Inbreeding variability and population structure in the invasive haplodiploid palm-seed borer (Coccotrypes dactyliperda).

We investigated the mating system and population genetic structure of the invasive haplodiploid palm-seed borer Coccotrypes dactyliperda in California. We focused on whether these primarily inbreeding beetles have a 'mixed-breeding' system that includes occasional outbreeding, and whether local inbreeding coefficients (F(IS)) varied with dominant environmental factors. We also analysed the genetic structure of C. dactyliperda populations across local and regional scales. Based on the analysis of genetic variation at seven microsatellite loci in 1034 individual beetles from 59 populations, we found both high rates of inbreeding and plentiful evidence of mixed-breeding. F(IS) ranged from -0.56 to 0.90, the highest variability reported within any animal species. There was a negative correlation between F(IS) and latitude, suggesting that some latitude-associated factor affecting mating decisions influenced inbreeding rates. Multiple regressions suggested that precipitation, but not temperature, may be an important correlate. Finally, we found highly significant genetic differentiation among sites, even over short geographic distances (< 1000 m).

On the track of the Red Queen: bark beetles, their nematodes, local climate and geographic parthenogenesis.

Geographic parthenogenesis has been explained as resulting from parasite pressure (Red Queen hypothesis): several studies have found high degrees of sexuals where the prevalence of parasites is high. However, it is important to address whether prevalence of parasites mirrors risk of infection. We explored geographic parthenogenesis of Ips acuminatus bark beetles and their nematodes. Local climate is crucial for nematode stages outside the host, in spring and summer, and prevalence should thus be associated with those temperatures if prevalence reliably reflects exposure risk across populations. This was the case; however, high prevalence of a virulent nematode species was not associated with many sexuals, whereas highly sexual populations were characterized by high infection risk of benign nematodes. Low virulence of the latter makes Red Queen dynamics unlikely. Geographical patterns of parthenogenesis were instead associated with winter temperature and variance in temperature.

Lack of nucleotide variability in a beetle pest with extreme inbreeding.

The coffee berry borer beetle Hypothenemus hampei (Ferrari) (Curculionidae: Scolytinae) is the major insect pest of coffee and has spread to most of the coffee-growing countries of the world. This beetle also displays an unusual life cycle, with regular sibling mating. This regular inbreeding and the population bottlenecks occurring on colonization of new regions should lead to low levels of genetic diversity. We were therefore interested in determining the level of nucleotide variation in nuclear and mitochondrial genomes of this beetle worldwide. Here we show that two nuclear loci (Resistance to dieldrin and ITS2) are completely invariant, whereas some variability is maintained at a mitochondrial locus (COI), probably corresponding to a higher mutation rate in the mitochondrial genome. Phylogenetic analysis of the mitochondrial data shows only two clades of beetle haplotypes outside of Kenya, the proposed origin of the species. These data confirm that inbreeding greatly reduces nucleotide variation and suggest the recent global spread of only two inbreeding lines of this bark beetle.

Human sexuality and the future.

PIP: Labeling certain developments which occurred in the 1960s and 1970s as a "sexual revolution" may make us believe that needed changes have already happened and that we can now direct our attention to other matters. Forthcoming changes in human sexuality are complex and multifaceted issues. Our control over the outcomes of sexual relating--with contraceptives, artificial insemination, germinal banks, and in vitro fertilization--have already altered many aspects of both sexual and human relating, and will alter them even more in the future. Another development offering greater control over the consequences of sexual relating comes from shifting from 1 discipline as an authority for moral sexual decision-making to another, and later still another. The locus of control has shifted from Christianity to medicine to a more human acceptance of sex and a more rational process of decision making. The integration of sexuality into a broader concept of thinking is moving us away from a concentration on the genitals and genital activity toward an awareness that we all are sexual persons. Judgments relating to suitable criteria for determining the rightness and wrongness of sexual behavior have experienced a marked change. There are, however, 4 factors which may lead in diametrically opposite directions: 1)the militaristic buildup which, if it continues, threatens to divide the world into armed camps; 2) dealing with certain environmental elements or technological developments--such as Chernobly--that may in the end exert so much power over our lives that we will be reduced to a struggle simply to remain alive; 3) our fragmented personal relationships and the often confusing and antagonistic attitude of 1 group to another; and 4) the spread of AIDS which is decreasing our present level of sexual activity and curtailing our freedom.^ieng