Publications by authors named "William J Rink"

2 Publications

  • Page 1 of 1

Sequential Subterranean Transport of Excavated Sand and Foraged Seeds in Nests of the Harvester Ant, Pogonomyrmex badius.

PLoS One 2015 28;10(10):e0139922. Epub 2015 Oct 28.

Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America.

During their approximately annual nest relocations, Florida harvester ants (Pogonomyrmex badius) excavate large and architecturally-distinct subterranean nests. Aspects of this process were studied by planting a harvester ant colony in the field in a soil column composed of layers of 12 different colors of sand. Quantifying the colors of excavated sand dumped on the surface by the ants revealed the progress of nest deepening to 2 m and enlargement to 8 L in volume. Most of the excavation was completed within about 2 weeks, but the nest was doubled in volume after a winter lull. After 7 months, we excavated the nest and mapped its structure, revealing colored sand deposited in non-host colored layers, especially in the upper 30 to 40 cm of the nest. In all, about 2.5% of the excavated sediment was deposited below ground, a fact of importance to sediment dating by optically-stimulated luminescence (OSL). Upward transport of excavated sand is carried out in stages, probably by different groups of ants, through deposition, re-transport, incorporation into the nest walls and floors and remobilization from these. This results in considerable mixing of sand from different depths, as indicated in the multiple sand colors even within single sand pellets brought to the surface. Just as sand is transported upward by stages, incoming seeds are transported downward to seed chambers. Foragers collect seeds and deposit them only in the topmost nest chambers from which a separate group of workers rapidly transports them downward in increments detectable as a "wave" of seeds that eventually ends in the seed chambers, 20 to 80 cm below the surface. The upward and downward transport is an example of task-partitioning in a series-parallel organization of work carried out by a highly redundant work force in which each worker usually completes only part of a multi-step process.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0139922PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4624972PMC
June 2016

New radiometric ages for the BH-1 hominin from Balanica (Serbia): implications for understanding the role of the Balkans in Middle Pleistocene human evolution.

PLoS One 2013 6;8(2):e54608. Epub 2013 Feb 6.

School of Geography and Earth Sciences, McMaster University, Hamilton, Ontario, Canada.

Newly obtained ages, based on electron spin resonance combined with uranium series isotopic analysis, and infrared/post-infrared luminescence dating, provide a minimum age that lies between 397 and 525 ka for the hominin mandible BH-1 from Mala Balanica cave, Serbia. This confirms it as the easternmost hominin specimen in Europe dated to the Middle Pleistocene. Inferences drawn from the morphology of the mandible BH-1 place it outside currently observed variation of European Homo heidelbergensis. The lack of derived Neandertal traits in BH-1 and its contemporary specimens in Southeast Europe, such as Kocabaş, Vasogliano and Ceprano, coupled with Middle Pleistocene synapomorphies, suggests different evolutionary forces acting in the east of the continent where isolation did not play such an important role during glaciations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0054608PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3566111PMC
December 2013