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Bond ML, Lee DE, Paniw M. Extinction risks and mitigation for a megaherbivore, the giraffe, in a human-influenced landscape under climate change. GLOBAL CHANGE BIOLOGY 2023; 29:6693-6712. [PMID: 37819148 DOI: 10.1111/gcb.16970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 09/20/2023] [Accepted: 09/20/2023] [Indexed: 10/13/2023]
Abstract
Megaherbivores play "outsized" roles in ecosystem functioning but are vulnerable to human impacts such as overhunting, land-use changes, and climate extremes. However, such impacts-and combinations of these impacts-on population dynamics are rarely examined using empirical data. To guide effective conservation actions under increasing global-change pressures, we developed a socially structured individual-based model (IBM) using long-term demographic data from female giraffes (Giraffa camelopardalis) in a human-influenced landscape in northern Tanzania, the Tarangire Ecosystem. This unfenced system includes savanna habitats with a wide gradient of anthropogenic pressures, from national parks, a wildlife ranch and community conservation areas, to unprotected village lands. We then simulated and projected over 50 years how realistic environmental and land-use management changes might affect this metapopulation of female giraffes. Scenarios included: (1) anthropogenic land-use changes including roads and agricultural/urban expansion; (2) reduction or improvement in wildlife law enforcement measures; (3) changes in populations of natural predators and migratory alternative prey; and (4) increases in rainfall as predicted for East Africa. The factor causing the greatest risk of rapid declines in female giraffe abundance in our simulations was a reduction in law enforcement leading to more poaching. Other threats decreased abundances of giraffes, but improving law enforcement in both of the study area's protected areas mitigated these impacts: a 0.01 increase in giraffe survival probability from improved law enforcement mitigated a 25% rise in heavy rainfall events by increasing abundance 19%, and mitigated the expansion of towns and blockage of dispersal movements by increasing abundance 22%. Our IBM enabled us to further quantify fine-scale abundance changes among female giraffe social communities, revealing potential source-sink interactions within the metapopulation. This flexible methodology can be adapted to test additional ecological questions in this landscape, or to model populations of giraffes or other species in different ecosystems.
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Affiliation(s)
- Monica L Bond
- Department of Conservation Biology, Estación Biológica de Doñana (EBD-CSIC), Seville, Spain
- Wild Nature Institute, Concord, New Hampshire, USA
| | - Derek E Lee
- Wild Nature Institute, Concord, New Hampshire, USA
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania, USA
| | - Maria Paniw
- Department of Conservation Biology, Estación Biológica de Doñana (EBD-CSIC), Seville, Spain
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2
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Lee DE, Lohay GG, Madeli J, Cavener DR, Bond ML. Masai giraffe population change over 40 years in Arusha National Park. Afr J Ecol 2023. [DOI: 10.1111/aje.13115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Derek E. Lee
- Department of Biology Pennsylvania State University University Park Pennsylvania USA
- Wild Nature Institute Concord New Hampshire USA
| | - George G. Lohay
- Department of Biology Pennsylvania State University University Park Pennsylvania USA
| | | | - Douglas R. Cavener
- Department of Biology Pennsylvania State University University Park Pennsylvania USA
| | - Monica L. Bond
- Department of Biology Pennsylvania State University University Park Pennsylvania USA
- Wild Nature Institute Concord New Hampshire USA
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
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3
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Kasozi H, Linden DW, Roloff GJ, Montgomery RA. Evaluating the prevalence and spatial distribution of giraffes injured by non‐target poaching. J Zool (1987) 2022. [DOI: 10.1111/jzo.13033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- H. Kasozi
- Department of Zoology, Entomology and Fisheries Sciences Makerere University Kampala Uganda
| | - D. W. Linden
- NOAA National Marine Fisheries Service Gloucester MA USA
| | - G. J. Roloff
- Department of Fisheries and Wildlife Michigan State University East Lansing MI USA
| | - R. A. Montgomery
- Wildlife Conservation Research Unit, Department of Zoology University of Oxford Tubney Oxon UK
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4
