Percorrer por autor "Hammond, Philippa"
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- Baboon route repetition in a seasonal environmentPublication . Lewis-Bevan, Lynn Catrin; Hammond, Philippa; Carvalho, Susana; Biro, DoraIntroduction: Route-based navigation is a common movement strategy for a variety of taxa, wherein animals repeatedly re-use familiar paths during travel. However, this type of navigation is understudied in wild animals that experience regular displacement, raising questions about the robustness and longevity of such routes and route memories. The seasonal flooding of Gorongosa National Park, Mozambique, provides an opportunity to test multiple facets of route-based navigation in wild primates, due to its high seasonality and annual flooding.Methods: Data was collected from GPS collars placed on four chacma baboons in two troops in Gorongosa National Park. Using GPS points taken every 15 minutes, we use nearest-neighbour analysis to compare daily paths across the year, to identify high-use paths. We then look at the identified high-use paths to see if they are used across the entire study period, with a focus on areas that were vacated for more than two months of the study period.Results: We find that the baboons do have vacated areas, but return to the same areas after displacement. We did not find high-use routes in these areas used both before and after displacement, although high-use routes did exist that were used across the study period in different areas.Discussion: Our results indicate that routes may not be maintained in long-term memory spanning several months, or that route reuse is in part dependant on seasonal resources or navigational aids. Although the study period did not span a full year, this study presents a replicable method of analysing route reuse and identifying high-use routes without traditional methods of manually overlaying and analysing daily paths.
- The behavioural ecology of hominin locomotion: what can we learn from landscapes of fear and primate terrestriality?Publication . Hammond, Philippa; Bobe, René; Carvalho, SusanaA defining feature of the hominin clade is bipedality, often parcelled together with terrestriality. However, there is increasing evidence of locomotor diversity, both within the hominin clade and amongst the Miocene apes that came before them. There is also growing recognition that bipedalism might have arboreal origins and that arboreality persisted in several hominin taxa, including our own genus Homo. Furthermore, the difference between terms like “habitual” and “obligate” bipedality is not clearly defined and is often inferred from fossil features, rather than a description of each behaviour in vivo. Combining fossil and palaeoecological evidence with insights from behavioural ecology facilitates new interpretations of evolutionary pathways and highlights the importance of considering convergent evolution in the emergence of locomotor traits and characteristics. Taking such an approach also moves away from assumptions of a straight-line trajectory towards modern human locomotion and explores the likelihood that independent forms of bipedality and terrestriality arose at different times and in different combinations with other features of ape morphology and behaviour. Evidence from extant primate species can broaden our understanding of the correlates, causes, and consequences of terrestriality and can be used to generate hypotheses which are then explored further using paleontological methods. In this paper, we explore the evolutionary origins of hominin locomotion, but extend our review to include broader timescales, a wider range of primate taxa, and an integrated set of methods and disciplines for generating and testing hypotheses about locomotion. Perceived risk (or, the “landscape of fear”) is a key pressure that has selected for primate arboreality – particularly nocturnal arboreality. We propose that shifts in Plio-Pleistocene landscapes of fear – caused by declining carnivoran abundance and diversity – might also have been a key selection pressure in changes to primate locomotion, particularly papionin and hominid terrestriality. We discuss this hypothesis and propose future research avenues to explore it further. Not only will such research provide a more nuanced view of the causes and consequences of a rare behavioural trait in primates, but it could ultimately help us explain how one group of African apes came to spend all their time on the ground, and how that made them human.
- Genomic variation in baboons from central Mozambique unveils complex evolutionary relationships with other Papio speciesPublication . Santander, Cindy; Molinaro, Ludovica; Mutti, Giacomo; Martínez, Felipe I.; Mathe, Jacinto; Ferreira da Silva, Maria J.; Caldon, Matteo; Oteo-Garcia, Gonzalo; Aldeias, Vera; Archer, Will; Bamford, Marion; Biro, Dora; Bobe, René; Braun, David R.; Hammond, Philippa; Lüdecke, Tina; Pinto, Maria J.; Meira Paulo, Luis; Stalmans, Marc; Regala, Frederico; Bertolini, Francesco; Moltke, Ida; Raveane, Alessandro; Pagani, Luca; Carvalho, Susana; Capelli, CristianBackground Gorongosa National Park in Mozambique hosts a large population of baboons, numbering over 200 troops. Gorongosa baboons have been tentatively identified as part of Papio ursinus on the basis of previous limited morphological analysis and a handful of mitochondrial DNA sequences. However, a recent morphological and morphometric analysis of Gorongosa baboons pinpointed the occurrence of several traits intermediate between P. ursinus and P. cynocephalus, leaving open the possibility of past and/or ongoing gene flow in the baboon population of Gorongosa National Park. In order to investigate the evolutionary history of baboons in Gorongosa, we generated high and low coverage whole genome sequence data of Gorongosa baboons and compared it to available Papio genomes. Results We confirmed that P. ursinus is the species closest to Gorongosa baboons. However, the Gorongosa baboon genomes share more derived alleles with P. cynocephalus than P. ursinus does, but no recent gene flow between P. ursinus and P. cynocephalus was detected when available Papio genomes were analyzed. Our results, based on the analysis of autosomal, mitochondrial and Y chromosome data, suggest complex, possibly male-biased, gene flow between Gorongosa baboons and P. cynocephalus, hinting to direct or indirect contributions from baboons belonging to the “northern” Papio clade, and signal the presence of population structure within P. ursinus. Conclusions The analysis of genome data generated from baboon samples collected in central Mozambique highlighted a complex set of evolutionary relationships with other baboons. Our results provided new insights in the population dynamics that have shaped baboon diversity.
