The niche conservatism hypothesis postulates that physiological and phylogenetic factors constrain species distributions, creating richness hotspots with older lineages in ancestral climatic ...conditions. Conversely, niche convergence occurs when species successfully disperse to novel environments, diversifying and resulting in areas with high phylogenetic clustering and endemism, low diversity, and lower clade age. The Mexican Transition Zone exhibits both patterns as its biotic assembly resulted from successive dispersal events of different biotic elements called cenocrons. We test the hypothesis that biogeographic transitionallity in the area is a product of niche conservatism in the Nearctic and Typical Neotropical cenocrons and niche convergence in the Mountain Mesoamerican cenocron.
We split the avifauna into three species sets representing cenocrons (sets of taxa that share the same biogeographic history, constituting an identifiable subset within a biota by their common biotic origin and evolutionary history). Then, we correlated richness, endemism, phylogenetic diversity, number of nodes, and crowning age with environmental and topographic variables. These correlations were then compared with the predictions of niche conservatism versus niche convergence. We also detected areas of higher species density in environmental space and interpreted them as an environmental transition zone where birds' niches converge.
Our findings support the expected predictions on how niches evolved. Nearctic and Typical Neotropical species behaved as predicted by niche conservatism, whereas Mountain Mesoamerican species and the total of species correlations indicated niche convergence. We also detected distinct ecological and evolutionary characteristics of the cenocrons on a macroecological scale and the environmental conditions where the three cenocrons overlap in the Mesoamerican region.
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•The new Onthophagus gonzaloi and O. yescaensis are described from Mexico.•New distributional records are provided for O. browni.•The Mexican fauna of Onthophagus now includes 122 ...species.
Two new species of Onthophagus Latreille, 1802 from the Pacific Slope of Mexico are described and illustrated: Onthophagus gonzaloi Moctezuma, Hernández & Sánchez-Huerta, sp. nov., and Onthophagus yescaensis Moctezuma, Hernández & Sánchez-Huerta,sp. nov. New records for Onthophagus browniHowden & Cartwright, 1963 from the Mexican states of Jalisco (the southernmost locality known to date) and Zacatecas are provided.
urn:lsid:zoobank.org:pub:51AA52C6-41BF-4A8B-9BC9-D78600EDB32E.
The genus Phanaeus is a well-known group whose taxonomy has been described multiple times. Its distribution was previously classified into 11 ecogeographic groups that are equivalent to areas of ...endemism. Here we use Species Distribution Models to describe species richness patterns. We measured beta-diversity and regionalized its distribution into one region and one transition zone, both with three dominions: Mexican Transition Zone (North American, Mexican, and Mesoamerican dominions) and Neotropical region (Pacific, Brazilian, and Atlantic Forest dominions). We also present a species checklist and updated the distribution maps for 73 of 81 species described so far that reflects all the taxonomical updates. We include a list of all the recorded locations (by country, state, and province), list the recorded habitats and biomes, and describe the modelled environmental conditions for each species.
The Mexican Transition Zone is a biogeographically complex area where old and new lineages of Neotropical and Nearctic affinities overlap. Its biota was assembled by successive dispersal events of ...cenocrons, which are sets of taxa that dispersed during a given time interval from both North and South America and then diversified in the area. The Mexican Plateau cenocron, with Neotropical affinities, is found in temperate and dry climates in the Nearctic region. We hypothesised that it underwent an adaptive shift in environmental niche. We tested this hypothesis using a phylogenetic comparative framework, measuring phylogenetic signal and fitting to single optima macroevolutionary models, and an Ornstein‐Uhlenbeck macroevolutionary model with multiple optima. We used phylogenetic and distributional information of the tribe Phanaeini to assess whether there exists a distinction in conservatism between the earliest (Mexican Plateau) and most recent (Typical Neotropical) cenocrons within the Mexican Transition Zone (MTZ) as this tribe stands as a classic example of the dispersal and diversification patterns of cenocrons originating in the Neotropics. We identified different shifts in environmental requirements that match the niche description of the Mexican Plateau cenocron, suggesting that it was established through multiple adaptive shifts in the Mexican Transition Zone.
Faunistical and ecological studies are lacking on dung beetles in the xerophytic scrublands at Villa de Cos, Zacatecas, of the Mexican Plateau Province. This study analyzed the effect of season and ...vegetation type on community structure. Pitfall traps baited with human dung were sampled at six sites on three dates (early rainy season, dog days, and late rainy season). In total, 4,040 beetles in 17 species were trapped. Vegetation type and sampling season affected average dung beetle abundance, species richness, and Simpson diversity index. Scrublands had more abundance and richness but least diversity than grasslands. Abundance diminished during dog days but richness increased during this season and the rains after it. Diversity had an inverse pattern with more during early rains than during the dog days or late rains. The community structure was determined by microhabitats for nesting provided by the combination of vegetation type and soil compaction. Telecoprids like Canthon humectus (Say) were dominant as predicted for Mexican arid zones; paracoprids were present in deeper soils and endocoprids in shallower soils. Abundance increased during periods of rainfall and diminished during dog days, which increased richness. This change because of vegetation and season could indicate a strategy to reduce interspecific competition by partial partitioning of the ecological niche. This was the first faunistical and ecological work and provided the first dung beetle records for the municipality.
