Tamarins are small-bodied, forest-dwelling, callitrichines that live in groups containing one to a few adult individuals of each sex. Within these groups, reproduction is usually heavily skewed ...toward a single dominant male and dominant female, females commonly give birth to cooperatively reared twin offspring, and individuals of both sexes disperse, most often to adjacent groups. Throughout their geographic range, tamarin species are being subject to habitat loss and fragmentation, which may influence their ability to survive and disperse successfully. Here, we use a spatially explicit agent-based population genetics simulation toolkit (GENESYS) to explore the potential effects of social structure and landscape features on the population genetic structure of tamarin primates. We first model the population genetic consequences of tamarin social organization in a homogeneous landscape unconstrained by any barriers to gene flow. We then repeat our analyses using the same social system parameters but in different landscapes that either introduce a barrier to gene flow that restricts dispersal from one half of the model world to the other or divide the world into regions with differing “permeabilities” to dispersal. Our results demonstrate that, in our simulated populations, the social system of tamarins results in the clear and rapid genetic differentiation of social groups within a very short time frame. Over time, the limited dispersal of both males and females leads to a pattern of isolation by distance, as expected from a stepping-stone model of gene flow among groups. Introducing a barrier results in a somewhat more complex pattern: isolation by distance still obtains among social groups within regions on each side of the barrier, but the barrier has a much more significant effect on the structuring of genetic variation, leading to strong genetic differentiation among groups on opposite sides that becomes more pronounced over time. Introducing a region of limited dispersal permeability also results in strong differentiation of groups across that region, even though gene flow throughout the landscape is still possible. Our study demonstrates the utility of the GENESYS toolkit for modeling,
in silico
, the genetic consequences of many features of the social systems of primates and other group-living animals and for simultaneously exploring the effects of landscape features on spatial genetic structure.
Patterns of ranging behavior and space use are key for evaluating current ideas about the evolution and maintenance of pair‐living and sexual monogamy as they provide insights into the dispersion of ...females, the potential for territoriality, and whether males are limited to defending an area that can support only one female and her offspring. We examined ranging behavior and space use to evaluate the potential for territoriality in five groups of red titi monkeys (Plecturocebus discolor) during a 10‐year study in Ecuadorian Amazonia. Mean home range size, calculated using a time‐sensitive local convex hull estimation procedure, was 4.0 ± 1.4 ha. Annual home ranges of neighboring groups overlapped, on average, 0%–7%. Mean daily path length was 670 ± 194 m, resulting in defendability indices of 2.2–3.6 across groups. Groups visited, on average, 4 of 12 sections of their home range border area per day, but that was not more often than would be expected by chance, and intergroup encounters were infrequent. We did not find evidence of active monitoring for intruders in border areas, in that groups did not travel either faster or slower when at the border than when in central areas of their range. The absence of overt monitoring might be compensated for by engaging in loud calls, which the study groups did throughout their home ranges; these calls may serve as an advertisement of occupancy and a deterrent to intruding conspecifics. Our finding that red titis have a high potential for territoriality is consistent with several of the main hypotheses proposed to explain pair‐living in mammals.
Graphical
Small, stable home ranges of five red titi monkey groups during the study period at the Tiputinu Biodiversity Station, Amazonian Ecuador.
Research Highlights
Red titis live in small, stable home ranges with low overlap with neighbors and that are theoretically defendable. Groups visit home range borders daily, but not more often than expected by chance, nor do they adjust travel speed at their borders.
Thus, red titis have the potential to be territorial, but evidence of active monitoring is lacking. Loud calling throughout the range may help discourage intrusions as intergroup encounters are infrequent.
These findings are consistent with several of the main hypotheses proposed to explain pair‐living and sexual monogamy in mammals: the female distribution, male mate‐guarding, and resource defense hypotheses.
Male philopatry in spider monkeys revisited Aureli, Filippo; Di Fiore, Anthony; Murillo-Chacon, Evin ...
