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van Noordwijk MA, LaBarge LR, Kunz JA, Marzec AM, Spillmann B, Ackermann C, Rianti P, Vogel ER, Atmoko SSU, Kruetzen M, van Schaik CP. Reproductive success of Bornean orangutan males: scattered in time but clustered in space. Behav Ecol Sociobiol 2023; 77:134. [PMID: 38076722 PMCID: PMC10700224 DOI: 10.1007/s00265-023-03407-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 11/13/2023] [Accepted: 11/15/2023] [Indexed: 12/22/2023]
Abstract
Abstract The social and mating systems of orangutans, one of our closest relatives, remain poorly understood. Orangutans (Pongo spp.) are highly sexually dimorphic and females are philopatric and maintain individual, but overlapping home ranges, whereas males disperse, are non-territorial and wide-ranging, and show bimaturism, with many years between reaching sexual maturity and attaining full secondary sexual characteristics (including cheek pads (flanges) and emitting long calls). We report on 21 assigned paternities, among 35 flanged and 15 unflanged, genotyped male Bornean orangutans (Pongo pygmaeus wurmbii), studied from 2003 to 2018 in Tuanan (Central Kalimantan, Indonesia). All 10 infants born since mid-2003 with an already identified sire were sired by flanged males. All adult males ranged well beyond the study area (c. 1000 ha), and their dominance relations fluctuated even within short periods. However, 5 of the 10 identified sires had multiple offspring within the monitored area. Several sired over a period of c. 10 years, which overlapped with siring periods of other males. The long-calling behavior of sires indicated they were not consistently dominant over other males in the area around the time of known conceptions. Instead, when they were seen in the area, the known sires spent most of their time within the home ranges of the females whose offspring they sired. Overall, successful sires were older and more often resident than others. Significance statement It is difficult to assess reproductive success for individuals of long-lived species, especially for dispersing males, who cannot be monitored throughout their lives. Due to extremely long interbirth intervals, orangutans have highly male-skewed operational sex ratios and thus intensive male-male competition for every conception. Paternity analyses matched 21 immature Bornean orangutans with their most likely sire (only 10 of 50 genotyped males) in a natural population. Half of these identified sires had multiple offspring in the study area spread over periods of at least 10 years, despite frequently ranging outside this area. Dominance was a poor predictor of success, but, consistent with female mating tactics to reduce the risk of infanticide, known "sires" tended to have relatively high local presence, which seems to contribute to the males' siring success. The results highlight the importance of large protected areas to enable a natural pattern of dispersal and ranging. Supplementary Information The online version contains supplementary material available at 10.1007/s00265-023-03407-6.
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Affiliation(s)
- Maria A. van Noordwijk
- Department of Evolutionary Anthropology, University of Zurich, Zürich, Switzerland
- Comparative Socio-Ecology Group, May Planck Institute of Animal Behavior, Konstanz, Germany
| | - Laura R. LaBarge
- Comparative Socio-Ecology Group, May Planck Institute of Animal Behavior, Konstanz, Germany
| | - Julia A. Kunz
- Department of Evolutionary Anthropology, University of Zurich, Zürich, Switzerland
- Institute des Sciences de l’Evolution Montpellier, University of Montpellier, Montpellier, France
| | - Anna M. Marzec
- Department of Evolutionary Anthropology, University of Zurich, Zürich, Switzerland
| | - Brigitte Spillmann
- Department of Evolutionary Anthropology, University of Zurich, Zürich, Switzerland
| | - Corinne Ackermann
- Department of Evolutionary Anthropology, University of Zurich, Zürich, Switzerland
| | - Puji Rianti
- Division of Animal Biosystematics and Ecology, Department of Biology, IPB University, Bogor, Indonesia
- Primate Research Center, IPB University, Bogor, Indonesia
| | - Erin R. Vogel
- Department of Anthropology, Center for Human Evolution Studies, Rutgers, The State University of New Jersey, New Brunswick, USA
| | | | - Michael Kruetzen
- Department of Evolutionary Anthropology, University of Zurich, Zürich, Switzerland
| | - Carel P. van Schaik
- Department of Evolutionary Anthropology, University of Zurich, Zürich, Switzerland
- Comparative Socio-Ecology Group, May Planck Institute of Animal Behavior, Konstanz, Germany
- Center for the Interdisciplinary Study of Language Evolution (ISLE), University of Zurich, Zürich, Switzerland
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