Evolution,altruism, and the prisoner's dilemma

I first argue against Peter Singer's exciting thesis that the Prisoner's Dilemma explains why there could be an evolutionary advantage in making reciprocal exchanges that are ultimately motivated by genuine altruism over making such exchanges on the basis of enlightened long-term self-interest. I then show that an alternative to Singer's thesis — one that is also meant to corroborate the view that natural selection favors genuine altruism, recently defended by Gregory Kavka, fails as well. Finally, I show that even granting Singer's and Kavka's claim about the selective advantage of altruism proper, it is doubtful whether that type of claim can be used in a particular sort of sociobiological argument against psychological egoism.     

Effects of invertebrate predation on the seasonal succession of a zooplankton community: a two year study in Lake Aydat,France

Saline playa lakes represent major geomorphic and hydrologic components of internal drainage basins in the arid to semiarid interior of Australia. These lakes mark the outcrop areas of regional shallow groundwater; thus, they are effective hydro-chemical sinks for elemental concentration and authigenic formation of carbonate, evaporite, and silica/silicate minerals.Field observations and petrochemical characterization of playa sediments from drainage basins in Western and Central Australia indicate that localized discharge of groundwater, from shallow aquifers in calcrete deposits, plays a fundamental role in geochemical evolution of playa-lake marginal facies. The available data indicates also that although evaporative concentration and salt recycling are major controls on geochemistry of the playas, yet a simple evaporative concentration model does not provide a complete explanation for brine evolution and particularly the geochemical process-product relationships observed in the individual playa lakes. The distribution of the chemical facies in the playas, in relation to geomorphic setting of the internal drainage basins, reflects a significant impact of variation in groundwater discharge pattern on the geochemical evolution of the playa lakes. Accordingly, the development of chemical facies in individual playas have progressed through repeated episodes of evaporative concentration, groundwater-level fluctuations and ion-exchange processes.     

Calcaneus secundarius: description and frequency in six skeletal samples

The calcaneus secundarius (CS) is a small accessory ossicle of the anterior calcaneal facet. A sample of 1,367 calcanei including early 20th century U.S. blacks and whites, XIIth Dynasty Egyptians, Islamic Period Bahrainis, and protohistoric American Indians from two states were examined to determine the frequency of this nonmetric trait. Statistical testing of the correlation of the trait with sex could only be performed on the blacks and whites, a documented cadaver collection. Tests of chi 2 indicated that, although sex differences were insignificant, significant group (not necessarily racial or geographical) differences existed at the .05 level. There was no correlation of side dominance in the overall sample, although significant population differences existed. The trait frequencies of the black and white samples were more similar to one another than to the nonindustrial groups who, in turn, were more similar to each other than to the Terry sample. The findings suggest that a CS is of genetic or congenital origin resulting in a secondary center of ossification in the anterior calcaneal facet.     

Investigation of double turnovers in Photosystem II charge separation and oxygen evolution with excitation flashes of different duration

The characteristics of double hitting in Photosystem II charge separation and oxygen evolution in algae and chloroplasts were investigated with saturating excitation flashes of 3 μs, 300 ns and 5 ns duration. Two types of double hitting or advancement in S-states were found to occur in oxygen evolution: a non-photochemical type found even with 5 ns flashes and a photochemical type seen only with microsecond-long flashes, which have extensive tails. The non-photochemical type, occurring with a probability of about 3%, is sensitive to the physiological condition of the sample, and is only present in algae or chloroplast samples that have been freshly prepared. In chloroplasts incubated with ferricyanide, a 3-fold increase in double advancement of S-states is observed with xenon-flash illumination but not with 300 ns or 5 ns laser illumination. However, double turnovers in Photosystem II reaction center charge separation are large with xenon flash or 300 ns laser illumination but not with 5 ns laser illumination. This indicates that quite different kinetic processes are involved in double advancement in S-states for oxygen evolution and double turnovers in charge separation. Various models of the Photosystem II reaction center are discussed. Also, based on experiments with chloroplasts incubated with ferricyanide, an unique solution to the oxygen S-state distribution in the dark suggested by Thibault (Thibault, P. (1978) C.R. Acad. Sci. Paris 287, 725–728) can be rejected.     

A COMPARATIVE CYTOCHEMICAL STUDY OF VOLVOCACEAN MATRIX POLYSACCHARIDES1

The colonial matrices of the volvocacean algae were examined for the presence of sulfated and carboxylated polysaccharides. These results were compared to a similar examination of the single-celled Chlamydomonas reinhardtii Dang. The colonial algae examined were Pandorina morum Bory, Eudorina elegans Ehr., Platydorina caudata Kofoid, Pleodorina californica Shaw, Pleodorina illinoisensis Kofoid and Volvox carteri var. nagariensis Iyengar. Alcian blue staining of whole colonies at pH 0.5 and 2.5 showed evidence for the presence of both sulfated and carboxylated polysaccharides in the extracellular matrix. Quantitative measurement of alcian blue bound to solubilized matrices supported the in vivo results. There was a trend toward an increase in sulfated polysaccharides in the more evolutionary advanced forms with the exception of Pleodorina. This trend was readily seen in the sulfate: carboxyl ratios: Pandorina morum—0.4, Eudorina elegans—1.0, Platydorina caudata—2.1 and Volvox carteri—2.2. The acidic nature of the Pleodorina matrix with a sulfate: carboxyl ratio of 0.2 appeared to be more like that of Pandorina rather than that of the more advanced Volvox.     

