The inference of gray whale (Eschrichtius robustus) historical population attributes from whole-genome sequences

Commercial whaling caused extensive demographic declines in many great whale species, including gray whales that were extirpated from the Atlantic Ocean and dramatically reduced in the Pacific Ocean. The Eastern Pacific gray whale has recovered since the 1982 ban on commercial whaling, but the Western Pacific gray whale-once considered possibly extinct-consists of only about 200 individuals and is considered critically endangered by some international authorities. Herein, we use whole-genome sequencing to investigate the demographic history of gray whales from the Pacific and use environmental niche modelling to make predictions about future gene flow.Our sequencing efforts and habitat niche modelling indicate that: i) western gray whale effective population sizes have declined since the last glacial maximum; ii) contemporary gray whale genomes, both eastern and western, harbor less autosomal nucleotide diversity than most other marine mammals and megafauna; iii) the extent of inbreeding, as measured by autozygosity, is greater in the Western Pacific than in the Eastern Pacific populations; and iv) future climate change is expected to open new migratory routes for gray whales.Our results indicate that gray whale genomes contain low nucleotide diversity and have been subject to both historical and recent inbreeding. Population sizes over the last million years likely peaked about 25,000 years before present and have declined since then. Our niche modelling suggests that novel migratory routes may develop within the next century and if so this could help retain overall genetic diversity, which is essential for adaption and successful recovery in light of global environmental change and past exploitation

Costly Signaling Theory in Archaeology

Why do people engage in seemingly wasteful behaviors and invest in extravagant material displays? Since its introduction into anthropological archaeology two decades ago, costly signaling theory (CST) has been used to provide an answer to this question. With broad origins in biology and social theory, costly signaling theory seeks to provide an evolutionary explanation for why humans engage in seemingly wasteful behaviors. In this chapter, I take stock of costly signaling theory in archaeology by (1) tracing its theoretical origins and history of adoption into anthropological archaeology, (2) highlighting key issues that archaeologists have been wrestling with in order to make CST applicable to the past, (3) discussing the breadth of uses of CST in the recent archaeological literature, and (4) presenting an analytical framework that can make CST more rigorous and in the future. Despite persistent doubts about the explanatory utility of CST, the study of signaling from an evolutionary perspective remains a key aspect of evolutionary archaeology

A new class of copolymer colloids with tunable, low refractive index for investigations of structure and dynamics in concentrated suspensions

Highly charged polymer colloids may serve as model systems for the investigation of condensed matter, if they self-organize to liquid-like, glassy or crystalline phases. Multiple scattering due to refractive index differences of colloidal particles and suspending medium is a serious problem when utilizing light scattering experiments for these investigations. In this work, a new class of monodisperse colloidal dispersions is prepared by means of emulsion copolymerization of the monomers n-butyl acrylate and 2,2,2-trifluoroethyl acrylate. By systematic variation of the molar ratio of fluorinated and non-fluorinated monomers, the refractive index n p of the colloidal copolymer particles is tuned in the range 1.38 < n p < 1.45. Thus, particles with any composition of both monomers can be index-matched by protic water/glycerol mixtures as demonstrated by minima of the relative transmission of suspensions in dependence on the refractive index of the suspending medium. Static and dynamic light scattering experiments as well as analysis of the static structure factors S(Q) by means of integral equations are employed to investigate the self-organization of the resulting colloidal copolymer particles. Hereby, the potential application of these new model systems to investigate dynamics in concentrated binary mixtures is demonstrated