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

Abstract

Aim Disentangling the relative importance of climatic and anthropogenic factors is crucial in conservation biology but problematic using short‐term data only. Long‐term (palaeobiological) data are thus increasingly being used to understand taxon history and to identify potential status and baseline (pre‐anthropogenic) conditions, which in turn allows the optimization of species conservation plans. We combined species distribution models (SDMs) with current and palaeo‐occurrences of Microtus cabrerae, a threatened Mediterranean rodent, to circumvent the limitations of the palaeorecord (e.g. spatio‐temporal bias), to characterize this rodent's history (potential status and baseline conditions) since the Mid‐Holocene (~6,000 yr BP), and to determine the relative importance of climatic and anthropogenic factors in its decline. Location Historic distributional range of M. cabrerae (Iberian Peninsula and SE France). Methods We used generalized linear models (GLMs) to study the effects of four climatic (temperature and precipitation seasonality, minimum temperature, aridity) and four anthropogenic variables (human influence index, surface area of irrigated crops, rain‐fed crops and pastures) on the species’ current distribution. Then, we used an ensemble of SDMs to estimate its current and Mid‐Holocene potential distributions based only on climate variables, and validated model projections against current and palaeo records. Finally, suitability maps were analysed to study the species’ range dynamics during the Late Holocene. Results Microtus cabrerae's current distribution is constrained by both climatic and anthropogenic variables. Temperature and precipitation seasonality—but not aridity or minimum temperature—play an important positive role in constraining its distribution, but agriculture is the main human activity that affects it negatively. Climatic changes during the Late Holocene probably led to an expansion of its distribution without fragmentating its range. Main conclusions Contrary to previous hypotheses, under natural conditions, M. cabrerae should be in an expansive phase of its taxon cycle. Yet, its potential and current conservation status is negatively affected by agricultural habitat destruction, suggesting that conservation strategies should aim to control agricultural intensification.

Using the past to contextualize anthropogenic impacts on the present and future distribution of an endemic Caribbean mammal

“…These 2 drivers require 2 different management responses (Garrido‐Garcia et al. ). We assessed whether the present fragmented distribution of S. paradoxus is due to natural decline in its taxon cycle by projecting past 1 (LGM) into the present as present 0.…”

Voles and Lemmings (Arvicolinae) of the Palaearctic Region

“…At the landscape scale, the colonies are small (mean diameter≈50 m) and far apart with the average distance of the nearest neighbour at ~365 m. Historical range was more extensive also encompassing northern and southern Spain, and until the Middle Ages, the coastal areas of the Balearic Sea and the Gulf of Lyon in southern France (Laplana & Sevilla 2013). Range contraction was ascribed to climate change (Laplana & Sevilla 2013) or intensification in agriculture (Garrido- García et al 2017). M. cabrerae occupy discrete tall herb patches scattered across the agricultural landscape (Pita et al 2014) which are associated with a high water table or are periodically flooded.…”