Physical Mapping of Human 7q and 14q Subtelomeric DNA Sequences in the Great Apes

Phylogenetic divergence of the members of the Pongidae familyhas been based on genetic evidence. The terminal repeat array(T₂AG₃) has lately been considered as an additional basis toanalyze genomes of highly related species. The recent isolationof subtelomeric DNA probes specific for human (HSA) chromosomes7q and 14q has prompted us to cross-hybridize them to the chromosomesof the chimpanzee (PTR), gorilla (GGO) and orangutan (PPY) tosearch for its equivalent locations in the great ape species.Both probes hybridized to the equivalent telomeric sites ofthe long (q) arms of all three great ape species. Hybridizationsignals to the 7q subtelomeric DNA sequence probe were observedat the telomeres of HSA 7q, PTR 6q, GGO 6q and PPY 10q, whilehybridization signals to the 14q subtelomeric DNA sequence probewere observed at the telomeres of HSA 14q, PTR 15q, GGO 18qand PPY 15q. No hybridization signals to the chromosome 7-specificalpha satellite DNA probe on the centromeric regions of theape chromosomes were observed. Our observations demonstratesequence homology of the subtelomeric repeat families D7S427and D14S308 in the ape chromosomes. An analogous number of subtelomericrepeat units exists in these chromosomes and has been preservedthrough the course of differentiation of the hominoid species.Our investigation also suggests a difference in the number ofalpha satellite DNA repeat units in the equivalent ape chromosomes,possibly derived from interchromosomal transfers and subsequentamplification of ancestral alpha satellite sequences.     

Humeral outlines in some hominoid primates and in Plio-Pleistocene hominids

A method of drawing outlines of the distal end of the humerus is presented and carried out on some pongids (Pan troglodytes, Pan paniscus, Pongo pygmaeus), on modern man, and on some casts of Plio-Pleistocene hominids. It appears that these outlines are good indicators of the overall morphology and permit the distinguishing of the different hominoids. For example, the morphology of the pillars surrounding the fossa olecrani is useful for this purpose. In modern man, the lateral pillar is quadrangular, contrasting with the triangular medial one. In pongids, both of them are triangular; however, it is possible to note differences between Pongo and Pan. In the South Asian ape, there is a stronger anteroposterior flattening of the pillars as well as the diaphysis. The similarity of the shape of the pillars might be considered as a result of an adaptation to suspension. The differences might be due to different weights of the animals. Plio-Pleistocene hominids are variable with regard to the morphology of this region. For example, Gombore IB 7594 is similar to Homo. KNM ER 739 exhibits features intermediate between hominids and pongids. Finally, AL 288.1M is closer to pongids. These results confirm a previous anatomical work.     

Male bimaturism and reproductive success in Sumatran orang-utans

Although orang-utans live solitary lives most of the time, theyhave a complex social structure and are characterized by extremesexual dimorphism. However, whereas some adult male orang-utansdevelop full secondary sexual characteristics, such as cheekflanges, others may stay in an "arrested" unflanged conditionfor up to 20 years after reaching sexual maturity. The resultis a marked bimaturism among adult males. Flanged males allowfemales to overlap with their home range and often toleratethe presence of unflanged males. However, wherever possibleflanged males actively prevent unflanged males from copulatingwith females. Two competing hypotheses, previously untested,have been advanced to explain male reproductive behavior andbimaturism in orang-utans: (1) the "range-guardian" hypothesis,which asserts that the flanged males are postreproductive anddefend a range in which they tolerate sexually active, unflangedmale relatives; and (2) the "female choice" hypothesis, whichasserts that flanged males tolerate unflanged males in their range because they rely on female preference to favor flangedmales. We investigated these hypotheses and a third hypothesisthat the two male morphs represent co-existing alternativemale reproductive strategies ("sitting, calling, and waiting"for flanged males versus "going, searching, and finding" forunflanged males). Fecal samples were collected from a well-studiedpopulation in Indonesia, and eight human microsatellites wereanalyzed for 30 individuals that have been behaviorally monitoredfor up to 27 years. By carrying out paternity analysis on 11offspring born over 15 years, we found that unflanged malesfathered about half (6) of the offspring. Relatedness betweensuccessful unflanged males and resident dominant males wassignificantly lower than 0.5, and for some unflanged/flangedmale pairs, relatedness values were negative, indicating thatunflanged males are not offspring of the flanged males.