Inbreeding and you will outbreeding anxiety
For every single maternal tree, the results out of nearby-next-door neighbor and you can enough time-length mating have been estimated as a consequence of indicator away from biparental inbreeding despair and you will outbreeding despair, respectively, according to cumulative physical fitness values. Given that analysis variety was in fact mostly or totally self-infertile, inbreeding despair as a result of selfing are neglected. Biparental inbreeding anxiety are solid but variable getting S. rubicundum, for which mating towards nearest next-door neighbor portrayed the typical physical fitness price of forty-five% (variety = ?46 to +94%), relative to crossing with sparingly more distant residents (Fig. 6). Getting Sh. cordifolia, the newest nearby-neighbor mating impression are significantly more unknown and you will varying across woods; merging all of the steps out-of crossing physical fitness, inbreeding depression averaged near to no (?6%, assortment = ?109 so you can +92%; Fig. 6). In contrast, the end result out-of between-tree crossing is actually reasonable for types (indicate outbreeding depression = 52 and you can 70% for S. rubicundum and you will Sh. cordifolia, respectively; Fig. meilleurs sites de pegging 6).
Obvious crossing outcomes toward exercise denied within amount of good fresh fruit lay and 1-yr-dated seedling dimensions. Of your four fitness actions, simply good fresh fruit place are swayed rather from the crossing medication. Because of the attrition when you look at the attempt items from the stage out of adult vegetables to just one-yr-old seedlings, although not, and the subsequent high version certainly one of procedures-by-maternal forest groups in both seedling survivorship and you will peak, the advantage in order to locate medication effects including diminished through the years. Consequently, inability to see or watch extreme crossing outcomes on the progeny exercise (seedling survivorship and growth in brand of) shouldn’t be felt definitive.
Discussion
Brand new extremely reduced fruits band of selfed plants of both species is generally because of good inbreeding anxiety or to genetic mind-incompatibility (Bawa, 1992). If reasonable worry about-fertility is actually attributable to genetic incompatibility, the brand new discrimination from care about-pollen is not over to possess possibly kinds (S. rubicundum, this study; Sh. cordifolia, Dayanandan et al., 1990). The newest widespread outcrossing observed for those woods is actually trait out-of woody types on the tropics (e.g., Ashton, 1969; Bawa, 1974, 1992; Chan, 1981; Bawa, Perry, and you will Seashore, 1985; Dayanandan ainsi que al., 1990; Murawski and you will Hamrick, 1991; Oliveira and you will 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 length didn’t significantly affect the kept strategies of crossing physical fitness, with partners conditions, suggest opinions out-of physical fitness tips implemented a generally uniform trend across solutions. For types, imply beliefs for everybody measures gradually improved having crossing point, peaking at the an intermediate distance (1–dos km for S. rubicundum and step 1–ten kilometer to own Sh. cordifolia), right after which dropping in the anywhere between-tree procedures. Departures from this trend are seen to have seeds germination and you may seedling proportions around-forest crosses away from Sh. cordifolia, hence surpassed the latest imply thinking for all almost every other service, for instance the discover-pollinated therapy (come across Hybrid vigor within the Shorea cordifolia below). When all of the physical fitness measures have been mutual inside the cumulative exercise scores, yet not, the fresh new trend away from peak physical fitness at advanced-range, within-forest crosses proceeded both for species.
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