Mate preference for multiple cues: interplay between male and nest size in the sand goby, Pomatoschistus minutus

Female mating preferences are often based on more than one cue. In empirical studies, however, different mate choice cues are typically treated separately ignoring their possible interactions. In the current work, we studied how male body size and size of the male's nest jointly affect mate preferences of female sand gobies, Pomatoschistus minutus. The females were given a binary choice between males that differed either in body size or size of their nest or both. We found that neither body size nor size of the nest alone affected male attractiveness, but together these 2 cues had a significant effect. Specifically, large males were more popular among females when they had a large nest than when they occupied a small nest. The results suggest that if interaction effects between multiple mate choice cues are not considered, there is a danger of ignoring or underestimating the importance of these cues in sexual selection by female choice. Copyright 2007, Oxford University Press.

Radical Constructivism and Radical Constructedness: Luhmann’s Sociology and the Non-linear Dynamics of Expectations

The communication (and reflexive translation) of denotations between semantic domains can generate “horizons of meaning” as reflexive orders that remain structurally coupled to individual minds. Luhmann noted that this elusive order contains a trade-off between “organization” at interfaces integrating (differently coded) expectations at each moment of time, and the potential of further differentiation among symbolically generalized codes of communication in a “self-organization” over time. One can model the coding in the communication of meaning as eigenvectors which evolve as an implication of the interacting intentions and expectations. The interacting horizons of meaning generate new options (redundancy) against the arrow of time, since meaning is provided to events from the perspective of hindsight. Using the theory and computation of anticipatory systems, “self-organization” and “interaction” can be considered as hyper-incursive routines that use (expectations of) future states for their reconstruction, whereas “organization” operates in terms of instantiations (of expectations). Mathematical metaphors can guide us in further exploring the nonlinear dynamics of a social order of intentions and expectations without reification

Two enzymes of diacylglyceryl-O-4′-(N,N,N,-trimethyl)homoserine biosynthesis are encoded by btaA and btaB in the purple bacterium Rhodobacter sphaeroides

Betaine lipids are ether-linked, nonphosphorous glycerolipids that resemble the more commonly known phosphatidylcholine in overall structure. Betaine lipids are abundant in many eukaryotes such as nonseed plants, algae, fungi, and amoeba. Some of these organisms are entirely devoid of phosphatidylcholine and, instead, contain a betaine lipid such as diacylglyceryl-O-4′-(N,N,N,-trimethyl)homoserine. Recently, this lipid also was discovered in the photosynthetic purple bacterium Rhodobacter sphaeroides where it seems to replace phosphatidylcholine under phosphate-limiting growth conditions. This discovery provided the opportunity to study the biosynthesis of betaine lipids in a bacterial model system. Mutants of R. sphaeroides deficient in the biosynthesis of the betaine lipid were isolated, and two genes essential for this process, btaA and btaB, were identified. It is proposed that btaA encodes an S-adenosylmethionine:diacylglycerol 3-amino-3-carboxypropyl transferase and btaB an S-adenosylmethionine-dependent N-methyltransferase. Both enzymatic activities can account for all reactions of betaine lipid head group biosynthesis. Because the equivalent reactions have been proposed for different eukaryotes, it seems likely that orthologs of btaA/btaB may be present in other betaine lipid-containing organisms