Inbreeding and you can outbreeding anxiety
For every maternal tree, the consequences out-of nearest-neighbors and much time-range mating was in fact estimated through indices away from biparental inbreeding despair and you may outbreeding depression, respectively, according to cumulative physical fitness philosophy. Just like the studies kinds had been largely otherwise totally thinking-infertile, inbreeding anxiety using selfing is actually overlooked. Biparental inbreeding despair is actually strong however, variable for S. rubicundum, which mating towards the nearby neighbor portrayed the average exercise cost of forty-five% (diversity = ?46 to help you +94%), in line with crossing which have sparingly even more faraway residents (Fig. 6). Getting Sh. cordifolia, the newest nearby-neighbors mating perception are a great deal more unknown and you will changeable across woods; combining every actions from crossing exercise, inbreeding depression averaged close to zero (?6%, range = ?109 to help you +92%; Fig. 6). In contrast, the result regarding between-tree crossing was reasonable for both species (mean outbreeding anxiety = 52 and you may 70% having S. rubicundum and Sh. cordifolia, respectively; Fig. 6).
Visible crossing outcomes towards the fitness rejected involving the levels regarding fresh fruit put meilleurs sites de rencontres ayant un écart d’âge and step 1-yr-dated seedling proportions. Of the five exercise measures, only fresh fruit place are influenced notably because of the crossing medication. As a result of the attrition in the try products in the stage out of mature seeds to one-yr-dated seedlings, yet not, and subsequent higher type certainly therapy-by-maternal tree categories both in seedling survivorship and you will level, the benefit to detect procedures effects along with reduced over the years. Consequently, incapacity to look at tall crossing outcomes toward progeny exercise (seedling survivorship and you can growth in type of) should not be believed definitive.
Talk
The fresh exceptionally reduced good fresh fruit selection of selfed flowers away from each other species tends to be due to solid inbreeding depression or to genetic mind-incompatibility (Bawa, 1992). If reasonable self-virility was due to hereditary incompatibility, this new discrimination of mind-pollen isn’t done for either types (S. rubicundum, this research; Sh. cordifolia, Dayanandan mais aussi al., 1990). The brand new prevalent outcrossing seen for those trees try trait regarding woody species on tropics (age.grams., Ashton, 1969; Bawa, 1974, 1992; Chan, 1981; Bawa, Perry, and Coastline, 1985; Dayanandan ainsi que al., 1990; Murawski and Hamrick, 1991; Oliveira and you can Gibbs, 1994).
In addition to a striking and predictable selfing effect for both species, the relationship between outcrossing distance and fruit set was significant for each. Peak fruit set corresponded to an outcrossing distance of ?1–2 km. Although not statistically significant, peak fruit set for S. rubicundum consistently exceeded those of open-pollinated flowers, suggesting that the bulk of the natural pollen distribution is restricted to distances <1–2 km. More specifically, similarity between fruit set of open-pollinated flowers and distant-neighbor crosses may indicate that these trees naturally cross with mates occurring very roughly within a radius of 80–500 m (the range of outcrossing distances used in the distant-neighbor treatment). Unfortunately, as the hand-pollination procedure had a negative impact on fruit set in Sh. cordifolia, comparisons of fruit set rates or cumulative fitnesses between hand-pollination and open-pollination treatments are not useful.
While you are outcrossing distance didn’t rather affect the kept measures out of crossing physical fitness, having partners exceptions, indicate viewpoints away from fitness strategies then followed a mostly consistent trend across the providers. Both for species, indicate viewpoints for all methods gradually improved which have crossing distance, peaking in the an advanced length (1–2 km to have S. rubicundum and you can step one–10 kilometres to own Sh. cordifolia), and then dropping at the ranging from-forest cures. Departures out of this development have emerged for seed products germination and you can seedling dimensions between-tree crosses from Sh. cordifolia, hence surpassed the fresh indicate philosophy for everyone most other treatments, such as the discover-pollinated medication (see Crossbreed vigor inside the Shorea cordifolia less than). When every exercise strategies was basically joint in the collective physical fitness score, however, brand new trend regarding level fitness at the advanced-length, within-tree crosses carried on for both species.
