Ricardo Pita

Microtus cabrerae (Rodentia: Cricetidae)

Abstract:  Microtus cabrerae Thomas, 1906, or Cabreras vole, is a medium-sized arvicoline, and one of the largest Microtus species. M. cabrerae is an Iberoccitane endemic, which is currently restricted to the Iberian Peninsula, where it presents a highly fragmented distribution. The species is the sole extant representative of the anagenetic Iberomys lineage with origin in the early Pleistocene. M. cabrerae is primarily restricted to wet habitats dominated by tall grasses, sedges, and rushes. The species has experienced strong population declines mainly during the past 10 years, particularly due to agricultural intensification. M. cabrerae is currently classified by the International Union for Conservation of Nature and Natural Resources as “Near Threatened,” and is listed in the Habitats Directive and Bern Convention, thus requiring appropriate conservation measures.

Endemic species may have complex histories: within-refugium phylogeography of an endangered Iberian vole

Glacial refugia protected and promoted biodiversity during the Pleistocene, not only at a broader scale, but also for many endemics that contracted and expanded their ranges within refugial areas. Understanding the evolutionary history of refugial endemics is especially important in the case of endangered species to recognize the origins of their genetic structure and thus produce better informed conservation practices. The Iberian Peninsula is an important European glacial refugium, rich in endemics of conservation concern, including small mammals, such as the Cabrera vole (Microtus cabrerae). This near‐threatened rodent is characterized by an unusual suite of genetic, life history and ecological traits, being restricted to isolated geographic nuclei in fast‐disappearing Mediterranean subhumid herbaceous habitats. To reconstruct the evolutionary history of the Cabrera vole, we studied sequence variation at mitochondrial, autosomal and sex‐linked loci, using invasive and noninvasive samples. Despite low overall mitochondrial and nuclear nucleotide diversities, we observed two main well‐supported mitochondrial lineages, west and east. Phylogeographic modelling in the context of the Cabrera voles detailed fossil record supports a demographic scenario of isolation of two populations during the Last Glacial Maximum from a single focus in the southern part of the Iberian Peninsula. In addition, our data suggest subsequent divergence within the east, and secondary contact and introgression of the expanding western population, during the late Holocene. This work emphasizes that refugial endemics may have a phylogeographic history as rich as that of more widespread species, and conservation of such endemics includes the preservation of that genetic legacy.

Revisión a nivel ibérico de la distribución del topillo de Cabrera o iberón, Iberomys cabrerae (Thomas, 1906)

Resumen Presentamos en este articulo el mapa con el area de distribucion global de Iberomys cabrerae, en cuadriculas UTM 10x10 km. A partir de los resultados obtenidos, destacamos que a) las 420 cuadriculas con citas se concentran en cuatro grandes nucleos disjuntos (Luso-Carpetano, Montiberico, Betico y Prepirenaico), de los cuales el mas extenso es el Luso-Carpetano y el mas pequeno, aislado y amenazado es el Prepirenaico; b) seria necesario intensificar la busqueda de poblaciones en areas proximas aun poco estudiadas; y c) los datos disponibles sobre la situacion de las poblaciones tienen una calidad y distribucion geografica muy desigual, con lo que no disponemos de una imagen clara de su estado de conservacion ni se pueden desarrollar estrategias de proteccion y gestion adecuadas. Palabras clave: atlas de distribucion, conservacion, Espana, Iberomys cabrerae, Portugal. Resumo Neste estudo e apresentado um mapa de quadriculas UTM 10x10 km para toda a area de distribuicao de Iberomys cabrerae. A partir dos dados obtidos destacamos que a) as 420 quadriculas com dados se concentram em 4 grandes nucleos disjuntos (Luso-Carpetano, Montiberico, Betico y Prepirenaico), das quais o mais importante e o Luso-Carpetano e o mais pequeno, isolado e ameacado e o Preirenaico; b) e necessario intensificar a procura de populacoes em areas ainda pouco estudadas; e c) os dados disponiveis sobre a situacao das populacoes tem uma qualidade muito desigual, diferindo igualmente entre regioes, o que nao permite ter uma imagem clara do seu estado de conservacao, nem desenvolver estrategias de protecao e gestao adequadas. Palavras-chave: atlas de distribuicao, conservacao, Espanha, Iberomys cabrerae, Portugal. Abstract In this article, we provide a map representing the whole distribution area of Iberomys cabrerae, displayed in UTM System, at a scale of 10x10 km squares. Our results show that a) the records are included in 420 squares, which are grouped in four large, disjunct nuclei: Luso-Carpetanian, Montiberian, Baetic and Prepyrenean, the Luso-Carpetanian grouping the largest number of populations, and the Prepyrenean (isolated and threatened) including the smallest number of populations; b) it is necessary to conduct surveys in certain poorly explored areas; and c) available data on the population status are unbalanced in quality and geographic distribution, providing an inaccurate picture of the global conservation status, and preventing the development of global strategies for an adequate conservation and management of the species. Keywords: conservation, distribution atlas, Iberomys cabrerae, Portugal, Spain. DOI: 10.7325/Galemys.2013.A4

Influence of land mosaic composition and structure on patchy populations: the case of the water vole (Arvicola sapidus) in Mediterranean farmland.

