Cooperation creates selection for tactical deception

Conditional social behaviours such as partner choice and reciprocity are held to be key mechanisms facilitating the evolution of cooperation, particularly in humans. Although how these mechanisms select for cooperation has been explored extensively, their potential to select simultaneously for complex cheating strategies has been largely overlooked. Tactical deception, the misrepresentation of the state of the world to another individual, may allow cheaters to exploit conditional cooperation by tactically misrepresenting their past actions and/or current intentions. Here we first use a simple game-theoretic model to show that the evolution of cooperation can create selection pressures favouring the evolution of tactical deception. This effect is driven by deception weakening cheater detection in conditional cooperators, allowing tactical deceivers to elicit cooperation at lower costs, while simple cheats are recognized and discriminated against. We then provide support for our theoretical predictions using a comparative analysis of deception across primate species. Our results suggest that the evolution of conditional strategies may, in addition to promoting cooperation, select for astute cheating and associated psychological abilities. Ultimately, our ability to convincingly lie to each other may have evolved as a direct result of our cooperative nature.     

Lignite mining and stream channelization influences on aquatic macroinvertebrate assemblages along the Natchez Trace Parkway,Mississippi, USA

The article describes the effects of channelization on selected water quality parameters and benthic macroinvertebrate assemblages in four Big Black River (Mississippi, USA) tributaries crossing the Natchez Trace Parkway [U.S. National Park Service (NPS)]. Two of the streams were unchannelized (Little Bywy Creek and McCurtain Creek), and two were channelized (Big Bywy Creek and Middle Bywy Creek). Lignite mining occurs in the headwaters of Little Bywy Creek and Middle Bywy Creek. During this 3-year study, benthic macroinvertebrates were collected monthly from all four streams using Hester-Dendy Multiple plate samplers, and enumerated taxonomically and functionally. Hypotheses were tested using analyses of variance. Relationships were determined using multivariate analyses. Relative abundances of mayflies (Ephemeroptera), stoneflies (Plecoptera), caddisflies (Trichoptera) and aquatic beetles (Coleoptera) were associated with moderate to high conductivity, alkalinity, pH, and dissolved oxygen. Hellgrammites (Megaloptera), midges, blackflies, and mosquitoes (Diptera), crayfish (Crustacea: Decapoda) and leeches (Annelida: Hirudinea) were associated with lower values for these parameters. These patterns reflected seasonal rather than spatial variation (i.e., among the streams). Invertebrate assemblage composition was similar among the four streams with respect to functional groups. Invertebrate relative abundances in the two channelized streams were approximately half those of the unchannelized streams. Macroinvertebrate species richness was greater in unchannelized streams. Environmental indices categorized all four streams as having fair to good condition. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effect of apolipoprotein C-II on the temperature dependence of lipoprotein lipase-catalyzed hydrolysis of phosphatidylcholines. A hydrophobic model for the mechanism

The lipoprotein lipase-catalyzed hydrolysis of diacylphosphatidylcholines (PC) in mixed micelles of Triton X-100/PC was studied as a function of temperature in the presence and absence of apolipoprotein C-II (apo-C-II), the activator protein for lipoprotein lipase. Dilauroyl-, dimyristoyl-, dipalmitoyl-, and distearoyl-phosphatidylcholine (di-C12-PC, di-C14-PC, di-C16-PC, and di-C18-PC, respectively) were used as substrates. No systematic relationship between substrate fatty acyl chain length and either the rates of the activation energies for hydrolysis in the presence or absence of apo-C-II was observed. However, there was a linear relationship between fatty acyl chain length and both the logarithm of the activation factor (the ratio of enzyme activity with apo-C-II to that without apo-C-II) and the difference in activation energy in the presence and absence of apo-C-II. These relationships were not the result of an alteration in the physical form of the substrate, since a mixture of di-C14-PC and di-C16-PC gave activation factors for each PC which were the same as those obtained for each individual lipid. From the temperature dependence of the activation factor, thermodynamic functions of the apo-C-II-induced change in the reaction pathway were calculated. The free energy of activation decreased linearly with increasing chain length as the result of a linear increase in activation entropy which more than offset the unfavorable increase in activation enthalpy. We propose that the apo-C-II-mediated increase in the rate of the lipoprotein lipase-catalyzed hydrolysis of phosphatidylcholine is associated with transfer of a fatty acyl chain of the substrate or product to a more hydrophobic environment within the transition state complex.     

Sequence-specific and DNA structure-dependent interactions of Escherichia coli MutS and human p53 with DNA

Many proteins involved in DNA repair systems interact with DNA that has structure altered from the typical B-form helix. Using magnetic beads to immobilize DNAs containing various types of structures, we evaluated the in vitro binding activities of two well-characterized DNA repair proteins, Escherichia coli MutS and human p53. E. coli MutS bound to double-stranded DNAs, with higher affinity for a G/T mismatch compared to a G/A mismatch and highest affinity for larger non-B-DNA structures. E. coli MutS bound best to DNA between pH 6 and 9. Experiments discriminated between modes of p53–DNA binding, and increasing ionic strength reduced p53 binding to nonspecific double-stranded DNA, but had minor effects on binding to consensus response sequences or single-stranded DNA. Compared to nonspecific DNA sequences, p53 bound with a higher affinity to mismatches and base insertions, while binding to various hairpin structures was similar to that observed to its consensus DNA sequence. For hairpins containing CTG repeats, the extent of p53 binding was proportional to the size of the repeat. In summary, using the flexibility of the magnetic bead separation assay we demonstrate that pH and ionic strength influence the binding of two DNA repair proteins to a variety of DNA structures.     

Mask of wax: Secretions of wax conceal aphids from detection by spider's eyes

Abstract

We investigated how insects use wax as a defence against visual predators, using a New Zealand salticid species, Marpissa marina, as the predator and Eriosoma lanigerum, an aphid that covers itself with wax, as the prey. For live‐prey testing, the predator was presented with two aphids, one with its wax covering intact and one with its wax removed. The predator ate more of the waxless than wax‐covered aphids. The predators were presented with two lures at a time: (1) one that was fully covered with wax (hid the aphid's head) compared with one that was without wax (waxless) or (2) one that was fully covered with wax compared with one that was only partially covered with wax (the head of the prey exposed), or (3) one that was waxless compared with one that was partially covered with wax. The predators stalked waxless prey more often than they stalked prey that was fully or partially covered with wax. When wax only partially covered the prey (i.e., when the prey's head was left exposed), the predator more often stalked than when the insect was fully covered. These findings suggest that the aphid's wax covering functions in part to hide prey‐identification cues from vision‐guided predators.