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31.
Spencer J. Ingley Eric J. Billman Chelsey Hancock Jerald B. Johnson 《Behavioral ecology and sociobiology》2014,68(10):1577-1587
Environmental effects on behavior have long been a focus of behavioral ecologists. Among the important drivers of behavior is predation environment, which can include the presence/absence of predators, differences in resource availability, and variation in individual density. Environments with predators are often more ecologically complex and “risky” than those without predators. Populations from these environments are sometimes more active and explorative than populations from low-risk, less complex environments. To date, most comparative studies of behavior are limited to within-species comparisons of populations from divergent environments, but neglect comparisons between species following speciation, thus limiting our understanding of post-speciation behavioral evolution. Brachyrhaphis fishes provide an ideal system for studying correlations between divergent environments and behavior within and between species. Here, we test for differences in two behavioral traits—activity and exploration —between sister species Brachyrhaphis roseni and Brachyrhaphis terrabensis that occur in divergent predation environments. Species differed in activity and exploration, with higher activity and exploration levels in populations that co-occur with predators. Furthermore, we found drainage-by-species interactions, indicating that the nature of divergence varied geographically. Using the recently developed phenotypic trajectory analysis (PTA), we quantified this difference and found that, while the geographically isolated populations of sister species tended to evolve in parallel, the magnitude of divergence between species differed between drainages. Our results highlight the utility of PTA for multivariate behavioral data and corroborate past predictions that complex and risky environments are correlated with increased activity and exploration levels and that divergence continues post-speciation. 相似文献
32.
Barbara K. Sullivan Danil Hancock 《Journal of the American Water Resources Association》1977,13(3):461-468
ABSTRACT: Studies on the responses of zooplankton to dredging are summarized and discussed. Design criteria for studies intended for impact assessment require careful consideration of sampling due to the highly variable spatial and temporal distributions of zooplankton. It is suggested that ocean dominated systems present different research requirements than those estuarine regions which have endemic zooplankton populations. 相似文献
33.
Tal Oron-Gilad James L Szalma Shawn C Stafford Peter A Hancock 《International journal of occupational safety and ergonomics》2008,14(2):119-131
We examined the relationship between perceived workload and performance by evaluating the responses of police officers to 4 different draw-and-shoot tasks in a night field training exercise which was part of their regular training regimen. Sixty-two police officers volunteered to participate. Results demonstrated an associative trend among 3 tasks where shooting performance decreased and workload increased as the tasks became more complex. However, performance on 1 specific shooting task did not correlate with any of the other 3 tasks, and in this 1 exceptional case, insensitivities were observed in which workload increased but performance remained constant. 相似文献
34.
G.J. Hancock C. LeslieS.E. Everett S.G. TimsG.J. Brunskill R. Haese 《Journal of environmental radioactivity》2011,102(10):919-929
The construction of high resolution chronologies of sediment profiles corresponding to the last 50-100 years usually entails the measurement of fallout radionuclides 210Pb and 137Cs. The anthropogenic radionuclide, 137Cs, originating from atmospheric nuclear weapons testing can provide an important “first appearance” horizon of known age (1954-1955), providing much-needed validation for the sometimes uncertain interpretations associated with 210Pb geochronology. However, while 137Cs usually provides a strong signal in sediment in the northern hemisphere, total fallout of 137Cs in the southern hemisphere was only 25% that of the north and the low activities of 137Cs seen in Australian and New Zealand sediments can make its horizon of first appearance somewhat arguable. Low 137Cs fallout also limited the size of the 1963-1964 fallout peak, a peak that is usually seen in northern hemisphere sediment profiles but is often difficult to discern south of the equator.This paper shows examples of the use of nuclear weapons fallout Pu as a chronomarker in sediment cores from Australia (3 sites) and New Zealand (1 site). The Pu profiles of five cores are examined and compared with the corresponding 137Cs profiles and 210Pb geochronologies. We find that Pu has significant advantages over 137Cs, including greater measurement sensitivity using alpha spectrometry and mass spectrometric techniques compared to 137Cs measurements by gamma spectrometry. Moreover, Pu provides additional chronomarkers associated with changes in the Pu isotopic composition of fallout during the 1950s and 1960s. In particular, the 238Pu/239+240Pu activity ratio shows distinct shifts in the early 1950s and the mid to late 1960s, providing important known-age horizons in southern hemisphere sediments. For estuarine and near-shore sediments Pu sometimes has another significant advantage over 137Cs due to its enrichment in bottom sediment relative to 137Cs resulting from the more efficient scavenging of dissolved Pu in seawater by sediment particles. 相似文献