Effective gene dispersal and female reproductive success in Mediterranean maritime pine (Pinus pinaster Aiton)

Abstract

Understanding population-scale processes that affect allele frequency changes across generations is a long-standing interest in genetic, ecological and evolutionary research. In particular, individual differences in female reproductive success and the spatial scale of gene flow considerably affect evolutionary change and patterns of local selection. In this study, a recently developed maximum-likelihood (ML) method based on established offspring, the Seedling Neighbourhood Model, was applied and exponentially shaped dispersal kernels were fitted to both genetic and ecological data in a widespread Mediterranean pine, Pinus pinaster Aiton. The distribution of female reproductive success in P. pinaster was very skewed (about 10% of trees mothered 50% of offspring) and significant positive female selection gradients for diameter (gamma = 0.7293) and cone crop (gamma = 0.4524) were found. The selective advantage of offspring mothered by bigger trees could be due to better-quality seeds. These seeds may show more resilience to severe summer droughts and microsite variation related to water and nutrient availability. Both approaches, ecological and of parentage, consistently showed a long-distance dispersal component in saplings that was not found in dispersal kernels based on seed shadows, highlighting the importance of Janzen-Connell effects and microenvironmental variation for survival at early stages of establishment in this Mediterranean key forest tree.

Mating system and pollen gene flow in Mediterranean maritime pine

“…However, O'Connell et al (2004) observed that outcrossing rates decreased with increasing tree height in four populations of Thuja plicata. This variety of results emphasizes the idea that tree size, apart from directly affecting outcrossing rates through increasing flower exposition to the pollen cloud, may also be a gauge for other factors affecting mating patterns, such as reproductive effort or tree social position within the stand (Burczyk et al, 1996;González-Martínez et al, 2006). There is growing evidence showing that the relative position of the crown Figure 4 Correlated mating (r p ) estimates based on progeny arrays from 61 mother trees (average and s.d.…”

Spruce colonization at treeline: where do those seeds come from?

“…Our results could be interpreted by hypothesizing an increasing survivorship coupled with the well-known decreasing seed dispersal probability from the seed source, as in Janzen-Connell recruitment pattern. J-C effects had been hypothesised in estimating effective seed dispersal distribution using parentage analysis in P. halepensis (Nathan et al, 2000;Troupin, 2005), P. pinaster (Gonzalez-Martinez et al, 2006) and Simarouba amara (Hardesty et al, 2006). However, J-C pattern implies that the increasing survivorship curve depends on the density of predators or pathogens.…”

Factors affecting cone production in Pinus pinaster Ait.: lack of growth-reproduction trade-offs but significant effects of climate and tree and stand characteristics

“…This result has been previously documented in other species such as Pinus ponderosa (Krannitz & Duralia, 2004) and Pseudotsuga menziesii (ElKassaby & Barclay, 1992), and is probably explained in part by the generally greater vigor of larger trees in even-aged stands. Higher tree vigor has also been shown to produce a higher number of recruits in next generation (González-Martínez et al, 2006). As thinning promotes diameter growth, an increase in cone production is expected as a longer-term benefit of thinning (Krannitz & Duralia, 2004).…”