Seasonal Distribution of the Broad-Tailed Hummingbird (Selasphorus platycercus): A Climatic Approach.

The seasonal movements of birds are a phenomenon that has historically been of interest in ecology and biogeography. Despite this, information on how environmental conditions influence migratory behavior and its regulation is still scarce. In this work, we study the Broad-Tailed hummingbird Selasphorus platycercus from an analysis of its populations through longitudinal and latitudinal gradients. We use the frequencies of monthly presence records throughout the annual cycle to identify the breeding areas (corresponding to the summer months), of winter presence (corresponding to the winter months), and annual residence (presence records throughout the year). Subsequently, we use ecological niche models to reconstruct the potential distribution of the summer and winter niches by correlating the climates of each season with the corresponding records. We evaluate the species' climatic preferences between the breeding and winter seasons by transferring the niches from each season to the opposite and by their capacity to inter-predict records between seasons. In addition, we quantify the overlap between the summer and winter niches using a niche similarity analysis. Geographically, we see a clear seasonal turnover pattern along a north-south gradient and records throughout the year (resident populations) in the south-central region of its distribution. We observed a low inter-prediction of records between seasons. Together with the similarity analysis, we suggest that the species is niche-switching (i.e., has different seasonal niches). We identified three seasonal migration patterns among the species' populations: long-distance migratory, short-distance summer migrant, and resident. Our findings suggest that the different migration patterns in this species' populations all over its distribution can be explained through seasonal climatic variations throughout the year.

Biogeografía del tomate Solanum lycopersicum var. cerasiforme (Solanaceae) en su centro de origen (sur de América) y de domesticación (México)

El tomate (Solanum lycopersicum) es una de las principales hortalizas en el mundo debido a las importantes ganancias económicas que genera su comercialización; sin embargo, a pesar de que la especie es ampliamente cultivada en el mundo, su diversidad genética se considera restringida. Esto hace que su resistencia a plagas y enfermedades en las variedades actualmente cultivadas sea baja. Existe la forma silvestre S. l. var ceraciforme que se distribuye desde Suramérica (centro de origen) hasta México (área de domesticación), específicamente en la vertiente del Golfo de México en Veracruz. Como objetivo, se quiso identificar patrones de diversificación ambiental con los que se pudiesen inferir procesos de adaptación de las poblaciones en el área de domesticación con respecto a su centro de origen. Asimismo, se planteó proponer medidas de conservación y rescate del tomate S. l. var. cerasiforme. Se realizaron modelos de nicho ecológico (MNE) con Maxent versión 3.4.1 (evaluados con AUC y ROC-parcial) para determinar la idoneidad de las condiciones ambientales, incluyendo proyecciones del centro de domesticación al área de origen y viceversa. Esto se realizó con base en ocho variables de temperatura y precipitación. Los registros de tomate fueron tomados de fuentes bibliográficas y trabajo de campo. Seguidamente, se realizó la prueba de comparación de nichos (equivalencia y similitud), propuesta por Broennimann et al. (2012), para evaluar la similitud de condiciones ambientales en ambas regiones. Posteriormente, se realizó un análisis de varianza seguido de una prueba de comparación de medias (Tukey, P ≤ 0.05) con las ocho variables ambientales utilizadas. Los valores de AUC (0.93 y 0.80) y ROC-parcial obtenidos (1.86 y 1.71; P = 0.0001) de los MNE muestran que fueron buenos modelos predictores. Se observó que en el centro de México existen condiciones ambientales similares a las del centro de origen, a diferencia de la vertiente del Golfo de México donde son diferentes. La prueba de equivalencia mostró que la comparación ambiental entre ambas regiones es menos equivalente que lo esperado por azar (P = 0.003). Mientras tanto, la otra prueba indica que la similitud que existe entre ambas regiones también se puede obtener por azar (P = 0.683). También, se encontraron diferencias significativas en tres variables de temperatura y precipitación. En conclusión, el centro de origen y de domesticación de S. l. var. cerasiforme tienen características ambientales en común a pesar de la distancia geográfica, pero existen zonas geográficas (vertiente del Golfo de México en Veracruz) en el área de domesticación con condiciones ambientales diferentes a las de su centro de origen y con un potencial importante como bancos de germoplasma.

