AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 67:123-126 (1985) Cytogenetic Study of a Female Lemur coronatus x Lemur macaco Hybrid S. WARTER AND Y.RUMPLER Faculte de M@decine,Institut d’Embryologie, 67085 Strasbourg Ceder, France KEY WORDS Lemur macaco Karyotype, Hybrid, Lemur coronatus, ABSTRACT Two species of lemur, Lemur rnacaco and Lemur coronatus, which do not hybridize in the wild, have produced a first, “definite” female hybrid in captivity. Its karyotype contains one haploid set from each parent. The analogy with the parental chromosomes is such that the pairing of the corresponding chromosomal arms leads to the formation of a n open chain and a ring. The difficulty in obtaining hybrids between these two species could reflect the existence of a prezygotic barrier. The presence of multivalents, with probably a negative action on the gametogenesis, would introduce a postzygotic barrier. Lemurs of the genus Lemur comprise six species, of which three have produced numerous hybrids in captivity, despite sometimes considerable morphological differences (Albignac et al., 1971; Saint-Pie, 1970). A possible hybridization between two particularly distinct species, Lemur coronatus t C 0 ) and Lemur macaco &MA) had been announced at Frankfurt am Main Zoo (de Boer, 1973). It concerned a n animal of unknown origin, slightly resembling a hybrid between LMA and Lemur fuEuus (LFU), with a diploid number equal to 45 and a karyotype without banding, compatible with this hypothesis. We report here on the karyotype of a second hybrid between LMA and LCO. MATERIALS AND METHODS The hybrid, a female, was born in 1983 a t the Duke Primate Center, of a male LCO and a female LMA housed together during a reproductive season in a collaborative research program between the Duke Primate Center and the University of Strasbourg. Fibroblast cultures were prepared from skin biopsies, using our usual technique. The karyotype was established after R-band (Dutrillaux and Lejeune, 1971) and C-band (Sumnet., 1972) marking. RESULTS The hybrid, “Galliope” presents a shiny brown-red pelage like that of a LMA female, but with the top of the head darker, and a tail similar to that of LCO. At the head there 0 1985 ALAN R. LISS, INC. are lateral white tufts, less developed than in LMA. The muzzle resembles that of LMA, while the ears are like those of LCO, but with darker fur. The karyotype of “Galliope” (Fig. 1) comprises 45 chromosomes: 19 meta- and submetacentrics, 2 large acrocentrics, representing the X chromosomes, and 22 acrocentrics smaller than the sex chromosomes. Two of these acrocentrics do not have homologues but correspond to the short arms of two submedian chromosomes. Among the submetacentric chromosomes are the two pairs common to all of the lemurs, but with a slight difference at the juxtacentromeric region of the two chromosomes of pair 1. This results from the importance of the heterochromatin of the juxtacentromeric region of chromosome 1 from LCO, evidenced by the C-bands. The karyotype of the hybrid contains one haploid set of LMA and one of LCO. According to previously established correspondences (Table 1) (Rumpler and Dutrillaux, 1976,1979), it appears that the pairing of the corresponding chromosomal arms forms two multivalents. One is a n open chain of 11 chromosomes, terminating with a n acrocentric a t each extremity, the other is a ring closing back on itself, comprising six chromosomes (Figs. 1,2). The differences in size Received August 30,1984; accepted January 14, 1985. 