| Records |
Author  |
Young, H.P. |
| Title |
The dynamics of social innovation |
Type |
Journal Article |
| Year |
2011 |
Publication |
Proceedings of the National Academy of Sciences |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
108 |
Issue |
Supplement 4 |
Pages |
21285-21291 |
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10.1073/pnas.1100973108 |
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Equine Behaviour @ team @ |
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5940 |
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| Author |
Weisbecker, V.; Goswami, A. |
| Title |
Brain size, life history, and metabolism at the marsupial/placental dichotomy |
Type |
Journal Article |
| Year |
2010 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
107 |
Issue |
37 |
Pages |
16216-16221 |
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| Abstract |
The evolution of mammalian brain size is directly linked with the evolution of the brain's unique structure and performance. Both maternal life history investment traits and basal metabolic rate (BMR) correlate with relative brain size, but current hypotheses regarding the details of these relationships are based largely on placental mammals. Using encephalization quotients, partial correlation analyses, and bivariate regressions relating brain size to maternal investment times and BMR, we provide a direct quantitative comparison of brain size evolution in marsupials and placentals, whose reproduction and metabolism differ extensively. Our results show that the misconception that marsupials are systematically smaller-brained than placentals is driven by the inclusion of one large-brained placental clade, Primates. Marsupial and placental brain size partial correlations differ in that marsupials lack a partial correlation of BMR with brain size. This contradicts hypotheses stating that the maintenance of relatively larger brains requires higher BMRs. We suggest that a positive BMR–brain size correlation is a placental trait related to the intimate physiological contact between mother and offspring during gestation. Marsupials instead achieve brain sizes comparable to placentals through extended lactation. Comparison with avian brain evolution suggests that placental brain size should be constrained due to placentals’ relative precociality, as has been hypothesized for precocial bird hatchlings. We propose that placentals circumvent this constraint because of their focus on gestation, as opposed to the marsupial emphasis on lactation. Marsupials represent a less constrained condition, demonstrating that hypotheses regarding placental brain size evolution cannot be generalized to all mammals. |
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Equine Behaviour @ team @ |
Serial |
5338 |
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Warmuth, V.; Eriksson, A.; Bower, M.A.; Barker, G.; Barrett, E.; Hanks, B.K.; Li, S.; Lomitashvili, D.; Ochir-Goryaeva, M.; Sizonov, G.V.; Soyonov, V.; Manica, A. |
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Reconstructing the origin and spread of horse domestication in the Eurasian steppe |
Type |
Journal Article |
| Year |
2012 |
Publication |
Proceedings of the National Academy of Sciences |
Abbreviated Journal |
Proc Natl Acad Sci U S A |
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Despite decades of research across multiple disciplines, the early history of horse domestication remains poorly understood. On the basis of current evidence from archaeology, mitochondrial DNA, and Y-chromosomal sequencing, a number of different domestication scenarios have been proposed, ranging from the spread of domestic horses out of a restricted primary area of domestication to the domestication of numerous distinct wild horse populations. In this paper, we reconstruct both the population genetic structure of the extinct wild progenitor of domestic horses, Equus ferus, and the origin and spread of horse domestication in the Eurasian steppes by fitting a spatially explicit stepping-stone model to genotype data from >300 horses sampled across northern Eurasia. We find strong evidence for an expansion of E. ferus out of eastern Eurasia about 160 kya, likely reflecting the colonization of Eurasia by this species. Our best-fitting scenario further suggests that horse domestication originated in the western part of the Eurasian steppe and that domestic herds were repeatedly restocked with local wild horses as they spread out of this area. By showing that horse domestication was initiated in the western Eurasian steppe and that the spread of domestic herds across Eurasia involved extensive introgression from the wild, the scenario of horse domestication proposed here unites evidence from archaeology, mitochondrial DNA, and Y-chromosomal DNA. |
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Equine Behaviour @ team @ |
Serial |
5612 |
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| Author |
Ward, A.J.W.; Sumpter, D.J.T.; Couzin, I.D.; Hart, P.J.B.; Krause, J. |
| Title |
Quorum decision-making facilitates information transfer in fish shoals |
Type |
Journal Article |
| Year |
2008 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
105 |
Issue |
19 |
Pages |
6948-6953 |
