The deflecting wrinkle on the teeth of Icelanders and the Mongoloid dental complex

Three local populations from Northeast Iceland are surveyed for the occurrence of the deflecting wrinkle of the metaconid on second deciduous and first permanent lower molars. The trait occurs more frequently on dm2 than on M1, and no sexual dimorphism is found, as expected. However, the frequencies are clearly within those predicted by the Mongoloid dental complex for Mongoloid populations. It is therefore suggested that the inclusion of the deflecting wrinkle in the Mongoloid dental complex be re-evaluated, and the racial diagnostic value of the trait taken with reservation.     

Amino acid increases in fruit infested by fruit flies of the family Tephritidae

Solanum mauritianum Scop, (wild tobacco) fruit is the major host of the fruit fly Dacus cacuminatus (Hering), and is a major source of food for the brown pigeon Macropygia phasianella (Temminck) in eastern Queensland. Amino acid analyses were undertaken on fruit fly infested and uninfested S. mauritianum fruits. Infested fruits contained approximately twice the level of protein and essential amino acids compared to uninfested fruit. This increase is probably due to the plant adding additional amino acids to infested tissue and the accompanying growth of bacteria established in the fruit during oviposition. The infested fruit would provide a valuable source of protein during the pigeon breeding season.     

Studies on the fungi associated with tomato fruit rots and effects of environment on storage

Seven fungi associated with fruit rot of tomato were isolated includingFusarium equiseti, F. chlamydosporum, Alternaria solani, Geotrichum candidum, Acremonium recifei, Aspergillus flavus andA. niger. They were all pathogenic on tomato fruits, most pathogenic beingGeotrichum candidum followed byA. niger. Least rot was caused byAlternaria solani. The optimum temperature for maximum rotting caused byG. candidum, A. niger andA. flavus was 30°C. The relative humidity for maximum rot ranged from 70–90%. Tomato fruits stored well at 0–10°C and rather poorly at 20–30°C. Fruits stored at 35°C showed blemishes. The best RH for storage ranged between 60 and 90%.     

Methods for the production of multi-marker strains

Summary The production of a multi-marker strain given a series of strains each carrying a single marker will require a considerable investment in time and resources when based on a series of formal crosses. Such strains can be produced rapidly and with only minimal resources by recurrent cycles of random mating and selection, with selection based on the number of desired alleles carried.     

Hyaluronidase activity and hyaluronate content of the developing chick embryo heart.

Hyaluronidase activity and hyaluronate content were measured in the developing chick heart from embryonic day 3 through posthatching stages. High levels of both enzyme and substrate were found during the earliest stages examined. Hyaluronidase activity gradually declined to 63% of the initial (day 3) level by embryonic day 16. Enzyme activity decreased more sharply during the next 4 days to 30% of the initial level and remained constant through 2 weeks after hatching. Low levels of enzyme activity (about 10% initial levels) were still detectable in 10-week-old chicken hearts. The heart hyaluronidase is an endoglycosidase with an estimated molecular weight of 62,000, which degrades hyaluronate and, to a lesser extent, chondroitin sulfate at an acid pH optimum. Hyaluronate constituted approximately 50% of the total glycosaminoglycan content at embryonic day 5. Between embryonic days 5 and 12, the concentration of hyaluronate decreased to 25–30% of the initial level and remained constant thereafter. The level of other glycosaminoglycans decreased more gradually than hyaluronate and did not reach a constant level until hatching. This pattern of hyaluronidase activity and hyaluronate concentration presumably reflects the extensive tissue remodeling which transforms the developing heart from a thin-walled tube containing extensive regions of extracellular matrix to a compact, thick-walled myocardium having a limited extracellular compartment.     

Selective genotyping to detect quantitative trait loci affecting multiple traits: interval mapping analysis

 Segregating quantitative trait loci can be detected via linkage to genetic markers. By selectively genotyping individuals with extreme phenotypes for the quantitative trait, the power per individual genotyped is increased at the expense of the power per individual phenotyped, but linear-model estimates of the quantitative-locus effect will be biased. The properties of single- and multiple-trait maximum-likelihood estimates of quantitative-loci parameters derived from selectively genotyped samples were investigated using Monte-Carlo simulations of backcross populations. All individuals with trait records were included in the analyses. All quantitative-locus parameters and the residual correlation were unbiasedly estimated by multiple-trait maximum-likelihood methodology. With single-trait maximum-likelihood, unbiased estimates for quantitative-locus effect and location, and the residual variance, were obtained for the trait under selection, but biased estimates were derived for a correlated trait that was analyzed separately. When an effect of the QTL was simulated only on the trait under selection, a “ghost” effect was also found for the correlated trait. Furthermore, if an effect was simulated only for the correlated trait, then the statistical power was less than that obtained with a random sample of equal size. With multiple-trait analyses, the power of quantitative-trait locus detection was always greater with selective genotyping. Received: 23 February 1998 / Accepted: 15 May 1998     

Associations between primates and other mammals in a central Amazonian forest landscape

Little information exists on mixed-species groups between primates and other mammals in Neotropical forests. In this paper, we describe three such associations observed during an extensive large-vertebrate survey in central Amazonia, Brazil. Mixed-species groups between a primate species and another mammal were observed on seven occasions between squirrel monkeys (Saimiri cf. ustus) and either South American coatis (Nasua nasua) or tayras (Eira barbara) and between brown capuchins (Cebus apella) and coatis. All associations were restricted to floodplain forest during its dry stage. We suggest that the associations involving the coatis are connected to foraging and vigilance but may be induced by a common alternative food resource at a time of food shortage.     