The tomato (Solanum lycopersicum) is one of the main horticultural crops in the world because of the important economic benefits that its commercialization generates. Even though the species is widely cultivated in the world, it is susceptible to pests, diseases, and environmental stresses due to the loss of its genetic diversity. There is a wild form called S. l. var ceraciforme that is distributed from South America (its center of origin) to Mexico (its area of domestication), specifically on the slope of the Gulf of Mexico in Veracruz. Due to the large genetic diversity of these wild tomatoes, it is important to improve its crop. The objective of this investigation was to identify patterns of environmental diversification of the tomato, infer the processes of adaptation of the populations in the area of domestication with respect to their center of origin and propose measures of conservation and variation of S. l. var. cerasiforme. We generated two ecological niche models (MNE) with Maxent version 3.4.1 (evaluated with AUC and partial-ROC) to determine the suitability of environmental conditions including their respective projections from the domestication center to the area of origin and vice versa. We used eight variables of temperature and precipitation. Additionally, we included tomato records from bibliographical sources and fieldwork. We also used the niche comparison test (equivalency and similarity) proposed by Broennimann et al. (2012) to evaluate the similarity of environmental conditions in both regions. Subsequently, we carried out an analysis of variance followed by a mean comparison test (Tukey, P ≤ 0.05) with all environmental variables measured. The values of AUC (0.93 and 0.80) and partial-ROC (1.86 and 1.71, P = 0.0001) of the MNE showed that they were good predictive models. We observed that, in the center of Mexico, there are environmental conditions similar to those of the center of origin, unlike the slope of the Gulf of Mexico where they are different. The equivalency test showed that the environmental comparison between both regions is less similar than expected by chance (P = 0.003). The similarity test indicated that the existing similarity between both regions can also be obtained by chance (P = 0.683). We also found significant differences in three temperature and precipitation variables. In conclusion, we determined that the center of origin and domestication of S. l. var. cerasiforme has similar environmental characteristics despite the geographic distance; nevertheless, there are geographical zones (the Gulf of Mexico in Veracruz) in the area of domestication with different environmental conditions. Those places have the potential to contain valuable germplasms.

Museum genomics reveals the speciation history of Dendrortyx wood-partridges in the Mesoamerican highlands.

Natural history collections are increasingly valued as genomic resources. Their specimens reflect the combined efforts of collectors and curators over hundreds of years. For many rare or endangered species, specimens are the only readily available source of DNA. We leveraged specimens from a historical collection to study the evolutionary history of wood-partridges in the genus Dendrortyx. The three Dendrortyx species are found in the highlands of central Mexico and Central America south to Costa Rica. One of these species is endangered, and in general, Dendrortyx are secretive and poorly represented in tissue collections. We extracted DNA from historical museum specimens and sequenced ultraconserved elements (UCEs) and mitochondrial DNA (mtDNA) to assess their phylogeny and divergence times. Phylogenies built from hundreds to thousands of nuclear markers were well resolved and largely congruent with an mtDNA phylogeny. The divergence times revealed an unusually old avian divergence across the Isthmus of Tehuantepec in the Pliocene around 3.6 million years ago. Combined with other recent studies, our results challenge the general pattern that highland bird divergences in Mesoamerica are relatively young and influenced by the Pleistocene glacial cycles compared to the older divergences of reptiles and plants, which are thought to overlap more with periods of mountain formation. We also found evidence for monophyletic genetic lineages in mountain ranges within the widespread D. macroura, which should be investigated further with integrative taxonomic methods. Our study demonstrates the power of museum genomics to provide insight into the evolutionary histories of groups where modern samples are lacking.

Crumble analysis of the historic sympatric distribution between Dendrortyx macroura and D. barbatus (Aves: Galliformes).

In Mexico, the Long-tailed Wood-Partridge (Dendrortyx macroura) is distributed in the mountains of the Trans-Mexican Volcanic Belt, Sierra Madre del Sur and Sierra Norte de Oaxaca; while the Bearded Wood-Partridge (D. barbatus) is distributed in the Sierra Madre Oriental (SMO). There is a controversial overlap in distribution (sympatry) between these two species (on the Cofre de Perote and Pico de Orizaba volcanoes, SMO and Sierra Norte de Oaxaca), based on the ambiguity and current lack of information regarding the distribution of these two species. In order to disentangle the possible presence of both species in the area of sympatry, we conducted a crumble analysis of the historic knowledge regarding the geographic distribution of both species, based on a review of scientific literature, database records, the specimen examination (in ornithological collections), field work and a reconstruction of the distribution range based on Ecological Niche Modeling. Our results support the presence of only one of these two species in the overlapping area, rejecting the existence of such an area of sympatry between the two species. We discuss alternative hypotheses that could explain the historically reported distribution pattern: 1) an error in the single existing historical record; 2) a possible local extinction of the species and 3) the past existence of interspecific competition that has since been resolved under the principle of competitive exclusion. We propose that the Santo Domingo River in northern Oaxaca and western slope of the Sierra Madre Oriental, mark the distribution limits between these species.