5,291 research outputs found
Characterization of spotted hyena, Crocuta crocuta microsatellite loci
We have isolated 10 polymorphic microsatellite loci in the spotted hyena,Crocuta crocuta.The loci displayed between eight and 14 alleles in a minimum of 12 individuals tested.
These loci will be used to investigate relatedness within social groups, the genetic structure of populations, sexual selection, and mate choice in spotted hyenas
Pleistocene hominins as a resource for carnivores. A c. 500,000-year-old human femur bearing tooth-marks in North Africa (Thomas Quarry I, Morocco)
In many Middle Pleistocene sites, the co-occurrence of hominins with carnivores, who both
contributed to faunal accumulations, suggests competition for resources as well as for living
spaces. Despite this, there is very little evidence of direct interaction between them to-date.
Recently, a human femoral diaphysis has been recognized in South-West of Casablanca
(Morocco), in the locality called Thomas Quarry I. This site is famous for its Middle Pleistocene
fossil hominins considered representatives of Homo rhodesiensis. The bone was
discovered in Unit 4 of the Grotte à Hominidés (GH), dated to c. 500 ky and was associated
with Acheulean artefacts and a rich mammalian fauna. Anatomically, it fits well within the
group of known early Middle Pleistocene Homo, but its chief point of interest is that the
diaphyseal ends display numerous tooth marks showing that it had been consumed shortly
after death by a large carnivore, probably a hyena. This bone represents the first evidence
of consumption of human remains by carnivores in the cave. Whether predated or scavenged,
this chewed femur indicates that humans were a resource for carnivores, underlining
their close relationships during the Middle Pleistocene in Atlantic Morocco
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Androgen-independent events in penile development in humans and animals.
The common view on penile development is that it is androgen-dependent, based first and foremost on the fact that the genital tubercle forms a penis in males and a clitoris in females. However, critical examination of the complex processes involved in human penile development reveals that many individual steps in development of the genital tubercle are common to both males and females, and thus can be interpreted as androgen-independent. For certain developmental events this conclusion is bolstered by observations in androgen-insensitive patients and androgen receptor mutant mice. Events in genital tubercle development that are common to human males and females include: formation of (a) the genital tubercle, (b) the urethral plate, (c) the urethral groove, (d) the glans, (e) the prepuce and (f) the corporal body. For humans 6 of 13 individual developmental steps in penile development were interpreted as androgen-independent. For mice 5 of 11 individual developmental steps were found to be androgen-independent, which were verified through analysis of androgen-insensitive mutants. Observations from development of external genitalia of other species (moles and spotted hyena) provide further examples of androgen-independent events in penile development. These observations support the counter-intuitive idea that penile development involves both androgen-independent and androgen-dependent processes
Preliminary assessment of illegal hunting by communities adjacent to the northern Gonarezhou National Park, Zimbabwe
Illegal hunting of wildlife is a major issue in today’s society, particularly in tropical ecosystems. In this study, a total of 114 local residents from eight villages located in four wards adjacent to the northern Gonarezhou National Park, south-eastern Zimbabwe were interviewed in 2009, using semi-structured questionnaires. The study aimed to answer the following questions: (i) what is the prevalence of illegal hunting and what are commonly used hunting methods? (ii) Which wild animal species are commonly hunted illegally? (iii) What are the main reasons for illegal hunting? (iv) What strategies or mechanisms are currently in place to minimize illegal hunting? Overall, 59% of the respondents reported that they saw bushmeat, meat derived from wild animals, and/or wild animal products being sold at least once every six months, whereas 41% of the respondents reported that they had never seen bushmeat and/or wild animal products being sold in their villages and/or wards. About 18% of the respondents perceived that illegal hunting had increased between 2000 and 2008, whereas 62% of the respondents perceived that illegal hunting had declined, and 20% perceived that it remained the same. Snaring (79%) and hunting with dogs (53%) were reportedly the most common hunting methods. A total of 24 wild animal species were reportedly hunted, with African buffalo (Syncerus caffer) (18%), Burchell’s zebra (Equus quagga) (21%), kudu (Tragelaphus strepsiceros) (25%) and impala (Aepyceros melampus) (27%) amongst the most targeted and preferred animal species. In addition, large carnivores, including spotted hyena (Crocuta crocuta) (11%), leopard (Panthera pardus) (10%) and African lion (Panthera leo) (8%), were reportedly hunted illegally. The need for bushmeat, for household consumption (68%), and raising money through selling of wild animal products (55%) were reported as being the main reasons for illegal hunting. Strengthening law enforcement, increasing awareness and environmental education, and developing mechanisms to reduce human-wildlife conflicts will assist in further minimizing illegal hunting activities in the Gonarezhou ecosystem
Aggression heuristics underlie animal dominance hierarchies and provide evidence of group-level social information
