Biodiversity cradles and museums segregating within hotspots of endemism

Abstract

The immense concentrations of vertebrate species in tropical mountains remain a prominent but unexplained pattern in biogeography. A long-standing hypothesis suggests that montane biodiversity hotspots result from endemic species aggregating within ecologically stable localities. Here, the persistence of ancient lineages coincides with frequent speciation events, making such areas both ‘cradles’ (where new species arise) and ‘museums’ (where old species survive). Although this hypothesis refers to processes operating at the scale of valleys, it remains supported primarily by patterns generated from coarse-scale distribution data. Using high-resolution occurrence and phylogenetic data on Andean hummingbirds, we find that old and young endemic species are not spatially aggregated. The young endemic species tend to have non-overlapping distributions scattered along the Andean treeline, a long and narrow habitat where populations easily become fragmented. By contrast, the old endemic species have more aggregated distributions, but mainly within pockets of cloud forests at lower elevations than the young endemic species. These findings contradict the premise that biogeographical cradles and museums should overlap in valley systems where pockets of stable climate persist through periods of climate change. Instead, Andean biodiversity hotspots may derive from large-scale fluctuating climate complexity in conjunction with local-scale variability in available area and habitat connectivity.

Up and down from North to South: Latitudinal Distribution of Flea Beetle Genera in Continental Africa (Coleoptera, Chrysomelidae, Galerucinae, Alticini)

“…The presence of genera exclusively associated with a single belt is mainly related to the occurrence of mountain systems, such as Celisaltica in the Ruwenzori Massif (Uganda), Perichilona in the Iringa region (Tanzania), Upembaltica in the Katanga region (Democratic Republic of Congo), and Drakensbergianella in the Drakensberg Mountains (Democratic Republic of South Africa). This is not surprising, considering the acknowledged role of tropical mountains as "cradles" and/or "museums" of biodiversity [10,11,[61][62][63]. Indeed, although other mountains, such as Mount Kenya, Mount Aberdare, and Mount Kilimanjaro, lack endemic flea beetle genera, they nonetheless host several endemicities at the species level.…”

The study of species and phylogenetic diversity on karst forest along Lijiang River

“…It was generally believed that species turnover among communities was jointly driven by ecological processes such as diffusion limitation and environmental ltration, while species richness differences among communities were mainly driven by habitat ltration on regional environmental gradients (Jamoneau et al 2018). Many studies believed that species turnover components are the main contributions of beta diversity differences in forest (Wang et al 2018;Sonne et al 2022). Thus, beta diversity differences in forest are mainly caused by diffusion limitation and environmental ltration.…”

Unveiling evolutionary cradles and museums of flowering plants in a neotropical biodiversity hotspot

“…However, a significant distinction between the study on neotropical birds and the current paper lies in the fact that the former used branch length and its evolutionary relationships within the tree of life analysed under phylogenetic null models. Consequently, due to the methodological differences, an additional layer of evolutionary information has been introduced to further support the theory, as demonstrated in recent studies [7]. royalsocietypublishing.org/journal/rsos R. Soc.…”

“…The northern Andes have been considered an area capable of harbouring both cradles and museums of biodiversity [1,5]. For example, in the case of tropical hummingbird species, research has revealed that the Andean mountain ranges of Colombia contain localized areas with endemic species of both recent (young) and ancient (old) origin [7]. In fact, the Sierra Nevada de Santa Marta, which is an isolated massif, represents the clearest example of a cradle for young endemic species in Colombia, while the western mountain range displays more characteristics of a museum for endemic hummingbird species [7].…”