Hierarchical social modularity in gorillas Morrison, Robin E; Groenenberg, Milou; Breuer, Thomas ...
Proceedings - Royal Society. Biological sciences/Proceedings - Royal Society. Biological Sciences,
07/2019, Volume:
286, Issue:
1906
Journal Article
Peer reviewed
Open access
Modern human societies show hierarchical social modularity (HSM) in which lower-order social units like nuclear families are nested inside increasingly larger units. It has been argued that this HSM ...evolved independently and after the chimpanzee-human split due to greater recognition of, and bonding between, dispersed kin. We used network modularity analysis and hierarchical clustering to quantify community structure within two western lowland gorilla populations. In both communities, we detected two hierarchically nested tiers of social structure which have not been previously quantified. Both tiers map closely to human social tiers. Genetic data from one population suggested that, as in humans, social unit membership was kin structured. The sizes of gorilla social units also showed the kind of consistent scaling ratio between social tiers observed in humans, baboons, toothed whales, and elephants. These results indicate that the hierarchical social organization observed in humans may have evolved far earlier than previously asserted and may not be a product of the social brain evolution unique to the hominin lineage.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Long-term studies of population dynamics can provide insights into life history theory, population ecology, socioecology, conservation biology and wildlife management. Here we examine 25 years of ...population dynamics of western gorillas at Mbeli Bai, a swampy forest clearing in Nouabalé-Ndoki National Park, the Republic of Congo. The Mbeli population more than doubled from 101 to 226 gorillas during the study. After adjusting for a net influx of gorillas into the study population, the increase represents an inherent growth rate of 0.7% per year, with 95% confidence limits between -0.7% and 2.6%. The influx of gorillas mainly involved immigration of individuals into existing study groups (social dispersal), but it also included the appearance of a few previously unknown groups (locational dispersal). The average group size did not change significantly during the study, which is consistent with the possibility that western gorillas face socioecological constraints on group size, even when the population is increasing. We found no significant evidence of density dependence on female reproductive success or male mating competition. The distribution of gorillas among age/sex categories also did not change significantly, which suggests that the population had a stable age structure. Our results provide evidence of population stability or growth for some western gorillas (albeit within a small area). The results highlight the value of law enforcement, long-term monitoring, and protected areas; but they do not diminish the importance of improving conservation for this critically endangered species.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
Is it possible to slow the rate of ageing, or do biological constraints limit its plasticity? We test the ‘invariant rate of ageing’ hypothesis, which posits that the rate of ageing is ...relatively fixed within species, with a collection of 39 human and nonhuman primate datasets across seven genera. We first recapitulate, in nonhuman primates, the highly regular relationship between life expectancy and lifespan equality seen in humans. We next demonstrate that variation in the rate of ageing within genera is orders of magnitude smaller than variation in pre-adult and age-independent mortality. Finally, we demonstrate that changes in the rate of ageing, but not other mortality parameters, produce striking, species-atypical changes in mortality patterns. Our results support the invariant rate of ageing hypothesis, implying biological constraints on how much the human rate of ageing can be slowed.
Long-term studies of population dynamics can provide insights into life history theory, population ecology, socioecology, conservation biology and wildlife management. Here we examine 25 years of ...population dynamics of western gorillas at Mbeli Bai, a swampy forest clearing in Nouabalé-Ndoki National Park, the Republic of Congo. The Mbeli population more than doubled from 101 to 226 gorillas during the study. After adjusting for a net influx of gorillas into the study population, the increase represents an inherent growth rate of 0.7% per year, with 95% confidence limits between -0.7% and 2.6%. The influx of gorillas mainly involved immigration of individuals into existing study groups (social dispersal), but it also included the appearance of a few previously unknown groups (locational dispersal). The average group size did not change significantly during the study, which is consistent with the possibility that western gorillas face socioecological constraints on group size, even when the population is increasing. We found no significant evidence of density dependence on female reproductive success or male mating competition. The distribution of gorillas among age/sex categories also did not change significantly, which suggests that the population had a stable age structure. Our results provide evidence of population stability or growth for some western gorillas (albeit within a small area). The results highlight the value of law enforcement, long-term monitoring, and protected areas; but they do not diminish the importance of improving conservation for this critically endangered species.