Carine, Mark A.

Caujapé‑Castells, Juli

Fernández-Palacios, José María

Repositorio Institucional de la Universidad de La Laguna

Island biogeography16 17PROCEEDINGS OF THE AMURGA INTERNATIONAL CONFERENCES ON ISLAND BIODIVERSITY 2011José María Fernández-Palacios et al.The current species composition of entire oceanic islands or specific insular ecosystems is the result of a complex scenario where several historical and ecological processes, including long-distance dispersal (LDD), subsequent colonization, speciation (within or among islands) and extinction may have played an important role.Recently, one of us (Carine, 2005) coined the concept of colonization window, referred to the colonization opportunities in some islands or archipelagos that emerged for vagile continental taxa when either specific geological events (such as volcanic eruptions that destroy entire communities and ecosystems, creating open space) or ecological events (e.g., the availability of vacant resources in the insular ecosystems due to species impoverishment or disharmony), create the conditions for those species to establish. In a parallel approach, here we vindicate the concept of window of opportunity for a long-distance dispersal (LDD) event, that could be defined as the time interval throughout which the different factors controlling LDD become simultaneously functional or available, in reference to the opportunities that appeared for vagile taxa to arrive to destinations usually locked to them due to the prevailing wind or marine current regimes. Usually, the occurrence of LDD windows of opportunity is analysed in retrospect; for instance, when palaeo-biogeographers try to reconstruct the past events that may have enabled a present bizarre (fossil or extant) species distribution. Among the items that have to be checked for hypothesizing the existence of such window(s) we should consider: A) The existence in the proper historical moment of continental ecosystems where the focal taxa thrived and may have later persisted in situ or not. This may have been, for instance, the case for the Iberian and North African Tethyan Palaeotropical Geoflora with respect to Macaronesia; its elements are not extant today, but they were present in the continental margins until the Pleistocene climate deterioration (Postigo-Mijarra et al., 2010).B) The existence in the proper historical moment of islands available to be reached and subsequently The importance of windows of opportunity for long-distance dispersal to or from oceanic islands: examples from the Macaronesian archipelagosJosé María Fernández-Palacios1, Mark A. Carine2,  Juli Caujapé-Castells31 Grupo de Investigación de Ecología y Biogeografía insular, Universidad de La Laguna, Tenerife (Spain);  2 Natural History Museum, London, (UK);  3 Jardín Botánico Canario “Viera y Clavijo”-Unidad Asociada CSIC (Cabildo de Gran Canaria, Spain)E-mails:jmferpal@gmail.comm.carine@nhm.ac.ukjulicaujape@gmail.comThe importance of windows of opportunity for long-distance dispersal to or from oceanic islandscolonized, which may as well have later persisted or vanished under the sea, as was the case for several Palaeo-Macaronesian islands, that are today seamounts (Fernández-Palacios et al., 2011).C) The historical occurrence of the proper dispersal facilitator agents, either physical (for instance, palaeo-sea-currents, palaeo-wind regimes, important rivers) or biological (birds, bats, etc.), which may be still active/extant today or not.D) The availability of stepping-stones facilitating dispersal; for instance, through the emergence of non-subsided flat-topped seamounts (guyots) due to eustatic sea-level transgressions.E) The existence of peak periods, i.e. the availability of discrete windows in time where the simultaneous occurrence of an array of downstream or leeward high islands enabled the transference (through island hoping) of species restricted to mountain and summit ecosystems in the decaying island before erosion and subsidence processes remove those ecosystems and their associated biota. For instance, Stillman (1999) and Acosta et al. (2003) argue that Fuerteventura may have reached 3,500 m of height in the past. Therefore, it is feasible that some of the species that, at present, only occur at high elevations in Tenerife originated in Palaeo-Fuerteventura and colonized Tenerife before losing their habitats in the former island.Until very recently, it was considered that islands were