American Journal of Primatology最新文献

Complex communication systems appear to evolve alongside social complexity. Comparing closely related species with similar social structures but distinct sociobiology offers valuable insights into the evolution of communicative variability. Here, we explore yawning (morphology, sensory modalities, contexts, contagious effect), a highly conserved behavioral trait, in two zoo-housed groups of geladas (Theropithecus gelada, n_subjects = 67, n_yawns = 1422) and hamadryas baboons (Papio hamadryas, n_subjects = 28, n_yawns = 602). The species are optimal candidates as they both form multilevel groups but differ in intra-group dynamics, cohesion, and cross-sex bonding. Although both species displayed distinct yawn morphologies, hamadryas yawned less frequently than geladas, mainly in non-social contexts and without vocalization. In contrast, geladas yawned more often during affiliative interactions, highlighting a more social dimension to their yawns. When focusing on silent yawns, hamadryas showed a male-biased yawning frequency, whereas geladas exhibited similar rates between sexes, suggesting a more prominent female role in their yawning patterns. We found that yawning is contagious not only in geladas, as previously known, but also in hamadryas baboons. However, geladas were more responsive to others' yawns, possibly due to their greater communicative complexity or to the need to maintain cohesion in larger groups. In geladas, both sexes exhibited similar levels of yawn contagion, whereas in hamadryas it was predominantly male-driven, reflecting the central role of males in hamadryas social dynamics. Our study suggests both evolutionary inertia and divergence in Papionine yawning evolution. The findings confirm the derived nature of gelada yawn vocalizations and highlight the link between multimodal communication and social complexity. Moreover, geladas exhibit more nuanced, context-dependent yawning, likely shaped by their intricate sociobiology. In contrast, hamadryas display a more male-dominated yawning pattern, reflecting their distinct social dynamics. To fully understand the ecological significance of this ancient behavior, further cross-species research on yawning and its contagious effect in wild populations is essential.

Bonobos (Pan paniscus) are successful at managing conflict and promoting group affiliation, but it is still uncertain how conflict affects the entire social group, particularly in captive populations. We conducted social network analyses using dyadic proximity data to understand the structure of five alternating social group compositions of a population of zoo-housed bonobos, using measures of centrality and social strength. We then compared social network measures between neutral, post-conflict (intergroup and intragroup), and post-single-party outburst (scream, display to the public) contexts to determine how conflict influences social behavior within the entire social network. We found that, across conflict contexts, dominant females have higher social group centralities than other individuals. Dominant females also received social initiations at a higher rate than others, suggesting this centrality is structurally maintained by other individuals. Further, rates of proximity are significantly higher following single-party outbursts than in other contexts, which indicates an important social distinction between this context and others and may be best explained by considering these outbursts as signals of group-level social tension, during which group members may seek social interaction and reassurance. Consistent differences in proximity rates were observed between dominant females and other group members, indicating that the social role of the dominant female in a bonobo social group across conflict contexts is different from that of other bonobos. The results of this study emphasize the flexible nature of bonobo sociality, highlight the distinct and important role of dominant females within the social network, and present social network analysis as a useful methodological tool for studying group-level changes in bonobo sociality and behavior.

El cuidado materno de los infantes en primates varía según varios factores, como el tamaño de la camada y la historia reproductiva y de salud de la madre. En especies con crianza cooperativa, la inversión materna también depende de la ayuda proporcionada por los compañeros de grupo. En este estudio, examinamos el cuidado materno en cuatro grupos silvestres de tamarinos lomo de silla (Leontocebus weddelli), recolectando muestras de pelo y heces de las que extraímos ADN para estimar las relaciones de parentesco entre los miembros del grupo. Usamos estos datos para analizar si el cuidado materno se ve influenciado por siete factores: a) tamaño del grupo de adultos; b) número de machos adultos; c) presencia de padres genéticamente identificados; d) número de parientes cercanos no parentales; e) número de infantes; f) peso corporal materno; y g) paridad materna. Para investigar cómo las madres manejan los costos reproductivos, comparamos sus tasas de descanso y alimentación con las de otros adultos durante las 15 semanas previas y posteriores al parto. En general, observamos que las madres contribuyen con un 16% al transporte de infantes y un 30% a la provisión de alimentos por grupo cada semana. Sin embargo, no encontramos efectos significativos de ninguna de las variables en la proporción de tiempo dedicado al transporte o provisión de alimentos. También notamos que las madres descansan menos que otros miembros del grupo durante los períodos pre y post parto. Nuestros resultados muestran que las madres participan en niveles bajos de cuidado infantil en comparación con especies sin crianza cooperativa, pero no pudimos identificar una explicación clara para la variación en el cuidado materno entre individuos.