Swimming with the giant: coexistence patterns of a new redfin minnow Pseudobarbus skeltoni from a global biodiversity hot spot

Ecological niche theory predicts that coexistence is facilitated by resource partitioning mechanisms that are influenced by abiotic and biotic interactions. Alternative hypotheses suggest that under certain conditions, species may become phenotypically similar and functionally equivalent, which invokes the possibility of other mechanisms, such as habitat filtering processes. To test these hypotheses, we examined the coexistence of the giant redfin Pseudobarbus skeltoni, a newly described freshwater fish, together with its congener Pseudobabus burchelli and an anabantid Sandelia capensis by assessing their scenopoetic and bionomic patterns. We found high habitat and isotope niche overlaps between the two redfins, rendering niche partitioning a less plausible sole mechanism that drives their coexistence. By comparison, environment–trait relationships revealed differences in species–environment relationships, making habitat filtering and functional equivalence less likely alternatives. Based on P. skeltoni's high habitat niche overlap with other species, and its large isotope niche width, we inferred the likelihood of differential resource utilization at trophic level as an alternative mechanism that distinguished it from its congener. In comparison, its congener P. burchelli appeared to have a relatively small trophic niche, suggesting that its trophic niche was more conserved despite being the most abundant species. By contrast, S. capensis was distinguished by occupying a higher trophic position and by having a trophic niche that had a low probability of overlapping onto those of redfins. Therefore, trophic niche partitioning appeared to influence the coexistence between S. capensis and redfins. This study suggests that coexistence of these fishes appears to be promoted by their differences in niche adaptation mechanisms that are probably shaped by historic evolutionary and ecological processes.     

Species Traits as Practical Tools for Ecological Restoration of Marly Eroded Lands

Plant functional traits are increasingly used in restoration ecology because they have the potential to guide restoration practices at a broad scale. This article presents a trait‐based multi‐criteria framework to evaluate and predict the performance of 17 plant seedlings to improve ecological restoration of marly eroded areas in the French Southern Alps. The suitability of these species to limit soil erosion was assessed by studying both their response to erosive forces and their effect on erosion dynamics. We assumed that species efficiency could be explained and predicted from plant traits and we looked for trait‐performance relationships. Our results showed that root slenderness ratio, the percentage of fine roots and root system topology, were the three root morphology traits best describing anchorage strength. Root system characterized by a long and thin tap root and many fine lateral ramifications would be the best to resist concentrated runoff. Species response to burial mainly depended on growth form and morphological flexibility. The abilities of species in reinforcing the soil and reducing erosion rates were negatively correlated to root diameter and positively to the percentage of fine roots. Moreover, root system density and root tensile strength also influenced root reinforcement. Finally, the ability to trap sediment was positively correlated to leaf area and canopy density. Species were then scored and classified in four clusters according to their global performance. This method allows identifying species that possess both response and effect traits related to the goal of preventing erosion during ecological restoration.     

Epizoochorous seed dispersal in relation to seed availability – an experiment with a red fox dummy

Questions: Is the red fox a potential vector for epizoochorous seed dispersal? Can seed attachment and retention be predicted from plant and seed traits? Location: Grasslands in southern Norway. Methods: Epizoochorous seed attachment on the red fox was studied by walking a dummy fox through the vegetation and comparing seeds found on the dummy with the estimated seed availability in the vegetation. Seed retention, i.e. the ability of different seeds to stay on the fox, was estimated in a separate experiment. Seed attachment and retention were related to plant and seed traits using statistical models that account for heteroscedasticity and zero‐inflated data. Results: The majority of seeds attached to the fox originated from a few species, but also species without specific seed traits that are supposed to enhance epizoochory attached at least some seeds to the fox. The probability of seed attachment was positively related to plant height, bristle and hooked seed appendages, and negatively related to winged appendages, seed mass, and seed sphericity. Seed retention was positively related to the seed traits bristles, hooks and pappus. For several species, the results indicate a high potential for dispersal over long distances. Conclusions: In modern agricultural landscapes, large herbivores are often restricted in their mobility or are found at low densities, and other animal vectors may therefore be important for seed dispersal. In our study, a range of plant species were able to disperse by attaching seeds to, and having their seeds retained in, the fox fur some distance. We suggest that the red fox may be an important vector for epizoochorous seed dispersal in the agricultural landscape.