For 2 tree variety into the Sri Lanka’s wet region woods, fruit put more than doubled with outcrossing point, peaking during the advanced-point within this-tree crosses (1–ten km according to kinds). Inside the crosses between trees consuming separate forest reserves, although not, fruit put is rather shorter (otherwise nearly very) for both kinds. Alternatively, vegetables germination and you can seedling level at the step one yr to have Sh. cordifolia recommended crossbreed energy in-between-tree crosses. The effects out of nearby-next-door neighbor mating ranged among trees site de rencontres pour les passionnés de fitness and you may variety; the indicate fitness cost of nearby-neighbor mating prior to mating having sparingly alot more faraway natives are 45% having S. rubicundum and you will 0% to possess Sh. cordifolia. In contrast, new physical fitness negative effects of between-forest crossing had been big both for variety (52 and you will 70% in accordance with in this-tree crosses for the very same a couple species). Crossing effects diminished involving the amounts off good fresh fruit set and step 1-yr-dated seedling dimensions; precisely the previous try high for species. Abilities indicate an effective potential for biparental inbreeding depression in this forest tree populations and limited reproductive isolation certainly trees consuming the rest tree reserves in the Sri Lanka’s wet area.
Inbreeding depression might be quoted given that an unavoidable consequence of anthropogenic interference so you can tropical woods (e.grams., forest fragmentation, logging), where idea predicts you to normal mating habits inside currently low-density tree communities try moved on in order to prefer quick-length crosses. Thus far, yet not, the effects off elevated close-neighbor mating getting populace physical fitness when you look at the exotic trees enjoys yet so you’re able to feel quantified empirically. A couple simple questions to-be handled is actually: Create people prevent maturing seeds derived from near-neighbors crosses and you may, if not, just how match was close-neighbor-derived progeny relative to anybody else? This research analyzes the consequences away from close-neighbor mating in 2 warm forest types myself owing to fitness reviews regarding crosses between nearest neighbors that have crosses involving alot more distant mates.
Shorea cordifolia (Dipterocarpaceae) is an in your area abundant head cover variety one to flowers heavily from the unpredictable supra-annual intervals (I. Good. U. N. Gunatilleke ainsi que al., unpublished investigation). Vegetation regarding the variety try white and you can brief-lived, therefore the winged fruit is distribute of the piece of cake otherwise the law of gravity. Because of its very restricted vegetables dispersal, hereditary relatedness one of near locals within the sheer tree is expected to getting large. When you look at the logged tree within Sinharaja, Sh. cordifolia usually happens in clumps away from ?5–20 adults, intermixed with quicker stems (private observance).
Study 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%, Fstep one,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 one,58 = 3.78, P < 0.06).
For Sh. cordifolia, cumulative fitness was maximum at 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). 2,8 = 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 one,twelve = 8.77, P = 0.012).
Near-neighbor crossing feeling
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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