Biogeography and Diversification of Bumblebees (Hymenoptera: Apidae), with Emphasis on Neotropical Species

Abstract

A detailed phylogeny of bumblebees is urgently needed to understand speciation and biogeographic diversification in the Neotropical region. We sequenced autosomal and mtDNA loci from nine Brazilian bumblebee species and compiled it with the data already available to obtain highly resolved phylogenetic trees with fossil-calibrated dates. The ancestral Bombus lineage was estimated to diversify between 47.08 and 34.27 million years ago (Ma) in the Holarctic region, but largely restricted to the eastern Old World. The Neotropical region was initially colonized in the Late Miocene, where bumblebee diversification was shown to be consistent with geologic and climatic events of the Late Cenozoic. Neotropical bumblebees likely originated from Nearctic lineages, which dispersed towards South America after 29 Ma.

Can biogeography help bumblebee conservation?

“…There then seems to have been a period with a burst of diversification of extant lineages centred on the mountains of southern Mexico (Williams et al 2022b). Discussion of the precise date continues (Hines 2008;Santos Junior et al 2022), but perhaps only as late as 3 Ma were bumblebees able to reach South America via the emerging Panama land bridge, most likely during periods when the climate was also cooler (Williams et al 2022b). Although there has been further speciation within South America, there has been less time for speciation there than nearer their origins in Asia, where by far the greatest diversity of bumblebees has had time to accumulate and still survives today.…”

“…The development of techniques for sequencing and interpreting DNA over the last two decades has added much new evidence for improving our understanding of the evolutionary relationships among bumblebee species (Kawakita et al 2004;Cameron et al 2007;Sun et al 2020). Nonetheless, dating the events on phylogenetic trees remains probably the most challenging and uncertain part of this process, with few informative fossils available for the calibration of models of DNA-sequence evolution (Hines 2008;Dehon et al 2019;Santos Junior et al 2022;Williams et al 2022b). In interpreting information on dates, most recent studies (Williams 1985;Kawakita et al 2004;Hines 2008;Dehon et al 2019) have agreed with Skorikov (1923) that the strong climatic cooling outside of the tropics at the beginning of the Oligocene (around 34 Ma) is likely to have been a significant factor favouring the early diversification of bumblebees.…”

“…It is most likely that bumblebees as we know them today originated in Asia, because that is where most of the early-diverging extant bumblebee species occur and where biogeographic reconstructions place their ancestors (Skorikov 1923;Williams 1985;Kawakita et al 2004;Hines 2008;Williams et al 2017bWilliams et al , 2022bSantos Junior et al 2022). However, one of the strongest patterns that has been hidden within the global distribution of bumblebee species richness (Fig.…”

“…They have also dispersed out from Asia to North America when land connections and suitable climatic conditions in Beringia allowed (Fig. 9) (Williams 1985;Kawakita et al 2004;Hines, 2008;Santos Junior et al 2022;Williams et al 2022b). They may have reached Central America around 8-12 Ma, but were probably prevented from reaching South America Figs 6-8.…”

A tribute to Fernando A. Silveira and his contributions to bee research

“…Two decades after Abelhas Brasileiras was published, this book has received over 1,000 citations (Google Scholar, accessed 03 November 2023). Fernando's contributions to taxonomy, phylogenetics, and biogeography extended well beyond exomalopsine bees, having encompassed other taxa of Apidae, as well as Colletidae, Halictidae, and Megachilidae (Azevedo & Silveira 2005;Ferrari et al 2016Ferrari et al , 2017Ferrari & Silveira 2015;Freitas et al 2018Freitas et al , 2019Freitas et al , 2023Freitas & Silveira 2017;Moure & Silveira 1992;Santos Júnior et al 2015, 2022Santos & Silveira 2009;Silveira 2009Silveira , 2007bSilveira & Martines 2009;Vélez & Silveira 2006;Zama et al 2019), totaling 22 new species and five new family-group taxa (Appendix). His contributions to bee biology were also important and considerably improved our knowledge of Brazilian bees (e.g., Cardoso & Silveira 2012;Carmo et al 2004;Martins et al 1999;Pompeu & Silveira 2005;Silveira 1991Silveira , 2002Simeão et al 2015), and put their conservation on a solid foundation (Machado et al 2008;Pinheiro-Machado et al 2002b;Pires et al 2008Pires et al , 2014aSilveira 2008;.…”