American journal of physical anthropology,
September 2013, Letnik:
152, Številka:
1
Journal Article
The threats facing Ecuador's Yasuní National Park are emblematic of those confronting the greater western Amazon, one of the world's last high-biodiversity wilderness areas. Notably, the country's ...second largest untapped oil reserves--called "ITT"--lie beneath an intact, remote section of the park. The conservation significance of Yasuní may weigh heavily in upcoming state-level and international decisions, including whether to develop the oil or invest in alternatives.
We conducted the first comprehensive synthesis of biodiversity data for Yasuní. Mapping amphibian, bird, mammal, and plant distributions, we found eastern Ecuador and northern Peru to be the only regions in South America where species richness centers for all four taxonomic groups overlap. This quadruple richness center has only one viable strict protected area (IUCN levels I-IV): Yasuní. The park covers just 14% of the quadruple richness center's area, whereas active or proposed oil concessions cover 79%. Using field inventory data, we compared Yasuní's local (alpha) and landscape (gamma) diversity to other sites, in the western Amazon and globally. These analyses further suggest that Yasuní is among the most biodiverse places on Earth, with apparent world richness records for amphibians, reptiles, bats, and trees. Yasuní also protects a considerable number of threatened species and regional endemics.
Yasuní has outstanding global conservation significance due to its extraordinary biodiversity and potential to sustain this biodiversity in the long term because of its 1) large size and wilderness character, 2) intact large-vertebrate assemblage, 3) IUCN level-II protection status in a region lacking other strict protected areas, and 4) likelihood of maintaining wet, rainforest conditions while anticipated climate change-induced drought intensifies in the eastern Amazon. However, further oil development in Yasuní jeopardizes its conservation values. These findings form the scientific basis for policy recommendations, including stopping any new oil activities and road construction in Yasuní and creating areas off-limits to large-scale development in adjacent northern Peru.
Until recently, most phylogenetic and population genetics studies of nonhuman primates have relied on mitochondrial DNA and/or a small number of nuclear DNA markers, which can limit our understanding ...of primate evolutionary and population history. Here, we describe a cost-effective reduced representation method (ddRAD-seq) for identifying and genotyping large numbers of SNP loci for taxa from across the New World monkeys, a diverse radiation of primates that shared a common ancestor ~20-26 mya. We also estimate, for the first time, the phylogenetic relationships among 15 of the 22 currently-recognized genera of New World monkeys using ddRAD-seq SNP data using both maximum likelihood and quartet-based coalescent methods. Our phylogenetic analyses robustly reconstructed three monophyletic clades corresponding to the three families of extant platyrrhines (Atelidae, Pitheciidae and Cebidae), with Pitheciidae as basal within the radiation. At the genus level, our results conformed well with previous phylogenetic studies and provide additional information relevant to the problematic position of the owl monkey (Aotus) within the family Cebidae, suggesting a need for further exploration of incomplete lineage sorting and other explanations for phylogenetic discordance, including introgression. Our study additionally provides one of the first applications of next-generation sequencing methods to the inference of phylogenetic history across an old, diverse radiation of mammals and highlights the broad promise and utility of ddRAD-seq data for molecular primatology.
Species‐specific demographic parameters and life history variables are important for understanding how individual primate taxa have adapted to evolutionary and ecological pressures and for conducting ...interspecific comparisons as well as for conducting population viability analyses and for managing captive populations. Here, we describe results from a 12+ year study of the demographic dynamics of a wild group of white‐bellied spider monkeys (Ateles belzebuth belzebuth) living near the Tiputini Biodiversity Station in a largely pristine rainforest in western Amazonia. Across the study period, group size varied between 25 and 37 individuals, and there was a clearly female‐biased sex ratio within all age classes. Females were the dispersing sex, as 19 females born into the group disappeared close to reaching adult body size and were presumed to have emigrated, while seven subadult or adult females joined the group during the study period. We estimated the age of dispersal for females at 5.9 ± SD 0.4 years (N = 13). Our study confirms that males are the philopatric sex, as all natal males have remained in the group and some have begun to reproduce, while no males have immigrated. Males began ranging independently from their mothers at ∼4.5 years of age and began copulating with adult females by the age of ∼5 years. Females had long inter‐birth intervals (44.2 ± SD 7.8 months; range: 32–64 months, N = 21). Based on our data, female spider monkeys might have longer life spans than males, as only one out of six adult males but 9 out of 11 adult females present in the group in mid 2005 were still present in January 2018. The slow development and extended life histories of wild spider monkeys pose significant challenges for the ability of these primates to cope with habitat degradation and hunting throughout their geographical distribution.
