Mammals communicate socially through visual, auditory and chemical signals. The chemical sense is the oldest sense and is shared by all organisms including bacteria. Despite mounting evidence for ...social chemo-signaling in humans, the extent to which it modulates behavior is debated and can benefit from comparative models of closely related hominoids. The use of odor cues in wild ape social communication has been only rarely explored. Apart from one study on wild chimpanzee sniffing, our understanding is limited to anecdotes. We present the first study of wild gorilla chemo-communication and the first analysis of olfactory signaling in relation to arousal levels and odor strength in wild apes. If gorilla scent is used as a signaling mechanism instead of only a sign of arousal or stress, odor emission should be context specific and capable of variation as a function of the relationships between the emitter and perceiver(s). Measured through a human pungency scale, we determined the factors that predicted extreme levels of silverback odor for one wild western lowland gorilla (Gorilla gorilla gorilla) group silverback. Extreme silverback odor was predicted by the presence and intensity of inter-unit interactions, silverback anger, distress and long-calling auditory rates, and the absence of close proximity between the silverback and mother of the youngest infant. Odor strength also varied according to the focal silverback's strategic responses during high intensity inter-unit interactions. Silverbacks appear to use odor as a modifiable form of communication; where odor acts as a highly flexible, context dependent signaling mechanism to group members and extra-group units. The importance of olfaction to ape social communication may be especially pertinent in Central African forests where limited visibility may necessitate increased reliance on other senses.
Can We Sustainably Harvest Ivory? Lusseau, David; Lee, Phyllis C.
Current biology,
11/2016, Letnik:
26, Številka:
21
Journal Article
Recenzirano
Odprti dostop
Despite the 1989 ivory trade ban, elephants continue to be killed to harvest their tusks for ivory. Since 2008, this poaching has increased to unprecedented levels driven by consumer demand for ivory ...products. CITES is now considering the development of a legal ivory trade 1, 2. The proposal relies on three assumptions: (1) harvest regulation will cease all illegal activities, (2) defined sustainable quotas can be enforced, and (3) we can define meaningful sustainable quotas that come close to the current demand. We know that regulation of harvest does not stop illegal takes. Despite whaling regulation after World War II, illegal whaling continued for decades 3. The introduction of wolf culls in the US actually increased poaching activities 4, and one-off ivory sales in 1999 and 2008 did nothing to halt elephant poaching. Governance issues over the ivory supply chains, including stockpiling, make enforcing quotas challenging, if not impossible 5, 6. We have not yet adequately assessed what could be a sustainable ivory yield. To do so, we develop a compartmental model composed of a two-sex age-structured demographic model and an ivory production and harvest model. We applied several offtake and quota strategies to define how much ivory could be sustainably harvested. We found that the sustainability space is very small. Only 100 to 150 kg of ivory could be removed from a reference population of 1,360 elephants, levels well below the current demand. Our study shows that lifting the ivory ban will not address the current poaching challenge. We should instead focus on reducing consumer demand.
•A harvest model is developed to estimate sustainable ivory yield from elephants•Even in the best-case scenario, the sustainable yield is well below the current demand•Any overexploitation quickly leads to population extirpation
Lusseau and Lee use a two-sex population model combined with a harvest model to estimate how much ivory can be sustainably harvested from elephant populations. They show that the volume of ivory that can be harvested sustainably is very small and that any overexploitation very quickly runs the risk of driving elephants to extinction.
Long-lived species such as elephants, whales and primates exhibit extended post-fertile survival compared to species with shorter lifespans but data on age-related fecundity and survival are limited ...to few species or populations. We assess relationships between longevity, reproductive onset, reproductive rate and age for 834 longitudinally monitored wild female African elephants in Amboseli, Kenya. The mean known age at first reproduction was 13.8 years; only 5 % commenced reproduction by 10 years. Early reproducers (<12.5 years) had higher age-specific fertility rates than did females who commenced reproduction late (15+ years) with no differences in survival between these groups. Age-specific reproductive rates of females dying before 40 years were reduced by comparison to same-aged survivors, illustrating a mortality filter and reproductive advantages of a long life. Overall, 95 % of fertility was completed before 50, and 95 % of mortality experienced by age 65, with a mean life expectancy of 41 years for females who survived to the minimum age at first birth (9 years). Elephant females have a relatively long period (c. 16 years) of viability after 95 % completed fertility, although reproduction does not entirely cease until they are over 65. We found no evidence of increased investment among females aged over 40 in terms of delay to next birth or calf mortality. The presence of a mother reproducing simultaneously with her daughter was associated with higher rates of daughter reproduction suggesting advantages from maternal (and grandmaternal) co-residence during reproduction.