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Using spot pattern recognition to examine population biology, evolutionary ecology, sociality, and movements of giraffes: a 70-year retrospective. Mamm Biol 2022. [DOI: 10.1007/s42991-022-00261-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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5
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Morandi K, Lindholm AK, Lee DE, Bond ML. Phenotypic matching by spot pattern potentially mediates female giraffe social associations. J Zool (1987) 2022. [DOI: 10.1111/jzo.13009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- K. Morandi
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - A. K. Lindholm
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - D. E. Lee
- Wild Nature Institute Concord NH USA
- Department of Biology Pennsylvania State University University Park PA USA
| | - M. L. Bond
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
- Wild Nature Institute Concord NH USA
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6
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OUP accepted manuscript. J Mammal 2022. [DOI: 10.1093/jmammal/gyac007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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7
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Muller Z, Harris S. A review of the social behaviour of the giraffe
Giraffa camelopardalis
: a misunderstood but socially complex species. Mamm Rev 2021. [DOI: 10.1111/mam.12268] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zoe Muller
- School of Biological Sciences University of Bristol Bristol Life Sciences Building, 24 Tyndall Avenue Bristol BS8 1TQ UK
| | - Stephen Harris
- School of Biological Sciences University of Bristol Bristol Life Sciences Building, 24 Tyndall Avenue Bristol BS8 1TQ UK
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8
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Paterson JT, Proffitt K, Rotella J, McWhirter D, Garrott R. Drivers of variation in the population dynamics of bighorn sheep. Ecosphere 2021. [DOI: 10.1002/ecs2.3679] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
| | - Kelly Proffitt
- Montana Department of Fish, Wildlife and Parks Bozeman Montana USA
| | - Jay Rotella
- Department of Ecology Montana State University Bozeman Montana USA
| | | | - Robert Garrott
- Department of Ecology Montana State University Bozeman Montana USA
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9
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Bond ML, König B, Ozgul A, Farine DR, Lee DE. Socially Defined Subpopulations Reveal Demographic Variation in a Giraffe Metapopulation. J Wildl Manage 2021. [DOI: 10.1002/jwmg.22044] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Monica L. Bond
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Barbara König
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Damien R. Farine
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Derek E. Lee
- Department of Biology Pennsylvania State University, University Park Pennsylvania USA
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10
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Bond ML, Lee DE, Farine DR, Ozgul A, König B. Sociability increases survival of adult female giraffes. Proc Biol Sci 2021; 288:20202770. [PMID: 33563118 DOI: 10.1098/rspb.2020.2770] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Studies increasingly show that social connectedness plays a key role in determining survival, in addition to natural and anthropogenic environmental factors. Few studies, however, integrated social, non-social and demographic data to elucidate what components of an animal's socio-ecological environment are most important to their survival. Female giraffes (Giraffa camelopardalis) form structured societies with highly dynamic group membership but stable long-term associations. We examined the relative contributions of sociability (relationship strength, gregariousness and betweenness), together with those of the natural (food sources and vegetation types) and anthropogenic environment (distance from human settlements), to adult female giraffe survival. We tested predictions about the influence of sociability and natural and human factors at two social levels: the individual and the social community. Survival was primarily driven by individual- rather than community-level social factors. Gregariousness (the number of other females each individual was observed with on average) was most important in explaining variation in female adult survival, more than other social traits and any natural or anthropogenic environmental factors. For adult female giraffes, grouping with more other females, even as group membership frequently changes, is correlated with better survival, and this sociability appears to be more important than several attributes of their non-social environment.