Members of a social species need to make appropriate decisions about who,
how, and when to interact with others in their group. However, it has been
difficult for researchers to detect the inputs to these decisions and, in
particular, how much information individuals actually have about their social
context. We present a new method that can serve as a social assay to quantify
how patterns of aggression depend upon information about the ranks of
individuals within social dominance hierarchies. Applied to existing data on
aggression in 172 social groups across 85 species in 23 orders, it reveals
three main patterns of rank-dependent social dominance: the downward heuristic
(aggress uniformly against lower-ranked opponents), close competitors (aggress
against opponents ranked slightly below self), and bullying (aggress against
opponents ranked much lower than self). The majority of the groups (133 groups,
77%) follow a downward heuristic, but a significant minority (38 groups, 22%)
show more complex social dominance patterns (close competitors or bullying)
consistent with higher levels of social information use. These patterns are not
phylogenetically constrained and different groups within the same species can
use different patterns, suggesting that heuristics use may depend on context
and the structuring of aggression by social information should not be
considered a fixed characteristic of a species. Our approach provides new
opportunities to study the use of social information within and across species
and the evolution of social complexity and cognition.Comment: Comments welcom
Usage of Specialized Fence-Gaps in a Black Rhinoceros Conservancy in Kenya
Fencing is increasingly used in wildlife conservation. Keeping wildlife segregated from local communities, while permitting wildlife access to the greater landscape matrix is a complex task. We investigated the effectiveness of specially designed fence-gaps on animal movement at a Kenyan rhinoceros conservancy, using camera-traps over a four-year period. The fence-gap design restricted the movement of black (Diceris bicornis) and white rhinoceroses (Ceratotherium simum simum) but permitted the movement of other species. We documented over 6000 crossing events of over 50 000 individuals which used the fence-gaps to enter or leave the conservancy. We recorded 37 mammal species and two species of bird using the fence-gaps. We conclude that this fence-gap design is effective at restricting rhinoceros movement and at permitting other wildlife movement into and out of the conservancy. We recommend that fenced-in rhinoceros conservancies that desire enhanced connectivity consider this fence-gap design to help re-connect their reserves to the outside landscape matrix while continuing to provide enhanced protection for their rhinoceroses
Grotta Romanelli (Southern Italy, Apulia). Legacies and issues in excavating a key site for the Pleistocene of the Mediterranean
Grotta Romanelli, located on the Adriatic coast of southern Apulia (Italy), is considered a key site for the Mediterranean Pleistocene for its archaeological and palaeontological contents. The site, discovered in 1874, was re-evaluated only in 1900, when P. E. Stasi realised that it contained the first evidence of the Palaeolithic in Italy. Starting in 1914, G. A. Blanc led a pioneering excavation campaign, for the first-time using scientific methods applied to systematic palaeontological and stratigraphical studies. Blanc proposed a stratigraphic framework for the cave. Different dating methods (C-14 and U/Th) were used to temporally constrain the deposits. The extensive studies of the cave and its contents were mostly published in journals with limited distribution and access, until the end of the 1970s, when the site became forgotten. In 2015, with the permission of the authorities, a new excavation campaign began, led by a team from Sapienza University of Rome in collaboration with IGAG CNR and other research institutions. The research team had to deal with the consequences of more than 40 years of inactivity in the field and the combined effect of erosion and legal, as well as illegal, excavations. In this paper, we provide a database of all the information published during the first 70 years of excavations and highlight the outstanding problems and contradictions between the chronological and geomorphological evidence, the features of the faunal assemblages and the limestone artefacts
An Adaptive Threshold in Mammalian Neocortical Evolution
Expansion of the neocortex is a hallmark of human evolution. However, it
remains an open question what adaptive mechanisms facilitated its expansion.
Here we show, using gyrencephaly index (GI) and other physiological and
life-history data for 102 mammalian species, that gyrencephaly is an ancestral
mammalian trait. We provide evidence that the evolution of a highly folded
neocortex, as observed in humans, requires the traversal of a threshold of 10^9
neurons, and that species above and below the threshold exhibit a bimodal
distribution of physiological and life-history traits, establishing two
phenotypic groups. We identify, using discrete mathematical models,
proliferative divisions of progenitors in the basal compartment of the
developing neocortex as evolutionarily necessary and sufficient for generating
a fourteen-fold increase in daily prenatal neuron production and thus traversal
of the neuronal threshold. We demonstrate that length of neurogenic period,
rather than any novel progenitor-type, is sufficient to distinguish cortical
neuron number between species within the same phenotypic group.Comment: Currently under review; 38 pages, 5 Figures, 13 Supplementary
Figures, 2 Table
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