Skippers are a species rich and widespread group of butterflies with evolutionary patterns and processes largely unstudied despite some recent efforts. Among Hesperiidae, the subfamily Heteropterinae is a moderately diverse clade comprising ca. 200 species distributed from North to South America and from Africa to the Palearctic region. While some regions are species rich, others are far less diverse. Using anchored phylogenomics, we infer a robust timetree and estimate ancestral ranges to understand the biogeographic history of these skippers. Inferences based on up to 383 exons recover a robust backbone for the subfamily along with the monophyly of all genera. Bayesian divergence time estimates suggest an origin of Heteropterinae in the late Eocene, ca. 40 million years ago. Maximum likelihood ancestral range estimates indicate an origin of the group in the New World. The eastern Palearctic was likely colonized via a Beringian route and a reverse colonization event resulted in two independent and extant American clades. We estimate a vicariant event between Central and South America that significantly predates estimates of the proto‐Caribbean seaway closure, indicating active overwater dispersal in the Oligocene. The colonization of Africa from the east Palearctic is synchronous with the closure of the Tethys Ocean, while the colonization of Madagascar appears to be comparatively recent. Our results shed light on the systematics and biogeography of Heteropterinae skippers and unveil the evolutionary history of a new leaf in the skipper tree‐of‐life.
Cork oaks (Quercus section Cerris) comprise 15 extant species in Eurasia. Despite being a small clade, they display a range of leaf morphologies comparable to the largest sections (>100 spp.) in Quercus. Their fossil record extends back to the Eocene. Here, we explore how cork oaks achieved their modern ranges and how legacy effects might explain niche evolution in modern species of section Cerris and its sister section Ilex, the holly oaks.
We inferred a dated phylogeny for cork and holly oaks using a reduced-representation next-generation sequencing method, restriction site-associated DNA sequencing (RAD-seq), and used D-statistics to investigate gene flow hypotheses. We estimated divergence times using a fossilized birth–death model calibrated with 47 fossils. We used Köppen profiles, selected bioclimatic parameters and forest biomes occupied by modern species to infer ancestral climatic and biotic niches.
East Asian and Western Eurasian cork oaks diverged initially in the Eocene. Subsequently, four Western Eurasian lineages (subsections) differentiated during the Oligocene and Miocene. Evolution of leaf size, form and texture was correlated, in part, with multiple transitions from ancestral humid temperate climates to mediterranean, arid and continental climates. Distantly related but ecologically similar species converged on similar leaf traits in the process.
Originating in temperate (frost-free) biomes, Eocene to Oligocene ranges of the primarily deciduous cork oaks were restricted to higher latitudes (Siberia to north of Paratethys). Members of the evergreen holly oaks (section Ilex) also originated in temperate biomes but migrated southwards and south-westwards into then-(sub)tropical southern China and south-eastern Tibet during the Eocene, then westwards along existing pre-Himalayan mountain ranges. Divergent biogeographical histories and deep-time phylogenetic legacies (in cold and drought tolerance, nutrient storage and fire resistance) thus account for the modern species mosaic of Western Eurasian oak communities, which are composed of oaks belonging to four sections.
- NSF-PAR ID:
- 10403027
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Annals of Botany
- ISSN:
- 0305-7364
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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