Higher temporal variability of forest breeding bird communities in fragmented landscapes

Understanding the relationship between animal community dynamics and landscape structure has become a priority for biodiversity conservation. In particular, predicting the effects of habitat destruction that confine species to networks of small patches is an important prerequisite to conservation plan development. Theoretical models that predict the occurrence of species in fragmented landscapes, and relationships between stability and diversity do exist. However, reliable empirical investigations of the dynamics of biodiversity have been prevented by differences in species detection probabilities among landscapes. Using long-term data sampled at a large spatial scale in conjunction with a capture-recapture approach, we developed estimates of parameters of community changes over a 22-year period for forest breeding birds in selected areas of the eastern United States. We show that forest fragmentation was associated not only with a reduced number of forest bird species, but also with increased temporal variability in the number of species. This higher temporal variability was associated with higher local extinction and turnover rates. These results have major conservation implications. Moreover, the approach used provides a practical tool for the study of the dynamics of biodiversity.

Multiple maternal origins and weak phylogeographic structure in domestic goats

Domestic animals have played a key role in human history. Despite their importance, however, the origins of most domestic species remain poorly understood. We assessed the phylogenetic history and population structure of domestic goats by sequencing a hypervariable segment (481 bp) of the mtDNA control region from 406 goats representing 88 breeds distributed across the Old World. Phylogeographic analysis revealed three highly divergent goat lineages (estimated divergence >200,000 years ago), with one lineage occurring only in eastern and southern Asia. A remarkably similar pattern exists in cattle, sheep, and pigs. These results, combined with recent archaeological findings, suggest that goats and other farm animals have multiple maternal origins with a possible center of origin in Asia, as well as in the Fertile Crescent. The pattern of goat mtDNA diversity suggests that all three lineages have undergone population expansions, but that the expansion was relatively recent for two of the lineages (including the Asian lineage). Goat populations are surprisingly less genetically structured than cattle populations. In goats only ≈10% of the mtDNA variation is partitioned among continents. In cattle the amount is ≥50%. This weak structuring suggests extensive intercontinental transportation of goats and has intriguing implications about the importance of goats in historical human migrations and commerce.

Genome projects and gene pools: New germplasm for plant breeding?

Crop gene pools have adapted to and sustained the demands of agricultural systems for thousands of years. Yet, very little is known about their content, distribution, architecture, or circuitry. The presumably shallow elite gene pools often continue to yield genetic gains while the exotic pools remain mostly untapped, uncharacterized, and underutilized. The concept and content of a crop’s gene pools are being changed by advancements in plant science and technology. In the first generation of plant genomics, DNA markers have refined some perceptions of genetic variation by providing a glimpse of a primary source, DNA polymorphism. The markers have provided new and more powerful ways of assessing genetic relationships, diversity, and merit by infusing genetic information for the first time in many scenarios or in a more comprehensive manner for others. As a result, crop gene pools may be supplemented through more rapid and directed methods from a greater variety of sources. Previously limited by the barriers of sexual reproduction, the native gene pools will soon be complemented by another gene pool (transgenes) and perhaps by other native exotic gene pools through comparative analyses of plants’ biological repertoire. Plant genomics will be an important force of change for crop improvement. The plant science community and crop gene pools may be united and enriched as never before. Also, the genomes and gene pools, the products of evolution and crop domestication, will be reduced and subjected to the vagaries and potential divisiveness of intellectual property considerations. Let the gains begin.