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Affiliation(s)
- M L Bond
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.,Wild Nature Institute, Concord, NH, USA
| | - D E Lee
- Wild Nature Institute, Concord, NH, USA.,Department of Biology, Pennsylvania State University, University Park, PA, USA
| | - D R Farine
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.,Department of Collective Behavior, Max Planck Institute of Animal Behavior, Konstanz, Germany.,Center for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany
| | - A Ozgul
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - B König
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
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Lohay GG, Weathers TC, Estes AB, McGrath BC, Cavener DR. Genetic connectivity and population structure of African savanna elephants ( Loxodonta africana) in Tanzania. Ecol Evol 2020; 10:11069-11089. [PMID: 33144949 PMCID: PMC7593188 DOI: 10.1002/ece3.6728] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 07/27/2020] [Accepted: 08/06/2020] [Indexed: 11/07/2022] Open
Abstract
Increasing human population growth, exurban development, and associated habitat fragmentation is accelerating the isolation of many natural areas and wildlife populations across the planet. In Tanzania, rapid and ongoing habitat conversion to agriculture has severed many of the country's former wildlife corridors between protected areas. To identify historically linked protected areas, we investigated the genetic structure and gene flow of African savanna elephants in Tanzania using microsatellite and mitochondrial DNA markers in 688 individuals sampled in 2015 and 2017. Our results indicate distinct population genetic structure within and between ecosystems across Tanzania, and reveal important priority areas for connectivity conservation. In northern Tanzania, elephants sampled from the Tarangire-Manyara ecosystem appear marginally, yet significantly isolated from elephants sampled from the greater Serengeti ecosystem (mean F ST = 0.03), where two distinct subpopulations were identified.Unexpectedly, elephants in the Lake Manyara region appear to be more closely related to those across the East African Rift wall in the Ngorongoro Conservation Area than they are to the neighboring Tarangire subpopulations. We concluded that the Rift wall has had a negligible influence on genetic differentiation up to this point, but differentiation may accelerate in the future because of ongoing loss of corridors in the area. Interestingly, relatively high genetic similarity was found between elephants in Tarangire and Ruaha although they are separated by >400 km. In southern Tanzania, there was little evidence of female-mediated gene flow between Ruaha and Selous, probably due to the presence of the Udzungwa Mountains between them. Despite observing evidence of significant isolation, the populations of elephants we examined generally exhibited robust levels of allelic richness (mean A R = 9.96), heterozygosity (mean µH E = 0.73), and effective population sizes (mean N e = 148). Our results may inform efforts to restore wildlife corridors between protected areas in Tanzania in order to facilitate gene flow for long-term survival of elephants and other species.
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Affiliation(s)
- George G. Lohay
- Biology DepartmentThe Pennsylvania State UniversityUniversity ParkPAUSA
| | - Thomas Casey Weathers
- Ecosystem Science and ManagementThe Pennsylvania State UniversityUniversity ParkPAUSA
| | - Anna B. Estes
- Environmental Studies DepartmentCarleton CollegeNorthfieldMNUSA
- The Nelson Mandela African Institution of Science and TechnologyArushaTanzania
| | | | - Douglas R. Cavener
- Biology DepartmentThe Pennsylvania State UniversityUniversity ParkPAUSA
- The Nelson Mandela African Institution of Science and TechnologyArushaTanzania
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12
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Bond ML, König B, Lee DE, Ozgul A, Farine DR. Proximity to humans affects local social structure in a giraffe metapopulation. J Anim Ecol 2020; 90:212-221. [PMID: 32515083 DOI: 10.1111/1365-2656.13247] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 01/01/2023]
Abstract
Experimental laboratory evidence suggests that animals with disrupted social systems express weakened relationship strengths and have more exclusive social associations, and that these changes have functional consequences. A key question is whether anthropogenic pressures have a similar impact on the social structure of wild animal communities. We addressed this question by constructing a social network from 6 years of systematically collected photographic capture-recapture data spanning 1,139 individual adult female Masai giraffes inhabiting a large, unfenced, heterogeneous landscape in northern Tanzania. We then used the social network to identify distinct social communities, and tested whether social or anthropogenic and other environmental factors predicted differences in social structure among these communities. We reveal that giraffes have a multilevel social structure. Local preferences in associations among individuals scale up to a number of distinct, but spatially overlapping, social communities, that can be viewed as a large interconnected metapopulation. We then find that communities that are closer to traditional compounds of Indigenous Masai people express weaker relationship strengths and the giraffes in these communities are more exclusive in their associations. The patterns we characterize in response to proximity to humans reflect the predictions of disrupted social systems. Near bomas, fuelwood cutting can reduce food resources, and groups of giraffes are more likely to encounter livestock and humans on foot, thus disrupting the social associations among group members. Our results suggest that human presence could potentially be playing an important role in determining the conservation future of this megaherbivore.
