Millennial-Scale Temperature Change Velocity in the Continental Northern Neotropics

Abstract

Climate has been inherently linked to global diversity patterns, and yet no empirical data are available to put modern climate change into a millennial-scale context. High tropical species diversity has been linked to slow rates of climate change during the Quaternary, an assumption that lacks an empirical foundation. Thus, there is the need for quantifying the velocity at which the bioclimatic space changed during the Quaternary in the tropics. Here we present rates of climate change for the late Pleistocene and Holocene from Mexico and Guatemala. An extensive modern pollen survey and fossil pollen data from two long sedimentary records (30,000 and 86,000 years for highlands and lowlands, respectively) were used to estimate past temperatures. Derived temperature profiles show a parallel long-term trend and a similar cooling during the Last Glacial Maximum in the Guatemalan lowlands and the Mexican highlands. Temperature estimates and digital elevation models were used to calculate the velocity of isotherm displacement (temperature change velocity) for the time period contained in each record. Our analyses showed that temperature change velocities in Mesoamerica during the late Quaternary were at least four times slower than values reported for the last 50 years, but also at least twice as fast as those obtained from recent models. Our data demonstrate that, given extremely high temperature change velocities, species survival must have relied on either microrefugial populations or persistence of suppressed individuals. Contrary to the usual expectation of stable climates being associated with high diversity, our results suggest that Quaternary tropical diversity was probably maintained by centennial-scale oscillatory climatic variability that forestalled competitive exclusion. As humans have simplified modern landscapes, thereby removing potential microrefugia, and climate change is occurring monotonically at a very high velocity, extinction risk for tropical species is higher than at any time in the last 86,000 years.

Ecological Speciation in Nolina parviflora (Asparagaceae): Lacking Spatial Connectivity along of the Trans-Mexican Volcanic Belt

“…Instead, our results are more similar to those reported by Bryson & Riddle [27], where tropical montane specialists persisted in isolation over longer periods of time, corroborated by empirical studies of vegetation change in central and western Mexico over the last 86,000 years [51], [52]. Our previous study [22] revealed relatively old divergence times between the eastern and western clades (see their Fig.…”

Vegetation assemblages of central Mexico through the late Quaternary: modern analogs and compositional turnover

“…; Correa‐Metrio et al. ), and moisture availability has been largely controlled by the millennial‐scale migration of the Intertropical Convergence Zone (e.g. Correa‐Metrio et al.…”

“…( b ) Isotopic record from Greenland core NGRIP as global temperature surrogate (NGRIP Members ), and temperature anomalies with respect to present at Chalco Basin, Central Basin of Mexico (Correa‐Metrio et al. ). ( c ) Hypothetical scenarios of likelihood of no‐analogue vegetation assemblage occurrence with (right) and without (left) a strong human influence on regional vegetation assemblages.…”

Climate risk on two vegetation axes—Tropical wet‐to‐dry and temperate arid‐to‐moist forests

“…Studying these zones to understand how species react or adapt to such limits, as well as identifying those segments of a population with resistance to extreme conditions (sensu Matyas, ), would be very informative and could help us mitigate forest mortality. Humans and climate have been provoking changes in vegetation distribution for centuries, if not millennia (Caballero‐Rodriguez, Lozano‐Garcia, & Correa‐Metrio, ; Correa‐Metrio, Bush, Lozano‐Garcia, & Sosa‐Najera, ), but in the face of extensive habitat fragmentation (Aguilar‐Santelises & del Castillo, ; Asbjornsen, Ashton, Vogt, & Palacios, ; Watson, ), having a more spatially explicit hypothesis of where climate exposure is likely to have the greatest impacts on existing patterns of vegetation could direct management efforts.…”