Phylogeographic Structure and Cryptic Speciation in the Trans-Antarctic Moss Pyrrhobryum Mnioides

Abstract

Abstract. Many bryophyte species have distributions that span multiple continents. The hypotheses historically advanced to explain such distributions rely on either long-distance spore dispersal or slow rates of morphological evolution following ancient continental vicariance events. We use phylogenetic analyses of DNA sequence variation at three chloroplast loci (atpB-rbcL spacer, rps4 gene, and trnL intron and 3Ј spacer) to examine these two hypotheses in the trans-Antarctic moss Pyrrhobryum mnioides. We find: (1) reciprocal monophyly of Australasian and South American populations, indicating a lack of intercontinental dispersal; (2) shared haplotypes between Australia and New Zealand, suggesting recent or ongoing migration across the Tasman Sea; and (3) reciprocal monophyly among Patagonian and neotropical populations, suggesting no recent migration along the Andes. These results corroborate experimental work suggesting that spore features may be critical determinants of species range. We use the mid-Miocene development of the Atacama Desert, 14 million years ago, to calibrate a molecular clock for the tree. The age of the trans-Antarctic disjunction is estimated to be 80 million years ago, consistent with Gondwanan vicariance, making it among the most ancient documented cases of cryptic speciation. These data are in accord with niche conservatism, but whether the morphological stasis is a product of stabilizing selection or phylogenetic constraint is unknown.

A Linkage Map Reveals a Complex Basis for Segregation Distortion in an Interpopulation Cross in the Moss Ceratodon purpureus

“…Although not all recombinant progeny reached sexual maturity, we were able to confidently map the sex-determining region on the linkage map. To determine the inheritance pattern of the chloroplast, we identified a minisatellite polymorphism in the chloroplastic atpB-rbcL spacer between the two parents, and sequenced this locus in 10 recombinant progeny (5 males and 5 females), using primers and PCR conditions and primers described in McDaniel and Shaw (2003).…”

Inter- and infraspecific relationships in the Gondwanan liverwort genus Hymenophyton (Hymenophytaceae, Hepaticophytina). Studies in austral temperate rain forest bryophytes 23

“…This is partly in accordance with a study in Pyrrhobryum mnioides (Hook.) Manuel showing rather strong genetic divergence despite of relative morphological stasis; the moss is interpreted as a Gondwanan species-vicariant between South America and Australasia (McDaniel and Shaw 2003). Today, Hymenophyton taxa of the two main distribution centres (southern South America, Australasia) are completely isolated, and no species is common to both regions.…”

Is the sword moss (Bryoxiphium) a preglacial Tertiary relict?

“…Altogether, these observations support the hypothesis that, in spore-producing plants (van Zanten and Pócs, 1981;Wolf et al, 2001) and other mobile organisms (Sanmartín and Ronquist, 2004;Yoder and Nowak, 2006;Perrie and Brownsey, 2007;Sanmartín et al, 2007;De Queiroz, 2014), dispersal has obscured any signature of vicariance. In fact, recent re-analysis of the only study inferring geographic vicariance due to continental drift in mosses (McDaniel and Shaw, 2003) yielded much younger ages for the relevant split that are incompatible with a continental drift scenario (Villarreal and Renner, 2014).…”