Mysterious bio-duck sound attributed to the Antarctic minke whale (Balaenoptera bonaerensis)

For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.     

A sticky situation: CCN1 promotes both proliferation and apoptosis of cancer cells

Connective tissue growth factor (CTGF/CCN2) is overexpressed in diabetes. Diabetic rats possess myocardial and cardiomyocyte hypertrophy. In a recent report, Wang and colleagues (Am J Physiol Cell Physiol. 2009 Jul 22. [Epub ahead of print]) show that CCN2 directly mediates cardiomyocyte hypertrophy as well as that induced by high glucose and fatty acid. CCN2 acted via the TrkA receptor. These data are the subject of this commentary, and emphasize that CCN2 may be an excellent target for therapy in diabetes.     

The twin threshold model: risk-intermediate foraging by rufous hummingbirds, Selasphorus rufus

I developed two versions of the twin threshold model (TTM) to assess risk-sensitive foraging decisions by rufous hummingbirds. The model incorporates energy thresholds for both starvation and reproduction and assesses how three reward distributions with a common mean but different levels of variance interact with these critical thresholds to determine fitness. Fitness, a combination of survival and reproduction, is influenced by both the amount of variance in the distributions and the relative position of the common mean between the thresholds. The model predicts that risk-intermediate foraging is often the optimal policy, and that risk aversion is favoured as the common mean of the distributions approaches the starvation threshold, whereas risk preference is favoured as the common mean approaches the reproduction threshold. Tests with free-living hummingbirds supported these predictions. Hummingbirds were presented with three distributions of nectar rewards that had a common mean but Nil, Moderate or High levels of variance. Birds preferred intermediate levels of variance (Moderate) when presented with all three rewards simultaneously, and became more risk-averse as the mean of the distributions was decreased but more risk-prone as the mean was increased. Birds preferred Nil when it was paired with Moderate or with High, but preferred Moderate in the presence of Nil and High together. This reversal of preference is a violation of regularity, conventionally interpreted as irrational choice behaviour. I provide an alternative version of the TTM demonstrating that violations of regularity can occur when relative instead of absolute evaluation mechanisms are used.     

Genetic and evolutionary relationships among Asian Macaques

Published gene frequency data, checked for consistency of allele definitions across laboratories and for comparability of geographically identical samples, were pooled into a data set containing frequencies at nine loci for each of 20 populations that encompassed 10 macaque species. Genetic distances were calculated by the methods of Kidd and Cavalli-Sforza (1974). These distances were used to construct phylogenetic trees and to evaluate the relationships between divergence times and effective population sizes. Inter-and intraspecific genetic distances and the groupings defined by phenetic tree analyses support Fooden’s (1976) classification of the genus Macacainto four species groups. A paleozoogeographical model of Asia including the known times of major sea-level changes allows us to explain Macacainto four species groups. A paleozoogeographical model of Asia including the known times of major sea-level changes allows us to explain qualitatively the inferred evolutionary relationships among macaque species. Many assumptions are required in order to estimate the variables necessary in the quantitative prediction of genetic differences for a comparison between any two populations. Examination of those assumptions demonstrates the need for more accurate genetic as well as paleozoogeographic information. An erratum to this article is available at .