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Affiliation(s)
- Monica L Bond
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland.,Wild Nature Institute, Concord, NH, USA
| | - Barbara König
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland
| | - Derek E Lee
- Wild Nature Institute, Concord, NH, USA.,Department of Biology, Pennsylvania State University, University Park, PA, USA
| | - Arpat Ozgul
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland
| | - Damien R Farine
- Department of Collective Behavior, Max Planck Institute of Animal Behavior, Konstanz, Germany.,Department of Biology, University of Konstanz, Konstanz, Germany.,Center for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany
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13
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Fission-fusion dynamics of a megaherbivore are driven by ecological, anthropogenic, temporal, and social factors. Oecologia 2019; 191:335-347. [PMID: 31451928 DOI: 10.1007/s00442-019-04485-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 08/08/2019] [Indexed: 10/26/2022]
Abstract
Fission-fusion dynamics hypothetically enable animals to exploit dispersed and ephemeral food resources while minimizing predation risk. Disentangling factors affecting group size and composition of fission-fusion species facilitates their management and conservation. We used a 6-year data set of 2888 group formations of Masai giraffes in Tanzania to investigate determinants of social group size and structure. We tested whether ecological (lion density, vegetation structure, and prevalence of primary forage plants), anthropogenic (proximity to human settlements), temporal (rainy or dry season), and social (local giraffe density, adult sex ratio, and proportion of calves) factors explained variation in group size and sex- and age-class composition. Food availability rather than predation risk mediated grouping dynamics of adult giraffes, while predation risk was the most important factor influencing congregations with calves. Smallest group sizes occurred during the food-limiting dry season. Where predation risk was greatest, groups with calves were in bushlands more than in open grasslands, but the groups were smaller in size, suggesting mothers adopted a strategy of hiding calves rather than a predator-detection-and-dilution strategy. Groups with calves also were farther from towns but closer to traditional human compounds (bomas). This may be due to lower predator densities, and thus reduced calf predation risk, near bomas but higher human disturbance near towns. Sex- and age-based differences in habitat use reflected nursing mothers' need for high-quality forage while also protecting their young from predation. Our results have implications for conservation and management of giraffes and other large-bodied, herd-forming ungulates in heterogeneous environments subject to anthropogenic threats.
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14
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Brown MB, Bolger DT, Fennessy J. All the eggs in one basket: A countrywide assessment of current and historical giraffe population distribution in Uganda. Glob Ecol Conserv 2019. [DOI: 10.1016/j.gecco.2019.e00612] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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16
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Buehler P, Carroll B, Bhatia A, Gupta V, Lee DE. An automated program to find animals and crop photographs for individual recognition. ECOL INFORM 2019. [DOI: 10.1016/j.ecoinf.2019.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Manlik O. The Importance of Reproduction for the Conservation of Slow-Growing Animal Populations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1200:13-39. [PMID: 31471793 DOI: 10.1007/978-3-030-23633-5_2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Both survival and reproduction are important fitness components, and thus critical to the viability of wildlife populations. Preventing one death (survival) or contributing one newborn (reproduction), has arguably the same effect on population dynamics-in each instance the population grows or is maintained by one additional member. However, for the conservation of slow-growing animal populations, the importance of reproduction is sometimes overlooked when evaluating wildlife management options. This has to do with the use of demographic sensitivity analyses, which quantify the relative contribution of vital rates to population growth. For slow-growing populations, the results of such analyses typically show that growth rates are more sensitive to changes in survival than to equal proportional changes in reproduction. Consequently, for slow-growing taxa, survival has been labelled a better fitness surrogate than reproduction. However, such a generalization, derived from conventional sensitivity analyses, is based on flawed approaches, such as omitting appropriate scaling of vital rates, and sometimes misinterpretations. In this chapter, I make the case that for the conservation of slow-growing species the role of reproduction is considerably greater than conventional sensitivity analyses would suggest. This is illustrated by case studies on wildlife populations that underscore the importance of reproduction for the conservation of slow-growing birds, ungulates, carnivores, and cetaceans.
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Affiliation(s)
- Oliver Manlik
- Biology Department, College of Science, United Arab Emirates University, Al Ain, United Arab Emirates. .,Evolution and Ecology Research Centre, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia.