Fission–fusion systems provide models for studying grouping decisions and social complexity in a range of taxa, as individuals act to manage risks and enhance reproductive success. African savannah ...elephants, Loxodonta africana africana, live in a fluid society where individual relationships persist over decades and affect reproductive success. Social structures have yet to be fully characterized for forest elephants, Loxodonta africana cyclotis. Aggregations at natural forest clearings, which are frequent in this subspecies, may offer social benefits in addition to nutritional resources. We examined the social functions of aggregations in Odzala–Kokoua National Park, Republic of Congo. We tested whether clearings function as ‘social arenas’ by examining how social opportunities affected the timing and duration of visits, and how short-term grouping decisions were affected by age, sex, group size and number of elephants present. Aggregations reflected a fission–fusion society similar to that observed in savannah elephants. Grouping patterns were largely unaffected by the number of elephants present, from which we infer that elephants were not acting to minimize competition. Social opportunities affected visit patterns such that visits were longer when others were present. Social opportunities were maximized by joining large groups, often including older elephants, or, for males, parties with females. Large and dynamically changing social groups in clearings offer potential for information exchange and the maintenance of social relationships. Demonstrating that fission–fusion operates in forest elephant society allows future research to focus on cost–benefit modelling, to understand the fitness consequences of these groupings.
► Forest elephant aggregations show fission–fusion similar to savannah elephants. ► Elephant visits increased by 50% when joining others. ► Elephants maximized social opportunities rather than minimize competition. ► Elephants often selected older partners, possibly for knowledge exchange.
Abstract Purpose To describe prevalence and relationships to cardiovascular morbidity of depression, anxiety, and medication use among Hispanic/Latinos of different ethnic backgrounds. Methods ...Cross-sectional analysis of 15,864 men and women aged 18 to 74 years in the population-based Hispanic Community Health Study/Study of Latinos. Depressive and anxiety symptoms were assessed with shortened Center for Epidemiological Studies Depression Scale and Spielberger Trait Anxiety Scale. Results Prevalence of high depressive symptoms ranged from low of 22.3% (95% confidence interval CI, 20.4–24.3) to high of 38.0% (95% CI, 35.2–41.0) among those of Mexican or Puerto Rican background, respectively. Adjusted odds ratios for depression rose monotonically with number of cardiovascular disease (CVD) risk factor from 1.46 (95% CI, 1.18–1.75) for those with one risk factors to 4.36 (95% CI, 2.47–7.70) for those with five risk factors. Antidepressant medication was used by 5% with striking differences between those with and without history of CVD (15.4% and 4.6%, respectively) and between insured (8.2%) and uninsured (1.8%). Conclusions Among US Hispanics/Latinos, high depression and anxiety symptoms varied nearly twofold by Hispanic background and sex, history of CVD, and increasing number of CVD risk factors. Antidepressant medication use was lower than in the general population, suggesting under treatment especially among those who had no health insurance.
The structure and dynamics of primate social groups are shaped by the social relationships of its members. These relationships are based on different types of interactions and vary in relation to the ...identity of the interactants and over time. Social network analysis tools represent a powerful and comprehensive method to characterise social interactions and recent methodological advances now allow the study of the multidimensionality of sociality via multilayer networks that incorporate multiple types of interactions. Here, we use a multidimensional network approach to investigate the multidimensionality of sociality of females in a captive group of mandrills. We constructed two multiplex networks based on agonistic, proximity and grooming interactions of 6-7 mature females to analyse the multidimensionality of relationships within two independent observation periods; and three multiplex networks (one for each interaction type) to examine how relationships changed between periods. Within each period, different individuals were the most central in each layer and at the multiplex level, and different layers (i.e., interaction types) contributed non-redundant information to the multilayer structure. Across periods, relationships based on the same interaction type also contained non-redundant information. These results indicate that female mandrills engage in multidimensional and dynamic relationships, suggesting that in order to represent the full complexity of relationships, networks need to be constructed from more than a single type of interaction and across time. Our results provide evidence for the potential value of the multilayer network approach to characterise the multidimensionality of primate sociality.