Data from a long‐term study of 12+ years on wild spider monkeys confirm their slow development and long life cycles. Females are the dispersing sex in spider monkeys, and leave their natal groups around 6 years of age; males are philopatric and begin ranging independently from their mothers at ∼4.5 years of age and copulating with adult females by the age of ∼5 years. Given their long life history variables, spider monkeys face significant challenges under scenarios of habitat degradation and hunting.
Objectives
Territoriality refers to the consistent defense of an area within the home range (HR) against intrusions of conspecifics. It implies exclusive space use with low degree of overlap among ...neighboring groups, high site fidelity, specific ranging behavior such as high mobility relative to HR size and frequent visits of territory borders, and monitoring behavior. We examined ranging behavior and use of space to evaluate territoriality in Pithecia aequatorialis in Ecuador.
Materials and methods
Between 2005 and 2015, we monitored one main study group continuously and five additional groups for shorter periods (5 months to 2.5 years) at the Tiputini Biodiversity Station, in eastern Ecuador. We scored the location of the study groups at 20 min intervals during, on average, 5 days per month. We estimated saki HRs and core areas (CAs) using the fixed kernel density method (95 and 50%, respectively).
Results
The average HR size was 57 ha and the average CA 14 ha. The degree of overlap between HRs of neighboring groups was low (2–9%). For the main study group, the average overlap between annual HRs was 82%. Mean daily path length across groups was 1,151 m; the defensibility index varied between 1.1 and 2.3 (values >1 are suggestive of territoriality), and the fractional monitoring rate varied between 0.06 and 0.15 (values >0.08 are suggestive of territoriality). Groups did not visit their HR borders (100 m inner buffer) more often than would be expected by chance. Travel speed and directness were comparable between the borders and the centers of groups' HRs.
Discussion
Our multiyear study suggests that equatorial sakis show low degree of range overlap and high site fidelity and have the potential to be territorial, given their high mobility relative to HR size that allows for frequent border monitoring. Nevertheless, their movement patterns in border areas did not reveal evidence for monitoring behavior.
Titi monkeys (
Callicebus
spp.) are one of two primate genera that live almost exclusively in groups with one adult-size individual of each sex and exhibit extensive biparental care of offspring. We ...provide a quantitative description of infant care and pairmate behavior in natural groups of
Callicebus discolor
that contributes to a limited literature on the behavioral ecology of wild titi monkeys. We collected data during a 3-year period from two social groups living in primary tropical rainforest at the Tiputini Biodiversity Station in Amazonian Ecuador before and after the birth of five infants. In order to evaluate the potential social and energetic costs associated with biparental care of offspring, we examined the relationships between infant care, pairmate behavior, and adult activity budgets. We found that males were almost exclusively responsible for transporting, grooming, sharing food, and playing with infants. As predicted, we found that, following the birth of an infant, adults groomed their partners less, spent less time in contact, and that huddling between pairmates decreased. Contrary to our predictions, after the birth of an infant, females did not increase the time spent feeding, and males did not decrease the time spent moving nor increase their resting time. Overall, our data suggest that the pair may experience social costs during times of intense infant care but that any putative energetic costs associated with infant care are not mitigated by adjusting physical activity. Future studies should investigate energy intake and expenditure, and consider how the variation observed in pairmate social relationships may affect reproductive success.
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