The role of dispersal for shaping phylogeographical structure of flightless beetles from the Andes

Abstract

Background Páramo is a tropical alpine ecosystem present in the northern Andes. Its patchy distribution imposes limits and barriers to specialist inhabitants. We aim to assess the effects of this habitat distribution on divergence across two independently flightless ground beetle lineages, in the genera Dyscolus and Dercylus. Methods One nuclear and one mitochondrial gene from 110 individuals from 10 sites across the two lineages were sequenced and analyzed using a combination of phylogenetics, population genetic analyses, and niche modeling methods. Results The two lineages show different degrees of population subdivision. Low levels of gene flow were found in Dyscolus alpinus, where one dominant haplotype is found in four out of the six populations analyzed for both molecular markers. However, complete population isolation was revealed in species of the genus Dercylus, where high levels of differentiation exist at species and population level for both genes. Maximum entropy models of species in the Dercylus lineage show overlapping distributions. Still, species distributions appear to be restricted to small areas across the Andes. Conclusion Even though both beetle lineages are flightless, the dispersal ability of each beetle lineage appears to influence the genetic diversity across fragmented páramo populations, where Dyscolus alpinus appears to be a better disperser than species in the genus Dercylus.

Mountains as Islands: Species Delimitation and Evolutionary History of the Ant-Loving Beetle Genus Panabachia (Coleoptera, Staphylinidae) from the Northern Andes

“…Yet, alpine beetle faunas from the Andes have only been superficially explored. Previous work in the Ecuadorian páramo has shown distinct patterns of genetic distribution in ground beetles, from higher population structure in flightless ground beetles [28] to high levels of genetic connectivity between populations of a macropterous species [27]. Still, the genetic diversity of other alpine beetle lineages from the Andes has not been assessed, leaving the question open as to whether other alpine insect lineages are following similar patterns as the ground beetles.…”

“…These studies have revealed that most páramo lineages are quite young (0.0025-5.33 Mya-Pliocene and Pleistocene; [5]), and that the orogeny of the Andes has played an important role shaping their phylogeographical patterns [5,15,[21][22][23]. The few studies done on insect lineages from high elevations have also shown that allopatric speciation is a contributing factor to their diversity patterns [24][25][26][27][28]. However, the specific patterns have varied depending on the dispersal capability of each insect lineage [27,28].…”

“…The few studies done on insect lineages from high elevations have also shown that allopatric speciation is a contributing factor to their diversity patterns [24][25][26][27][28]. However, the specific patterns have varied depending on the dispersal capability of each insect lineage [27,28]. These studies have revealed some lineages to exhibit high levels of gene flow among populations, while others show higher genetic structure across páramo patches [27,28].…”

“…However, the specific patterns have varied depending on the dispersal capability of each insect lineage [27,28]. These studies have revealed some lineages to exhibit high levels of gene flow among populations, while others show higher genetic structure across páramo patches [27,28]. Basic evolutionary processes are not well understood for most alpine lineages [29], and the discrepancies among high elevation lineages analyzed to date offer distinct hypotheses that may be tested with insect lineages occurring in páramo.The rove beetles (Coleoptera: Staphylinidae) represent one of the most diverse families of beetles (61,300 spp.)…”

“…(3) Is the distribution of genetic diversity limited by major geographic features such as rivers, dry valleys, and other subdivisions within the Ecuadorian Andes, as observed for some ground beetle lineages from páramo? and (4) Is the timing of diversification of Panabachia across páramo contemporary with establishment of Páramo in the high Andes (Miocene-Pliocene), or did it precede the current distribution of this ecosystem, as is apparent in some ground beetle lineages (e.g., Pelmatellus columbianus, 11.9 Mya and Dyscolus alpinus, 6.32 Mya [27,28]. These questions will be addressed through a combination of methods including species delimitation, phylogenetics and divergence time estimation.…”