Earthquake hazard assessment after Mexico (1985)

The 1985 Mexican earthquake ranks foremost amongst the major earthquake disasters of the twentieth century. One of the few positive aspects of the disaster is that it provided massive quantities of data that would otherwise have been unobtainable. Every opportunity should be taken to incorporate the findings from these data in earthquake hazard assessments. The purpose of this paper is to provide a succinct summary of some of the more important lessons from Mexico. It stems from detailed field investigations, and subsequent analyses, conducted by the author on the behalf of reinsurance companies.     

A basidiomycete isolated from the skeleton of<Emphasis Type="Italic"> Pocillopora damicornis</Emphasis> (Scleractinia) selectively stimulates short-term survival of coral skeletogenic cells

Endolithic fungi bore through the extracellular calcium carbonate skeleton of reef-building scleractinian corals, both healthy and dead, and effect net erosion of coral reefs. Potential fungal interactions with coral tissue were investigated using an in vitro approach suggested by earlier observations of skeletal repair cones at the site of fungal perforation in Porites sp. A fungal strain was isolated from the skeleton of a long-term culture of healthy, tissue-covered, Pocillopora damicornis Linnaeus colonies maintained in a recirculating system in Monaco. As coral soft tissue spontaneously dissociated in vitro, the skeleton became exposed and hyaline hyphae emerged radially from 15% of the total clipped branches. In this study, which was performed between January 2001 and March 2003, 35 skeleton–hypha explants were embedded in agar-based solid medium, yielding 60% hyphal growth. A fungal strain (F19-3-1) of the dominant (80%) morphology was isolated and propagated in agar-based solid medium. The strain was identified by 18S and 26S rDNA gene sequence analysis as a basidiomycete in the genus Cryptococcus. Co-cultures were used to provide experimental exposure of coral soft tissue to the fungus. The fungus extended the survival of coral cells by 2 days, selectively maintaining skeletogenic cell types. This effect may be interpreted as stimulation by the fungus of a short-term coral defense response.Communicated by J.P. Grassle, New Brunswick     

Genomic erosion in a demographically recovered bird species during conservation rescue

The pink pigeon (Nesoenas mayeri) is an endemic species of Mauritius that has made a remarkable recovery after a severe population bottleneck in the 1970s to early 1990s. Prior to this bottleneck, an ex situ population was established from which captive-bred individuals were released into free-living subpopulations to increase population size and genetic variation. This conservation rescue led to rapid population recovery to 400–480 individuals, and the species was twice downlisted on the International Union for the Conservation of Nature (IUCN) Red List. We analyzed the impacts of the bottleneck and genetic rescue on neutral genetic variation during and after population recovery (1993–2008) with restriction site-associated sequencing, microsatellite analyses, and quantitative genetic analysis of studbook data of 1112 birds from zoos in Europe and the United States. We used computer simulations to study the predicted changes in genetic variation and population viability from the past into the future. Genetic variation declined rapidly, despite the population rebound, and the effective population size was approximately an order of magnitude smaller than census size. The species carried a high genetic load of circa 15 lethal equivalents for longevity. Our computer simulations predicted continued inbreeding will likely result in increased expression of deleterious mutations (i.e., a high realized load) and severe inbreeding depression. Without continued conservation actions, it is likely that the pink pigeon will go extinct in the wild within 100 years. Conservation rescue of the pink pigeon has been instrumental in the recovery of the free-living population. However, further genetic rescue with captive-bred birds from zoos is required to recover lost variation, reduce expression of harmful deleterious variation, and prevent extinction. The use of genomics and modeling data can inform IUCN assessments of the viability and extinction risk of species, and it helps in assessments of the conservation dependency of populations.     

Lack of population subdivision among the minke whales (Balaenoptera acutorostrata) from Icelandic and Norwegian waters based on mitochondrial DNA sequences

The minke whale (Balaenoptera acutorostrata) is subject to commercial whaling, but stock identification and assessment are still uncertain. Mitochondrial DNA (mtDNA) sequences were determined to examine the population structure of minke whales from the central and northeastern parts of the North Atlantic, as well as the Antarctic regions IV and V. The analyses include 345 nucleotide positions of the control region of 110 individuals, and 250 nucleotide positions of the NADH dehydrogenase subunit 2 gene for a representative selection of North Atlantic minke whales. Maximum parsimony analyses and sequence divergence calculations did not reveal any genetic differentiation between individuals from the central and northeastern parts of the North Atlantic. These results do not support the International Whaling Commission's separation of minke whales in this area into different management units, and they are in conflict with previously reported results from allozyme analyses. Comparison of minke whale control region sequences showed that the sequence diversity of North Atlantic minke whales is substantially lower (0.0065) than that of Antarctic minke whales (0.0166), and clearly demonstrated that individuals from these two areas represent genetically distinct populations.     

Sex ratio and host size in a parasitoid wasp

Summary Parasitoid wasps often lay male eggs in small hosts and female eggs in larger hosts. The selective advantage of this strategy can be explained by assuming wasp fitness increases with host size and that this fitness increase is greater in females than in males. I conducted experiments to test a model based on this explanation and found the results generally supported the model with one exception; unlike what the model assumed, these wasps were unable to adjust their offspring sex ratios in each generation to different host size distributions. This finding suggests an alternate view as to how selection might operate in the evolution of parasitoid sex ratios.     

Prenatal diagnosis of NADH:ubiquinone oxidoreductase deficiency

NADH:ubiquinone oxidoreductase (complex I of the mitochondrial respiratory chain) deficiency is a severe disorder with an often early fatal outcome. Prenatal diagnosis for complex I defects currently relies mainly on biochemical assays of complex I in fetal tissues such as chorionic villi (CV), and is only in a minority of cases possible by means of mutational analysis of nuclear-encoded genes of complex I. We report on our experience to date with prenatal diagnosis in pregnancies at risk for complex I deficiency. We measured complex I activity in native CV and/or cultured CV in 23 pregnancies in 15 families. In accordance with the results of the investigations in CV, 15 children were born clinically unaffected. Two prenatally diagnosed unaffected fetuses and two prenatally diagnosed affected fetuses were lost prematurely with spontaneous or provoked abortions, respectively. Two affected children were born (prenatally found to be affected). In two pregnancies a discrepancy between native and cultured cells was found. We conclude that prenatal diagnosis for complex I deficiency can be reliably performed. Pitfalls were encountered in using cultured CV as a result of maternal cell contamination (MCC). Future research on pathogenic nuclear mutations underlying complex I deficiency will extend the possibilities for prenatal diagnosis at the molecular level. Copyright © 2001 John Wiley & Sons, Ltd.