The Iberian Peninsula – corridor or cul-de-sac? Mammalian faunal change and possible routes of dispersal in the last 2 million years

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Abstract

The Iberian Peninsula is almost surrounded by the sea and is topographically and ecologically variable. These factors will have impacted on both the distribution and dispersal patterns of large mammals (including hominins) within Iberia, and are considered in detail in this paper. There are two routes of mammalian dispersal into Iberia: across the Pyrenees and across the Gibraltar Strait. With an increasing interest in the possible use of coastlines by early hominins the latter route has been the focus of much discussion. However, the arguments are limited by the relative lack of hominin remains and archaeology from the Early Pleistocene. This paper takes a wider perspective to hominin dispersals by examining what is known of the evolution and movements of other taxa in Iberia and how these may inform our understanding of the hominin fossil record. Beginning by briefly reviewing the present day and Pleistocene glacial and interglacial vegetation of Iberia, it then considers the large-mammal fauna. Particular attention is paid to the potential routes of movement for terrestrial animals in and out of the peninsula, and the evidence for each route is assessed. Iberia was a refuge for temperate species during the Quaternary glacial cycles and movements of Quaternary faunas are reviewed in the light of modern phylogeographic analyses and studies of fossil assemblages. Iberian faunas are highly variable, with some absences of otherwise widespread European animals, but cold-phase taxa such as reindeer and woolly rhinoceros did cross the Pyrenees. It seems that the large mountain ranges were less a barrier for the dispersal of these taxa than the line which today forms the limit of the summer drought. Iberia also provided the last refuge for extinct species such as the Neanderthals and endangered extant species such as the Iberian lynx.

Introduction

The last 2.5 million years have seen enormous changes in global climate, most obviously in the Quaternary glacial/interglacial cycles. This has been particularly apparent in Europe, where a relatively small landmass contains several large mountain ranges and peninsulas that have made conditions at any one point in time differ in different regions. Iberia is almost surrounded by sea and when large quantities of fresh water were locked into ice sheets during glacial periods, the available landmass would have been larger through the expansion of the coastal shelves. Iberia also contains one of the four plausible routes for hominin dispersals out of Africa, the Strait of Gibraltar, the others being from Tunisia to Sicily, across the Sinai Peninsula and across the Bab al-Mandab Strait. In the Pleistocene, with the exception of the Sinai Peninsula, all of these routes would have involved some ability to cross water, and there is increasing interest in the potential use of coastal environments by hominins, both for resources and for the migration opportunities that they may have offered (e.g. Erlandson, 2001, Flemming et al., 2003, Turner and O'Regan, 2007). The Gibraltar Strait may have been crossed by hominins, but it is difficult to assess the fossil or archaeological evidence for hominin settlement of Iberia as the record is so sparse. However, many other animals have migrated, evolved or become extinct in Iberia during the Quaternary, and understanding what has happened to other taxa may provide a context for examining hominin dispersal and occupation. The climatic changes and geographic restrictions of the Quaternary have had a great effect on the evolution and dispersal of a myriad of different creatures, from the grasshopper (Chorthippus parallelus) (Hewitt, 1996) to the roe deer (Capreolus capreolus) (Lorenzini and Lovari, 2006). For extant animals some of these movements can be traced using phylogeographic methods (see Hewitt, 1999 for a review), but for extinct species the fossil record must be examined to see how and when creatures were moving. For much of the Quaternary Iberia was also a refugium for temperate animals restricted by the encroachment of glaciers and tundra to the north. It contains the latest occurrences of extinct species (e.g. Neanderthals (Homo neanderthalensis)), and some of the earliest finds in Europe of African taxa such as Theropithecus, and Hippopotamus, which have been used to argue for faunal dispersal across the Strait of Gibraltar (e.g. Agustí and Moyà-Solà, 1992, Agustí and Moyà-Solà, 1998). However, Iberia has a second much more obvious route for dispersal across the Pyrenees and the faunal evidence for the use of both the terrestrial (Pyrenees) and water (Gibraltar) crossings will be considered here.

