Fluctuation of ecological niches and geographic range shifts along chile pepper's domestication gradient.

Domestication is an ongoing well-described process. However, while many have studied the changes domestication causes in plant genetics, few have explored its impact on the portion of the geographic landscape in which the plants exist. Therefore, the goal of this study was to understand how the process of domestication changed the geographic space suitable for chile pepper (Capsicum annuum) in its center of origin (domestication). C. annuum is a major crop species globally whose center of domestication, Mexico, has been well-studied. It provides a unique opportunity to explore the degree to which ranges of different domestication classes diverged and how these ranges might be altered by climate change. To this end, we created ecological niche models for four domestication classes (wild, semiwild, landrace, modern cultivar) based on present climate and future climate scenarios for 2050, 2070, and 2090. Considering present environment, we found substantial overlap in the geographic niches of all the domestication classes. Yet, environmental and geographic aspects of the current ranges did vary among classes. Wild and commercial varieties could grow in desert conditions, while landraces could not. With projections into the future, habitat was lost asymmetrically, with wild, semiwild, and landraces at greater risk of territorial declines than modern cultivars. Further, we identified areas where future suitability overlap between landraces and wilds is expected to be lost. While range expansion is widely associated with domestication, we found little support of a constant niche expansion (either in environmental or geographical space) throughout the domestication gradient in chile peppers in Mexico. Instead, particular domestication transitions resulted in loss, followed by capturing or recapturing environmental or geographic space. The differences in environmental characterization among domestication gradient classes and their future potential range shifts increase the need for conservation efforts to preserve landraces and semiwild genotypes.

Population structure in diverse pepper (Capsicum spp.) accessions.

BACKGROUND: Peppers, bell and chile, are a culturally and economically important worldwide. Domesticated Capsicum spp. are distributed globally and represent a complex of valuable genetic resources. OBJECTIVES: Explore population structure and diversity in a collection of 467 peppers representing eight species, spanning the spectrum from highly domesticated to wild using 22,916 SNP markers distributed across the twelve chromosomes of pepper. RESULTS: These species contained varied levels of genetic diversity, which also varied across chromosomes; the species also differ in the size of genetic bottlenecks they have experienced. We found that levels of diversity negatively correlate to levels of domestication, with the more diverse being the least domesticated.

Genetic evidence of hybridization between Magellanic (Sphensicus magellanicus) and Humboldt (Spheniscus humboldti) penguins in the wild.

The process of hybridization between closely related species plays an important role in defining the genetic integrity and overall genetic diversity of species. The distribution range of Magellanic (Spheniscus magellanicus) and Humboldt (Spheniscus humboldti) penguins is predominantly allopatric; however, the species share a region of sympatry where they may hybridize. We analyzed four types of genetic markers (including nuclear and mitochondrial markers) to assess their utility in detecting hybridization events between Magellanic and Humboldt penguins. Genetic assessment of non-introgressed reference samples allowed us to identify three types of informative markers (microsatellites, major histocompatibility complex, and mitochondrial DNA) and detect positive evidence of introgressive hybridization in the wild. Four out of six putative hybrids showed positive evidence of hybridization, revealed by the detection of Humboldt mitochondrial DNA and Magellanic species-specific alleles from nuclear markers. Bayesian Structure analysis, including samples from the sympatric region of the species in the southern Pacific Ocean, confirmed the use of nuclear markers for detecting hybridization and genetic admixture of putative hybrids, but revealed relatively low levels of genetic introgression at the population level. These findings provide insights into the role of hybridization in regions of species sympatry and its potential consequences on the levels of genetic introgression, genetic diversity, and conservation of these penguin species.