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The Tracking of Moist Habitats Allowed Aiphanes (Arecaceae) to Cover the Elevation Gradient of the Northern Andes

ABSTRACT: The topographic gradients of the Tropical Andes may have triggered species divergence by different mechanisms. Topography separates species’ geographical ranges and offers climatic heterogeneity, which could potentially foster local adaptation to specific climatic conditions and result in narrowly distributed endemic species. Such a pattern is found in the Andean centered palm genus Aiphanes. To test the extent to which geographic barriers and climatic heterogeneity can explain distribution patterns in Aiphanes, we sampled 34 out of 36 currently recognized species in that genus and sequenced them by Sanger sequencing and/or sequence target capture sequencing. We generated Bayesian, likelihood, and species-tree phylogenies, with which we explored climatic trait evolution from current climatic occupation. We also estimated species distribution models to test the relative roles of geographical and climatic divergence in their evolution. We found that Aiphanes originated in the Miocene in Andean environments and possibly in mid-elevation habitats. Diversification is related to the occupation of the adjacent high and low elevation habitats tracking high annual precipitation and low precipitation seasonality (moist habitats). Different species in different clades repeatedly occupy all the different temperatures offered by the elevation gradient from 0 to 3,000 m in different geographically isolated areas. A pattern of conserved adaptation to moist environments is consistent among the clades. Our results stress the evolutionary roles of niche truncation of wide thermal tolerance by physical range fragmentation, coupled with water-related niche conservatism, to colonize the topographic gradient.

SUBMITTER: Sanin M

PROVIDER: S-EPMC9272002 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The tropical Andes are characterized by extreme topographic and climatic complexity, which has likely contributed to their outstanding current species diversity, composed of many range-restricted species. However, little is known about how the distribution and abundance of highly mobile organisms, like long-distance migratory birds, varies across different land covers, elevations, and climatic conditions within the Andes. We conducted 1,606 distance-sampling point counts across the Colombian Andes, spanning elevations from 253 to 3,708 m, a range of precipitation regimes and representative land covers. We then employed a novel application of a multispecies hierarchical modeling approach to evaluate how elevation, local land cover, aboveground woody biomass, cloud cover, precipitation, and seasonality in precipitation shape the abundance of the migratory land bird community in the Andes. We detected 1,824 individuals of 29 species of migratory land birds, six of which were considered incidental in our study region. We modeled the abundance of the remaining 23 species, while considering observer and time of day effects on detectability. We found that both elevation and land cover had an overriding influence on the abundance of migratory species across the Andes, with strong evidence for a mid-elevation peak in abundance, and species-specific responses to both variables. As a community, migratory birds had the highest mean abundance in shade coffee plantations, secondary forest, and mature forest. Aboveground woody biomass did not affect the abundance of all species as a group, but a few showed strong responses to this variable. Contrary to predictions of a positive correlation between abundance and precipitation, we found no evidence for community-level responses to precipitation, aside for a weak tendency for birds to select areas with intermediate levels of precipitation. This novel use of a multispecies model sheds new light on the mechanisms shaping the winter distribution of migratory birds and highlights the importance of elevation and land cover types over climatic variables in the context of the Colombian Andes.

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The Tracking of Moist Habitats Allowed Aiphanes (Arecaceae) to Cover the Elevation Gradient of the Northern Andes

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