Genetic gains in oil yields after nine years of breeding Melaleuca alternifolia (Myrtaceae)

A breeding program to enhance the economics of producing essential oil (Australian tea tree oil) from Melaleuca alternifolia plantations in eastern Australia by improving oil yields and oil quality commenced in 1993. This paper reports the results of the first (2003) and second harvests (2004) of a yield trial established by the program in 2002. The trial compares the performance of three grades of seed (clonal seed orchard, first generation seedling seed orchard and selected provenance) released to the industry by the breeding program against an unimproved seedlot (industry standard). Industry standard is representative of seed available to growers in 2001 from alternative sources within the industry. Progeny from the clonal seed orchard had the highest oil yield, giving an estimated average improvement in yield over industry standard of 83%. This was followed by selected provenance and first generation seedling seed orchard with 55% and 43% improvement, respectively. These yield improvements were accompanied by desirable changes in oil quality traits among breeding program seedlots which gave lower 1,8-cineole and higher terpinen-4-ol levels than industry standard. Economic analyses have demonstrated that, with current prices less than $20 per kg of oil, older plantations need to be replanted with new germplasm that will yield 90% more oil per hectare than plantings based on unselected seed if they are to deliver a 10% rate of return on investment. Gains of this magnitude are possible through the use of the breeding program’s clonal seed orchard seedlot. If the price drops further, then even greater yield gains will be necessary for farms to remain profitable. These gains will be delivered by the breeding program in the coming years through the release of seed from a second generation seedling seed orchard and fully tested clones suitable for mass propagation

Phylogenomic Analysis of Seal Lice Reveals Co-divergence with their Hosts

Lice are considered a model system for studying the process of cospeciation because they are obligate and permanent parasites and are often highly host-specific. Among lice, species in the family Echinophthiriidae Enderlein (Anoplura) are unique in that they infest mammalian hosts with an amphibious lifestyle, i.e. pinnipeds and the river otter. There is evidence that the ancestor of this group infested the terrestrial ancestor of pinnipeds, which suggests these parasites coevolved with their hosts during the transition to marine environments. However, there has been no previous study investigating the phylogenetic relationships among sucking lice parasitizing seals and sea lions. To uncover the evolutionary history of these parasites, we obtained genomic data for Antarctophthirus microchir Trouessart and Neumann (from two hosts), Antarctophthirus carlinii Leonardi et al., Antarctophthirus lobodontis Enderlein, Antarctophthirus ogmorhini Enderlein, Lepidophthirus macrorhini Enderlein, and Proechinophthirus fluctus Ferris. From genomic sequence reads, we assembled >1000 nuclear genes and used these data to infer a phylogenetic tree for these lice. We also used the assembled genes in combination with read-mapping to estimate heterozygosity and effective population size from individual lice. Our analysis supports the monophyly of lice from pinnipeds and uncovers phylogenetic relationships within the group. Surprisingly, we found that A. carlinii, A. lobodontis, and A. ogmorhini have very little genetic divergence among them, whereas the divergence between different geographic representatives of A. microchir indicate that they are possibly different species. Nevertheless, our phylogeny of Echinophthiriidae suggests that these lice have consistently codiverged with their hosts with minimal host switching. Population genomic metrics indicate that louse effective population size is linked to host demographics, which further highlights the close association between pinnipeds and their lice.Fil: Leonardi, María Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Virrueta Herrera, Stephany. Illinois Natural History Survey; Estados UnidosFil: Sweet, Andrew. Illinois Natural History Survey; Estados Unidos. Purdue University; Estados UnidosFil: Negrete, Javier. Universidad Nacional de La Plata; Argentina. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; ArgentinaFil: Johnson, Kevin P.. University of Illinois; Estados Unido