Distribution Patterns of Tropical Plant Foods as an Evolutionary Stimulus to Primate Mental Development

Primates are noted for their mental abilities but the selective basis for such traits has remained obscure. It is hypothesized that the element of predictability associated with the spatial and temporal distribution patterns of plant foods in tropical forests has served to stimulate mental development in primates taking much of their food from the first trophic level. Primates able to remember the locations and phenological patterns of a wide variety of plant foods could move directly to such foods when and where available without wasting time and energy in random search. This would enhance overall foraging success by lowering procurement costs associated with a varied and patchily distributed plant diet. Membership in a cohesive social unit, that utilized the same supplying area over many consecutive generations, would also enhance foraging success by serving to transmit important information about diet to close kin. Data on the foraging behavior of howler and spider monkeys are presented to test certain implications of this hypothesis. Similar selective pressures, but applied to foods from the second trophic level, may have been of critical importance in the mental development of hominids . [primates, evolution, intelligence, plant foods, Aleles, Alouatta ]     

Pre-flowering Growth and Development of the Inflorescences of Maize: I. PRIMORDIA PRODUCTION AND APICAL DOME VOLUME

The growth and development of the main stem and the two uppermostaxillary apices of maize were studied during the period fromemergence until flowering. Plants were grown in the field undervarying levels of applied nitrogen fertilizer at two times ofsowing. The effects of daylength were isolated from those oftemperature by making comparisons of growth and developmenton a thermal time basis. The growth and development of the terminal (male) apex and thetwo uppermost axillary (female) apices followed the same patterns,with apex volumes increasing curvilinearly with increase innumber of leaf or husk primordia. The RGR(relative growth rateof volume) of the terminal apex was, however, only approximatelyone-tenth of the axillary apices. There was no difference ingrowth and development between the first and second axillaryapices before flowering: other factors, such as accumulationof dry weight, rather than primordia production, must be responsiblefor an axillary apex's potential to bear grain. Applied N, andto a lesser extent short days, increased the rates of growthand development of all the apices. For example, applied N increasedthe RGR (volume) of the apical domes, and the rate of productionof spikelet primordia, by about 25%. All axillary apices and treatments showed a single relationshipbetween number of spikelets and surface area of the ear: a favourableenvironment (e.g. high N) simply accelerated the progressionof spikelet production and area expansion along this singlepath. We conclude that this path is probably determined geneticallyand that N and time of sowing influence potential yield of maizethrough effects on the surface area of the ear but not on thedensity of spikelets formed. Key words: Maize, inflorescence, N application, daylength, temperature, apex volume     

Whole-genome duplications in South American desert rodents (Octodontidae)

The discovery of tetraploidy in the red viscacha rat, Tympanoctomys barrerae (4 n  = 102) has emphasized the evolutionary role of genome duplication in mammals. The tetraploid status of this species is corroborated here by in situ PCR and Southern blot analysis of a single-copy gene. The species meiotic configuration strongly suggests a hybrid derivation. To investigate the origin of T. barrerae further, the recently described Pipanacoctomys aureus was studied. This 92-chromosome species also has a duplicated genome size, redundant gene copy number and diploid-like meiotic pairing, consistent with an event of allotetraploidization. Phylogenetic analysis of mitochondrial sequences indicates sister-group relationships between these two tetraploid rodents. The new karyotypic data and the phylogenetic relationships suggest the participation of the ancestral lineages of Octomys mimax in the genesis of P. aureus . The high overall DNA similarity and shared band homology revealed by genomic Southern hybridization as well as matching chromosome numbers between O. mimax and the descendant tetraploid species support the notion of introgressive hybridization between these taxa.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 443–451.     

HIV risk behaviors among outpatients with severe mental illness in Rio de Janeiro,Brazil

We conducted the first study to examine rates of sexual activity, sexual risk behaviors, sexual protective behaviors, injection drug use (IDU), needle sharing, and knowledge about HIV/AIDS among outpatients with severe mental illness (SMI) in Rio de Janeiro, Brazil. Using a measure with demonstrated reliability, we found that 42% of 98 patients engaged in vaginal or anal sex within the past three months. Comorbid substance use disorder was significantly associated with sexual activity. Only 22% of sexually active patients used condoms consistently, despite having better HIV knowledge than those who were sexually abstinent. Overall, 45% of patients reported not engaging in any HIV protective behaviors. There were no reports of drug injection. Adults with SMI in Brazil are in need of efficacious HIV prevention programs and policies that can sustain these programs within mental health treatment settings.