- Landscape‐scale effects of season and predation risk on the terrestrial behavior of chacma baboons (Papio ursinus)Publication . Hammond, Philippa; Gaynor, Kaitlyn; Easter, Tara; Biro, Dora; Carvalho, SusanaObjectives: “Terrestrial” primates are not common nor well defined across the order. In those species that do use the ground, terrestriality is rarely documented outside daylight hours. Predation risk is thought to have shaped conserved behaviors like primates' selection of arboreal sleep sites, but it is less clear—particularly at the landscape scale—how predation risk interacts with other ecological and seasonal variables to drive terrestriality. This camera trapping study investigates patterns in terrestrial behavior both spatially and temporally across neighboring populations of chacma baboons. Materials and Methods: We use camera trap data from two terrestrial grids, one established within and one outside the boundaries of Gorongosa National Park, Mozambique. We model how baboon terrestrial activity varies with woody cover, proximity to water, season, anthropogenic variables, as well as predation risk. We also model how terrestrial activity varies across the diel cycle and use overlap analyses to explore differences in the baboon populations' activity patterns. Results: We find no significant predictors of geospatial variation in the terrestrial activity of baboons across each grid but do find evidence of higher terrestrial activity in the late dry season. We also find significantly different diel patterns of baboon activity detected across each grid. Discussion: Baboons likely use the ground more in the dry season for accessing water and resources when arboreal foods are less abundant. Diel variation between the two populations suggests that baboons might utilize the ground more during “riskier” crepuscular and nocturnal hours where leopards are not present.
- Predictors of baboon sleep site selection in gorongosa national parkPublication . Lewis‐Bevan, Lynn; Hammond, Philippa; Carvalho, Susana; Biro, DoraObjectives: This research aimed to understand how sleep site selection compared to other study sites in baboons living in a lowpredator density, highly seasonal environment. We compared baboon troops in two distinct habitat types with different seasonal influences within the park, one that flooded annually and one that did not. We compared their sleep site use, reuse, and location relative to home range boundaries and areas of interest (AOIs) with each other and baboons in other areas to understand whether season, habitat familiarity, or position in the home range influenced sleep site choice. Methods: Using GPS collar data taken at 15-min intervals from four gray-footed chacma baboons (Papio ursinus griseipes) in Gorongosa National Park, Mozambique, we established the location of sleep sites, home range boundaries, and AOIs, or places where the baboons repeatedly stopped for more than 15 min. Study subjects ranged either in dense woodland or in a seasonally flooded alluvial floodplain. We used a linear mixed-effects model to predict sleep site reuse based on distance to the habitat edge and AOIs, and Wilcoxon signed-rank tests to determine if morning or evening AOIs influenced sleep site location. We counted the number of reuses of each sleep site before and after the flooding period and compared this data to data in other baboon study sites. Results: We found that, as in other study sites with less seasonality and higher predation risk, baboons in Gorongosa change sleep site frequently and utilize multiple sleep sites throughout their home range, although they more often use sleep sites closer to the center of their home ranges. However, unlike other studies, we found that the location of the last AOI of the day more strongly predicted sleep site location than the first AOI of the next day in one troop, with baboons traveling further from their sleep site to their first AOI in the morning than from their last evening AOI to the sleep site. Conclusions: Despite high seasonality and low predator density, baboons in Gorongosa National Park changed sleep sites frequently, as do other studied baboon troops in areas with high nocturnal predation rates. In addition, their propensity to sleep closer to the last AOI of the day may imply that they plan their daily paths toward their chosen sleep site, or that they sleep opportunistically at the end of the day. This study provides a baseline of behavioral data for comparison to other sites and future work in Gorongosa, where predator density continues to rise since the time of the study.