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Dry deciduous dipterocarp forests (DDF) cover about 15%–20% of Southeast Asia and are the most threatened forest type in the region. The jungle cat (Felis chaus) is a DDF specialist that occurs only ...in small isolated populations in Southeast Asia. Despite being one of the rarest felids in the region, almost nothing is known about its ecology. We investigated the ecology of jungle cats and their resource partitioning with the more common leopard cats (Prionailurus bengalensis) in a DDF‐dominated landscape in Srepok Wildlife Sanctuary, Cambodia. We used camera‐trap data collected from 2009 to 2019 and DNA‐confirmed scats to determine the temporal, dietary and spatial overlap between jungle cats and leopard cats. The diet of jungle cats was relatively diverse and consisted of murids (56% biomass consumed), sciurids (15%), hares (Lepus peguensis; 12%), birds (8%), and reptiles (8%), whereas leopard cats had a narrower niche breadth and a diet dominated by smaller prey, primarily murids (73%). Nonetheless, dietary overlap was high because both felid species consumed predominantly small rodents. Both species were primarily nocturnal and had high temporal overlap. Two‐species occupancy modelling suggested jungle cats were restricted to DDF and had low occupancy, whereas leopard cats had higher occupancy and were habitat generalists. Our study confirmed that jungle cats are DDF specialists that likely persist in low numbers due to the harsh conditions of the dry season in this habitat, including annual fires and substantial decreases in small vertebrate prey. The lower occupancy and more diverse diet of jungle cats, together with the broader habitat use of leopard cats, likely facilitated the coexistence of these species. The low occupancy of jungle cats in DDF suggests that protection of large areas of DDF will be required for the long‐term conservation of this rare felid in Southeast Asia.
We studied the ecology of jungle cat, one of the rarest felids in Southeast Asia, and its resource partitioning with the more common leopard cat. The diet, activity, and habitat use overlapped considerably between the two felid species, suggesting high‐niche overlap. Overall, we found that jungle cats were habitat specialists for open dry deciduous forests and were rare, suggesting that large areas of this habitat will be required for their long‐term conservation.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
We describe a case of lumpy skin disease in an endangered banteng in Cambodia and the subsequent initiation of a vaccination campaign in domestic cattle to protect wild bovids from disease ...transmission at the wildlife-livestock interface. Lumpy skin disease virus (LSDV) was first detected in domestic cattle in Cambodia in June of 2021 and rapidly spread throughout the country. In September 2021, a banteng was seen in Phnom Tnout Phnom Pok wildlife sanctuary with signs of lumpy skin disease. Scab samples were collected and tested positive for LSDV. Monitoring using line transect surveys and camera traps in protected areas with critical banteng and gaur populations was initiated from December 2021-October 2022. A collaborative multisector vaccination campaign to vaccinate domestic livestock in and around priority protected areas with banteng and gaur was launched July 2022 and a total of 20,089 domestic cattle and water buffalo were vaccinated with Lumpyvax
TM
. No signs of LSDV in banteng or gaur in Cambodia have been observed since this initial case. This report documents the first case of lumpy skin disease in wildlife in Cambodia and proposes a potential intervention to mitigate the challenge of pathogen transmission at the domestic-wildlife interface. While vaccination can support local livestock-based economies and promote biodiversity conservation, it is only a component of an integrated solution and One Health approach to protect endangered species from threats at the wildlife-livestock interface.
In conservation science, observation-based methods are generally applied to wildlife monitoring. While useful, such approaches are often restricted to well-characterized and conspicuous species. ...Environmental DNA (eDNA) can complement observation-dependent surveys, as sample collection is generally less labor-intensive. Furthermore, eDNA can be used to simultaneously detect multiple taxa in various habitats. Most eDNA applications rely on short PCR product-based meta-barcoding approaches. However, such approaches may be less robust when applied to genetically uncharacterized species. Hybridization capture techniques while less sensitive than metabarcoding, can identifying divergent sequences, especially those obtained from highly degraded DNA. To assess eDNA based methods for surveillance in a conservation context, we collected samples during the dry season from randomly selected waterholes from a protected area in eastern Cambodia. We applied both hybridization capture enrichment and metabarcoding targeting mammal mitogenomes to water (N = 46) and sediment (N = 10) samples. Seventeen species were detected, including 11 mammals, three amphibians, two reptiles, and one bird. Six species overlapped between the two applied methods. Seven species were hybridization capture-specific detections, and four were metabarcoding-specific. Metabarcoding was more sensitive to abundant or large body-size species while hybridization capture provided more mitogenomic information. While both methods have some advantages over observational approaches, combining them may improve the sensitivity, number of species detected and amount of genetic information obtained from eDNA. We demonstrate that eDNA from tropical forest waterholes can be used to determine the presence of wildlife that may be difficult to detect using other observational approaches.
