Out of Antarctica: Quaternary Colonization of Sub-Antarctic Marion Island by the Limpet Genus Nacella (Patellogastropoda: Nacellidae)
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Polar Biol DOI 10.1007/s00300-014-1620-9 ORIGINAL PAPER Out of Antarctica: quaternary colonization of sub-Antarctic Marion Island by the limpet genus Nacella (Patellogastropoda: Nacellidae) Claudio A. Gonza´lez-Wevar • Steven L. Chown • Simon Morley • Nestor Coria • Thomas Sauce´de • Elie Poulin Received: 29 January 2014 / Revised: 3 November 2014 / Accepted: 12 November 2014 Ó Springer-Verlag Berlin Heidelberg 2014 Abstract The distribution of the Southern Ocean near- Nacella concinna and its sub-Antarctic relative Nacella shore marine benthic fauna is the consequence of major delesserti from Marion Island stands against this tenet. geologic, oceanographic, and climatic changes during the Here, we performed new phylogenetic reconstructions in last 50 Ma. As a result, a main biogeographic principle in Nacella with special emphasis on the relationship between the Southern Ocean is the clear distinction of the Antarctic N. concinna and N. delesserti. Similarly, we performed biota. The Antarctic Polar Front (APF) represents an population-based analyses in N. concinna and N. delesserti important barrier between Antarctica and other sub-Ant- to further understand the genetic legacy of the Quaternary arctic provinces. However, the high degree of genetic glacial cycles. Phylogenetic reconstructions recognized N. affinity between populations of the Antarctic limpet concinna and N. delesserti as two closely but distinct monophyletic entities and therefore as valid evolutionary units. The cladogenetic process separating them occurred This article is an invited contribution on Life in Antarctica: *0.35 Ma and is consistent with the origin of Marion Boundaries and Gradients in a Changing Environment as the main Island (*0.45 Ma). Exceptional long-distance dispersal theme of the XIth SCAR Biology Symposium. J.-M. Gili and R. Zapata Guardiola (Guest Editors). between provinces located inside and outside the APF, rather than revealing the permeability of the Antarctic C. A. Gonza´lez-Wevar Polar Front, seems to be related to latitudinal shift in the GAIA-Anta´rtica, Universidad de Magallanes, Avenida Bulnes position of the APF during coldest periods of the Quater- 01890, Punta Arenas 621-0427, Chile nary. Diversity indices, neutrality tests, haplotype net- C. A. Gonza´lez-Wevar (&) Á E. Poulin works, and demographic inference analysis showed that the Laboratorio de Ecologı´a Molecular (LEM), Instituto de Ecologı´a demography of both species exhibits a clear signal of ˜ y Biodiversidad (IEB), Las Palmeras 3425, Nun˜oa, Santiago, postglacial expansion. Chile e-mail: [email protected] Keywords Biogeography Á Southern Ocean Á Antarctic S. L. Chown Polar Front Á Long-distance dispersal Á Marion Island Á School of Biological Sciences, Monash University, Melbourne, Bayesian skyline plot VIC 3800, Australia S. Morley British Antarctic Survey, Madingley Road, High Cross, Introduction Cambridge, UK N. Coria Waters of the Southern Ocean encircling Antarctica are Departamento de Aves Marinas, Instituto Anta´rtico Argentino, moved around this continent by the strong eastward flow of Cerrito 1248, Buenos Aires, Argentina the Antarctic Circumpolar Current (ACC) that is delimited by two main boundaries: the Antarctic Polar Front (APF) to T. Sauce´de Bioge´osciences, UMR CNRS 6282, Universite´ de Bourgogne, the south and the sub-Antarctic Front (SAF) to the north Dijon 21000, France (Rintoul et al. 2001; Barker et al. 2007; Rintoul 2011). The 123 Polar Biol positions of these fronts have major biogeographic conse- islands) and peri-Antarctic islands including South Geor- quences for the SO biota (Lawver and Gahagan 2003; gia, South Sandwich, and Bouvet (Bo¨lter et al. 2002). Mackensen 2004; Greve et al. 2005; Linse et al. 2006; Phylogenetic reconstructions based on mtDNA sequen- Griffiths et al. 2009; Pierrat et al. 2013). On the one hand, ces recognized marked divergences among lineages of the ACC constitutes a major oceanographic barrier for Nacella from Antarctica, sub-Antarctic Heard Island, and many invertebrate groups (Shaw et al. 2004; Gonza´lez- South America (Gonza´lez-Wevar et al. 2010). However, a Wevar et al. 2010, 2012a; Poulin et al. 2014) and delimits recent population-based study in the Antarctic limpet Antarctic and sub-Antarctic provinces. On the other hand, including western Antarctic Peninsula populations recog- the ACC can transport organisms between geographically nized high levels of genetic identity ([99 %) with a single distant sub-Antarctic areas of the Southern Ocean, espe- individual of N. delesserti from Marion Island (Gonza´lez- cially in those species with high dispersive potential such Wevar et al. 2011b). Levels of genetic