STUDIES ON THE BREEDING STRUCTURE OF TREE SPECIES IN THE TROPICAL RAIN FOREST. I: FAMILY CLUMPS AND INTRAPOPULATION DIFFERENTIATION
AbstractBreedingÂ structuresÂ ofÂ twoÂ tropicalÂ rainÂ forestÂ tree species,Â AltingiaÂ excelsaÂ inÂ JavaÂ andÂ Agathis borneensis inÂ KalimantanÂ wereÂ investigated.Â AssumingÂ thatÂ similarityÂ inÂ theÂ assortmentÂ patternÂ ofÂ the isoperoxidase bands tells genetic relationship between trees, on the one hand, and that inbreedingÂ increases smallerÂ valuesÂ ofÂ theÂ disagreementÂ counts,Â onÂ theÂ other,Â itÂ hasÂ beenÂ concluded thatÂ inbreedingÂ occurs considerably in Altingia excelsa and to some extent in Agathis borneensis. Finding that trees showing very low disagreement counts are located close to each other, they were grouped as an assumptive family. It was found that different families were quite dissimilar with respect to isoperoxideÂ constitution and in severalÂ leaf characters as well. The distance between two trees at which they can mate is estimated to be 16 to 18 meters or 16.5 meters and the area one family occupies is 200 to 250 m^, assuming that a family clump can be a breeding unit in Altingia excelsa, within which trees mate at random. Some families were distributed mixed with each other withinÂ the matingÂ distance,Â butÂ theyÂ wereÂ foundÂ stillÂ genetically differentiatedÂ fromÂ eachÂ other. This reproductiveÂ isolationÂ amongÂ familiesÂ isÂ interpretedÂ toÂ beÂ dueÂ toÂ geneticÂ differencesÂ betweenÂ familiesÂ in flowering time. In Agathis borneensis,Â there was no indication of family clump formation. Related trees may have been widely scattered in the forest, and the inbreeding of the species may be due to self-fertilization of individual trees and not to outcrossing between relatives.
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