Publications (6) View all
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Article: Sexual signalling in female crested macaques and the evolution of primate fertility signals.
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ABSTRACT: BACKGROUND: Female signals of fertility have evolved in diverse taxa. Among the most interesting study systems are those of multimale multifemale group-living primates, where females signal fertility to males through multiple signals, and in which there is substantial inter-specific variation in the composition and reliability of such signals. Among the macaques, some species display reliable behavioural and/or anogenital signals while others do not. One cause of this variation may be differences in male competitive regimes: some species show marked sexual dimorphism and reproductive skew, with males fighting for dominance, while others show low dimorphism and skew, with males queuing for dominance. As such, there is variation in the extent to which rank is a reliable proxy for male competitiveness, which may affect the extent to which it is in females' interest to signal ovulation reliably. However, data on ovulatory signals are absent from species at one end of the macaque continuum, where selection has led to high sexual dimorphism and male reproductive skew. Here we present data from 31 cycles of 19 wild female crested macaques, a highly sexually dimorphic species with strong mating skew. We collected measures of ovarian hormone data from faeces, sexual swelling size from digital images, and male and female behaviour. RESULTS: We show that both sexual swelling size and female proceptivity are graded-signals, but relatively reliable indicators of ovulation, with swelling size largest and female proceptive behaviours most frequent around ovulation. Sexual swelling size was also larger in conceptive cycles. Male mating behaviour was well timed to female ovulation, suggesting that males had accurate information about this. CONCLUSION: Though probabilistic, crested macaque ovulatory signals are relatively reliable. We argue that in species where males fight over dominance, male dominance rank is surrogate for competitiveness. Under these circumstances it is in the interest of females to increase paternity concentration and assurance in dominants beyond levels seen in species where such competition is less marked. As such, we suggest that it may be variation in male competitive regimes that leads to the evolution of fertility signalling systems of different reliability.BMC Evolutionary Biology 06/2012; 12(1):89. · 3.52 Impact Factor -
Article: Assessing dominance hierarchies: validation and advantages of progressive evaluation with Elo rating
Animal Behaviour 12/2011; 82:911-921. · 3.49 Impact Factor -
Article: Mitochondrial evidence for multiple radiations in the evolutionary history of small apes.
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ABSTRACT: Gibbons or small apes inhabit tropical and subtropical rain forests in Southeast Asia and adjacent regions, and are, next to great apes, our closest living relatives. With up to 16 species, gibbons form the most diverse group of living hominoids, but the number of taxa, their phylogenetic relationships and their phylogeography is controversial. To further the discussion of these issues we analyzed the complete mitochondrial cytochrome b gene from 85 individuals representing all gibbon species, including most subspecies. Based on phylogenetic tree reconstructions, several monophyletic clades were detected, corresponding to genera, species and subspecies. A significantly supported branching pattern was obtained for members of the genus Nomascus but not for the genus Hylobates. The phylogenetic relationships among the four genera were also not well resolved. Nevertheless, the new data permitted the estimation of divergence ages for all taxa for the first time and showed that most lineages emerged during four short time periods. In the first, between approximately 6.7 and approximately 8.3 mya, the four gibbon genera diverged from each other. In the second (approximately 3.0 - approximately 3.9 mya) and in the third period (approximately 1.3 - approximately 1.8 mya), Hylobates and Hoolock differentiated. Finally, between approximately 0.5 and approximately 1.1 mya, Hylobates lar diverged into subspecies. In contrast, differentiation of Nomascus into species and subspecies was a continuous and prolonged process lasting from approximately 4.2 until approximately 0.4 mya. Although relationships among gibbon taxa on various levels remain unresolved, the present study provides a more complete view of the evolutionary and biogeographic history of the hylobatid family, and a more solid genetic basis for the taxonomic classification of the surviving taxa. We also show that mtDNA constitutes a useful marker for the accurate identification of individual gibbons, a tool which is urgently required to locate hunting hotspots and select individuals for captive breeding programs. Further studies including nuclear sequence data are necessary to completely understand the phylogeny and phylogeography of gibbons.BMC Evolutionary Biology 03/2010; 10:74. · 3.52 Impact Factor -
Article: Assessment of Fertility Status in the Male Sumatran Rhino at the Sumateran Rhino Sanctuary, Way Kambas National Park, Lampung
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ABSTRACT: Sumatran rhino is the most endangered rhino species. Its population is estimated less than 300 individuals remaining in the wild with highly declining rate to 50% in the last 15 years. The number of male rhinoceroses in the captivity are very few, therefore the assessment of its fertility is very important in order to support the breeding success since the captive breeding success is very poor. The objectives of this study were (i) to determine the male reproductive status, (ii) to establish a reliable semen collection method, and (iii) to assess semen parameters of the fresh collected sample. Three methods of semen collection were examined to determine its fertilizing potential, i.e. (i) stimulated combination of artificial vagina (AV), penile massage (PM) and accessory gland massage (AGM); (ii) AV and PM; and (iii) only with PM. The first method gave the best result with an ejaculation success of 85.71% (6/7, n = 7). The second and third methods obtained an ejaculation success rate of 50% (2/4, n = 4)) and 25% (1/4, n = 4), respectively. The collected ejaculates had a volume of 1.2-12.4 ml with whitish to cream turbid colour and pH 6.90-6.99. Sperm concentration was (143-333) x 103 sperm/ml. The quality of the sperm was low with only approximately 1% of them moved forward slowly. Approximately 80% of the spermatozoa were immature (prox. cytoplasmic droplet) with head (macro-, microcephalic) and tail abnormalities (broken tail). Semen quality increased after several collections and the amount of immature sperm decreased up to 5%. Electroejaculation procedure could produce 34 ml semen, but no sperm was found in the ejaculate. Hence, the combination of AV, PM, and AGM could get higher volume of ejaculate compared to other methods, but sperm concentration was better obtained using AV and PM only. Repeated semen collection increased semen quality, although the male has low fertilizing capacity due to low sperm concentration (oligozoospermia) and small volume of the ejaculate (oligospermia).HAYATI Journal of Biosciences. 01/2008; -
Article: Morfologi dan Biometri Spermatozoa Anoa (Bubalus Sp.) yang Diwarnai dengan Pewarna William’s dan Eosin-Nigrosin
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ABSTRACT: Anoa is Indonesia endemic fauna that included into Appendix I by CITES. Anoa breeding efforts have not succeed, due to their agressivity, soliter, wildness and monogamous. The aim of this experiment was to observe morphology and biometry of anoa’s sperm stained using William’s (W) and eosin-nigrosin (EN). Semen was collected from two male anoas by electroejaculator. Slides was made for morphology and biometry observation of ejaculate. The results showed that abnormal sperm morphology of the mature anoa (10 years) was 32.27%-35.00%, meanwhile the young one (3 years) was 24.03%–31.89%. In mature anoa, measurement for head width, and midpiece and tail length of sperm were not signficantly different between W and EN staining, but significantly different (P<0.05) for head and total length. In the young anoa, sperm biometry for head width was not significanly different between W and EN staining. In both W and EN staining, biometry for head width and total length were not significantly different between mature and young anoas, but significantly different for head, midpiece and tail length. According to sperm morphology, semen from the young anoa was slightly better than those of the mature anoa. Staining method and age could affect to biometry of the anoa’s sperm.Media Peternakan. 01/2010;
