Jolles - Research Evolution in the Arctic: a...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
© New Phytologist (2003) 161 : 211–224 www.newphytologist.org 211 Research Blackwel Publishing Ltd. Evolution in the Arctic: a phylogeographic analysis of the circumarctic plant, Saxifraga oppositifolia (Purple saxifrage) Richard J. Abbott 1 and Hans Peter Comes 2 1 Harold Mitchell Building, School of Biology, University of St Andrews, St Andrews, Fife KY16 9TH, UK; 2 Institut für Spezielle Botanik und Botanischer Garten, Johannes Gutenberg-Universität Mainz, Bentzelweg 9b, 55099 Mainz, Germany Summary •A survey of chloroplast DNA variation in the circumarctic-alpine plant, Saxifraga oppositifolia , has resolved two highly divergent cpDNA lineages with geographi- cally widespread and mainly allopatric distributions that are largely concordant with those of two subspecies, that is, subspp. oppositifolia and glandulisepala . These subspecies differ for a single morphological trait and hence level of morphological divergence does not equate to molecular divergence within the species. • The two cpDNA lineages were estimated to have diverged from their most recent common ancestor 5.37–3.76 Ma, that is, during the early to mid-Pliocene. nested clade analysis was conducted in an attempt to determine how past epi- sodes of range fragmentation, range expansion and long distance dispersal may have inFuenced the geographical distribution of cpDNA haplotypes. • In Alaska – a known refugium for the species during the last ice-age – high levels of cpDNA diversity may be partly explained by divergence between populations that were isolated in different ice-free regions. It remains to be established whether the two subspecies of S. oppositifolia exhibit some form of reproductive isolation from each other under conditions of sympatry. Key words: Arctic Fora, plant evolution, phylogeography, molecular clock, nested clade analysis, glacial refugia, Quaternary, Saxifraga oppositifolia (Purple saxifrage). © New Phytologist (2003) 161 : 211–224 Author for correspondence: Richard J. Abbott Tel: +44 1334 463350 Fax: +44 1334 463366 Email: rja@st-and.ac.uk Received: 31 July 2003 Accepted: 10 October 2003 doi: 10.1046/j.1469-8137.2003.00953.x Introduction The highly dynamic nature of climate change in the Arctic during the late Tertiary (approximately 15–2 Ma) and throughout the Quaternary (2 Ma to the present) led to the origin of an entirely new ±ora in the region and created numerous scenarios for the potential origin of new plant species. The present-day arctic ±ora became established during the late Pliocene ( c . 3 Ma) and is currently composed of approx. 1500 species (Murray, 1981; Murray et al ., 1995). Global temperatures decreased markedly from the mid- Miocene (15 Ma) until the beginning of the Pleistocene (approx. 2 Ma; Lear et al. , 2000; Zachos et al ., 2001), and by the late Pliocene a circumarctic belt of tundra was present (Matthews, 1979; Matthews & Ovenden, 1990; Murray, 1995). The arctic ±ora is derived partly from the pre-existing Arcto-Tertiary ±ora and also from ancestors that lived at high altitudes in mountain ranges to the south during the Tertiary (Hultén, 1937; Tolmachev, 1960; Weber, 1965, 2003; Hedberg, 1992; Murray, 1995). These mountain ranges extend north to
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 14

Jolles - Research Evolution in the Arctic: a...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online