our database concerning ecophysiology of tropical tree crops are indicated, major advances are examined, and needs of further researches are delineated.
Viruses in reptiles
Ellen Ariel
Veterinary Research , 2011, DOI: 10.1186/1297-9716-42-100
Abstract: 1. Introduction2. Methods for working with reptilian viruses3. Reptilian viruses described by virus families3.1. Herpesviridae3.2. Iridoviridae3.2.1 Ranavirus3.2.2 Erythrocytic virus3.2.3 Iridovirus3.3. Poxviridae3.4. Adenoviridae3.5. Papillomaviridae3.6. Parvoviridae3.7. Reoviridae3.8. Retroviridae and inclusion body disease of Boid snakes3.9. Arboviruses3.9.1. Flaviviridae3.9.2. Togaviridae3.10. Caliciviridae3.11. Picornaviridae3.12. Paramyxoviridae4. Summary5. Acknowledgements6. Competing interests7. ReferencesThe etiology of reptilian viral diseases can be attributed to a wide range of viruses occurring across different genera and families. Thirty to forty years ago, studies of viruses in reptiles focused mainly on the zoonotic potential of arboviruses in reptiles and much effort went into surveys and challenge trials of a range of reptiles with eastern and western equine encephalitis as well as Japanese encephalitis viruses [1-3]. In the past decade, outbreaks of infection with West Nile virus in human populations and in farmed alligators in the USA have seen the research emphasis placed on the issue of reptiles, particularly crocodiles and alligators, being susceptible to, and reservoirs for, this serious zoonotic disease [4-7]. Although there are many recognised reptilian viruses, the evidence for those being primary pathogens is relatively limited. Transmission studies establishing pathogenicity and cofactors are likewise scarce, possibly due to the relatively low commercial importance of reptiles, difficulties with the availability of animals and permits for statistically sound experiments, difficulties with housing of reptiles in an experimental setting or the inability to propagate some viruses in cell culture to sufficient titres for transmission studies. Viruses as causes of direct loss of threatened species, such as the chelonid fibropapilloma associated herpesvirus and ranaviruses in farmed and wild tortoises and turtles, have re-focused attention bac
Viruses Infecting Reptiles  [PDF]
Rachel E. Marschang
Viruses , 2011, DOI: 10.3390/v3112087
Abstract: A large number of viruses have been described in many different reptiles. These viruses include arboviruses that primarily infect mammals or birds as well as viruses that are specific for reptiles. Interest in arboviruses infecting reptiles has mainly focused on the role reptiles may play in the epidemiology of these viruses, especially over winter. Interest in reptile specific viruses has concentrated on both their importance for reptile medicine as well as virus taxonomy and evolution. The impact of many viral infections on reptile health is not known. Koch’s postulates have only been fulfilled for a limited number of reptilian viruses. As diagnostic testing becomes more sensitive, multiple infections with various viruses and other infectious agents are also being detected. In most cases the interactions between these different agents are not known. This review provides an update on viruses described in reptiles, the animal species in which they have been detected, and what is known about their taxonomic positions.
Parasites in pet reptiles
Aleksandra Rataj, Renata Lindtner-Knific, Ksenija Vlahovi?, Ur?ka Mavri, Alenka Dov?
Acta Veterinaria Scandinavica , 2011, DOI: 10.1186/1751-0147-53-33
Abstract: Reptiles have become increasingly common domestic pets. While several reptile species sold as pet animals are bred in captivity, most of them are taken from the wild or are the offspring of wild-caught parents. Wildlife smuggling is on the increase. At the beginning of this century, illegal trade in endangered species had become the third in the world regarding to profit, close behind drugs and arms smuggling. Business may be even more remunerative for other two reasons: culinary specialities and traditional medicine drugs prepared from exotic animals. Further more, non-indigenous species can be found in our environment, upsetting delicate ecosystems eventually leading to the extinction of native species. Reptiles can also be interesting for their potential use in bioterrorism.Poor capture techniques, compounded by poor or inadequate shipping can kill many reptiles before they reach the pet stores. About 90% of wild-caught reptiles die in the first year of captivity because of physical trauma prior to purchasing or because their owners cannot meet their complex dietary and habitat needs. Reptiles are among the most inhumanely treated animals in the pet trade, because of their special needs for diets and habitats. For many species, the basic requirements for nutrition and housing are unknown, so pet reptiles are highly susceptible to metabolic diseases. In the wild, reptiles rarely come into contact with their own waste or uneaten food, which is a common occurrence in the captivity.The infestation with parasites plays an important role. Stressful life, concentration of animals and the presence of different species in a small living space actuate development, multiplication and spreading of parasites, which in nature live in cohabitation with their hosts. All these factors suppress the immune response in reptiles and increase the opportunity for viruses, bacteria, yeast and funguses to cause infections and consequent diseases. Reptiles may carry diseases, which can be
Observations on medically important arthropods in Brazil
Marsden, Philip D.;
Cadernos de Saúde Pública , 1993, DOI: 10.1590/S0102-311X1993000400012
Abstract: a brief review of some medically important arthropods in brazil is presented. it is sufficient to show that we must expand our training of biologists in this field if endemic diseases are to be controlled in the next decade.
Book Review: Ecotoxicology of Amphibians and Reptiles
Larry Kapustka
Phyllomedusa : Journal of Herpetology , 2010,
Abstract: A review of the book: Sparling, D. W., G. Linder, C. A. Bishop, and S. K. Krest. 2010. Ecotoxicology of Amphibians and Reptiles. Second Edition. CRC Press. xxv+916 pp.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.