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Despite the growing interest in collective phenomena such as “swarm intelligence” and “wisdom of the crowds,” little is known about the mechanisms underlying decision-making in vertebrate animal groups. How do animals use the behavior of others to make more accurate decisions, especially when it is not possible to identify which individuals possess pertinent information? One plausible answer is that individuals respond only when they see a threshold number of individuals perform a particular behavior. Here, we investigate the role of such “quorum responses” in the movement decisions of fish (three-spine stickleback, Gasterosteus aculeatus). We show that a quorum response to conspecifics can explain how sticklebacks make collective movement decisions, both in the absence and presence of a potential predation risk. Importantly our experimental work shows that a quorum response can reduce the likelihood of amplification of nonadaptive following behavior. Whereas the traveling direction of solitary fish was strongly influenced by a single replica conspecific, the replica was largely ignored by larger groups of four or eight sticklebacks under risk, and the addition of a second replica was required to exert influence on the movement decisions of such groups. Model simulations further predict that quorum responses by fish improve the accuracy and speed of their decision-making over that of independent decision-makers or those using a weak linear response. This study shows that effective and accurate information transfer in groups may be gained only through nonlinear responses of group members to each other, thus highlighting the importance of quorum decision-making. |
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10.1073/pnas.0710344105 |
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no |
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Equine Behaviour @ team @ |
Serial |
5252 |
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Uzawa, T.; Akiyama, S.; Kimura, T.; Takahashi, S.; Ishimori, K.; Morishima, I.; Fujisawa, T. |
| Title |
Collapse and search dynamics of apomyoglobin folding revealed by submillisecond observations of alpha-helical content and compactness |
Type |
Journal Article |
| Year |
2004 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
101 |
Issue |
5 |
Pages |
1171-1176 |
| Keywords |
Animals; Apoproteins/*chemistry; Circular Dichroism; Cytochromes c/chemistry; Horses; Myoglobin/*chemistry; *Protein Folding; *Protein Structure, Secondary; Scattering, Radiation |
| Abstract |
The characterization of protein folding dynamics in terms of secondary and tertiary structures is important in elucidating the features of intraprotein interactions that lead to specific folded structures. Apomyoglobin (apoMb), possessing seven helices termed A-E, G, and H in the native state, has a folding intermediate composed of the A, G, and H helices, whose formation in the submillisecond time domain has not been clearly characterized. In this study, we used a rapid-mixing device combined with circular dichroism and small-angle x-ray scattering to observe the submillisecond folding dynamics of apoMb in terms of helical content (f(H)) and radius of gyration (R(g)), respectively. The folding of apoMb from the acid-unfolded state at pH 2.2 was initiated by a pH jump to 6.0. A significant collapse, corresponding to approximately 50% of the overall change in R(g) from the unfolded to native conformation, was observed within 300 micros after the pH jump. The collapsed intermediate has a f(H) of 33% and a globular shape that involves >80% of all its atoms. Subsequently, a stepwise helix formation was detected, which was interpreted to be associated with a conformational search for the correct tertiary contacts. The characterized folding dynamics of apoMb indicates the importance of the initial collapse event, which is suggested to facilitate the subsequent conformational search and the helix formation leading to the native structure. |
| Address |
Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo, Kyoto 615-8510, Japan |
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English |
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0027-8424 |
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PMID:14711991 |
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no |
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Equine Behaviour @ team @ |
Serial |
3779 |
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Sol, D.; Duncan, R.P.; Blackburn, T.M.; Cassey, P.; Lefebvre, L. |
| Title |
Big brains, enhanced cognition, and response of birds to novel environments |
Type |
Journal Article |
| Year |
2005 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
102 |
Issue |
15 |
Pages |
5460-5465 |
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The widely held hypothesis that enlarged brains have evolved as an adaptation to cope with novel or altered environmental conditions lacks firm empirical support. Here, we test this hypothesis for a major animal group (birds) by examining whether large-brained species show higher survival than small-brained species when introduced to nonnative locations. Using a global database documenting the outcome of >600 introduction events, we confirm that avian species with larger brains, relative to their body mass, tend to be more successful at establishing themselves in novel environments. Moreover, we provide evidence that larger brains help birds respond to novel conditions by enhancing their innovation propensity rather than indirectly through noncognitive mechanisms. These findings provide strong evidence for the hypothesis that enlarged brains function, and hence may have evolved, to deal with changes in the environment. |
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10.1073/pnas.0408145102 |
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Equine Behaviour @ team @ |
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4739 |
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Seyfarth, R.M.; Cheney, D.L. |
| Title |
What are big brains for? |
Type |
Journal Article |
| Year |
2002 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
99 |
Issue |
7 |
Pages |
4141-4142 |
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Animals; Brain/*anatomy & histology; *Intelligence; Learning; Primates/*anatomy & histology/*psychology; Social Behavior |
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Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA. seyfarth@psych.upenn.edu |
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0027-8424 |
