Multiple transgressions of Wallace's Line explain diversity of flightlessTrigonopterusweevils on Bali

Abstract

The fauna of Bali, situated immediately west of Wallace's Line, is supposedly of recent Javanese origin and characterized by low levels of endemicity. In flightless Trigonopterus weevils, however, we find 100% endemism for the eight species here reported for Bali. Phylogeographic analyses show extensive in situ differentiation, including a local radiation of five species. A comprehensive molecular phylogeny and ancestral area reconstruction of Indo-Malayan-Melanesian species reveals a complex colonization pattern, where the three Balinese lineages all arrived from the East, i.e. all of them transgressed Wallace's Line. Although East Java possesses a rich fauna of Trigonopterus, no exchange can be observed with Bali. We assert that the biogeographic picture of Bali has been dominated by the influx of mobile organisms from Java, but different relationships may be discovered when flightless invertebrates are studied. Our results highlight the importance of in-depth analyses of spatial patterns of biodiversity.

To what extent do new fossil discoveries change our understanding of clade evolution? A cautionary tale from burying beetles (Coleoptera:Nicrophorus)

“…In contrast, the second set of calibrations implies a colonization during the early Miocene when both the Sunda and Sahul regions collided (Seton et al ., ). This geological rearrangement resulted in a massive orogeny in Wallacea (Hall, , ) and Melanesia (Toussaint et al ., ) responsible for the exchange of biotas between the Oriental and Australian regions (Tänzler et al ., ; Toussaint et al ., ; Condamine et al ., ). Hence, these contrasting results imply either a climatic or a geological factor to explain the biogeographic history of Nicrophorus in Southeast Asia. The biogeographic reconstruction based on the first calibration set recovers four Neotropical colonization events in the last 4 Myr (Fig.…”

Complex inter‐island colonization and peripatric founder speciation promote diversification of flightless Pachyrhynchus weevils in the Taiwan–Luzon volcanic belt

“…Recent studies on a few flightless weevils have suggested that they have been able to colonize numerous remote archipelagos and islands likely due to their long and complex histories in the regions (Claridge et al, 2017;Machado et al, 2017;T€ anzler et al, 2016). However, the mechanism and transporting vectors of effective long-distance dispersal across oceanic barriers remain elusive for these weevils.…”

“…flightless Trigonopterus weevils in Bali, T€ anzler, Toussaint, Suhardjono, Balke, & Riedel, 2014). Conservation of insular species and endangered populations in their peripheral ranges is crucial for preserving rare alleles and unique phenotypes.…”

“…The P. orbifer complex represents an excellent set of organisms to test the stepping-stone hypothesis, not only because of the existence of closely related endemic species on nearly every sizable island across the archipelago, but also due to three intriguing adaptations that may facilitate their cross-ocean dispersal through rafting on floating vegetation by oceanic currents: (1) Pachyrhynchus adults are wingless and have completely fused elytra; (2) they have the ability to draw and keep air under their elytra, allowing them to float on water for at least several hours (Schultze, 1923); (3) their eggs are inserted into plant tissues, and the larvae live and feed inside the stems of the host plants. Recent studies suggested that flightless weevils were able to colonize remote archipelagos of Southeast Asia and the Pacific via stepping-stone islands (Claridge, Gillespie, Brewer, & Roderick, 2017;Machado, Rodr ıguez-Exp osito, L opez, & Hern andez, 2017;T€ anzler et al, 2016).…”

Closing the gap: Avian lineage splits at a young, narrow seaway imply a protracted history of mixed population response

“…Indeed, only about 30% of bird, reptile, amphibian, butterfly and snail species are distinct to one side or another of Lombok Strait (Mayr, ). The majority of taxa are shared by Lombok and Bali, and phylogeographic data demonstrate some plants and animals have experienced numerous exchanges of individuals across Lombok Strait (e.g., Tänzler, Toussaint, Suhardjono, Balke, & Riedel, ; Thomas et al., ). Even well‐recognized features such as Wallace's line involve a mixture of ecological and evolutionary processes in their maintenance (e.g., Condamine et al., ).…”