Two of the more interesting and controversial platyrrhine primate taxa from the Miocene of Patagonia are Soriacebus and Mazzonicebus. Although they are known basically from isolated teeth and partial mandibles and maxillae, their morphology is highly distinctive. Opinions about their phylogenetic relationships differ widely. We interpret these fossils as belonging to the lineage of the anatomically derived, living pitheciine seed-predators; others hold the view that they are stem platyrrhines with convergent adaptations with pitheciines (with the single exception of Proteropithecia among the Patagonian forms), somewhat distant relatives converging coincidently with pitheciines. Here we tested these hypotheses in two ways: (1) by summarizing a character analysis of taxonomically informative traits; (2) we implemented “blind” parsimony analyses using the software package TNT, including a combined matrix of both morphological and molecular data, and replication studies of other matrices. We make some criticisms on the applied methodology of Parsimony in our analysis. Soriacebus and Mazzonicebus resulted sister-taxa nested deeply within the pitheciid clade; thus, and according to our inferences, they are not stem platyrrhines. Most of the differences separating them from the younger and uniformly recognized pitheciine fossils Proteropithecia, Nuciruptor and Cebupithecia are explained as being of more primitive character states; the vast majority of resemblances and their broader functional patterns are definitively pitheciine, as typified by the living pitheciines (sakis and uakaris). We therefore found that none of the Miocene Patagonian genera treated here can be reliably interpreted as stem platyrrhines. Rather, they tend to ratify the Long Lineage Hypothesis.

Estradiol is known to have a variety of biological and behavioral effects, but monitoring its function is complex given the many factors influencing its variation. This necessitates large sample sizes which are challenging in captive and wild situations. This study validates the use of opportunistically collected urinary estradiol levels (E2) for use in reproductive monitoring and behavioral research in bonobos (Pan paniscus). We analyzed frozen urine samples from four Columbus Zoo adult females over 4 years for estradiol and creatinine concentrations (n = 117). While E2 was significantly higher in pregnant versus nonpregnant females (F = 66.30, df = 1, p < 0.001) it was not significantly different between lactating and regularly cycling females (F = 0.40, df = 1, p = 0.5304). Among the regularly cycling females, there was a significant positive regression between E2 and sexual swelling size (F = 4.43, df = 1, 81, p = 0.0384). No differences in E2 variation were detected between individuals in this study. Specifically, when the amount of variation in estradiol due to sexual swelling was statistically controlled for, there was no significant effect of age (n = 83, r = 0.08059, p = 0.4689) or rank (n = 83, r = 0.1361, p = 0.22) on estradiol variation. Overall, these findings indicate that opportunistically sampled urinary estradiol can be paired with visual observation to help detect changes in reproductive status. The shift from lactational amenorrhea back to estrogen cycling may be less clearly defined than expected, and uneven sampling may exacerbate difficulty in detecting some of the more subtle shifts in estradiol levels. While it is known that extended maximal tumescence in bonobos may function to obscure the exact date of ovulation, we did confirm that ratings of visual tumescence still provide useful information regarding relative estradiol levels. By publishing more methodologies and results of this kind, we hope to promote the continued study of estradiol in bonobos as it is relevant to both health monitoring and behavioral research goals.

Alouatta, a genus widely distributed throughout South and Central America, displays remarkable species diversity across various morphoclimatic domains. To clarify the ancestral distribution and its role in the radiation of Alouatta, our study employed time-tree phylogenetic analyses to better understand the current distribution patterns of the cis-Andean species. We generated 36 mitogenomes, including a species and representatives of populations not previously analyzed, to reconstruct a molecular-dated tree, estimate genetic distance-based analyses, and infer the ancestral distribution range of Alouatta. Our study suggests an initial split within the Alouatta during the Miocene, leading to the separation of the cis-Andean and trans-Andean clades. Through ancestral range reconstruction, we found that the most recent common ancestor of Alouatta was broadly distributed across South America. Within the cis-Andean clade, two major splits were identified. One split revealed a close relationship between the Amazonia-endemic species A. seniculus and A. caraya, a species adapted to open-dry domains, with ancestral range in the Amazonia and dry-open domains. In contrast, for the A. guariba and A. belzebul groups, which occur in Amazonia and the Atlantic Forest, the ancestral range included both domains. The diversification of the Alouatta was driven by two cladogenesis events. The formation of the extant species was primarily driven by founder events during the Pleistocene and involved long-distance dispersal events with posterior population isolation. These events played a crucial role in the formation of new populations that underwent rapid divergence, resulting in distinct phylogenetic lineages. Our findings shed new light on the origins of cis-Andean lineages of Alouatta across a broad geographic range, as well as the emergence of more recent taxa during the Pleistocene. This provides insights into their relationships, highlighting the crucial role of Pleistocene climatic changes and founder events in shaping the diversification and geographic distribution of extant species.