The development and application of genomic tools to loblolly pine (Pinus taeda L.) offer promising insights into the organization and structure of conifer genomes. The application of a high-throughput genotyping assay across diverse forest tree species, however, is currently limited taxonomically. This is despite the ongoing development of genome-scale projects aiming at the construction of expressed sequence tag (EST) libraries and the resequencing of EST-derived unigenes for a diverse array of forest tree species. In this paper, we report on the application of Illumina's high-throughput GoldenGate™ SNP genotyping assay to a loblolly pine mapping population. Single nucleotide polymorphisms (SNPs) were identified through resequencing of previously identified wood quality, drought tolerance, and disease resistance candidate genes prior to genotyping. From that effort, a 384 multiplexed SNP assay was developed for high-throughput genotyping. Approximately 67% of the 384 SNPs queried converted into high-quality genotypes for the 48 progeny samples. Of those 257 successfully genotyped SNPs, 70 were segregating within the mapping population. A total of 27 candidate genes were subsequently mapped onto the existing loblolly pine consensus map, which consists of 12 linkage groups spanning a total map distance of 1,227.6 cM. The ability of SNPs to be mapped to the same position as fragment-based markers previously developed within the same candidate genes, as well as the pivotal role that SNPs currently play in the dissection of complex phenotypic traits, illustrate the usefulness of high-throughput SNP genotyping technologies to the continued development of pine genomics.

We use 10 microsatellite DNA markers to assess genetic diversity within and among the four runs (winter, spring, fall, and late fall) of chinook salmon (Oncorhynchus tshawytscha) in California's Central Valley. Forty-one population samples are studied, comprising naturally spawning and hatchery stocks collected from 1991 through 1997. Maximum likelihood methods are used to correct for kinship in juvenile samples and run admixture in adult samples. Through simulation, we determine the relationship between sample size and number of alleles observed at polymorphic microsatellite markers. Most samples have random-mating equilibrium proportions of single and multilocus genotypes. Temporal and spatial genetic heterogeneity is minimal among samples within subpopulations. An F ST of 0.082 among subpopulations, however, indicates substantial divergence among runs. Thus, with the exception of our discovery of two distinct lineages of spring run, genetic structure accords with the diverse chinook life histories seen in the Central Valley and provides a means for discrimination of protected populations. Résumé : Nous nous sommes servis de dix marqueurs microsatellites de l'ADN pour estimer la diversité génétique dans et entre les quatre remontes (hiver, printemps, automne et fin de l'automne) de quinnat (Oncorhynchus tshawytscha) dans la vallée centrale de la Californie. Nous avons étudié 41 échantillons de populations, représentant des poissons à reproduction naturelle et des stocks d'écloserie, prélevés entre 1991 et 1997. Les méthodes du maximum de vraisemblance ont servi à faire la correction pour la parenté génétique dans les échantillons de juvéniles et pour le mélange des remontes dans les échantillons d'adultes. Par la simulation, nous déterminons la relation entre la taille de l'échantillon et le nombre d'allèles observés aux marqueurs polymorphes microsatellites. La plupart des échantillons présentent des proportions équilibrées d'appariement aléatoire de génotypes à un et à plusieurs locus. L'hétérogénéité génétique temporelle et spatiale est minime entre les échantillons au sein des sous-populations. Un F ST de 0,082 entre les sous-populations indique toutefois une divergence substantielle entre les remontes. Ainsi, à l'exception de notre découverte de deux lignées distinctes dans la remonte du printemps, la structure génétique concorde avec les divers cycles biologiques du quinnat observés dans la vallée centrale et fournit un moyen de distinguer les populations protégées. [Traduit par la Rédaction] Banks et al. 927

Abstract.We examined interactions between the ant Iridomyrmex nitidiceps and the lycaenid butterfly Paralucia aurifera in southeastern Australia, and present data supporting the hypothesis that both participants benefit from their association. In the field, lycaenids persisted only on those host plants that ants subsequently colonized. In the laboratory, lycaenid larvae reared with ants were 31-76% heavier, developed 37% faster, and commonly completed one or two fewer instars than larvae reared without ants. Ant tending also resulted in 20% heavier pupae, 69% shorter pupal duration, and 5% larger adults as measured by forewing length; adults were not significantly different as measured by body length. We hypothesize that these positive effects occurred largely because ant-tended lycaenid larvae spent more time feeding than did untended larvae. Field data documented that ants colonized host plants only after lycaenid larvae were present, indicating that ants actively maintained the association. In laboratory experiments, 40% more ant workers survived when lycaenid larvae were present than when they were absent, although ant mass was not significantly affected. We hypothesize that the survivorship effects occurred because ants consumed the lycaenid's nectary gland secretions, which contained considerable amounts of glucose and amino acids. Our results show that lycaenids can benefit from ants in ways other than, or in addition to, protection from natural enemies and that they incur minimal developmental costs from associating with ants.

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