Stream flow alone does not predict population structure of diving beetles across complex tropical landscapes

Abstract

Recent theoretical advances have hypothesized a central role of habitat persistence on population genetic structure and resulting biodiversity patterns of freshwater organisms. Here, we address the hypothesis that lotic species, or lineages adapted to comparably geologically stable running water habitats (streams and their marginal habitats), have high levels of endemicity and phylogeographic structure due to the persistent nature of their habitat. We use a nextRAD DNA sequencing approach to investigate the population structure and phylogeography of a putatively widespread New Guinean species of diving beetle, Philaccolilus ameliae (Dytiscidae). We find that P. ameliae is a complex of morphologically cryptic, but geographically and genetically well‐differentiated clades. The pattern of population connectivity is consistent with theoretical predictions associated with stable lotic habitats. However, in two clades, we find a more complex pattern of low population differentiation, revealing dispersal across rugged mountains and watersheds of New Guinea up to 430 km apart. These results, while surprising, were also consistent with the original formulation of the habitat template concept by Southwood, involving lineage‐idiosyncratic evolution in response to abiotic factors. In our system, low population differentiation might reflect a young species in a phase of range expansion utilizing vast available habitat. We suggest that predictions of life history variation resulting from the dichotomy between lotic and lentic organisms require more attention to habitat characterization and microhabitat choice. Our results also underpin the necessity to study fine‐scale processes but at a larger geographical scale, as compared to solely documenting macroecological patterns, to understand ecological drivers of regional biodiversity. Comprehensive sampling especially of tropical lineages in complex and threatened environments such as New Guinea remains a critical challenge.

Historical biogeography of the hyperdiverse hidden snout weevils (Coleoptera, Curculionidae, Cryptorhynchinae)

“…These latter dates are in line with our current reconstruction and indicate that New Guinea may have acted as a museum of diversity in addition to being a cradle as suggested by recent evolutionary studies focusing on the island fauna (e.g. Unmack et al ., ; Georges et al ., ; Toussaint et al ., ; Janda et al ., ; Oliver et al ., ; Lam et al ., ; Tallowin et al ., ). Our study brings more evidence to the potential role of New Guinea as an older land mass that may have hosted the early stages of several island clades.…”

Philaccolilus sagatai sp.n. from the Bewani Mountains of Papua New Guinea (Coleoptera: Dytiscidae: Laccophilinae)

“…KEY WORDS: Coleoptera, Dytiscidae, Philaccolilus, new species, Papua New Guinea, lotic species КЛЮЧЕВЫЕ СЛОВА: Coleoptera, Dytiscidae, Philaccolilus, новый вид, Папуа Новая Гвинея, виды текучих вод ly structured tropical landscapes [Lam et al, 2018]. That paper suggested lineage idiosyncratic population structure in the studied species, and also suggested presence of cryptic species.…”

NextRAD phylogenomics, sanger sequencing and morphological data to establish three new species of New Guinea stream beetles

“…This is an approach to perform genotyping by sequencing and collect genomic data e.g. for population genomic questions (Lam et al 2018). We discovered hidden diversity in the clades studied, with larger scale geographic structuring.…”