Fine- and landscape-scale spatial genetic structure of cushion rockjasmine, Androsace tapete (Primulaceae), across southern Qinghai-Tibetan Plateau

Abstract

The cushion rockjasmine, Androsace tapete (Primulaceae), is among the angiosperms with highest altitudal distribution in the world. Cushion rockjasmine is a prominent pioneer species in alpine deserts and alpine flowstone slope habitats up to 5,300 m on Qinghai-Tibetan Plateau. In this study, we use inter simple sequence repeat (ISSR) markers to investigate the spatial genetic structure of A. tapete at both fine-scale and landscape-scale, with emphasis on testing the hypothesis that the low-altitude valley of the Brahmaputra River, running from west to east across Qinghai-Tibetan Plateau, has significant effects on the spatial population structure of A. tapete. A total of 235 individuals were collected from five populations in disjunct ridges (i.e. two populations located in the north, and three in the south of the Brahmaputra River), including 158 individuals that were spatial explicitly sampled from a 30 m x 90 m plot. At fine scale, spatial autocorrelation analysis indicates a significant genetic structure within a short distance (less than 10 m), which is probably due to limited gene dispersal via pollen and/or seeds. At landscape scale, however, AMOVA suggests that most of the total genetic variation (85%) is among individuals within populations; and the Brahmaputra River plays a weak role in shaping the spatial population structure of A. tapete. In addition, the results of PCA and STRUCTURE assignment show significant genetic associations between the populations across the Brahmaputra River. The historical gene exchanges and slow genetic drift may be responsible for the lack of deep genetic differentiation among topographically separated populations in A. tapete.

A systematic review of the recent ecological literature on cushion plants: champions of plant facilitation

“…As these organisms have been estimated to be up to 3000 years old (Ralph 1978), the genetic structure can be influenced by historic distributions and colonization events (Heads 1999, Geng et al 2009). Conversely, however, high genetic variation has been found within populations (Abbott et al 1995, Gehring and Delph 1999, Gugerli et al 1999, Pluess and Stocklin 2004, suggesting long distance pollen transport by insects (Gugerli et al 1999).…”

Testing the effect of the Himalayan mountains as a physical barrier to gene flow in Hippophae tibetana Schlect. (Elaeagnaceae)

“…Whether or not cold-adapted alpine species can survive or shift upwards to higher elevations and find optimal new habitats in response to ongoing climate warming [16], [17], [18], [19], largely depends on the ability of alpine plants to disperse from their original habitat and their ability to adapt to new habitats by rapid evolution [16], [20]. Studying the genetic structure of species today can provide informations on their population dynamics in response to past geological or climatic changes and the evolutionary ability of the species [21].…”

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“…Genetic variation in a population can be induced and maintained by the force of natural selection in heterogeneous habitats (Zhang 2004). Altitude can also affect the genetic variation and lead to rapid evolution in alpine plant species (Geng et al 2009). Plant populations rapidly diverge in response to changes in soil conditions (Snaydon and Davies 1982), and a population's genetic variation is related to the level of soil nutrients (Orians et al 2003).…”