evolutionary dead-ends of lineages, like no-way-out streets for taxa able to colonize them in proper moments, but unable to leave them, thus awaiting extinction (for instance, due to the taxon cycle). Nevertheless, increasing phylogenetic and phylogeographical evidence accumulated in the last years (from e.g., Bellemain & Ricklefs, 2008; Laenen et al., 2010), challenges the traditional perspective of islands as dead-ends, and points to the putative role of oceanic islands as refugia for continental taxa, especially during Plio-Pleistocene Glaciations, when the climatic conditions were much milder on the islands (due to the buffer effect of the oceans and to the opportunity for altitudinal migration) than on the continent.Thus, windows of opportunity for long-distance dispersal can be hypothesized as well for explaining these bizarre (at least under today’s prevailing conditions) retro-colonization or back-colonization events from the islands to the mainland, i.e. the colonization of ecologically similar and available mainland ecosystems by insular (usually neoendemic) species, originally derived from mainland ancestors, when abrupt tectonic (for instance the closure of Gibraltar or Panamá straits) or climate changes (e.g., Plio-Pleistocene glaciations) have transformed in specific moments of the past history the marine-currents and wind-regimes nowadays prevailing in the zone.In this context, recently published coupled-model simulations for the Last Glacial Maximum (LGM) evidence a substantial equatorward shift in the Westerlies position, 7° for a 3 K degree cooling and 11° for a 6 K degree cooling, in the Northern Hemisphere (Williams & Bryan, 2006) (Fig. 1). In the same line, Rognon & Coudé-Gausen (1996) asserted more than a decade ago that several geomorphological features of Canarian Island biogeography18 19PROCEEDINGS OF THE AMURGA INTERNATIONAL CONFERENCES ON ISLAND BIODIVERSITY 2011José María Fernández-Palacios et al.and Maghrebian natural landscapes point towards the dominance of the Westerlies wind regime across the Madeiran-Canarian latitudes (25-30° N) during the glacial periods in the Pleistocene. A shift of the Azores high southwards occurs due to the pressure exerted by the North Polar Front. Figure 1. Hypothesized southwards shift of the Northern Hemisphere Westerlies during the LGM, affecting the Canarian latitude (Source: Uriarte, 2003). These pieces of evidence include the existence of dune fields (ergs) in several Canary Islands (especially Esquinzo and Lajares dune fields in Fuerteventura) and Maghrebian areas (especially Agadir dune fields) that could not been formed under the influence of the present wind regime –the dune fields exhibit a triangle shape with the basis on the coast and the vertex pointing to the interior– (Fig. 2). The great amount of organogenic sands that have been deposited forming the dune fields that can only have been originated from deposits, today unavailable, located under the sea level, but available in the past due to the sea level transgression during the glaciations. Figure 2. Recent ergs (dune fields) in the Eastern Canaries and Morocco formed due to the Westerlies activity during the LGM (Source: Rognon & Coudé-Gaussen, 1996).The importance of windows of opportunity for long-distance dispersal to or from oceanic islandsAmong other major climatic features (for instance, lower temperatures and precipitations), the Plio-Pleistocene glaciation climatic context on the Madeira–Canaries region implied: the existence of archipelagos larger (almost twice as large as today), higher (ca. 120 m higher) and less isolated from the African continent (just 60 km away) than during interglacial periods. Concomittantly, the reiterative emergence of an important array of seamounts feasibly facilitated the dispersal processes among archipelagos (Fig. 3; for instance Selvagens and Dacia for the Madeiran-Canarian connection, but also between the archipelagos and the Iberian and North African mainland (Conception, Seine, Ampere, Coral Patch, Ormonde, etc.) (Fernández-Palacios et al., 2011) (Fig. 3).Figure 3. Reconstruction of Palaeo-Macaronesia ca. 18 Ky BP (Source: Fernández-Palacios et al., 2011). Today, it is considered that these climatic conditions have prevailed several times, perhaps as much as twenty, during the Late Pliocene and Pleistocene (Lisiecki & Raymo, 2007) coinciding with the different glacial maxima. Westerlies may have enhanced the retro-colonization