The complex geological and ecological processes that have generated high levels of biodiversity and endemism in the Baja California Peninsula have been the subject of intensive study. However, relatively little is known about phylogeography of the iconic endemic palm species of this region. We therefore analyzed a total of 2,294 bp of chloroplast and 738 bp of nuclear sequence data in 169 samples of five native palm species from Baja California, Sonora and Guadalupe Island. We found that Washingtonia and Brahea palms had low levels of genetic diversity and were highly structured, with the majority of species and major geographic regions being characterized by distinct haplotypes. We also found strong support for currently recognized species in Washingtonia, but our results were less clear cut for Brahea due to haplotype sharing. Furthermore, patterns of population structure were broadly consistent with historical vicariant events such as the inundation of the Isthmus of La Paz, the formation of the Sea of Cortez, and the more recent colonization and isolation of Guadalupe Island's palms. Our findings contribute toward a growing appreciation of the complexity of plant responses to past geological changes and also provide valuable baseline genetic data on relict American palm species.

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Population structure has direct consequences on species evolution, local adaptation, and the capacity of a metapopulation to adapt to climate change. In this study we assess the genetic structure and demographic history of the Pacific angel shark, Squatina californica, along the northwestern coast of Mexico using the mitochondrial control region. Results showed high levels of genetic diversity and reveal genetic differentiation between the samples from the Pacific coast of the Baja California Peninsula and those from the Gulf of California. These genetic differences are consistent with ontogenetic differences previously reported for S. californica off the northwestern coast of Mexico. Our findings can be explained by the low dispersal ability and habitat preference of the angel shark and by the complex geomorphology off the northwestern coast of Mexico. Contrasting historical demographic patterns were observed: population expansion in the gulf and population stability, with a declining trend, in the Pacific; however, more studies are required to corroborate demographic patterns in both populations. Our results point to 2 distinct management units of the Pacific angel shark in the study area, and this may have direct implications for the management and conservation of this species in Mexico. RESUMEN.La estructura poblacional tiene consecuencias directas sobre la evolución de las especies, la adaptación local y la capacidad de una metapoblación para adaptarse al cambio climático. En el presente estudio, se analizó la estructura genética y la historia demográfica del tiburón ángel del Pacífico, Squatina californica, a lo largo de la costa noroccidental de México con base en la región control del ADN mitocondrial. Los resultados mostraron elevados niveles de diversidad genética y diferenciación genética entre las muestras del Pacífico frente a la península de Baja California y aquellas del golfo de California. Estas diferencias genéticas son consistentes con las diferencias ontogenéticas reportadas previamente para S. californica en la costa noroccidental de México. Los resultados pueden ser explicados por la baja capacidad de dispersión y la preferencia de hábitat de S. californica y por la compleja geomorfología frente a la costa noroccidental de México. Además, se observaron diferentes patrones demográficos históricos: la población del golfo exhibió una tendencia a la expansión y la población del Pacífico exhibió estabilidad con tendencia a disminuir; sin embargo, es necesario realizar más estudios para corroborar los patrones demográficos detectados en ambas poblaciones. Los resultados sugieren la presencia de 2 diferentes unidades para la gestión pesquera del tiburón ángel del Pacífico en el área de estudio, lo cual tiene implicaciones directas para la conservación y gestión de esta especie en México.Palabras clave: tiburón demersal, grupos ecológicos, diferenciación genética, golfo de California, costa del Pacífico.

Endangered species with small population sizes are susceptible to genetic erosion, which can be detrimental to long-term persistence. Consequently, monitoring and mitigating the loss of genetic diversity are essential for conservation. The Peninsular pronghorn (Antilocapra americana peninsularis) is an endangered pronghorn subspecies that is almost entirely held in captivity. Captive breeding has increased the number of pronghorns from 25 founders in 1997 to around 700 individuals today, but it is unclear how the genetic diversity of the captive herd may have changed over time. We therefore generated and analysed data for 16 microsatellites spanning 2009–2021. We detected a decline in heterozygosity and an increase in the proportion of inbred individuals over time. However, these trends appear to have been partially mitigated by a genetically informed breeding management attempt that was implemented in 2018. We also reconstructed the recent demographic history of the Peninsular pronghorn, revealing two sequential population declines putatively linked to the desertification of the Baja California peninsula around 6000 years ago, and hunting and habitat loss around 500 years ago, respectively. Our results provide insights into the genetic diversity of an endangered antelope and indicate the potential for genetically informed management to have positive conservation outcomes.

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