Crosses between members of commonly broke up communities, ergo, can get produce progeny out-of suboptimal fitness because of outbreeding anxiety (Bateson, 1978; Rates and you may Waser, 1979). Most proof outbreeding anxiety from inside the herbs comes out of crosses ranging from populations (age.grams., Ritland and you will Ganders, 1987; Sobrevila, 1988; Fischer and you will Matthies, https://datingranking.net/de/latin-dating-sites/ 1997). not, proof of outbreeding depression within this populations has been reported to own good couple species (Waser and you can Rate, 1983, 1989, 1991, 1993, 1994; Schemske and Pautler, 1984; Waser ainsi que al., 1987; McCall, Mitchell-Olds, and you may Waller, 1988). Best effects out of outbreeding despair should include support out of reproductive isolation of the distance and you may improved hereditary distinction more particular spatial measure, possibly causing speciation. From inside the warm forests, models towards the development out of high forest kinds range normally invoke genetic divergence from populations more particular spatial size (age.g., Fedorov, 1966; Ashton, 1969). Very little known, however, of the spatial scale from hereditary divergence from inside the exotic tree kinds.
Whenever you are trend towards outbreeding depression was indeed recorded to have a number out of bush kinds (citations a lot more than), there aren’t any authored records off outbreeding depression in just about any tree forest (Coles and you may Fowler, 1976; Park and you can Fowler, 1982, 1984; Crome and you will Irvine, 1986; Hardner, Potts, and Gore, 1998). This study assesses the significance and you may approximate spatial scale of outbreeding depression (because the a beneficial proxy to have genetic divergence) in two tropical tree species using exercise evaluations away from enough time-distance crosses which have crosses more quick and you may moderate distances.
Per out-of a few exotic tree varieties, next questions was in fact handled: (1) Why does mix-fertility are different which have outcrossing length? (2) What is the potential for inbreeding depression during the close-neighbors crosses? (3) What is the possibility of outbreeding anxiety more higher ranges within this and you may anywhere between tree supplies? and you can (4) Just how do the newest strengths of inbreeding and you will outbreeding outcomes are very different certainly early lifetime record stages, in addition to seed set, seed products germination, while the survivorship and you will growth of seedlings?
Studies site and you can kinds
That it really works is actually carried out in the bedroom of aseasonal Sinharaja Globe Society Site, a keen 8800-ha, UNESCO Child while the Biosphere Set aside, found in the southwest moist zone out-of Sri Lanka (Fig. 1). The fresh forests regarding southwest Sri Lanka is actually really fragmented because the an excellent outcome of cleaning having coffee and plastic plantations one to occurred in British colonial period (>100 year ago)pared to many exotic precipitation forest, new blossoms out of Sinharaja is fairly types-poor (?230 types of woody herbs), however, described as high endemism (Gunatilleke and you may Gunatilleke, 1980). The analysis kinds (Syzygium rubicundum and you may Shorea cordifolia) was basically selected to help you represent a couple of major canopy-prominent, economically very important genera of island’s precipitation woods. One another variety are pollinated predominantly of the bees (Apis spp.) and create unmarried-seeded fruits. The two species disagree during the mode out-of seeds dispersal (bird- or bat-dispersal versus. wind- or gyration-dispersal) and therefore are expected to exhibit some other society hereditary formations during the natural really stands (Loveless and Hamrick, 1984; Hamrick, Murawski, and you will Nason, 1993). Brand new communities targeted for this analysis, yet not, occurred in twenty-five+-yr-old signed tree at the Sinharaja Put aside. Adults of each and every kinds are highly clumped about logged tree in line with the distributions inside unlogged really stands. This compare suggests that the populace structures of those kinds has actually been altered regarding the large-white, post-signing ecosystem, where regeneration probably triggered brand new place out of sets of sibs otherwise associated individuals. The study communities, thus, given an amazing possibility to assess the possibility of biparental inbreeding despair during the forest woods.
Information And methods
Syzygium rubicundum (Myrtaceae), and this usually vegetation a year, try a dominating canopy types of mid-mountain parts close to Sinharaja. Mature occurrence is extremely adjustable both in unlogged and logged forest within Sinharaja Set aside (Stacy, Harischandran, and you can Gunatilleke, from inside the push). Plants associated with the varieties are small and brush-like, and also the drupes are mainly bird-spreading.