- Risk perception and terrestriality in primates: a quasi‐experiment through habituation of chacma baboons (Papio ursinus) in Gorongosa National Park, MozambiquePublication . Hammond, Philippa; Lewis‐Bevan, Lynn; Biro, Dora; Carvalho, SusanaObjectives Habituation is a common pre-requisite for studying noncaptive primates. Details and quantitative reporting on this process are often overlooked but are useful for measuring human impact on animal behavior, especially when comparing studies across time or sites. During habituation, perceived risk of a stimulus-human observers-is assumed to decline with repeated exposure to that stimulus. We use habituation as a quasi-experiment to study the landscape of fear, exploring relationships between actual risk, perceived risk, mediating environmental variables, and behavioral correlates. Materials and Methods We recorded vocalizations and observer-directed vigilance as indicators of perceived risk during habituation of two troops of chacma baboons (Papio ursinus) in Gorongosa National Park, Mozambique. Here, we model changes in these variables as a function of habituation time, troop, time of day, and habitat features. We also model the relationship between each of the anti-predator behaviors and ground-use, exploring whether they predict greater terrestriality in the baboons. Results In both troops, vocalization rates and observer-directed vigilance declined with cumulative exposure to observers, but were heightened later in the day and in denser habitat types. We found that terrestrial activity was negatively related to levels of both vocalizations and observer-directed vigilance. Discussion This study provides a quantitative assessment of the impact of human observation on primate behavior and highlights environmental variables that influence anti-predator behaviors, perhaps indicating heightened perception of risk. The relationship between perceived risk and terrestriality is significant for understanding the evolution of this rare trait in primates.
- Sex-mediated gene flow in grayfoot chacma baboons (Papio ursinus griseipes) in Gorongosa National Park, MozambiquePublication . Silva, Maria Joana Ferreira da; Tralma, Paula; Colmonero-Costeira, Ivo; Cravo-Mota, Mariana; Farassi, Rassina; Hammond, Philippa; Lewis-Bevan, Lynn; Bamford, Marion K.; Biro, Dora; Lüdecke, Tina; Mathe, Jacinto; Bobe, René; Capelli, Cristian; Martínez, Felipe I.; Carvalho, SusanaDispersal behavior influences gene flow and the spatial distribution of genetic diversity, which is crucial for a species' evolutionary trajectory and population persistence under environmental changes. We used gene flow as a proxy to investigate dispersal patterns in the grayfoot chacma baboon (Papio ursinus griseipes) in Gorongosa National Park (GNP), central Mozambique. The baboons inhabit a mosaic landscape with a seasonally variable environment. Thirty-two years ago, GNP was the epicenter of a major war that severely reduced apex predators, resulting in limited mammalian predation on baboons. We aimed to characterize genetic diversity, examine the extent and direction of sex-biased gene flow at different time frames and investigate changes in population size and recent migration events. We collected 121 non-invasive DNA samples and analyzed uni- and bi-parentally inherited markers, comprising mitochondrial DNA, autosomal and Y-linked microsatellites, at two geographic locations (GNP and Catap & uacute; Forest Reserve) 150 km apart. We observed high genetic diversity and no evidence of a recent population decline. We identified six mitochondrial haplotypes, including a genetically distinct one in Catapu Forest Reserve. We found molecular evidence for historical and current male-mediated gene flow and female philopatry. Our results highlight the resilience of dispersal patterns in Papio sp. in diverse and seasonally variable ecosystems which have been disturbed by anthropogenic activities.
- West side story: regional inter‐troop variation in baboon bark‐stripping at gorongosa national park, MozambiquePublication . Biro, Dora; Muschinski, Jana; Hammond, Philippa; Bobe, René; Bamford, Marion K.; Capelli, Cristian; de Oliveira Coelho, João; Farassi, Rassina; Lüdecke, Tina; Martinez, Felipe I.; Silva, Maria Joana Ferreira; Carvalho, Susana; Mathe, JacintoObjectives: Baboons possess sophisticated physical and social cognitive abilities; hence, the lack of evidence to date of largescale behavioral variation in these primates is puzzling. Here we studied a candidate for such variation—the stripping of bark from Acacia robusta trees for consumption of the sap and soft tissue underneath—in Gorongosa National Park, Mozambique. Materials and Methods: We surveyed an area inhabited by ~60 troops of chacma baboons, recording the availability and characteristics of the target trees, as well as the presence or absence of bark-stripping at 45 habitat plots distributed across a grid covering an area of ~300km2. Results: Camera traps confirmed the presence of baboons at all habitat plots, and we identified regional clumping in the distribution of the behavior, a pattern consistent across two consecutive years. Proportion and mean height/width of A. robusta did not predict whether bark-stripping behavior was present at a given site, nor did broader ecological variables such as habitat type and distance to the nearest water source. However, stripping sites had significantly higher numbers of A. robusta than non-stripping sites, and within a given bark-stripping site, baboons preferred to strip taller and wider trees among those available. Discussion: The prominent geographical clustering we uncovered may have been driven by opportunity (i.e., the prevalence of A. robusta at a given site), but is also consistent with a possible (non-mutually exclusive) cultural interpretation. We propose avenues for future research on Gorongosa's baboons to better quantify the relative contributions of ecology, genetics, and social.