Genetics and conservation of the southern South American conifers
Item statusRestricted Access
Embargo end date30/11/2021
Cano Niklitschek, Mauricio Javier
Coniferous trees dominate many northern forests, and globally there are around 627 species of conifers, from eight families and 70 genera. Although the largest abundance of conifers is in the great boreal forests of Eurasia and North America, the species diversity increases further south, even though the land area is smaller. The conifer flora of Chile comprises only nine conifer species, but these include 3/8 extant conifer families (Araucariaceae, Cupressaceae, Podocarpaceae) and eight genera, with all of these species and four genera just restricted to southern South America. Chilean conifers are concentrated in the Chilean Temperate Rainforest, one of the world’s plants biodiversity hotspots. Although some species of Chilean conifer such as Araucaria araucana (Molina) K. Koch (Monkey Puzzle) have been subject to intensive research, most have not. Knowledge gaps in their basic biology represent a limitation in the development of effective conservation strategies. This is a pressing challenge given the extensive threat to plant biodiversity in the region (harvesting, climate change, pathogens, expanding plantation forestry and agriculture, and natural and human-induced fires). To address this challenge, this research project focuses on assessing population connectivity/differentiation in four emblematic endemic conifers from South America each with a restricted area of distribution: Saxegothaea conspicua Lindley, Prumnopitys andina (Poepp. ex Endl) de Laubenfels, Podocarpus salignus D. Don all members of the Podocarpaceae; and Fitzroya cupressoides (Molina) Johnston (Cupressaceae). Between seven and ten populations (per species) were included in this investigation, covering the entire natural distribution of each conifer species in Chile. Restriction site-associated DNA markers (RAD-seq) analysis was conducted. RAD-seq was first optimised (de novo assembly) to accommodate the large and complex genomes of conifers, before being deployed to assess patterns of population genetic structure. The main finding of population genetic analyses was a similar level of nucleotide diversity and low levels of genetic structure in all four conifer species. The low population structure over relatively large geographical distances was particularly noteworthy. This result is likely due to the extreme longevity of individuals of these species restricting divergence due to genetic drift, despite their currently fragmented ranges. A regeneration survey was also conducted for one of the conifer species involved in this project (Pr. andina), and supplemented with informal observations on regeneration for the other three species. Regeneration was frequent throughout most of the natural distribution of Pr. andina. However, a very low number of saplings was observed in all of the populations (most of them had no saplings at all). Informal observations on S. conspicua, P. salignus and F. cupressoides suggest that regeneration is common for all these species (both seedlings and saplings). How- ever, there was some variation and P. salignus showed a higher level of regeneration than S. conspicua and F. cupressoides. A field-based observation of threats was also undertaken for each conifer species, following the methodology proposed by the IUCN which is directed on recording and evaluating the impact of threats in situ. The most common threats with the highest impact were associated with land-conversion to exotic plantations and livestock. This work represents one of the very few studies optimising RAD-seq data for conifers and provides a combination of field and laboratory data to support conservation planning for these important and iconic species.