from Macaronesian lineages to the African mainland. We also know that several Macaronesian lineages have representatives in the African and European continents (Table 1), and a number ofrecent molecular phylogenetic studies place Macaronesian taxa as basal to continental congeners (Table 1, Fig. 4). Retro-colonization events involving insular taxa have been termed boomerangs elsewhere (Caujapé-Castells, 2004, 2011).Table 1. Some putative boomerangs suggested by molecular evidence for the Macaronesian flora (extracted from Caujapé-Castells 2011) and fauna. (A = Azores, CV = Cape Verde, E = Europe, EA = E-Asia, I = Iberia, Mac = Macaronesia, Ma = Madeira, Me = Mediterranean, Mu = Multiple, NEA = NE-Africa, NWA = NW-Africa, NW = New World, SA = S-Africa).Island biogeography20 21PROCEEDINGS OF THE AMURGA INTERNATIONAL CONFERENCES ON ISLAND BIODIVERSITY 2011José María Fernández-Palacios et al.TAXON FAMILY ORIGIN TARGET REFERENCEPLANTSAeonium balsamiferumE,S Crassulaceae Mac1 NEA (A. leucoblepharum) Mort et al. 2002Andryala pinnatifidaS Asteraceae Ma Me (A. ragusina, A. integrifolia) Fehrer et al. 2007Arbutus canariensisE,S Arbutoideae NW Me (A. andrachne, A. unedo) Hileman et al. 2001ConvolvulusS Convolvulaceae Mac I (C. fernandezii) Carine et al. 2004Helichrysum gossypinumS,P Asteraceae Ma1 Me (ancestor of several spp.) Galbany-Casals et al. 2009Ilex peradoE Aquifoliaceae Mu EA (I. leucoclada, I. latifolia, I. rugosa) Manen et al. 2002Kleinia neriifoliaS Asteraceae EA NWA (K. anteuphorbium) Pelser et al. 2007Lotus campylocladusS Fabaceae NWA NWA (L. assakensis) Allan et al. 2004Matthiola bolleanaS Brassicaceae NWA NWA (M. bolleana, M. longipetala ssp. viridis) Jaén-Molina et al. 2009Sideroxylon mirmulanoE Sapotaceae EA CV (S. marginatum), SA (S. inerme) Smedmark et al. 2006Teline stenopetala (ssp. micropauci)S Fabaceae NWA NWA (T. monspessulana) Percy & Cronk 2002Tinguarra montana E Apiaceae NWA NWA (T. sicula) Downie et al. 2000Tolpis azoricaS Asteraceae A1 NWA (T. virgata, T. barbata) Moore et al. 2002BIRDSRegulusregulusssp. ellen-thareae Regulidae E E (R. regulus ssp. regulus) Päckert et al. 2006Erythacus rubecula Muscicapidae E E (E. rubecula) Dietzen et al. 2003Fringilla teydea Fringillidae E NWA, E (F. coelebs) Marshall & Baker 1998E Possible major influence of extinction. P Phylogenetic tree poorly resolved (i.e., low support for the derived position of the mainland taxa, or polytomic topology combining mainland and island populations). S Sampling deficiencies, especially in mainland areas near the Canaries (i.e., the ‘Macarone-sian enclave’ and its surroundings). 1Canarian taxa with putative origin in Macaronesia have been included in this list on the grounds on their ultimate origin via a continental ancestor.Figure4. Cladogram showing Lotus subgenus Pedrosia + L. subg. Rhyncholotus (= Pedrosia s.l. Clade), where L. assakensis is a possible example of a boomerang (Source: Allan et al., 2004).The importance of windows of opportunity for long-distance dispersal to or from oceanic islandsIf transient in nature, such a dispersal window will be followed by a period where the dispersal route is impossible or highly improbable, because the transportation means it ceased to exist. Of course, the existence of a certain dispersal window does not preclude a colonization event in exactly the opposite direction, but it makes it much unlikely. Thus, biodiversity boomerangs can’t be older than the window onset, and several colonization events may be recognized within a specific taxon.Dispersal windows may also disrupt the “normal” dispersal patterns within archipelagos. It has been postulated that in the Canaries the more common dispersal route within the archipelago is the so-called progression rule (Whittaker & Fernández-Palacios, 2007), which implies a general propagule movement from the older, eastward Canaries to the younger, westward islands. Under Westerlies conditions the normal dispersal routes may have been substituted by other usually bizarre routes, for instance: from the western to the eastern islands within the Canaries, from Azores to Madeira or the Canaries or from Macaronesia to Iberia (Carine et al., 2004).References:Acosta, J., Uchupi, E., Muñoz, A., Herranz, P., Palomo, C., Ballesteros M. &  ZEE Work-ing Group (2003) Geologic evolution of the Canarian Islands of Lanzarote, Fuerteventura, Gran Canaria and La Gomera and comparison of landslides at these islands with those at Tenerife, La Palma