Evolutionary trends in arvicolids and the endemic murid Mikrotia e New data and a critical overview Lutz C. Maul a, * , Federico Masini b , Simon A. Parfitt c, d , Leonid Rekovets e , Andrea Savorelli f a Senckenberg Research Station of Quaternary Palaeontology, Am Jakobskirchhof 4, 99423 Weimar, Germany b Earth and Sea Sciences Department, University of Palermo, Via Archirafi 22, I-90123 Palermo, Italy c Institute of Archaeology, University College London, 31e34 Gordon Square, London WC1H 0PY, UK d Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK e Department of Zoology and Ecology, Wroclaw University of Environmental and Life Sciences, ul. Ko _ zuchowska 5B, PL-51631 Wroclaw, Poland f Earth Sciences Department, University of Florence, via G. La Pira, 4, 50121 Firenze, Italy article info Article history: Received 6 May 2013 Received in revised form 30 August 2013 Accepted 13 September 2013 Available online xxx Keywords: Evolutionary trends Hypsodonty Neogene Arvicolidae Mikrotia abstract The study of evolutionary rates dates back to the work of Simpson and Haldane in the 1940s. Small mammals, especially Plio-Pleistocene arvicolids (voles and lemmings), are particularly suited for such studies because they have an unusually complete fossil record and exhibit significant evolutionary change through time. In recent decades, arvicolids have been the focus of intensive research devoted to the tempo and mode of evolutionary change and the identification of trends in dental evolution that can be used to correlate and date fossil sites. These studies have raised interesting questions about whether voles and lemmings had unique evolutionary trajectories, or show convergent evolutionary patterns with other hypsodont rodents. Here we review evolutionary patterns in selected arvicolid lineages and endemic Messinian murids (Mikrotia spp.) and discuss reasons for convergence in dental morphology in these two groups of hypsodont rodents. The results substantiate previously detected patterns, but the larger dataset shows that some trends are less regular than previous studies have suggested. With the exception of a pervasive and sustained trend towards increased hypsodonty, our results show that other features do not follow consistent patterns in all lineages, exhibiting a mosaic pattern comprising stasis, variable rate evolution and gradual unidirectional change through time. Evidence for higher evolutionary rates is found in lineages apparently undergoing adaptations to new ecological niches. In the case of Mikrotia, Microtus voles and the water vole (MimomyseArvicola) lineage, a shift to a fossorial lifestyle appears to have been an important driving force in their evolution. For other characters, different causes can be invoked; for example a shift to a semi-aquatic lifestyle may be responsible for the trend towards increasing size in Arvicola. Biochronological application of the data should take into account the complexity and biases of the data. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The ‘modern’ study on the rates of biological evolution based on the fossil record started with Simpson (1944). Simpson proposed two different approaches to the problem. The first approach is to evaluate the number of taxa (species, genera etc.) deriving from an evolutionary radiation and then to define appropriate parameters (e.g., turnover rates) to describe the pattern. The second is to measure morphological features and to express numerically the amount of change that occurred within a single or several phyletic lines. As Haldane (1949) wrote: “. the dimensions of a solid organ such as a tooth. are often measurable with great precision; and when we have a series of fossil populations believed to form a lineage, we can calculate the rate of change of the mean value of any measure“. The pioneering work undertaken by these authors provided the bedrock on which subsequently studies in the bur- geoning field of evolutionary mode and rates have been built. Some 60 years later, Fitch and Ayala (1995) commented in the introduction of the proceedings of the conference Tempo and Mode in Evolution: Genetics and Paleontology 50 Years after Simpson: “Simpson failed to anticipate that molecular biology would make it possible to measure rates of evolution ‘most desirably’ as ‘amount of genetic change in a population per year, century, or other unit of absolute time’“. * Corresponding author. Tel.: þ49 3643 49 309 3331. E-mail address: lmaul@senckenberg.de (L.C. Maul). Contents lists available at ScienceDirect Quaternary Science Reviews journal homepage: www.elsevier.com/locate/quascirev 0277-3791/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.quascirev.2013.09.017 Quaternary Science Reviews xxx (2013) 1e19 Please cite this article in press as: Maul, L.C., et al., Evolutionary trends in arvicolids and the endemic murid Mikrotia e New data and a critical overview, Quaternary Science Reviews (2013), http://dx.doi.org/10.1016/j.quascirev.2013.09.017