Assessing early fitness consequences of exotic gene flow in the wild: a field study with Iberian pine relicts

Abstract

Gene flow from plantations of nonlocal (genetically exotic) tree provenances into natural stands of the same species is probably a widespread phenomenon, but its effects remain largely unexamined. We investigated early fitness consequences of intraspecific exotic gene flow in the wild by assessing differences in survival among native, nonlocal, and F1 intraspecific hybrid seedlings naturally established within two native pine relicts (one of Pinus pinaster and the other of P. sylvestris) surrounded by nonlocal plantations. We obtained broad‐scale temporally sequential genotypic samples of a cohort of recruits in each pine relict, from seeds before dispersal to established seedlings months after emergence, tracking temporal changes in the estimated proportion of each parental cross‐type. Results show significant proportions of exotic male gametes before seed dispersal in the two pine relicts. Subsequently to seedling establishment, the frequency of exotic male gametes became nonsignificant in P. pinaster, and dropped by half in P. sylvestris. Exotic zygotic gene flow was significantly different from zero among early recruits for P. sylvestris, decreasing throughout seedling establishment. Seedling mortality resulted in small late sample sizes, and temporal differences in exotic gene flow estimates were not significant, so we could not reject the null hypothesis of invariant early viability across parental cross types in the wild.

Seed Sourcing Strategies Considering Climate Change Forecasts: A Practical Test in Scots Pine

“…Another aspect not considered in our study is the possibility of a combination of alleles from different populations to produce new combinations for natural selection to occur. However, it is possible that some outbreeding depression might occur as a result of these new combinations [47,48]. Therefore we need to take these results with caution, as the context (early estimation under the climate change scenario, non-significant variation among provenances in survival) can hinder some of the advantages of these methods as proposed by different authors [7][8][9][10][11].…”

Measuring viability selection from prospective cohort mortality studies: A case study in maritime pine

“…Protocols for DNA extraction can be found in Unger et al. (). The 255 seedlings were genotyped with an oligo pool assay including a selection of 384 SNPs using the Illumina VeraCode platform (see table S2 in Budde et al., ; see also Jaramillo‐Correa et al., ).…”

“…Seed dispersal by wind typically spans from May to October in Iberian populations of P. pinaster, with seedlings emerging from October to November, enhanced with the first rains after the summer drought (Juez et al, 2014;personal observations). In a preceding study at Fuencaliente, Unger, Heuertz, Vendramin, and Robledo-Arnuncio (2016) tested the presence of exotic gene flow from conspecific plantations growing in the surroundings of the native stand, and its potential early fitness consequences. For this purpose, they took three random sequential seedling samples from a contemporary seedling cohort in the native stand, from the time of emergence in autumn until the summer of the following year.…”

“…We investigated for the first time whether genotypically based selection could determine nonrandom mortality during a critical early developmental stage in a tree species. In line with the model assumptions, seedling emergence is expected to be largely synchronous in the species, and samples were obtained over the entire population area, proportionally to local abundance and nondestructively whenever possible (Unger et al, 2016). Despite the vast cohort size at the as it changes the genetic background available for selection at subsequent life stages, especially in novel environments or extreme climatic events, and when pleiotropy is present (Donohue, 2014).…”

Effective Seed Dispersal and Fecundity Variation in a Small and Marginal Population of Pinus pinaster Ait. Growing in a Harsh Environment: Implications for Conservation of Forest Genetic Resources

“…This population has a marked reduction in allelic richness, compared to other populations of maritime pine in Spain [22]. In order to aid Fuencaliente's conservation, recent investigations have studied genetic introgression patterns from nearby exotic plantations of unknown origin [23][24][25]. Another recent study has evaluated the damage that deer (Cervus elaphus L.) cause to dynamics and its dispersal potential is still scarce, and this data would serve well to establish an adequate conservation plan, which has yet to be reported.…”