The flickering connectivity system of the north Andean páramos

Abstract

Aim To quantify the effect of Pleistocene climate fluctuations on habitat connectivity across páramos in the Northern Andes. Location Northern Andes. Methods The unique páramos habitat underwent dynamic shifts in elevation in response to changing climate conditions during the Pleistocene. The lower boundary of the páramos is defined by the upper forest line, which is known to be highly responsive to temperature. Here, we reconstruct the extent and connectivity of páramos over the last 1 million years (Myr) by reconstructing the upper forest line from the long fossil pollen record of Funza09, Colombia, and applying it to spatial mapping on modern topographies across the Northern Andes for 752 time slices. Data provide an estimate of how often and for how long different elevations were occupied by páramos and estimate their connectivity to provide insights into the role of topography in biogeographical patterns of páramos. Results Our findings show that connectivity amongst páramos of the Northern Andes was highly dynamic, both within and across mountain ranges. Connectivity amongst páramos peaked during extreme glacial periods but intermediate cool stadials and mild interstadials dominated the climate system. These variable degrees of connectivity through time result in what we term the ‘flickering connectivity system’. We provide a visualization (video) to showcase this phenomenon. Patterns of connectivity in the Northern Andes contradict patterns observed in other mountain ranges of differing topographies. Main conclusions Pleistocene climate change was the driver of significant elevational and spatial shifts in páramos causing dynamic changes in habitat connectivity across and within all mountain ranges. Some generalities emerge, including the fact that connectivity was greatest during the most ephemeral of times. However, the timing, duration and degree of connectivity varied substantially among mountain ranges depending on their topographical configuration. The flickering connectivity system of the páramos uncovers the dynamic settings in which evolutionary radiations shaped the most diverse alpine biome on Earth.

Why mountains matter for biodiversity

“…Islands may also serve as refugia during periods of climatic change, as in the case of conifers in New Caledonia, which originally derived from the Australian mainland (Condamine, Leslie, & Antonelli, ). Likewise, during ice ages local populations may persist on nunataks (exposed peaks otherwise surrounded by a glacier or snow), recolonizing downhill when the surrounding environment subsequently warms (Flantua & Hooghiemstra, ; Flantua et al, ; Flantua, O'Dea, Onstein, Giraldo, & Hooghiemstra, ; Parducci et al, ).…”

“…Likewise, during ice ages local populations may persist on nunataks (exposed peaks otherwise surrounded by a glacier or snow), recolonizing downhill when the surrounding environment subsequently warms (Flantua & Hooghiemstra, 2018;Flantua et al, 2014;Flantua, O'Dea, Onstein, Giraldo, & Hooghiemstra, 2019;Parducci et al, 2012).…”

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

“…Additionally, a widespread species appears to be present in northern páramo sites, and some sister species sympatry may indicate other diversification processes have operated on certain lineages of Panabachia. Divergence time estimates suggest that Panabachia originated in the Miocene, but most species analyzed diverged during the Pliocene and Pleistocene (5.3-0.11 Mya), contemporaneous with the evolution of páramo plant species.Insects 2020, 11, 64 2 of 19 allowing species to exchange genetic material between populations that were usually separated by elevation [5,14], or, alternately, driving the fragmentation of species distributions [5,13,15,16].In the present day, a tropical alpine ecosystem known as páramo is found in the northern Andes above 2800 m, comprising numerous isolated island patches [17,18]. Multiple factors, including isolation due to elevation and climatic oscillations, have played into shaping the current diversity in the páramo [9,18].…”

“…These include morphological, physiological and behavioral adaptations as results of experiencing harsh abiotic conditions, such as extreme temperatures, higher solar radiation, desiccation and reduced oxygen pressure [19][20][21].The phylogeographic structure of few Andean species has been assessed, most focusing on vascular plants and vertebrate species in a larger phylogeographical context [9,15,22,23]. 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].…”

“…Insects 2020, 11, 64 2 of 19 allowing species to exchange genetic material between populations that were usually separated by elevation [5,14], or, alternately, driving the fragmentation of species distributions [5,13,15,16].…”