The relationship between outcrossing length and you may cumulative exercise wasn’t high (quadratic regression: F

For 2 forest variety when you look at the Sri Lanka’s moist area forest, fruit lay increased significantly that have outcrossing length, peaking from the intermediate-range contained in this-tree crosses (1–ten kilometer dependent on varieties). Within the crosses ranging from woods consuming independent forest reserves, although not, good fresh fruit lay are notably shorter (otherwise nearly very) both for kinds. Conversely, seed germination and you can seedling height on 1 yr having Sh. cordifolia recommended crossbreed energy between-forest crosses. The effects off nearby-neighbors mating varied one of trees and you can species; the newest indicate fitness price of nearby-next-door neighbor mating prior to mating that have modestly even more distant residents are 45% for S. rubicundum and you can 0% to have Sh. cordifolia. Conversely, the physical fitness ramifications of between-forest crossing was in fact good for types (52 and 70% prior to within-tree crosses for similar a couple of types). Crossing outcomes decreased between the levels out of fresh fruit put and you will 1-yr-dated seedling size; precisely the former try significant for types. Show mean a robust possibility of biparental inbreeding despair inside tree tree communities and you can partial reproductive separation among trees consuming the rest tree supplies within the Sri Lanka’s wet zone.

Inbreeding anxiety can often be cited while the an unavoidable results of anthropogenic disturbance in order to tropical forests (elizabeth.grams., forest fragmentation, logging), in which concept forecasts you to normal mating models contained in this currently lowest-density tree communities is actually shifted to prefer short-point crosses. Thus far, yet not, the results out of increased near-neighbor mating to have population physical fitness in exotic trees possess but really in order to getting quantified empirically. A couple of fundamental questions are addressed is: Create grownups stop maturing vegetables produced from close-next-door neighbor crosses and you will, otherwise, how match is close-neighbor-derived progeny relative to someone else? This study assesses the consequences out of near-neighbors mating in 2 tropical forest kinds privately using fitness reviews regarding crosses anywhere between nearby residents which have crosses associated with way more faraway mates.

Shorea cordifolia (Dipterocarpaceae) try an in your area abundant chief cover varieties you to definitely plant life greatly in the irregular supra-annual menstruation (I. Good. U. Letter. Gunatilleke mais aussi al., unpublished study). Vegetation in the varieties are light and small-lived, and also the winged fruits are dispersed of the wind or gravity. Because of its highly limited seed products dispersal, hereditary relatedness among close residents inside the pure tree is expected so you’re able to end up being large. From inside the signed tree from the Sinharaja, Sh. cordifolia always occurs in clumps out of ?5–20 people, intermixed that have shorter stems (personal observation).

Data research

For both species, within-treatment variation among maternal trees in fruit set was substantial for all outcrosses involving pollen donors within Sinharaja Reserve. In contrast, variation in fruit set rate was very low for between-forest crosses (Fig. 2). For Sh. cordifolia, fruit set for the distant between-forest treatment ranged from only 0.5 to 0.6% and was significantly lower than the mean fruit set rate for all within-forest outcrossing treatments combined (mean = 2.71%, F1,58 = 9.94, P < 0.0003). For S. rubicundum, mean fruit set for the distant between-forest treatment (2.67%) was low relative to mean fruit set rate for all within-forest outcrossing treatments combined (mean = 5.97%). The difference was nearly significant (Fstep 1,58 = 3.78, P < 0.06).

For Sh. cordifolia, cumulative fitness was maximum at sites de rencontres musique gratuite both the distant neighbor and distant within-forest treatments (Fig. 5). Peak cumulative fitness observed for these intermediate crossing treatments was 2 and 4.3 times the cumulative fitnesses of the nearest-neighbor and distant between-forest treatments, respectively, although these differences were not significant (Table 3B). dos,8 = 3.70, P = 0.073). Mean cumulative fitness of open-pollinated flowers exceeded that of all other hand-pollination treatments, again likely due to the detrimental effect of the hand-pollination procedure on fruit set in this species. As for fruit set, mean cumulative fitness (relative) of the distant between-forest treatment (mean = 0.12) was significantly lower than that of all within-forest outcrossed classes combined (mean = 0.51, Fstep 1,several = 8.77, P = 0.012).

Near-neighbor crossing perception

Near-neighbor crossing effects have been demonstrated for a number of coniferous species (Coles and Fowler, 1976; Park and Fowler, 1982, 1984; Latta et al., 1998), but only three studies have yielded evidence of near-neighbor crossing effects in woody angiosperms (Syzygium cormiflorum-Crome and Irvine, 1986; Schiedea spp.-Sakai, Karoly, and Weller, 1989; Eucalyptus globules-Hardner, Potts, and Gore, 1998). In another study suggestive of biparental inbreeding depression, mean fruit set rates were significantly lower for intraspecific crosses <0.5 km distance than for crosses >1 km distance for three subcanopy tree species (Inga spp.) in Costa Rica (Koptur, 1984). In fact, it may be that biparental inbreeding depression is common in natural populations of forest trees, but that estimation of its potential through experimental cross-pollinations has been limited to only a few species due to the obvious difficulty of working in the canopy. To my knowledge, there are no published reports of failed attempts to find near-neighbor crossing effects in natural populations of forest trees.

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