Hostikka, S. L., Eddy, R. L., Byers, M. G., Hoyhtya, M., Shows, T. B., & Tryggvason, K. (1990). Identification of a distinct type IV collagen alpha chain with restricted kidney distribution and assignment of its gene to the locus of X chromosome-linked Alport syndrome. Proc. Natl. Acad. Sci. U.S.A., 87(4), 1606–1610.
Abstract: We have identified and extensively characterized a type IV collagen alpha chain, referred to as alpha 5(IV). Four overlapping cDNA clones isolated contain an open reading frame for 543 amino acid residues of the carboxyl-terminal end of a collagenous domain, a 229-residue carboxyl-terminal noncollagenous domain, and 1201 base pairs coding for a 3' untranslated region. The collagenous Gly-Xaa-Yaa repeat sequence has five imperfections that coincide with those in the corresponding region of the alpha 1(IV) chain. The noncollagenous domain has 12 conserved cysteine residues and 83% and 63% sequence identity with the noncollagenous domains of the alpha 1(IV) and alpha 2(IV) chains, respectively. The alpha 5(IV) chain has less sequence identity with the putative bovine alpha 3(IV) and alpha 4(IV) chains. Antiserum against an alpha 5(IV) synthetic peptide stained a polypeptide chain of about 185 kDa by immunoblot analysis and immunolocalization of the chain in human kidney was almost completely restricted to the glomerulus. The gene was assigned to the Xq22 locus by somatic cell hybrids and in situ hybridization. This may be identical or close to the locus of the X chromosome-linked Alport syndrome that is believed to be a type IV collagen disease.
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Begall, S., Cervený, J., Neef, J., Vojtech, O., & Burda, H. (2008). Magnetic alignment in grazing and resting cattle and deer. Proc. Natl. Acad. Sci. U.S.A., 105(36), 13451–13455.
Abstract: We demonstrate by means of simple, noninvasive methods (analysis of satellite images, field observations, and measuring “deer beds” in snow) that domestic cattle (n = 8,510 in 308 pastures) across the globe, and grazing and resting red and roe deer (n = 2,974 at 241 localities), align their body axes in roughly a north–south direction. Direct observations of roe deer revealed that animals orient their heads northward when grazing or resting. Amazingly, this ubiquitous phenomenon does not seem to have been noticed by herdsmen, ranchers, or hunters. Because wind and light conditions could be excluded as a common denominator determining the body axis orientation, magnetic alignment is the most parsimonious explanation. To test the hypothesis that cattle orient their body axes along the field lines of the Earth's magnetic field, we analyzed the body orientation of cattle from localities with high magnetic declination. Here, magnetic north was a better predictor than geographic north. This study reveals the magnetic alignment in large mammals based on statistically sufficient sample sizes. Our findings open horizons for the study of magnetoreception in general and are of potential significance for applied ethology (husbandry, animal welfare). They challenge neuroscientists and biophysics to explain the proximate mechanisms.
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Biegler, R., McGregor, A., Krebs, J. R., & Healy, S. D. (2001). A larger hippocampus is associated with longer-lasting spatial memory. Proc. Natl. Acad. Sci. U.S.A., 98(12), 6941–6944.
Abstract: Volumetric studies in a range of animals (London taxi-drivers, polygynous male voles, nest-parasitic female cowbirds, and a number of food-storing birds) have shown that the size of the hippocampus, a brain region essential to learning and memory, is correlated with tasks involving an extra demand for spatial learning and memory. In this paper, we report the quantitative advantage that food storers gain from such an enlargement. Coal tits () a food-storing species, performed better than great tits (), a nonstoring species, on a task that assessed memory persistence but not on a task that assessed memory resolution or on one that tested memory capacity. These results show that the advantage to the food-storing species associated with an enlarged hippocampus is one of memory persistence.
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Sol, D., Duncan, R. P., Blackburn, T. M., Cassey, P., & Lefebvre, L. (2005). Big brains, enhanced cognition, and response of birds to novel environments. Proc. Natl. Acad. Sci. U.S.A., 102(15), 5460–5465.
Abstract: 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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Leadbeater, E., & Dawson, E. H. (2017). A social insect perspective on the evolution of social learning mechanisms. Proc. Natl. Acad. Sci. U.S.A., 114(30), 7838–7845.