Section snippets

Topography, climate and vegetation

Although a refugium for temperate plants and animals in the Quaternary glacials, the Iberian Peninsula was by no means a homogeneous temperate landscape in which warm-adapted animals could live until the glaciers retreated to the north. In fact the Iberian Peninsula itself contains a number of east–west running mountain ranges and areas of high land (over 1000 m a.s.l.), particularly the Sierra Nevada in the south, the central Sierra de Guadarrama and the northern Cordillera Cantábrica, as well

The Plio-Pleistocene large-mammal fauna of Iberia

The locations of all the sites mentioned in this discussion are shown in Fig. 1, and their approximate dates are given in Fig. 2. The mammalian fauna of Iberia was reviewed by Agustí and Moyà-Solà, 1992, Turner, 1995, Kahlke, 1999 and García and Arsuaga (2003). These reviews will not be repeated here as, overall, most of the observations made still hold true, but the main points will be summarised and some distributions will be updated. For example, the elk (Alces) has still not been found in

Routes into and out of Iberia

There are two plausible routes into and out of Iberia, the first is over the Pyrenees, while the second is the perilous crossing of the Gibraltar Strait. Initially the Gibraltar Strait looks attractive, and there is the circumstantial evidence of the early appearances of African taxa in Spain to bolster support for the idea of a crossing, but can this route be substantiated? Although narrow, the Strait is deep, and there has been a permanent body of water there since the end of the Messinian

Phylogeography and crossing the Pyrenees

The glacial periods lasted much longer than the interglacials in the Quaternary (one estimate suggests that 80% of the Quaternary was spent in glacial periods (Willis and Whittaker, 2000) while another suggests that 12% of the Quaternary was spent at full glacial maximum (van Kolfschoten, 1995), which in the Middle-Late Pleistocene Milankovic cycles of 100,000 years would make approximately 12,000 years of isolation in refugia when the glaciers were at their peak). Such isolation might well

Conclusions

Iberia represents a highly heterogeneous collection of habitats which would have fluctuated with both small scale and large scale Quaternary climate changes. Such variations would have provided the opportunity for some mammals to diversify, whilst for others it may have ultimately led to extirpation or extinction. Several taxa failed to recolonize the Peninsula after local extinction and these include such large and usually wide-ranging taxa as hyaenas and big cats, and also smaller creatures

Acknowledgements

Many of the thoughts in this paper were generated during a NERC EFCHED project grant, number NER/T/S/2002/00431. I would like to thank Anne-Marie Nuttall for helping to generate Fig. 1, and the two anonymous referees whose comments improved the manuscript.

References (112)

  • N. García et al.

    Carnivores from the Early Pleistocene hominid-bearing Trinchera Dolina 6 (Sierra de Atapuerca, Spain)

    Journal of Human Evolution

    (1999)
  • D. Geraads

    La grande faune associée aux derniers Néandertaliens de Zafarraya (Andalousie, Espagne): systématique et essai d'interprétation

    Comptes Rendus de l'Académie des Sciences, Paris, Sciences de la Terre et des Planètes

    (1997)
  • J. Gibert et al.

    Presence of the Cercopithecid genus Theropithecus in Cueva Victoria (Murcia, Spain)

    Journal of Human Evolution

    (1995)
  • P. González-Sampériz et al.

    Glacial and Lateglacial vegetation in northeastern Spain: new data and a review

    Quaternary International

    (2005)
  • G.M. Hewitt

    Some genetic consequences of ice ages, and their role in divergence and speciation

    Biological Journal of the Linnaean Society

    (1996)
  • G.M. Hewitt

    Post-glacial re-colonisation of European biota

    Biological Journal of the Linnaean Society

    (1999)
  • J.K. Hughes et al.

    Theropithecus and ‘Out of Africa’ dispersals in the Plio-Pleistocene

    Journal of Human Evolution

    (2008)
  • B.M. Martínez-Navarro et al.

    Fuente Nueva-3 (Orce, Granada, Spain) and the first human occupation of Europe

    Journal of Human Evolution

    (1997)
  • B. Martínez-Navarro et al.

    Early Pleistocene ‘hominid remains’ from southern Spain and the taxonomic assignment of the Cueva Victoria phalanx

    Journal of Human Evolution

    (2005)
  • J. van der Made

    Ungulates from Atapuerca TD6

    Journal of Human Evolution

    (1999)
  • P. Montoya et al.

    Une faune très divesifiée du Pléistocène inférieur de la Sierra de Quibas (province de Murcia, Espagne)

    Comptes Rendus de l'Académie des Sciences, Paris, Sciences de la Terre et des Planètes

    (2001)
  • J.E. Ortiz et al.

    The palaeoenvironmental and palaeohydrological evolution of Padul Peat Bog (Granada, Spain) over one million years, from elemental, isotopic and molecular organic geochemical proxies

    Organic Geochemistry

    (2004)
  • B.A. Patel et al.

