Quaternary Ice-Age dynamics in the Colombian Andes: developing an understanding of our legacy

Abstract

Pollen records from lacustrine sediments of deep basins in the Colombian Andes provide records of vegetation history, the development of the floristic composition of biomes, and climate variation with increasing temporal resolution. Local differences in the altitudinal distribution of present-day vegetation belts in four Colombian Cordilleras are presented. Operating mechanisms during Quaternary Ice-Age cycles that stimulated speciation are discussed by considering endemism in the asteraceous genera Espeletia, Espeletiopsis and Coespeletia. The floristically diverse lower montane forest belt (1000-2300 m) was compressed by ca. 55% during the last glacial maximum (LGM) (20 ka), and occupied the slopes between 800 m and 1400 m during that period. Under low LGM atmospheric p CO 2 values, C 4 -dominated vegetation, now occurring below 2200 m, expanded up to ca. 3500 m. Present-day C 3 -dominated paramo vegetation is therefore not an analogue for past C 4 -dominated vegetation (with abundant Sporobolus lasiophyllus).Quercus immigrated into Colombia 478 ka and formed an extensive zonal forest from 330 ka when former Podocarpus-dominated forest was replaced by zonal forest with Quercus and Weinmannia. During the last glacial cycle the ecological tolerance of Quercus may have increased. In the ecotone forests Quercus was rapidly and massively replaced by Polylepis between 45 and 30 ka illustrating complex forest dynamics in the tropical Andes.

Island radiation on a continental scale: Exceptional rates of plant diversification after uplift of the Andes

“…This scale creates extensive opportunities for geographical isolation, which is thought to be one of the main factors underlying the higher species diversification rates found on larger islands (29). Second, repeated fragmentation of high-altitude habitats due to altitudinal shifts in Andean vegetation zones prompted by Quaternary climate fluctuations are likely to have contributed to geographical isolation and diversification in the Andes (16,17,22,30). Third, the extremely dissected topography in the high Andes and steep tropical montane environmental gradients associated with altitude (31) further enhance opportunities for geographical isolation that is evident from the prevalence of narrowly restricted endemics among the Andean Lupinus species today.…”

Phylogeography of the Mountain Tapir (Tapirus pinchaque) and the Central American Tapir (Tapirus bairdii) and the Origins of the Three Latin-American Tapirs by Means of mtCyt-B Sequences

“…Effectively, after rising slowly for millions of years, the Central Andes had a rapid and final uplift in the last 6-10 MYA (Garzione et al 2008). The final uplift of the northern Andes in the Eastern Cordillera in Colombia was in the last 3-6 MYA (Hooghiemstra and Van der Hammen 2004), while the beginning of the haplotype diversification in T. pinchaque was around 2.1 MYA. This molecular result did not agree with the fact that T. pinchaque could be more primitive and to be in origin of T. terrestris as certain authors claimed (Hershkovitz 1954).…”

A stochastic, evolutionary model for range shifts and richness on tropical elevational gradients under Quaternary glacial cycles

“…The biogeographical drama played out on this shifting physiographic and climatic template, among essentially modern lineages, continues to be revealed by stoichiometry, by pollen and phytoliths, by plant and animal macrofossils, and by phylogeographic analysis of living populations (e.g. Colinvaux et al 1996;Schluter & Rambaut 1996;MacFadden et al 1999;Marchant et al 2002Marchant et al , 2009Hooghiemstra & Van der Hammen 2004;Bush & Flenley 2007;Dick & Heuertz 2008;Blois et al 2010;Voelker 2010).…”

“…Estimates for the scope of terrestrial temperature change in the tropics, at any given elevation, range from 48C to 108C between glacial lows and interglacial peaks (Wille et al 2001), accompanied by complex changes in the amount and seasonality of precipitation Marchant et al 2009) and the advance and retreat of high-elevation glaciers (Hooghiemstra & Van der Hammen 2004). Although mean annual temperature (MAT), at any given elevation, declines almost linearly with latitude outside the tropics, elevation-specific MAT varies little across tropical latitudes (Ahrens 2006), a pattern that has apparently persisted, on average, throughout the Pleistocene (MacFadden et al 1999).…”