and El Hierro. Marine Geophys. Res. 24: 1-40.Allan, G.J., Francisco-Ortega, J.,  Santos-Guerra, A.,  Boerner, E. &Zimmer, E.A. (2004) Molecular phylogeneticevidenceforthegeographicorigin and classification of Canary Is-land Lotus (Fabaceae: Loteae). Molecular Phylogenetics and Evolution, 32: 123–138.Bellemain, E. & Ricklefs, R. E. (2008) Are islands the end of the colonization road? Trends in Ecology and Evolution, 23, 536–537.Carine, M. (2005) Spatio-temporal relationships of the Macaronesian endemic flora. Tax-on, 54: 895-903.Carine, M. A., Russell, S. J., Santos-Guerra, A., and Francisco-Ortega, J. (2004) Relation-ships of the Macaronesian and Mediterranean floras: molecular evidence for multiple col-onizations into Macaronesia and back-colonization of the continent in Convolvulus (Con-volvulaceae). American Journal of Botany, 91: 1070-1085.Caujapé-Castells, J. (2004) Boomerangs of biodiversity?: the interchange of biodiversity between mainland north Africa and the Canary Islands as inferred from cpDNA RFLPs in genus Androcymbium. Botánica Macaronésica, 25: 53-69.Island biogeography22 23PROCEEDINGS OF THE AMURGA INTERNATIONAL CONFERENCES ON ISLAND BIODIVERSITY 2011José María Fernández-Palacios et al.Caujapé-Castells, J. (2011) Jesters, red queens, boomerangs and surfers. A molecular out-look on the diversity of the Canarian endemic flora. The biology of island floras (ed. by D. Bramwell and J. Caujapé-Castells). Cambridge UniversityPress, Cambridge (in press).Fernández-Palacios, J.M., de Nascimento, L., Otto, R., Delgado J. D.,García-del-Rey, E., Arévalo, J.R. & Whittaker, R.J. (2011) A reconstruction of Palaeo-Macaronesia, with par-ticular reference to the long-term biogeography of the Atlantic island laurel forests. Journal of Biogeography, 38: 226-246.Laenen, B., Désamoré, A., Devos, N., Shaw, J., González-Mancebo, J.M., Carine, M. &Van-derpoorten, A. (2010) Macaronesia: a source of hidden genetic diversity for post glacial recolonization of Western Europe in the leafy liverwort Radulalindenbergiana. Journal of Biogeography, doi: 10.1111/j.1365-2699.2010.02440.x.Lisiecki, L.E. & Raymo, M.E. (2007) Plio-Pleistocene climate evolution: trends and transi-tions in glacial cycle dynamics. Quaternary Science Reviews, 26: 56-69.Postigo Mijarra, J.M., Barrón, E., Gómez Manzaneque, F. & Morla, C. (2009) Floristic changes in the Iberian Peninsula and Balearic Islands. Journal of Biogeography, 36, 2025–2043.Rognon, P. & Coudé-Gaussen, G. (1996) Paleoclimates off Northwest Africa (28º- 35º N) about 18.000 yr B.P. based on continental Eolian deposits. Quaternary Research 46: 118-126.Stillman, C.J. (1999) Giant Miocene landslides and evolution of Fuerteventura, Canary Islands, J. Vol. Geoth. Res.94: 89-104.Uriarte, A. (2003) La historia del clima de La Tierra. Ed. Elhuyar.Whittaker R. J. & Fernández-Palacios, J. M. (2007) Island Biogeography, Ecology, evolution and conservation. 2nd Ed. Oxford University Press, Oxford.Williams, G.P. & Bryan, K. (2006) Ice Age Winds: An Aquaplanet Model. Journal of Cli-mate, 19: 1706-1715.The importance of windows of opportunity for long-distance dispersal to or from oceanic islandsJosé María Fernández-PalaciosJosé María Fernández-Palacios (Las Palmas de Gran Canaria, 1958) is Professor in Ecology at La Laguna University since 1996 and Senior Research Associate of the Oxford University. He is as well head of the Island Ecology and Biogeography Group of La Laguna University, integrated by ca. 20 teachers and researchers, which is active in several research projects and contracts. He has supervised 8 PhD Thesis and authored or co-authored 60 research papers in JCR Journals as well as 10 books dealing with Island Ecology and Canarian Ecology, among them one edited by Oxford University Press (Island Biogeography. Ecology, Evolution and Conservation, 2nd Ed.). His research lines include palaeoecology, pine and laurel forest dynamics, ecological restoration and island ecology. Since 2005 is member of the Editorial Board of Journal of Biogeography, a high ranked Journal published by Wiley-Blackwell.

The importance of windows of opportunity for long-distance dispersal to or from oceanic islands: examples from the Macaronesian archipelagos

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The importance of windows of opportunity for long-distance dispersal to or from oceanic islands: examples from the Macaronesian archipelagos

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