ORIGINAL PAPER Better up, worse down: bidirectional consequences of three decades of climate change on a relict population of Erebia cassioides Stefano Scalercio • Teresa Bonacci • Antonio Mazzei • Roberto Pizzolotto • Pietro Brandmayr Received: 30 January 2014 / Accepted: 15 July 2014 Ó Springer International Publishing Switzerland 2014 Abstract Orophilous species are often unable to escape the consequences of climate change because mountains are surrounded by unsuitable habitats. Among them, several endemic species belonging to the genus Erebia Dalman (Lepidoptera, Nymphalidae, Satyrinae) can be considered as key species to assess the risk of biodiversity loss of mountain habitats. The aim of this paper is to measure changes that have occurred in the altitudinal distribution of Erebia cas- sioides on the Pollino Massif (Southern Italy) during the last 37 years. Sixteen sites sampled in 1975 have been resampled after about three decades (2004, 2012). In 1975 56 % of the sampled population inhabited sites above and 44 % sites below the treeline, while in 2004 and 2012 99 % of the population were observed above the treeline. Furthermore, we observed an uphill shift of 180 m in the barycentre alti- tude of the species distribution and an unexpected increased density of the population above the treeline which led to a range reduction coupled to population increase of E. cassio- ides. This pattern contrasts with the usually observed one that couples habitat reduction to population decreasing. The reason for the observed pattern is unclear, but the implication for conservation strategies could be important if confirmed for other species. In fact, during coming decades local extinctions as a consequence of climate change might be fewer and more delayed than expected, and relict populations of cold adapted species could be preserved for a longer time span within optimal habitat refugia. Keywords Climate changes  Conservation  Extinction  Italy  Lepidoptera  Treeline Introduction Several evidences suggest that animals respond to climate changes with altitudinal and latitudinal shifts of their ran- ges (Parmesan and Yohe 2003; Wilson et al. 2005; Hic- kling et al. 2006). Orophilous cold adapted species are often unable to escape climate warming northward because mountains are surrounded by unsuitable habitats. Uphill shifts are necessarily associated with the reduction and fragmentation of the suitable habitat and the extinction risk of such species increases due to fitness lowering and genetic impoverishment (Schmitt and Hewitt 2004). The loss of suitable habitat is related to population size reduc- tion, but the relationship is not linear. Evidences from birds demonstrated that population size usually decreases more rapidly than habitat area (Shoo et al. 2005), enhancing the extinction risks of a given species. The genus Erebia Dalman (Lepidoptera, Nymphalidae, Satyrinae) is one of the most diverse groups of butterflies, several endemic species are strictly alpine or arctic and distributed on the mountains of the Holarctic region (Brandmayr et al. 2003). It can be considered a key group to assess the risk of biodiversity loss of Mediterranean mountain habitats and some species are the objective of conservation initiatives (Cizek et al. 2003; Schmitt et al. 2005; De Groot et al. 2009). A very isolated population of Erebia cassioides (Reiner and Hohenwarth 1792) was discovered some decades ago on the Pollino Massif, the S. Scalercio (&) Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Unita ` di Ricerca per la Selvicoltura in Ambiente Mediterraneo, Contrada Li Rocchi-Vermicelli, 87036 Rende, CS, Italy e-mail: stefano.scalercio@entecra.it T. Bonacci  A. Mazzei  R. Pizzolotto  P. Brandmayr Dipartimento di Biologia, Ecologia e Scienze Della Terra, Universita ` Della Calabria, Via Pietro Bucci, 87036 Rende, CS, Italy 123 J Insect Conserv DOI 10.1007/s10841-014-9669-x