Many arctic‐alpine plant genera have undergone speciation during the Quaternary. The bases for these radiations have been ascribed to geographic isolation, abiotic and biotic differences between populations, and/or hybridization and polyploidization. The Cordilleran
- Award ID(s):
- 1930030
- PAR ID:
- 10429732
- Editor(s):
- Eaton, Deren
- Date Published:
- Journal Name:
- Systematic Biology
- ISSN:
- 1063-5157
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Campanula L. (Campanulaceae Juss.), a monophyletic clade of mostly endemic arctic‐alpine taxa from western North America, experienced a recent and rapid radiation. We set out to unravel the factors that likely influenced speciation in this group. To do so, we integrated environmental, genetic, and morphological datasets, tested biogeographic hypotheses, and analyzed the potential consequences of the various factors on the evolutionary history of the clade. We created paleodistribution models to identify potential Pleistocene refugia for the clade and estimated niche space for individual taxa using geographic and climatic data. Using 11 nuclear loci, we reconstructed a species tree and tested biogeographic hypotheses derived from the paleodistribution models. Finally, we tested 28 morphological characters, including floral, vegetative, and seed characteristics, for their capacity to differentiate taxa. Our results show that the combined effect of Quaternary climatic variation, isolation among differing environments in the mountains in western North America, and biotic factors influencing floral morphology contributed to speciation in this group during the mid‐Pleistocene. Furthermore, our biogeographic analyses uncovered asynchronous consequences of interglacial and glacial periods for the timing of refugial isolation within the southern and northwestern mountains, respectively. These findings have broad implications for understanding the processes promoting speciation in arctic‐alpine plants and the rise of numerous endemic taxa across the region. -
Functional traits of vertebrates can be used to infer paleoenvironmental conditions, allowing research into past climate changes and biotic responses. Birds are generally considered poor palaeoclimatic proxies due to their high vagility. Here, we analyze biogeographical and climatic niche information from multiple vertebrate groups including small mammals, reptiles, and birds to infer the paleoclimatic conditions present during the Late Pleistocene (~14,500–17,000 years BP) at Talara, an asphaltic paleontological locality on the northern Peruvian coast. We created Ecological Niche Models for the nearest living relative of each fossil species identified at Talara. We then used the Mutual Ecogeographic Range method, obtaining the overlapping area between distributions for each vertebrate group (birds, reptiles, and small mammals) as well as for combinations of groups, to infer the paleoclimate at Talara and to determinate what taxonomic groups are best for reconstructing climate in this system. Our analyses indicate that conditions at Talara were slightly cooler and significantly wetter than those of the present day. Individually, different vertebrate groups provide different paleoclimatic information. Birds were found to be a poor paleoclimatic proxy. Mammals were good for inferring paleoprecipitation but not paleotemperature. Reptiles were good group for inferring paleotemperature but not paleoprecipitation. While analyzing all vertebrate groups together yields the most robust conclusions, reptiles and small mammals combined are a good proxy for inferring both paleoprecipitation and paleotemperature. Our results suggest an interstadial period that agrees with paleotemperatures inferred from isotopic and sedimentary information. Our research indicates that today, the southern portion of the Cauca biogeographic province (230 km NE from Talara) has comparable climatic conditions to Late Pleistocene Talara. Understanding how the Talara region transitioned from this biodiverse ecosystem to the hyperarid coastal desert of today could have important implications for predicting biotic response and tipping points in the context of modern climate change.more » « less
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Abstract We present a phylogeographic study of at least six reproductively isolated lineages of new world harvester ants within the
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Abstract Although the impact of Pleistocene glacial cycles on the diversification of the tropical biota was once dismissed, increasing evidence suggests that Pleistocene climatic fluctuations greatly affected the distribution and population divergence of tropical organisms. Landscape genomic analyses coupled with paleoclimatic distribution models provide a powerful way to understand the consequences of past climate changes on the present‐day tropical biota. Using genome‐wide SNP data and mitochondrial DNA, combined with projections of the species distribution across the late Quaternary until the present, we evaluate the effect of paleoclimatic shifts on the genetic structure and population differentiation of
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Premise: A switch in pollinator can occur when a plant lineage enters a new habitat where the ancestral pollinator is less common and a novel pollinator is more common. Since pollinator communities vary according to environmental tolerances and availability of resources, there may be consistent associations between pollination mode and specific regions and habitats. Such associations can be studied in lineages that have experienced multiple pollinator transitions, representing evolutionary replicates. Methods: Our study focused on a large clade of Penstemon wildflower species in western North America that has repeatedly evolved hummingbird-adapted flowers from ancestral bee-adapted flowers. For each species, we estimated geographic ranges from occurrence data and inferred environmental niches from climate, topographical, and soil data. Using a phylogenetic comparative approach, we investigated whether hummingbird-adapted species occupy distinct geographic regions or habitats relative to beeadapted species. Results: Hummingbird-adapted species occur at lower latitudes and lower elevations than bee-adapted species, resulting in a difference in their environmental niche. Hummingbird-adapted species seem to evolve in lineages that previously adapted to lower latitudes and elevations, since bee-adapted species sister to hummingbird-adapted species also occur in these regions and habitats. Sister species pairs – regardless of whether they differ in pollinator – show relatively little geographic range overlap. Conclusions: Adaptation to a novel pollinator may often occur in geographic and ecological isolation from ancestral populations. The ability of a given lineage to adapt to novel pollinators may critically depend on its ability to colonize regions and habitats associated with novel pollinator communities.more » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/sysbio/syad018
