The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Joseph I Hoffman - One of the best experts on this subject based on the ideXlab platform.

  • extreme natal philopatry in female antarctic fur seals arctocephalus gazella
    Mammalian Biology, 2012
    Co-Authors: Joseph I Hoffman, Jaume Forcada
    Abstract:

    Natal philopatry is an important component of mammalian behaviour but is difficult to study in natural vertebrate populations due to the requirement for long-term individual-based spatial observations. Consequently, we quantified fine-scale patterns of natal philopatry in an intensively studied colony of Antarctic fur seals (Arctocephalus gazella), where a scaffold walkway allows individual locations to be measured to the nearest metre. Using subcutaneous PIT tags, we tracked the early life histories of 335 females born within the colony, of which 38 were resighted as breeding adults. We found that individual females returned to as little as one body length (2 m) of their birth locations. Moreover, distances between natal and pupping sites were not correlated with female age, but instead tended to decrease with the number of seasons an individual was sighted ashore. This suggests that breeding experience may be a better predictor than age of the ability of females to occupy preferred sites within fur seal colonies.

  • genetic analysis of twinning in antarctic fur seals arctocephalus gazella
    Journal of Mammalogy, 2009
    Co-Authors: Joseph I Hoffman, Jaume Forcada
    Abstract:

    Twinning in natural pinniped populations is often inferred from observations of suckling behavior, but this approach has been criticized because nonfilial nursing occurs at high frequencies in many seal species. Consequently, we used 9 highly polymorphic microsatellite markers to examine the parentage of 11 putative pairs of twins in Antarctic fur seals (Arctocephalus gazella) breeding at Bird Island, South Georgia. Only 3 pairs (27%) were found to be genuine twins, indicating that suckling observations are an unreliable means of identifying twins in this species. All of the twins were female; 1 pair was monozygotic and the other 2 were dizygotic. Using a strict exclusion approach, paternity was assigned to the monozygotic but not the dizygotic twins. However, likelihood tests revealed that, of the latter, 1 pair was significantly more likely to be full siblings against the null of half sibship suggesting shared paternity, whereas the other pair was more likely to be half siblings against the null of full sibship indicating probable multiple paternity. Our results provide novel insights into the reproductive ecology of fur seals and also support an earlier study showing that molecular genetic analysis can provide an effective means of validating field observations of pinniped twins.

  • permanent genetic resources ten novel polymorphic dinucleotide microsatellite loci cloned from the antarctic fur seal arctocephalus gazella
    Molecular Ecology Resources, 2008
    Co-Authors: Joseph I Hoffman, Kanchon K Dasmahapatra, Hazel J Nichols
    Abstract:

    Ten new dinucleotide microsatellite loci were isolated from the Antarctic fur seal Arctocephalus gazella. These markers should prove useful for studying the reproductive ecology of Antarctic fur seals and other related pinniped species.

  • ten novel dinucleotide microsatellite loci cloned from the galapagos sea lion zalophus californianus wollebaeki are polymorphic in other pinniped species
    Molecular Ecology Notes, 2006
    Co-Authors: Joseph I Hoffman, Sebastian Steinfartz, Jochen B W Wolf
    Abstract:

    We isolated and characterized 10 novel dinucleotide microsatellite loci from the Galapagos sea lion (Zalophus californianus wollebaeki) and tested their amplification utility in four further otariid species (Zalophus californianus californianus, Arctocephalus gazella, Arctocephalus australis and Eumetopias jubatus) and three phocid species (Hydrurga leptonyx, Halichoerus grypus and Phoca vitulina). All of the loci amplified polymorphic polymerase chain reaction (PCR) products in at least three species other than the Galapagos sea lion. These markers will be useful for studies of pinniped mating systems, genetic structure and genetic diversity.

Eva V. Bärmann - One of the best experts on this subject based on the ideXlab platform.