The old REH theory remains unsatisfactory and the new REH theory is problematical - a reply to holmquist and jukes

Summary In response to criticism of REH theory (Fitch 1980), Holmquist and Jukes (1981) have mostly avoided the criticism or misunderstood it. Since they themselves state in their response that Amino acid sequence data alone cannot be used to estimate total nucleotide substitutions, they agree with the criticism. Most of their paper treats the newer theory (here designated as the REHN theory) which attempts to use the nucleotide sequences encoding proteins to better estimate total nucleotide substitutions (Holmquist and Pearl 1980). Since I made no criticism of REHN theory, their comments are frequently beside the point of my original criticism of REH theory. Nevertheless, it is shown here that REHN theory is also unsatisfactory in that: One, the varions are now more clearly defined but in such a way as to preclude the same codon from suffering a nucleotide substitution in more than one evolutionary interval. Two, the set of codons that accepts silent substitutions is identical to the set that accepts amino acid changing nucleotide substitutions. Three, the uncertainty in the REH estimate is considerable in that alternative excellent fits to the same observatuonal data may give alternative REH values that differ significantly even before stochastic variation and selective bias are considered. Four, the fit of their model to data is an irrelevancy where there are zero degrees of freedom.     

A possible role of fluctuating clay-water systems in the production of ordered prebiotic oligomers

Summary A model is proposed for the intermediate stages of prebiotic evolution, based on the characteristics of the adsorption and condensation of amino acids and nucleotides on the surface area of clay minerals in a fluctuating environment. Template replication and translation of adsorbed oligonucleotides and catalytic effects by peptide products on further condensation are proposed, due to specific properties of hypohydrous clay surfaces as well as the biomolecules themselves. Experimental evidence supports some of the proposed interactions, and all of them can be tested experimentally.on leave from the Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel, 1975–76     

Systematics and phylogeny of the Aglajidae (Opisthobranchia: Mollusca)

The generic limits within the Aglajidae are reviewed and modified, based on the study of 21 species. Navanax Pilsbry, 1895 is reinstated as a genus distinct from Aglaja. The generic placement of several species is altered from previous works. An evaluation of morphological characters suggests that each of six genera has distinctive external morphology. The systematic value of twelve characters is critically reviewed. The evolutionary relationships of the Aglajidae and its genera to other philinacean familes are discussed.     

Comparaison entre des Crustacésa Céphalon isolé, a propos d'un beau matériel de syncarides du paléozoïque implications phylogéniques

Are the Eumalacostraca issued from a model of Crustacea which the carapace would have disapeared later on in some of them, and persisted in others, or from one without carapace that some of its decendants would have acquired? In the two instances this ancestor would goes far back, seeing that, already, in the Devonian, Syncarida, Stomatopoda, Phyllocarida and Eocarida were differenciated. With regard to the preliminary survey on a fine material of Syncarida from the Stephanian of the region of Autun, comparisons between two models of Crustaceans from which the cephalon includes only sensorial and gnathal segments, without adjunction of any thoracic metamere, allow to specify the notion of carapace, and to surround the question. The great oldness of the origin of the phyla possessing or not possessing a carapace seems to exclude the hypothesis of a passing over from one model to the other and suggests a representation of the common ancestor which have to be searched in the Cambrian period.     

Inhibition of Photosystem II by formate. Possible evidence for a direct role of bicarbonate in photosynthetic oxygen evolution

In broken chloroplasts the presence of 100 mM sodium formate at pH 8.2 will specifically lengthen the Photosystem II relaxation times of the reactions S′₂ → S₃ and S′₃ → S₀. Rates of reactions S′₀ → S₁ and S′₁ → S₂ remain unaffected. Evidence is presented which indicates the discrimination among S-states by formate cannot be attributed to a block imposed on the reducing side of Photosystem II. The results are interpreted in context of the known interaction of formate and CO₂ which is bound to the Photosystem II reaction center complex. It is proposed that those S-state transitions which show extended relaxation times in the presence of formate must result in the momentary release and rebinding of CO₂. Furthermore since formate is acting on the oxygen-evolving side of Photosystem II, it would seem that CO₂ is released in reactions that occur there. A chemical model of oxygen evolution is presented. It is based on the hypothesis that hydrated CO₂ is the immediate source of photosynthetically evolved oxygen and explains why, under certain conditions formate slows only the S-state transitions S′₂ → S₃ and S′₃ → S₀.