Genetic diversity of AndeanPolylepis(Rosaceae) woodlands and inferences regarding their fragmentation history

Abstract

There is a long‐standing debate on whether the occurrence of the iconic high‐Andes Polylepis woodlands as small and isolated fragments is of natural or anthropogenic origin. We make inferences regarding the fragmentation history based on both a new population genetic study on P. besseri and a synthesis of available studies on the population genetics of Polylepis woodlands. We infer the timing of the main woodland fragmentation event by analysing: (1) the remaining levels of population genetic diversity and the relation to population size; (2) among‐population genetic differentiation; and (3) the difference in genetic diversity between the offspring and adult generation. We retrieved seven publications on the population genetics of five Polylepis spp. We did not find a relationship between population size and genetic diversity, and genetic differentiation was low compared with that reported for similar plant species. These findings do not support a history of long‐term fragmentation. The offspring showed a loss of genetic diversity and increasing differentiation compared with adults, suggesting that the main habitat fragmentation event is of relatively recent origin. For P. besseri, no significant differences were found between the adult and offspring genetic variation. We discuss the conservation and restoration consequences for this important high‐Andean genus. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society, 2013, 172, 544–554.

Genetic diversity of the Salix lapponum L. population intended as a source of material for reintroduction

“…In spite of that, in each of the analyzed groups of S. lapponum individuals (A-E) the parameters determining within-population diversity (the proportion of polymorphic loci, heterozygosity) were high. Such comparison of the results shows that the fragmentation occurred relatively recently, which is also indicated by the conclusions drawn by Gareca et al (2013) who analyzed divided populations of species of the genus Polylepis. Downy willow is a long-living species and the individuals that are now growing on Lake Bikcze were most probably present there over a dozen or even several dozen years ago; hence, we can assume that no significant transformation between the generations has taken place there over this time and that the high genetic diversity of the particular groups is a remnant after a numerous and dense population that existed there previously.…”

“…Downy willow is a long-living species and the individuals that are now growing on Lake Bikcze were most probably present there over a dozen or even several dozen years ago; hence, we can assume that no significant transformation between the generations has taken place there over this time and that the high genetic diversity of the particular groups is a remnant after a numerous and dense population that existed there previously. Unfortunately, each successive generation produced by generative reproduction in a population whose habitat has been fragmented is usually characterized by a much lower level of heterozygosity (Aguilar et al, 2008;Gareca et al, 2013). Taking into account that it is the only population in Łęczna-Włodawa Lakeland with young individuals, this can be a reason for the smallest value of heterozygosity of the Bikcze population in Pogorzelec et al (2014c).…”

Pleistocene climatic oscillations rather than recent human disturbance influence genetic diversity in one of the world's highest treeline species

“…Pollen evidence indicates that the current distribution of Polylepis forests has been affected by Pleistocene glacial–interglacial cycles (Gosling et al, 2009). The impacts of both Pleistocene climatic changes and more recent human disturbance on the genetic diversity of several Polylepis species has been shown by previous genetic studies (Hensen et al, 2011, 2012; Gareca et al, 2013).…”

“…Additional recent fragmentation through human activity (e.g., timber extraction) might be reflected in the higher genetic diversity observed in adults that germinated before fragmentation and lower diversity in seedlings that developed after fragmentation. This pattern was found for Polylepis incana in Ecuador (Hensen et al, 2012), while genetic diversity of Polylepis subtusalbida in Bolivia appears not to have been greatly affected by recent human activities (Gareca et al, 2013).…”

Rosids

“…In this issue, Wrońska‐Pilarek, Bocianowski & Jagodziński () evaluate the use of pollen morphology for assessing hybridization in Crataegus , and Gareca et al . () study genetic diversity in remnant stands of Polylepis Ruiz & Pav. in the Andes and discuss the implications for conservation and restoration.…”