    Cercopithecoid cervical vertebral morphology and implications for the presence of Theropithecus in Early Pleistocene Europe

    Journal of Human Evolution

    (2007)
  • J.P. Raynal et al.

    The earliest occupation of North-Africa: the Moroccan perspective

    Quaternary International

    (2001)
  • J. Rodríguez

    Stability in Pleistocene Mediterranean mammalian communities

    Palaeogeography, Palaeoclimatology, Palaeoecology

    (2004)
  • L. Rook et al.

    Occurrence of Theropithecus sp. in the late Villafranchian of southern Italy and implication for Early Pleistocene “out of Africa” dispersals

    Journal of Human Evolution

    (2004)
  • K.H. Roucoux et al.

    Combined marine proxy and pollen analyses reveal rapid Iberian vegetation responses to North Atlantic millennial-scale climate oscillations

    Quaternary Research

    (2001)
  • M.F. Sánchez Goñi et al.

    High resolution palynological record off the Iberian margin: direct land–sea correlation for the Last Interglacial complex

    Earth and Planetary Science Letters

    (1999)
  • G.R. Scott et al.

    Magnetostratigraphy of the Orce region (Baza Basin), SE Spain: new chronologies for Early Pleistocene faunas and hominid occupation sites

    Quaternary Science Reviews

    (2007)
  • L.G. Straus

    Africa and Iberia in the Pleistocene

    Quaternary International

    (2001)
  • J.R. Stewart

    The ecology and adaptation of Neanderthals during the non-analogue environment of Oxygen Isotope Stage 3

    Quaternary International

    (2005)
  • J.R. Stewart et al.

    Cryptic northern refugia and the origins of modern biota

    Trends in Ecology and Evolution

    (2001)
  • J. Agustí et al.

    Mammoths, Sabertooths and Hominids

    (2002)
  • J. Agustí et al.

    Mammalian dispersal events in the Spanish Pleistocene

    Courier Forschungsinstitut Senckenburg

    (1992)
  • J. Agustí et al.

    The Early Pleistocene mammal turnover in Spain: evidence against an ‘end-Villafranchian’ event

    Mededelingen Nederlands Instituut voor Toegepaste Geowetenschappen TNO

    (1998)
  • J. Agusti et al.

    Venta Micena (Guadix-Baza basin, south-eastern Spain): its place in the Plio-Pleistocene mammal succession in Europe

    Geologica Romana

    (1986)
  • M.T. Alberdi et al.

    Consideraciones biostratigráficas sobre la fauna de Vertebrados fósiles de la cuenca de Guadix-Baza (Granada, España)

  • L. Alcala et al.

    Los carnívoros del Pleistoceno medio de Cullar de Baza-1 y Huescar-1 (Cuenca de Guadix-Baza)

  • M.T. Antunes

    Acerca de um osso de Plistocenico da Mealhada: presenca de um tigre dentre de sabre Homotherium latidens (Owen, 1846)

    Ciencias da Terra

    (1986)
  • G. Ardito et al.

    An overview of the geographic and chronologic distribution of west European cercopithecoids

    Human Evolution

    (1987)
  • R.G. Bednarik

    Seafaring in the Pleistocene

    Cambridge Archaeological Journal

    (2003)
  • K.D. Bennett et al.

    Quaternary refugia of North European trees

    Journal of Biogeography

    (1991)
  • D.T. Bilton et al.

    Mediterranean Europe as an area of endemism for small mammals rather than a source for northwards postglacial colonisation

    Proceedings of the Royal Society, Series B

    (1998)
  • H.J.B. Birks et al.

    Glacial refugia of European trees – a matter of chance?

    Dissertationes Botanicae

    (1993)
  • A. Bolomey

    Die Fauna zweier villafrankischer Fundstellen in Rumänien

    Berichte der geologischen Gesellschaft der DDR, Berlin

    (1965)
  • L. Caloi et al.

    Functional aspects and ecological implications in hippopotami and cervids of Crete

  • J.-F. Cosson et al.

    Phylogeographical footprints of the Strait of Gibraltar and Quaternary climatic fluctuations in the western Mediterranean: a case study with the greater white-toothed shrew, Crocidura russula (Mammalia: Soricidae)

    Molecular Ecology

    (2005)
  • A.P. Currant

    A review of the Quaternary mammals of Gibraltar

  • M. Dobson et al.

    Faunal relationships and zoogeographical affinities of mammals from north-west Africa

    Journal of Biogeography

    (2000)
  • J.M. Erlandson

    The archaeology of aquatic adaptations: paradigms for a new millennium

    Journal of Archaeological Research

    (2001)
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