1 3 Metapopulations in temporary streams – The role of drought–flood 4 cycles in promoting high genetic diversity in a critically endangered 5 freshwater fish and its consequences for the future 6 7 8 Carla Sousa-Santos a,⇑ Q1 , Joana I. Robalo a , Sara M. Francisco a , Carlos Carrapato b , Ana Cristina Cardoso b , 9 Ignacio Doadrio c 10 a Eco-Ethology Research Unit, ISPA University Institute, Rua Jardim do Tabaco 34, 1149-041 Lisbon, Portugal 11 b ICNF – Institute for Nature Conservation and Forests, Natural Park of the Guadiana Valey, Rua D. Sancho II 15, 7750-350 Mértola, Portugal 12 c Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain 13 14 15 17 article info 18 Article history: 19 Received 29 April 2014 20 Revised 23 July 2014 21 Accepted 4 August 2014 22 Available online xxxx 23 Keywords: 24 Conservation genetics 25 Future distribution 26 Paleodrainages 27 Phylogeography 28 Strong population structure 29 Temporary rivers 30 31 abstract 32 Genetic factors have direct and indirect impacts in the viability of endangered species. Assessing their 33 genetic diversity levels and population structure is thus fundamental for conservation and management. 34 In this paper we use mitochondrial and nuclear markers to address phylogeographic and demographic 35 data on the critically endangered Anaecypris hispanica, using a broad sampling set which covered its 36 known distribution area in the Iberian Peninsula. Our results showed that the populations of A. hispanica 37 are strongly differentiated (high and significant U ST and F ST values, corroborated by the results from 38 AMOVA and SAMOVA) and genetically diversified. We suggest that the restricted gene flow between pop- 39 ulations may have been potentiated by ecological, hydrological and anthropogenic causes. Bayesian sky- 40 line plots revealed a signal for expansion for all populations (t MRCA between 68 kya and 1.33 Mya) and a 41 genetic diversity latitudinal gradient was detected between the populations from the Upper (more diver- 42 sified) and the Lower (less diversified) Guadiana river basin. We postulate a Pleistocenic westwards col- 43 onization route for A. hispanica in the Guadiana river basin, which is in agreement with the tempo and 44 mode of paleoevolution of this drainage. The colonization of River Guadalquivir around 60 kya with 45 migrants from the Upper Guadiana, most likely by stream capture, is also suggested. This study highlights 46 the view that critically endangered species facing range retreats (about 47% of its known populations 47 have disappeared in the last 15 years) are not necessarily small and genetically depleted. However, the 48 extinction risk is not negligible since A. hispanica faces the combined effect of several deterministic 49 and stochastic negative factors and, moreover, recolonization events after localized extinctions are very 50 unlikely to occur due to the strong isolation of populations and to the patchily ecologically-conditioned 51 distribution of fish. The inferred species distribution models highlight the significant contribution of tem- 52 perature seasonality and isothermality to A. hispanica occurrence in Guadiana environments and empha- 53 size the importance of stable climatic conditions for the preservation of this species. Given the strong 54 population structure, high percentage of private haplotypes and virtual absence of inter-basin gene flow 55 we suggest that each A. hispanica population should be considered as an independent Operational Con- 56 servation Unit and that ex-situ and in-situ actions should be conducted in parallel to allow for the 57 long-term survival of the species and the preservation of the genetic integrity of its populations. 58 Ó 2014 Elsevier Inc. All rights reserved. 59 60 61 62 1. Introduction 63 Freshwater fish are amongst the most endangered groups of 64 vertebrates (Duncan and Lockwood, 2001). It is estimated that 65 36–48% of the freshwater fish species assessed for the IUCN Red 66 List are facing extinction in a near future (Carrizo et al., 2013). 67 The family Cyprinidae comprises more than 2420 species, included 68 in 220 genera (Nelson, 2006). In the Iberian Peninsula, located in 69 the Mediterranean Basin hotspot (Myers et al., 2000), the native 70 freshwater fish fauna comprises 11 cyprinid genera and more than 71 36 species, 31 of which are endemic (Doadrio et al., 2011a). 72 The Iberian fluvial network is characterized by a high number of 73 Mediterranean-type Rivers, with autumn–winter floods and strong http://dx.doi.org/10.1016/j.ympev.2014.08.007 1055-7903/Ó 2014 Elsevier Inc. All rights reserved. ⇑ Corresponding author. E-mail addresses: carla.santos@ispa.pt (C. Sousa-Santos), jrobalo@ispa.pt (J.I. Robalo), sara.francisco@ispa.pt (S.M. Francisco), carlos.carrapato@icnf.pt (C. Carrapato), ana.cardoso@icnf.pt (A.C. Cardoso), doadrio@mncn.csic.es (I. Doadrio). Molecular Phylogenetics and Evolution xxx (2014) xxx–xxx Contents lists available at ScienceDirect Molecular Phylogenetics and Evolution journal homepage: www.elsevier.com/locate/ympev YMPEV 4991 No. of Pages 16, Model 5G 16 August 2014 Please cite this article in press as: Sousa-Santos, C., et al. Metapopulations in temporary streams – The role of drought–flood cycles in promoting high genetic diversity in a critically endangered freshwater fish and its consequences for the future. Mol. Phylogenet. Evol. (2014), http://dx.doi.org/ 10.1016/j.ympev.2014.08.007