Abstract: The social world offers a wealth of opportunities to learn from others, and across the animal kingdom individuals capitalize on those opportunities. Here, we explore the role of natural selection in shaping the processes that underlie social information use, using a suite of experiments on social insects as case studies. We illustrate how an associative framework can encompass complex, context-specific social learning in the insect world and beyond, and based on the hypothesis that evolution acts to modify the associative process, suggest potential pathways by which social information use could evolve to become more efficient and effective. Social insects are distant relatives of vertebrate social learners, but the research we describe highlights routes by which natural selection could coopt similar cognitive raw material across the animal kingdom.
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Bergstrom, C. T., & Lachmann, M. (1998). Signaling among relatives. III. Talk is cheap. Proc. Natl. Acad. Sci. U.S.A., 95(9), 5100–5105.
Abstract: The Sir Philip Sidney game has been used by numerous authors to show how signal cost can facilitate honest signaling among relatives. Here, we demonstrate that, in this game, honest cost-free signals are possible as well, under very general conditions. Moreover, these cost-free signals are better for all participants than the previously explored alternatives. Recent empirical evidence suggests that begging is energetically inexpensive for nestling birds; this finding led some researchers to question the applicability of the costly signaling framework to nestling begging. Our results show that cost-free or inexpensive signals, as observed empirically, fall within the framework of signaling theory.
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Ballew, R. M., Sabelko, J., & Gruebele, M. (1996). Direct observation of fast protein folding: the initial collapse of apomyoglobin. Proc. Natl. Acad. Sci. U.S.A., 93(12), 5759–5764.
Abstract: The rapid refolding dynamics of apomyoglobin are followed by a new temperature-jump fluorescence technique on a 15-ns to 0.5-ms time scale in vitro. The apparatus measures the protein-folding history in a single sweep in standard aqueous buffers. The earliest steps during folding to a compact state are observed and are complete in under 20 micros. Experiments on mutants and consideration of steady-state CD and fluorescence spectra indicate that the observed microsecond phase monitors assembly of an A x (H x G) helix subunit. Measurements at different viscosities indicate diffusive behavior even at low viscosities, in agreement with motions of a solvent-exposed protein during the initial collapse.
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Jansen, T., Forster, P., Levine, M. A., Oelke, H., Hurles, M., Renfrew, C., et al. (2002). Mitochondrial DNA and the origins of the domestic horse. Proc. Natl. Acad. Sci. U.S.A., 99(16), 10905–10910.
Abstract: The place and date of the domestication of the horse has long been a matter for debate among archaeologists. To determine whether horses were domesticated from one or several ancestral horse populations, we sequenced the mitochondrial D-loop for 318 horses from 25 oriental and European breeds, including American mustangs. Adding these sequences to previously published data, the total comes to 652, the largest currently available database. From these sequences, a phylogenetic network was constructed that showed that most of the 93 different mitochondrial (mt)DNA types grouped into 17 distinct phylogenetic clusters. Several of the clusters correspond to breeds and/or geographic areas, notably cluster A2, which is specific to Przewalski's horses, cluster C1, which is distinctive for northern European ponies, and cluster D1, which is well represented in Iberian and northwest African breeds. A consideration of the horse mtDNA mutation rate together with the archaeological timeframe for domestication requires at least 77 successfully breeding mares recruited from the wild. The extensive genetic diversity of these 77 ancestral mares leads us to conclude that several distinct horse populations were involved in the domestication of the horse.
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Lergetporer, P., Angerer, S., Glätzle-Rützler, D., & Sutter, M. (2014). Third-party punishment increases cooperation in children through (misaligned) expectations and conditional cooperation. Proc. Natl. Acad. Sci. U.S.A., 111(19), 6916–6921.
Abstract: The human ability to establish cooperation, even in large groups of genetically unrelated strangers, depends upon the enforcement of cooperation norms. Third-party punishment is one important factor to explain high levels of cooperation among humans, although it is still somewhat disputed whether other animal species also use this mechanism for promoting cooperation. We study the effectiveness of third-party punishment to increase children’s cooperative behavior in a large-scale cooperation game. Based on an experiment with 1,120 children, aged 7 to 11 y, we find that the threat of third-party punishment more than doubles cooperation rates, despite the fact that children are rarely willing to execute costly punishment. We can show that the higher cooperation levels with third-party punishment are driven by two components. First, cooperation is a rational (expected payoff-maximizing) response to incorrect beliefs about the punishment behavior of third parties. Second, cooperation is a conditionally cooperative reaction to correct beliefs that third party punishment will increase a partner’s level of cooperation.
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Weisbecker, V., & Goswami, A. (2010). Brain size, life history, and metabolism at the marsupial/placental dichotomy. Proc. Natl. Acad. Sci. U.S.A., 107(37), 16216–16221.
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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