Individual reproductive success in Norway spruce natural populations depends on growth rate, age and sensitivity to temperature

Abstract

Quantifying the individual reproductive success and understanding its determinants is a central issue in evolutionary research for the major consequences that the transmission of genetic variation from parents to offspring has on the adaptive potential of populations. Here, we propose to distil the myriad of information embedded in tree-ring time series into a set of tree-ringbased phenotypic traits to be investigated as potential drivers of reproductive success in forest trees. By using a crossdisciplinary approach that combines parentage analysis and a thorough dendrophenotypic characterisation of putative parents, we assessed sex-specific relationships between such dendrophenotypic traits (i.e., age, growth rate and parameters describing sensitivity to climate and to extreme climatic events) and reproductive success in Norway spruce. We applied a full probability method for reconstructing parent-offspring relationships between 604 seedlings and 518 adult trees sampled within five populations from southern and central Europe. We found that individual female and male reproductive success was positively associated with tree growth rate and age. Female reproductive success was also positively influenced by the correlation between growth and the mean temperature of the previous vegetative season. Overall, our results showed that Norway spruce individuals with the highest fitness are those who are able to keep high-growth rates despite potential growth limitations caused by reproductive costs and climatic limiting conditions. Identifying such functional links between the individual ecophysiological behaviour and its evolutionary gain would increase our understanding on how natural selection shapes the genetic composition of forest tree populations over time.

Individual fitness is decoupled from coarse‐scale probability of occurrence in North American trees

“…In general, individual growth rate is a key component of individual fitness of an organism (Violle et al 2007). Specifically, growth rate of trees enhances individual competitive ability in natural forest ecosystems (Morgenstern 1996) and can positively influence reproductive success of individuals (Avanzi et al 2015). In addition, individual growth rate has been previously shown having a positive coupling with SDM-modelled probability of occurrence in grass carp Ctenopharyngodon idella (Wittmann et al 2016).…”

Fine‐scale spatial genetic structure across the species range reflects recent colonization of high elevation habitats in silver fir (Abies alba Mill.)

“…Such pronounced reproductive skew is commonly observed in trees (e.g., Chybicki & Burczyk, 2013 ; Oddou‐Muratorio et al, 2018 ), and can be driven by genetic or micro‐environmental differences. For example, Avanzi et al ( 2020 ) showed that in Norway spruce, trees that were able to maintain high‐growth rates despite environmental growth limitations had the highest reproductive success. The assessment of reproductive success also greatly depends on the ontological stage.…”

Identification of determinants of pollen donor fecundity using the hierarchical neighborhood model

“…However, flower traits are often difficult to quantify, especially if there are many candidate parents within a study plot or if a study species is characterized by large dimensions, as many trees. Fortunately, flower abundance usually covaries with individual size, making size‐related phenotypic variables a right choice for covariates of reproductive success (Avanzi et al, 2020; Younginger et al, 2017). In trees, trunk diameter is the easiest and the most accurately measurable predictor of this kind.…”