The ability of patchy populations to persist in human-dominated landscapes is often assessed using focal patch approaches, in which the local occurrence or abundance of a species is related to the properties of individual patches and the surrounding landscape context. However, useful additional insights could probably be gained through broader, mosaic-level approaches, whereby whole land mosaics with contrasting patch-network and matrix characteristics are the units of investigation. In this study we addressed this issue, analysing how the southern water vole (Arvicola sapidus) responds to variables describing patch-network and matrix properties within replicated Mediterranean farmland mosaics, across a gradient of agricultural intensification. Patch-network characteristics had a dominant effect, with the total amount of habitat positively influencing both the occurrence of water voles and the proportion of area occupied in land mosaics. The proportions of patches and area occupied by the species were positively influenced by mean patch size, and negatively so by patch isolation. Matrix effects were weak, although there was a tendency for a higher proportion of occupied patches in more intensive, irrigated agricultural landscapes, particularly during the dry season. In terms of conservation, results suggest that water voles may be able to cope well with, or even be favoured by, the on-going expansion of irrigated agriculture in Mediterranean dry-lands, provided that a number of patches of wet herbaceous vegetation are maintained within the farmland mosaic. Overall, our study suggests that the mosaic-level approach may provide a useful framework to understand the responses of patchy populations to land use change.

Genetic non-invasive sampling (gNIS) as a cost-effective tool for monitoring elusive small mammals

Genetic non-invasive sampling (gNIS) may provide valuable information for population monitoring, as it allows inferences of population density and key behavioural traits such as dispersal, kinship and reproduction. Despite its enormous potential, gNIS has rarely been applied to small mammals, for which live-trapping is still the most commonly used sampling method. Here we evaluated the applicability and cost-effectiveness of gNIS compared with live-trapping, to monitor a metapopulation of an Iberian endemic and elusive rodent: the Cabrera vole (Microtus cabrerae). We compared the genetic diversity, kinship and dispersal movements inferred using both methods. For that, we optimised microsatellite markers for individual identification of M. cabrerae, using both tissue (n = 31) and faecal samples (n = 323) collected from a metapopulation in south-western Iberia. An initial set of 20 loci was optimised for tissue samples, from which 11 were selected to amplify in faecal samples. Overall, gNIS revealed a higher number of identified individuals (65) than live-trapping (31), and the estimated genetic diversity was similar using data from tissues and gNIS. Kinship analysis showed a higher number of inferred relationships and dispersal events when including gNIS, and indicated absence of sex-biased dispersal. The total cost (fieldwork and genetic analysis) of each genotype obtained through live-trapping was three times greater than for gNIS. Our data strongly supports the high potential and cost-effectiveness of gNIS for monitoring populations of elusive and/or threatened small mammals. We also illustrate how this genetic tool can be logistically feasible in conservation.

An R package for simulating metapopulation dynamics and range expansion under environmental change

The metapopulation paradigm is central in ecology and conservation biology to understand the dynamics of spatially-structured populations in fragmented landscapes. Metapopulations are often studied using simulation modelling, and there is an increasing demand of user-friendly software tools to simulate metapopulation responses to environmental change. Here we describe the MetaLandSim R package, which integrates ideas from metapopulation and graph theories to simulate the dynamics of real and virtual metapopulations. The package offers tools to (i) estimate metapopulation parameters from empirical data, (ii) to predict variation in patch occupancy over time in static and dynamic landscapes, either real or virtual, and (iii) to quantify the patterns and speed of metapopulation expansion into empty landscapes. MetaLandSim thus provides detailed information on metapopulation processes, which can be easily combined with land use and climate change scenarios to predict metapopulation dynamics and range expansion for a variety of taxa and ecological systems. We present the new freely available R package MetaLandSim.MetaLandSim balances modest data requirements with usability and output quality.MetaLandSim simulates metapopulation dynamics in dynamic landscapes.MetaLandSim simulates metapopulation range expansion into empty landscapes.MetaLandSim estimates dispersal kernels to refine forecasts of species range shifts.

Mismatches between habitat preferences and risk avoidance for birds in intensive Mediterranean farmland

Land use intensification may create habitats that organisms perceive as suitable, but where reproduction or survival is insufficient to maintain self-sustaining populations. Such conditions may qualify as ecological traps, but their existence is often hard to prove. Here, we provide a practical framework to evaluate a potential ecological trap resulting from mismatch between habitat preferences and predation risk, focusing on ground-nesting farmland birds of conservation concern. The framework is based on species-specific associations with safe or unsafe habitat types (i.e. field and landscape types with high or low nest survival), and the occurrence of risk avoidance (i.e. negative responses to predator abundances or to nest failure rates after controlling for habitat effects). Bird densities were far more influenced by field characteristics than landscape context. Corn bunting and fan-tailed warbler were associated with tall swards (safe habitats), and did not show risk avoidance. Tawny pipit and and Galerida larks were associated with short swards (unsafe habitats), with the former avoiding fields with high nest predation rates, and the later avoiding high mongoose abundances. Short-toed lark was associated with fields with short swards and low nest trampling rates. Results suggest that short-toed lark may be the most vulnerable to ecological trapping, because it nests on unsafe habitats and did not show predation risk avoidance. Our approach provides a practical first step to infer vulnerability to a potential ecological trap, though further research is needed to confirm this effect. Management actions increasing nest survival in short sward fields will likely favour grassland bird conservation in intensive Mediterranean farmland.