  • a morphometric and genetic framework for the genus gazella de blainville 1816 ruminantia bovidae with special focus on arabian and levantine mountain gazelles
    Zoological Journal of the Linnean Society, 2013
    Co-Authors: Torsten Wronski, Eva V. Bärmann, Saskia Börner, Dirk Erpenbeck, Gertrud E. Rössner, Hannes Lerp, Beatriz Azanza, Gert Wörheide
    Abstract:

    Gazella is one of the most species-rich genera within horned ruminants. Despite overall similarity in body size and morphology, gazelles show variability in coloration and horn morphology. Unfortunately, however, species differentiation based on these characters, or on discrete skull characters, is very difficult due to high intraspecific variability. Furthermore, most species have fragmented and allopatric distributions, so that species boundaries were hard to define in the past. Mitochondrial DNA sequences have proven useful for investigating gazelle taxonomy in recent years, but especially for old museum material, i.e. type specimens, destructive sampling is often impossible. We provide a comprehensive morphometric framework for the genus Gazella based on linear skull measurements reconciled with results from molecular phylogenetic analysis based on the largest dataset available so far. In particular for males, the skull morphology shows interspecific differences concurrent with DNA data and provides a reliable tool for species identification. Based on morphometric data we synonymize G. karamii with G. marica, and confirm the identification of the G. arabica and G. a. rueppelli type skulls from analyses of mitochondrial DNA sequences. © 2013 The Linnean Society of London

Rafael De La Madrid - One of the best experts on this subject based on the ideXlab platform.

  • on the inconsistency of the bohm Gadella theory with quantum mechanics
    Journal of Physics A, 2006
    Co-Authors: Rafael De La Madrid
    Abstract:

    The Bohm–Gadella theory, sometimes referred to as the time asymmetric quantum theory of scattering and decay, is based on the Hardy axiom. The Hardy axiom asserts that the solutions of the Lippmann–Schwinger equation are functionals over spaces of Hardy functions. The preparation–registration arrow of time provides the physical justification for the Hardy axiom. In this paper, it is shown that the Hardy axiom is incorrect, because the solutions of the Lippmann–Schwinger equation do not act on spaces of Hardy functions. It is also shown that the derivation of the preparation–registration arrow of time is flawed. Thus, Hardy functions neither appear when we solve the Lippmann–Schwinger equation nor should they appear. It is also shown that the Bohm–Gadella theory does not rest on the same physical principles as quantum mechanics, and that it does not solve any problem that quantum mechanics cannot solve. The Bohm–Gadella theory must therefore be abandoned.

Susana Pedraza-díaz - One of the best experts on this subject based on the ideXlab platform.

Torsten Wronski - One of the best experts on this subject based on the ideXlab platform.

  • dark grey gazelles gazella cetartiodactyla bovidae in arabia threatened species or domestic pet
    Hystrix-italian Journal of Mammalogy, 2017
    Co-Authors: Torsten Wronski, Hannes Lerp, Eva Verena Baermann, Thomas M Butynski, Martin Plath
    Abstract:

    True gazelles (genus Gazella) are a prime example of a mammalian group with considerable taxonomic confusion. This includes the descriptions of several dark grey taxa of questionable validity. Here, we examined captive dark grey putative Neumann’s gazelle Gazella erlangeri. Our concerted efforts to retrieve mitochondrial sequence information from old museum specimens of two dark grey gazelles, putative G. erlangeri and putative Muscat gazelle G. muscatensis, were unsuccessful. We did, however, find the mtDNA haplotypes of extant putative G. erlangeri to be nested within the haplotype variation of the Arabian gazelle G. arabica. The observed population genetic divergence between G. arabica and putative G. erlangeri (based on 11 nuclear microsatellites) was driven by genetic impoverishment of putative G. erlangeri. These results, along with morphological signatures of domestication (e.g., reduced brain case size), suggest genetic bottle necks and domestication effects as a consequence of prolonged captive breeding. Three hypotheses are discussed: (a) G. erlangeri and/or G. muscatensis are valid species but are now extinct; (b) one or both taxa represent phenotypic variation within G. arabica and, therefore, are synonyms of G. arabica; and (c) captive stocks, exhibiting the effects of domestication and inbreeding, are the sources for the descriptions of G. erlangeri and G. muscatensis. As concerns the conservation of gazelles, based on current knowledge, we strongly advise against using putative G. erlangeri for any introduction initiative but recommend the continued captive management of putative G. erlangeri.

