Geographic range and habitat reconstructions shed light on palaeotropical intercontinental disjunction and regional diversification patterns in Artabotrys (Annonaceae)

Abstract

AimThe biogeographical and habitat history of the species‐rich angiosperm genus Artabotrys is reconstructed to assess hypotheses relating to processes that underlie palaeotropical intercontinental disjunction (PID) and regional diversification patterns.LocationPalaeotropics.TaxonArtabotrys (Annonaceae).MethodsPhylogenetic relationships were estimated based on 53 Artabotrys species, using four chloroplast and 10 nuclear markers (c. 15.7 kb). Divergence times were estimated using two fossil calibrations and an uncorrelated lognormal relaxed clock model. Ancestral range estimation was performed under a dispersal–extinction–cladogenesis model while ancestral habitat reconstruction was conducted using the BAYAREALIKE model.ResultsArtabotrys is unequivocally monophyletic, with a species‐rich main Artabotrys clade (MAC) comprising distinct African and Asian sister clades, and an early divergent grade (EDG) comprising two African species. An ancestral range in Africa is inferred, with a single dispersal to Asia. The PID at the MAC crown occurred in the Miocene. A broad habitat tolerance spanning rain forests and seasonally dry forests/savannas was inferred at the MAC stem and crown nodes. Several shifts from rain forests to seasonally dry habitats were inferred, but there is no indication of a reverse transition.Main conclusionsThe most plausible explanation for the PID involves overland migration across Arabia in the Miocene, prior to subsequent climate deterioration. Long‐standing differences in climatic niche may have resulted in a significant yet porous biogeographical divide at the Isthmus of Kra, but Wallace's line does not reflect differences in climatic niches. Niche conservatism is an underlying pattern in Artabotrys, with local niche shifts occurring rather recently.

Correlated evolution of diaspore traits and potential frugivore‐mediated selection in a fleshy‐fruited tropical lineage ( Artabotrys , Annonaceae)

“…The species sampled were essentially identical to those used for phylogenetic reconstruction by Chen et al. (2019), although 10 species with incomplete morphological data were excluded, yielding a dataset of 43 Artabotrys species. All seeds and monocarps were sampled from dried herbarium material as it is difficult to obtain fresh material for such a widely distributed lineage.…”

“…The extraction of locality data and WorldClim bioclimatic variables followed Chen et al. (2019). We examined seven bioclimatic variables: annual mean temperature, isothermality, temperature seasonality, annual precipitation, precipitation of the driest month, precipitation seasonality, and precipitation of the driest quarter.…”

“…The Artabotrys dataset extracted from Chen et al. (2019) contained 1221 occurrences, ranging from 1 to 151 locality points for each species, with a mean of 23 points per species. All continuous traits and climatic data were log‐transformed prior to analysis, but all data presented in the results and discussion were back‐transformed.…”

“…All PGLS analyses were run using a pruned version of the maximum clade credibility (MCC) tree from Chen et al. (2019).…”

“…The habitat diversity, well‐studied seed anatomy, well‐resolved phylogeny (Chen et al. 2019), and substantially variable diaspore traits render Artabotrys suitable for investigating correlated evolution.…”