124 S . WARTER AND Y.RUMPLER A B Y Y 4' h Fig. 1. A) R-banded karyotype of Lemur macaco x Lemur coronatus hybrid female with a chain of eleven elements and a ring of six elements ; m = macaco; c = coronatus. B) C-banded metaphase of the same hybrid. Note the enlarged C-band material in the Lemur coronatus 125 CYTOGENETIC STUDY OF LEMUR HYBRID TABLE 1. Correspondences between the chromosomes ofLemur fulvus fulvus (LFU), Lemur macaco fLMA), Lemur coronatus (LCO), and the hypothetical ancestral karvotvoe IANC) ANC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 X 8 min LFU LMA LC 0 LMA LCO 1q 10 4q Iq 5 3 8 6 7 9 10 4 6P 3q 5P 5q 2P 2q 9q IP 3P 6q 8q 7P 7q 8P 4P 2q 1P 11 12 14 15 13 16 17 19 18 23 20 21 h1:i 7 min 9P Xshi 12 min 'shi = shift. between the homologous arms of the chromosomes involved in these multivalents are due to the presence of a large quantity of juxtacentromeric heterochromatin on the LCO chromosomes LC1, LC2, LC3, LC4, LCs, LC7. DISCUSSION Fig. 2. Scheme of the chromosomal evolution of the lemurs studied. The evolution probably started out with an ancestral karyotype composed only of acrocentric autosomes and gave rise to the karyotype of Lemur fuluus. It is a turning point of chromosomal evolution of most Lemuridae, including Lemur coronatus and Lemur macuco. The numbers indicate the chromosomes involved, using the nomenclature of the ancestor (ANC) except for LMA7 and LC04. Open square, Robertsonian translocation; half-solid circle, centromeric shift; H, heterochromatin change. It is at present more difficult to confirm the existence of a postzygotic barrier, since this hybrid has not yet reached sexual maturity. Given what we know about other lemur hybrids, this hybrid is probably sterile. In fact, even if large numbers of Robertsonian translocations per se do not appear to disturb gametogenesis in hybrids such as by producing trivalents, they are associated with important disturbances when they give rise to important meiotic multivalents. The genic environment likewise plays a significant role in the development of gametogenesis, such that chromosomal multivalents have more serious repercussions in males than in females, in both mice (Gropp and Winking, 1981) and lemurs (Ratomponirina et al., 1982). It thus appears probable that the existence of two multivalents has a negative effect on gametogenesis, especially in such distinct genic backgrounds. There are considerable morphological and ethological differences between LMA and LCO, which indicate a fairly ancient divergence between these two distinct species. In the north of Madagascar (Foret de la Montagne d'Ambre), LCO is sympatric with another lemur ethologically very similar to LMA, namely, Lemur fulvus sanfordi No natural hybridization has ever been observed between these two species, which often meet in the same forest strata (Arbelot-Tracqui, 1983). A prezygotic barrier separates the two species; they remain in their respective groups, whereas within a species there are often movements of individuals from one group to another between breeding seasons (Arbelot-Tracqui, 1983). The difficulty in obtaining hybrids between LMA and LCO, even CONCLUSIONS in captive mixed pairs housed apart from other animals, also illustrates the prezygotic Two species of lemurs differing in very imbarrier between the two species. portant chromosomal rearrangements are S. WARTER AND Y.RUMPLER 126 capable of hybridization. It seems probable that such hybrids have reduced fertility. Inasmuch as such hybrids would have gonads containing germinal cells capable of division, a study of meiosis in males would be of considerable interest. ACKNOWLEDGMENTS The authors thank Duke Primate Center for the loan of the hybrid, Mr. M. Hauwy for technical assistance, and Mme. M. Lavaux for secretarial assistance. LITERATURE CITED Albignac, R, Rumpler, Y, and Petter, JJ (1971) L'hybridation des Mmuriens de Madagascar. Mammalia 35: 358-368. Arbelot-Traqui, V (1983) Etude Qcoethologique de d e w primates prosimiens: Lemur coronatus Gray et Lemur fuluus sanfordi Archbold These d'Etat, Universite de Rennes, 18juillet. Boer, LEM de (1973) Studies in the cytogenetics of F'rosimians. J. Hum. Evol. 2.271-278. Dutrillaux, B, and Lejeune, J (1971) Sur une nouvelle technique dailalyse du caryotype humain. C.R. %antes Acad. Sci. (Paris) 272t2638-2640. 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