identity recorded as marine invertebrates with planktotrophic larvae (Page between these nominal species fell within the range of and Linse 2002;Dı´az et al. 2011; Mortimer et al. 2011), intraspecific variation detected in nacellids (Goldstien et al. kelps (Fraser et al. 2009; Macaya and Zuccarello 2010), 2006; Bird et al. 2007) and Nacella species from the and kelp-dwelling organisms (Nikula et al. 2010; Cumming Magellanic Province (de Aranzamendi et al. 2011; Gon- et al. 2014). Recent biogeographic reviews highlighted za´lez-Wevar et al. 2012b). At the same time, some ecologic both the high level of endemism of the Antarctic biota and features of N. concinna, including reproductive strategy, the marked differentiation among sub-Antarctic, low Ant- predation avoidance, population density, and growth rate, arctic, and Antarctic/high Antarctic marine species (Linse are similar to the ones described in N. delesserti (Blankley et al. 2006; Griffiths et al. 2009; Terauds et al. 2012). and Branch 1985). Accordingly, the taxonomic status of N. Faunal relationships among provinces of the SO perfectly concinna and N. delesserti is still unclear and the latter match with the flows of the two main oceanographic cur- could just represent an eastward population of the Antarctic rents, the ACC and the Antarctic Coastal currents (Pierrat limpet. However, this statement is questionable consider- et al. 2013). ing that few epipelagic species, with the exception of True limpets of the genus Nacella (Patellogastropoda: mammals and birds, are distributed both inside and outside Nacellidae) are dominant organisms of inter- and sub-tidal the APF (Dell 1972; Aronson et al. 2007). rocky ecosystems of the Southern Ocean. Nacella currently In this study, we present new molecular reconstructions includes at least 11 nominal species distributed in different in Nacella using phylogenetic and phylogeographic provinces of the Southern Ocean: South America, sub- approaches with special emphasis on the relationship Antarctic Islands, and Antarctica (Powell 1973; Valdovi- between the Antarctic limpet and sub-Antarctic Marion nos and Ru¨th 2005; Fig. 1). Species of Nacella are dioe- Island N. delesserti. Using different DNA sources, we aim cious organisms with external fertilization, and their larval to examine the validity of these nominal species and life span can extend for more than 2 months (Bowden et al. thereby to determine whether the Antarctic Polar Front 2006). At least eight nominal species were described in constitutes an efficient barrier between Antarctic and sub- Patagonia (Powell 1973; Valdovinos and Ru¨th 2005) but Antarctic Nacella populations. At the same time, levels of recent molecular and morphometric analyses (de Aranza- genetic diversity and structure are expected to clarify the mendi et al. 2011; Gonza´lez-Wevar et al. 2011a) indicate influence of contemporary climate change over benthic that only four of them represent valid evolutionary units marine invertebrate populations of the Southern Ocean, (Gonza´lez-Wevar et al. 2011a). One South American spe- especially in remote island endemic lineages. These results cies, Nacella clypeater, expands its distribution up north to should help us to further understand the role of historic and the Peruvian Province following the cold waters of the recent processes in the distribution of the biota of the Humboldt Current System (Powell 1973; Valdovinos and Southern Ocean. Ru¨th 2005). Almost half of the species of the genus are endemic to one or two remote sub-Antarctic isolated islands including Kerguelen, Heard, Macquarie, Campbell, Materials and methods and Marion (Fig. 1). One of them, Nacella delesserti,is endemic to sub-Antarctic Marion Island, an extremely Sample collection isolated volcanic island located north of the APF close to South Africa (Chown and Froneman 2008; Hall 2009; Hall Specimens were collected between 2006 and 2012 from et al. 2011). Finally, the Antarctic limpet Nacella concinna maritime Antarctica, South Georgia Island, and sub-Ant- is one of the dominant macroinvertebrate species of ice- arctic Marion Island. New N. concinna individuals were free rocky ecosystems and is currently restricted to mari- collected at Signy Island (60°430S; 45°360W: n = 16) time Antarctica (Antarctic Peninsula and associated during the summer of 2012. Additionally, we include 16 123 Polar Biol South America Central Chile Nacella clypeater Patagonia Falkland/Malvinas Is Nacella deaurata Nacella magellanica South Georgia Is Nacella mytilina Nacella flammea South Sandwich Is Antarctica Africa Nacella concinna Marion Is. Antarctica Nacella delesserti Campbell Is. Nacella terroris Heard Is. Macquarie Is. Kerguelen Is. New Zealand Nacella kerguelenensis Nacella macquariensis Nacella kerguelenensis Nacella. cf. macquariensis Nacella edgari Australia Fig. 1 Distribution of Nacella