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PMID:11929989 |
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no |
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refbase @ user @ |
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692 |
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Sebilo, M.; Mayer, B.; Nicolardot, B.; Pinay, G.; Mariotti, A. |
| Title |
Long-term fate of nitrate fertilizer in agricultural soils |
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Journal Article |
| Year |
2013 |
Publication |
Proceedings of the National Academy of Sciences |
Abbreviated Journal |
PNAS |
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Increasing diffuse nitrate loading of surface waters and groundwater has emerged as a major problem in many agricultural areas of the world, resulting in contamination of drinking water resources in aquifers as well as eutrophication of freshwaters and coastal marine ecosystems. Although empirical correlations between application rates of N fertilizers to agricultural soils and nitrate contamination of adjacent hydrological systems have been demonstrated, the transit times of fertilizer N in the pedosphere–hydrosphere system are poorly understood. We investigated the fate of isotopically labeled nitrogen fertilizers in a three–decade-long in situ tracer experiment that quantified not only fertilizer N uptake by plants and retention in soils, but also determined to which extent and over which time periods fertilizer N stored in soil organic matter is rereleased for either uptake in crops or export into the hydrosphere. We found that 61–65% of the applied fertilizers N were taken up by plants, whereas 12–15% of the labeled fertilizer N were still residing in the soil organic matter more than a quarter century after tracer application. Between 8–12% of the applied fertilizer had leaked toward the hydrosphere during the 30-y observation period. We predict that additional exports of 15N-labeled nitrate from the tracer application in 1982 toward the hydrosphere will continue for at least another five decades. Therefore, attempts to reduce agricultural nitrate contamination of aquatic systems must consider the long-term legacy of past applications of synthetic fertilizers in agricultural systems and the nitrogen retention capacity of agricultural soils. |
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Equine Behaviour @ team @ |
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5730 |
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Scheffer, M.; van Nes, E.H. |
| Title |
Self-organized similarity, the evolutionary emergence of groups of similar species |
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Journal Article |
| Year |
2006 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
103 |
Issue |
16 |
Pages |
6230-6235 |
| Keywords |
Animals; *Competitive Behavior; *Ecosystem; *Evolution; *Models, Biological |
| Abstract |
Ecologists have long been puzzled by the fact that there are so many similar species in nature. Here we show that self-organized clusters of look-a-likes may emerge spontaneously from coevolution of competitors. The explanation is that there are two alternative ways to survive together: being sufficiently different or being sufficiently similar. Using a model based on classical competition theory, we demonstrate a tendency for evolutionary emergence of regularly spaced lumps of similar species along a niche axis. Indeed, such lumpy patterns are commonly observed in size distributions of organisms ranging from algae, zooplankton, and beetles to birds and mammals, and could not be well explained by earlier theory. Our results suggest that these patterns may represent self-constructed niches emerging from competitive interactions. A corollary of our findings is that, whereas in species-poor communities sympatric speciation and invasion of open niches is possible, species-saturated communities may be characterized by convergent evolution and invasion by look-a-likes. |
| Address |
Aquatic Ecology and Water Quality Management Group, Department of Environmental Sciences, Wageningen University, P.O. Box 8080, 6700 DD, Wageningen, The Netherlands. marten.scheffer@wur.nl |
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0027-8424 |
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PMID:16585519 |
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refbase @ user @ |
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510 |
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Reiss, D.; Marino, L. |
| Title |
Mirror self-recognition in the bottlenose dolphin: a case of cognitive convergence |
Type |
Journal Article |
| Year |
2001 |
Publication |
Proceedings of the National Academy of Sciences of the United States of America |
Abbreviated Journal |
Proc. Natl. Acad. Sci. U.S.A. |
| Volume |
98 |
Issue |
10 |
Pages |
5937-5942 |
| Keywords |
Animals; *Cognition; Dolphins/*physiology; *Visual Perception |
| Abstract |
The ability to recognize oneself in a mirror is an exceedingly rare capacity in the animal kingdom. To date, only humans and great apes have shown convincing evidence of mirror self-recognition. Two dolphins were exposed to reflective surfaces, and both demonstrated responses consistent with the use of the mirror to investigate marked parts of the body. This ability to use a mirror to inspect parts of the body is a striking example of evolutionary convergence with great apes and humans. |
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Osborn Laboratories of Marine Sciences, New York Aquarium, Wildlife Conservation Society, Brooklyn, NY 11224, USA. dlr28@columbia.edu |
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0027-8424 |
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PMID:11331768 |
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Equine Behaviour @ team @ |
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2822 |
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