Adaptive Differentiation in Seedling Traits in a Hybrid Pine Species Complex, Pinus densata and Its Parental Species, on the Tibetan Plateau

Abstract

Evidence from molecular genetics demonstrates that Pinus densata is a natural homoploid hybrid originating from the parent species Pinus tabuliformis and Pinus yunnanensis, and ecological selection may have played a role in the speciation of P. densata. However, data on differentiation in adaptive traits in the species complex are scarce. In this study, we performed a common garden test on 16 seedling traits to examine the differences between P. densata and its parental species in a high altitude environment. We found that among the 16 analyzed traits, 15 were significantly different among the species. Pinus tabuliformis had much earlier bud set and a relatively higher bud set ratio but poorer seedling growth, and P. yunnanensis had opposite responses for the same traits. P. densata had the greatest fitness with higher viability and growth rates than the parents. The relatively high genetic contribution of seedling traits among populations suggested that within each species the evolutionary background is complex. The correlations between the seedling traits of a population within a species and the environmental factors indicated different impacts of the environment on species evolution. The winter temperature is among the most important climate factors that affected the fitness of the three pine species. Our investigation provides empirical evidence on adaptive differentiation among this pine species complex at seedling stages.

Effects of geoclimatic factors on the variability in Pinus pinea cone, seed, and seedling traits in Turkey native habitats

“…Also, there was a strong correlation between NC and BS. It could be that BS relates better to mean annual rainfall in our study, while Meng et al (2015) indicated that annual mean temperature and mean temperature of the coldest month have a stronger relationship with BS in P. yunnanensis over 2 years.…”

Effects of Microbial Communities on Elevational Gradient Adaptation Strategies of Pinus yunnanensis Franch. and Pinus densata Mast. in a Mixed Zone

“…Pinus densata is considered a homoploid hybrid speciation (HHS) type species tha originated from the putative parent species P. tabuliformis and P. yunnanensis [14]. The intermediate morphology of pine hybrids is contributed by both parental species, and hy brid derivatives are more similar to the parent with higher genetic contribution, resulting in cryptic introgression [49].…”

“…and Pinus yunnanensis Franch. [14]. Evidence from molecular genetics, for example, chloroplast DNA polymorphism [15], allozyme [16][17][18], simultaneous DNA probes of the 18S rRNA gene and the 5S rRNA gene [19], the paternally inherited chloroplast rbcL gene and maternally inherited mitochondrial nad1 fragments [20,21], demonstrates that P. densata is a natural homoploid hybrid and that ecological selection may have played a role in its speciation.…”

Microscale trait‐environment associations in two closely‐related South African shrubs

“…It might also be that trait differences are less apparent in seedlings than in adults (Mediavilla et al., ), since functional traits within an individual can vary drastically among ontogenetic stages (Mason et al., ). Differences in seedling traits of single species have been detected across genotypes within species or hybrid groups, but typically only across genotypes from drastically different environments (Abrams et al., ; Meng et al., ). Still, previous common‐garden and greenhouse studies in Protea have found relationships at early life history stages consistent with field correlations (Carlson et al., , ; Prunier et al., ) as well as evidence for plasticity in leaf size and stomatal traits (Carlson and Holsinger, ).…”