  • a morphometric and genetic framework for the genus gazella de blainville 1816 ruminantia bovidae with special focus on arabian and levantine mountain gazelles
    Zoological Journal of the Linnean Society, 2013
    Co-Authors: Torsten Wronski, Eva V. Bärmann, Saskia Börner, Dirk Erpenbeck, Gertrud E. Rössner, Hannes Lerp, Beatriz Azanza, Gert Wörheide
    Abstract:

    Gazella is one of the most species-rich genera within horned ruminants. Despite overall similarity in body size and morphology, gazelles show variability in coloration and horn morphology. Unfortunately, however, species differentiation based on these characters, or on discrete skull characters, is very difficult due to high intraspecific variability. Furthermore, most species have fragmented and allopatric distributions, so that species boundaries were hard to define in the past. Mitochondrial DNA sequences have proven useful for investigating gazelle taxonomy in recent years, but especially for old museum material, i.e. type specimens, destructive sampling is often impossible. We provide a comprehensive morphometric framework for the genus Gazella based on linear skull measurements reconciled with results from molecular phylogenetic analysis based on the largest dataset available so far. In particular for males, the skull morphology shows interspecific differences concurrent with DNA data and provides a reliable tool for species identification. Based on morphometric data we synonymize G. karamii with G. marica, and confirm the identification of the G. arabica and G. a. rueppelli type skulls from analyses of mitochondrial DNA sequences. © 2013 The Linnean Society of London

  • cross infection with gastro intestinal tract parasites between domestic goat and endemic farasan gazelle gazella gazella farasani in farasan islands saudi arabia
    Journal of King Saud University - Science, 2013
    Co-Authors: Ann Apio, Sawsan A. Omer, Osama B. Mohammed, Torsten Wronski
    Abstract:

    Abstract Host related variations in helminth egg and coccidian oocyst counts were compared between a naturally infected endemic population of Farasan gazelle and domestic goats on the Farasan Islands, Saudi Arabia in April 2009. Both bovid species inhabit and browse in the same area but no cross-infection could be detected. The prevalence and mean intensity quantified as the number of eggs and oocysts per gram of faeces were taken as a measure of parasite burdens. Host related differences in prevalence values of Eimeria spp. were significantly higher in domestic goats than in wild gazelles. A similar trend was observed for nematode prevalence (strongyle-type eggs), with no infection in gazelle and low infection in goats. There was also a significant difference in mean intensity values between different Eimeria spp. found in domestic goats.

  • camera trapping confirms the persistence of arabian gazelles gazella arabica in the asir mountains saudi arabia
    Zoology in The Middle East, 2012
    Co-Authors: Ahmed Boug, Zafarul M Islam, Abdullah Al Shehry, Torsten Wronski
    Abstract:

    Abstract Arabian Gazelles, Gazella arabica, are increasingly threatened by hunting and habitat destruction, and since 2001 no confirmed observations have been reported from the Asir Mountains, a previously known area of occurrence. This study presents camera trapping images of Arabian Gazelles captured in Wadi Tarj, and confirms the persistence of this species in the proposed protected area for the first time since 1997. Images were analysed regarding habitat, time of day, group composition and activity of captured individuals. Moreover, the photographs were used to determine the species/subspecies of the gazelles encountered and are viewed in the light of the disputed taxonomy of Mountain/Arabian Gazelles.

  • A phylogeographic framework for the conservation of Saharan and Arabian Dorcas gazelles (Artiodactyla: Bovidae)
    Organisms Diversity & Evolution, 2011
    Co-Authors: Hannes Lerp, Torsten Wronski, Markus Pfenninger, Martin Plath
    Abstract:

    Many species of gazelles ( Gazella spp.) are nowadays threatened by hunting, poaching, habitat loss and habitat deterioration. Conservation efforts for this group not only face the problem of maintaining remnant populations, but often natural populations have been extirpated from the wild. In some cases, though, captive breeding programs exist that might provide a valuable source for future reintroductions. A major problem in this context is that phylogeographic relationships among different (potentially locally adapted) populations, and even basic phylogenetic relationships between species, are poorly understood, thus hampering the assignment of management units, breeding groups or stocks for reintroduction projects. Our present study focused on Dorcas gazelles ( G. dorcas and G. saudiya ) from the species’ entire distribution range, with samples originating from western Saharan Africa into Saudi Arabia. In stark contrast to previous studies reporting on pronounced genetic structure in taxa such as Mountain gazelles ( G. gazella ), we detected low genetic diversity and no evidence for major phylogenetic lineages when analyzing two mitochondrial genetic markers. Using a coalescent approach we infer a steep population decline that started approximately 25,000 years before present and is still ongoing, which coincides with human activities in Saharan Africa. Our phylogenetic analyses, statistical parsimony network analysis and inferred colonization patterns shed doubt on the validity of various described subspecies of G. dorcas .