In the wild, coordinated behaviour across group members is essential for maintaining spatial coherence, with potential implications for individual fitness. Such coordination often leads to ...behavioural synchrony (performing the same behaviour at the same time). Tufted capuchins (
) and squirrel monkeys (
) are known to form mixed-species groups (MSGs), travelling and foraging together. Yet, it is unclear if it is necessary to synchronize behaviours in captivity when ecological pressures are minimal compared to the wild. We investigated the extent to which two MSGs of capuchins (
35) and squirrel monkeys (
= 26) synchronized their behaviour with conspecifics and heterospecifics at the Living Links to Human Evolution Research Centre, RZSS, Edinburgh Zoo, UK. Group activities were sampled by instantaneous scans of all visible individuals. Scans (
= 180) were analysed for five most frequently observed behaviours. Intraspecies synchrony was calculated using Simpson's Diversity Index, and interspecies synchrony was measured using cross-correlations. Intraspecific synchrony was significantly greater compared to randomly aggregated data, while cross-correlations indicated interspecific asynchrony. Living together did not lead to interspecific synchrony as may be expected given the coordination and behaviour described in the wild, and shared husbandry in captivity. Overall, our findings highlight differences in the behavioural structure of single- versus MSGs. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'.
Social structure is proposed to influence the transmission of both directly and environmentally transmitted infectious agents. However in natural populations, many other factors also influence ...transmission, including variation in individual susceptibility and aspects of the environment that promote or inhibit exposure to infection. We used a population genetic approach to investigate the effects of social structure, environment, and host traits on the transmission of Escherichia coli infecting two populations of wild elephants: one in Amboseli National Park and another in Samburu National Reserve, Kenya. If E. coli transmission is strongly influenced by elephant social structure, E. coli infecting elephants from the same social group should be genetically more similar than E. coli sampled from members of different social groups. However, we found no support for this prediction. Instead, E. coli was panmictic across social groups, and transmission patterns were largely dominated by habitat and host traits. For instance, habitat overlap between elephant social groups predicted E. coli genetic similarity, but only in the relatively drier habitat of Samburu, and not in Amboseli, where the habitat contains large, permanent swamps. In terms of host traits, adult males were infected with more diverse haplotypes, and males were slightly more likely to harbor strains with higher pathogenic potential, as compared to adult females. In addition, elephants from similar birth cohorts were infected with genetically more similar E. coli than elephants more disparate in age. This age-structured transmission may be driven by temporal shifts in genetic structure of E. coli in the environment and the effects of age on bacterial colonization. Together, our results support the idea that, in elephants, social structure often will not exhibit strong effects on the transmission of generalist, fecal-oral transmitted bacteria. We discuss our results in the context of social, environmental, and host-related factors that influence transmission patterns.
Context
East African ecosystems are characterized by the migrations of large herbivores that are highly vulnerable to the recent development of anthropogenic land use change.
Objectives
We analyzed ...land cover changes in the Kenyan-Tanzanian borderlands of the greater Amboseli ecosystem to evaluate landscape connectivity using African elephants as an indicator species.
Methods
We used multi-temporal Landsat imagery and a post classification approach to monitor land cover changes over a 43-year period. GIS based methods were accompanied by a literature review for spatial data on land cover changes and elephant migrations.
Results
Land cover changed considerably between 1975 and 2017. Wood- and bushlands declined by 16.3% while open grasslands increased throughout the study region (+ 10.3%). Agricultural expansion was observed (+ 12.2%) occupying important wildlife habitats and narrowing migration corridors. This development has led to the isolation of Nairobi National Park which was previously part of a large contiguous ecosystem. Eight migration corridors were identified of which only one is formally protected. Two others are almost completely blocked by agriculture and three are expected to become endangered under continuing land use changes.
Conclusions
Landscape connectivity is still viable for this ecosystem (except for Nairobi National Park). However, the current situation is very fragile as anthropogenic land use changes are threatening most of the identified large mammal migration corridors. Sustainable land use planning with regard to important wildlife habitats and connecting corridors is a crucial task for further conservation work to safeguard a viable future for wildlife populations in the Kenyan-Tanzanian borderlands.
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