Display omitted
•Hybridization capture detects more taxa and provides more genomic information, while metabarcoding is more sensitive.•Ungulates were the most frequently detected species consistent with camera trap surveys.•Nine species were exclusively detected by eDNA methods compared with camera trap surveys.•Hybridization capture enrichment provided over 70% mitogenome coverage in some cases and at least 10% in most cases.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper we report on the context and evaluation of a system for an automatic interpretation of sightings of individual western lowland gorillas (Gorilla gorilla gorilla) as captured in facial ...field photography in the wild. This effort aligns with a growing need for effective and integrated monitoring approaches for assessing the status of biodiversity at high spatio-temporal scales. Manual field photography and the utilisation of autonomous camera traps have already transformed the way ecological surveys are conducted. In principle, many environments can now be monitored continuously, and with a higher spatio-temporal resolution than ever before. Yet, the manual effort required to process photographic data to derive relevant information delimits any large scale application of this methodology. The described system applies existing computer vision techniques including deep convolutional neural networks to cover the tasks of detection and localisation, as well as individual identification of gorillas in a practically relevant setup. We evaluate the approach on a relatively large and challenging data corpus of 12,765 field images of 147 individual gorillas with image-level labels (i.e. missing bounding boxes) photographed at Mbeli Bai at the Nouabal-Ndoki National Park, Republic of Congo. Results indicate a facial detection rate of 90.8% AP and an individual identification accuracy for ranking within the Top 5 set of 80.3%. We conclude that, whilst keeping the human in the loop is critical, this result is practically relevant as it exemplifies model transferability and has the potential to assist manual identification efforts. We argue further that there is significant need towards integrating computer vision deeper into ecological sampling methodologies and field practice to move the discipline forward and open up new research horizons.
Understanding how interspecific variation in functional traits influences species’ capacity to persist in fragments and use patches in fragmented landscapes is fundamental for the creation of ...effective conservation plans. This study uses phylogenetic comparative methods to investigate which functional traits of bat species are correlated with their vulnerability to fragmentation in a tropical landscape with low fragment–matrix contrast. Bats were captured over two years in eight forest fragments, nine control sites in continuous forest, and in the secondary forest matrix at the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. We tested the hypothesis that there is a significant relationship between species functional traits, environmental gradients (continuous forest and fragment interiors, edges and matrix) and patterns of species distribution using phylogenetic generalized least squares (PGLS) models, as well as a combination of RLQ and fourth‐corner analyses. Mobility, body mass, wing morphology, and trophic level were the most important traits linked to fragmentation sensitivity based on the PGLS analysis, while body mass and trophic level emerged as the best predictors in the fourth‐corner analysis. These last two traits were correlated with the loss of continuous forest characteristics, such as high‐stature trees and forest cover. Many animalivorous bat species rarely persist in small fragments (<100 ha) and in the secondary forest matrix, reflecting strong effects of trait‐mediated environmental filters that selectively benefit the smaller and phytophagous species. Synthesis and applications. Functional traits of species and environmental variables jointly predict local variation in patterns of bat occupancy and abundance in fragmented tropical landscapes. To minimize local extinctions, we recommend increasing habitat availability and enhancing structural and functional connectivity at the landscape scale through the creation, restoration and maintenance of corridors and stepping stones. These measures should be coupled with improving matrix quality by promoting secondary forest regeneration and persistence to effectively reduce fragment–matrix contrast.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Hierarchical social modularity in gorillas Morrison, Robin E.; Groenenberg, Milou; Breuer, Thomas ...
Proceedings of the Royal Society. B, Biological sciences,
07/2019, Volume:
286, Issue:
1906
Journal Article
Peer reviewed
Modern human societies show hierarchical social modularity (HSM) in which lower-order social units like nuclear families are nested inside increasingly larger units. It has been argued that this HSM ...evolved independently and after the chimpanzee–human split due to greater recognition of, and bonding between, dispersed kin. We used network modularity analysis and hierarchical clustering to quantify community structure within two western lowland gorilla populations. In both communities, we detected two hierarchically nested tiers of social structure which have not been previously quantified. Both tiers map closely to human social tiers. Genetic data from one population suggested that, as in humans, social unit membership was kin structured. The sizes of gorilla social units also showed the kind of consistent scaling ratio between social tiers observed in humans, baboons, toothed whales, and elephants. These results indicate that the hierarchical social organization observed in humans may have evolved far earlier than previously asserted and may not be a product of the social brain evolution unique to the hominin lineage.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
PDF
