Using the palaeontological record of Microtus to test species distribution models and reveal responses to climate change

Abstract

Aim We used newly identified fossil specimens to reconstruct the Quaternary distributions of five Microtus species (Rodentia: Arvicolinae) from the Pacific coast of the United States. We used these distributions to test the hypothesis that when projected onto past, alternative climate surfaces, species distribution models (SDMs) created using only climate variables are concordant with the empirical data of fossil Microtus species occurrences.Location Specimens from 11 fossil localities in California, Oregon and Nevada were identified and evaluated.Methods Geometric morphometrics and discriminant analyses were used to identify fossil Microtus specimens. Using a maximum-entropy modelling approach, the best model for all five species was selected using the Akaike information criterion. Nineteen bioclimate variables were used to create SDMs for the five Microtus species using both Community Climate System Model (CCSM) and Model for Interdisciplinary Research on Climate (MIROC) models. ResultsWe confidently identified 144 Microtus fossils, including the first fossil specimens of Microtus oregoni and Microtus townsendii. SDMs reconstructed approximately half the extralimital fossil occurrences (i.e. those found outside the present-day range). Those species with extralimital occurrences not reconstructed have niche models primarily influenced by precipitation variables. The two species whose extralimitals were well predicted occupy indistinguishable climatic niches.Main conclusions The ranges of Pacific coast Microtus species have undergone substantial regional contractions since the Last Glacial Maximum (LGM; 21 ka). Inconsistencies between LGM SDMs and Quaternary fossil ranges indicate potential problems with LGM precipitation reconstructions, although interspecific interactions are also likely to contribute to these differences. Overall, the study highlights the need for further, detailed, species-level palaeodistributions to put recent observations in a broader temporal context and examine the effectiveness of SDMs coupled with climate models for predicting range dynamics under scenarios of climate change.

Agricultural intensification during the Late Holocene rather than climatic aridification drives the population dynamics and the current conservation status ofMicrotus cabrerae, an endangered Mediterranean rodent

“…Despite strong predictive performance, the model failed to identify the occurrence of some fossil records. Other studies have found similar problems and usually attribute this to uncertainty and errors in palaeoclimate reconstruction, changes in realized species niches, or inability of SDMs to capture realized niches (McGuire & Byrd Davis, ; Veloz et al., ). In our study, however, false negatives (fossil records predicted as absences) are predicted as suboptimal but not completely unsuitable (Figure S5 in Appendix S5).…”

“…Like most Arvicolinae species, M. cabrerae does not fully occupy its potential distributional range (McGuire & Byrd Davis, ). We posit that this phenomenon is a result of intense human‐derived land use changes of Mediterranean landscapes since the Mid‐Holocene (Quèzel & Médail, ), which led to habitat reduction and fragmentation.…”

Distributions of mammals in Southeast Asia: The role of the legacy of climate and species body mass

“…Indeed, by using a snapshot of the current species distribution and assuming that the ecological requirements of the species were similar in the past, we hindcasted the habitat suitability of this species to the past periods. Although the niche conservatism assumption is highly debated (Davis et al, ; Martínez‐Meyer et al, ; Mcguire & Davis, ) no better alternative is yet available for projecting the habitat suitability of hundreds of species on a large spatial extent. To fit our SDMs we used species distribution maps available from the IUCN Red List, which despite of the lack of accuracy for some of the mammal species in our analysis, provide the best available data source for mammals.…”

Paleodistribution modeling in archaeology and paleoanthropology

“…These predictions have, in some cases, been validated against paleodistribution data from fossils, pollen, etc. (Martinez--Meyer et al, 2004;McGuire and Davis, 2013;Waltari and Guralnick, 2009).…”