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Lee DE, Cavener DR, Bond ML. Seeing spots: quantifying mother-offspring similarity and assessing fitness consequences of coat pattern traits in a wild population of giraffes ( Giraffa camelopardalis). PeerJ 2018; 6:e5690. [PMID: 30310743 PMCID: PMC6173159 DOI: 10.7717/peerj.5690] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 09/04/2018] [Indexed: 12/21/2022] Open
Abstract
Polymorphic phenotypes of mammalian coat coloration have been important to the study of genetics and evolution, but less is known about the inheritance and fitness consequences of individual variation in complex coat pattern traits such as spots and stripes. Giraffe coat markings are highly complex and variable and it has been hypothesized that variation in coat patterns most likely affects fitness by camouflaging neonates against visually hunting predators. We quantified complex coat pattern traits of wild Masai giraffes using image analysis software, determined the similarity of spot pattern traits between mother and offspring, and assessed whether variation in spot pattern traits was related to fitness as measured by juvenile survival. The methods we described could comprise a framework for objective quantification of complex mammal coat pattern traits based on photographic coat pattern data. We demonstrated that some characteristics of giraffe coat spot shape were likely to be heritable, as measured by mother-offspring regression. We found significant variation in juvenile survival among phenotypic groups of neonates defined by multivariate clustering based on spot trait measurement variables. We also found significant variation in neonatal survival associated with spot size and shape covariates. Larger spots (smaller number of spots) and irregularly shaped or rounder spots (smaller aspect ratio) were correlated with increased survival. These findings will inform investigations into developmental and genetic architecture of complex mammal coat patterns and their adaptive value.
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Affiliation(s)
- Derek E Lee
- Wild Nature Institute, Concord, NH, United States of America.,Department of Biology, Pennsylvania State University, University Park, United States of America
| | - Douglas R Cavener
- Department of Biology, Pennsylvania State University, University Park, United States of America
| | - Monica L Bond
- Wild Nature Institute, Concord, NH, United States of America.,Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zürich, Switzerland
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19
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Lee DE. Evaluating conservation effectiveness in a Tanzanian community wildlife management area. J Wildl Manage 2018. [DOI: 10.1002/jwmg.21549] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Derek E. Lee
- Pennsylvania State University; State College; PA 16802 USA
- Wild Nature Institute; Concord NH 03302 USA
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20
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Genovart M, Bécares J, Igual JM, Martínez-Abraín A, Escandell R, Sánchez A, Rodríguez B, Arcos JM, Oro D. Differential adult survival at close seabird colonies: The importance of spatial foraging segregation and bycatch risk during the breeding season. GLOBAL CHANGE BIOLOGY 2018; 24:1279-1290. [PMID: 29178374 DOI: 10.1111/gcb.13997] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/20/2017] [Accepted: 11/07/2017] [Indexed: 05/10/2023]
Abstract
Marine megafauna, including seabirds, are critically affected by fisheries bycatch. However, bycatch risk may differ on temporal and spatial scales due to the uneven distribution and effort of fleets operating different fishing gear, and to focal species distribution and foraging behavior. Scopoli's shearwater Calonectris diomedea is a long-lived seabird that experiences high bycatch rates in longline fisheries and strong population-level impacts due to this type of anthropogenic mortality. Analyzing a long-term dataset on individual monitoring, we compared adult survival (by means of multi-event capture-recapture models) among three close predator-free Mediterranean colonies of the species. Unexpectedly for a long-lived organism, adult survival varied among colonies. We explored potential causes of this differential survival by (1) measuring egg volume as a proxy of food availability and parental condition; (2) building a specific longline bycatch risk map for the species; and (3) assessing the distribution patterns of breeding birds from the three study colonies via GPS tracking. Egg volume was very similar between colonies over time, suggesting that environmental variability related to habitat foraging suitability was not the main cause of differential survival. On the other hand, differences in foraging movements among individuals from the three colonies expose them to differential mortality risk, which likely influenced the observed differences in adult survival. The overlap of information obtained by the generation of specific bycatch risk maps, the quantification of population demographic parameters, and the foraging spatial analysis should inform managers about differential sensitivity to the anthropogenic impact at mesoscale level and guide decisions depending on the spatial configuration of local populations. The approach would apply and should be considered in any species where foraging distribution is colony-specific and mortality risk varies spatially.
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Affiliation(s)
- Meritxell Genovart
- IMEDEA (CSIC-UIB), Esporles, Mallorca, Spain
- CEAB (CSIC), Accés Cala Sant Francesc, Blanes,Girona, Catalonia, Spain
| | - Juan Bécares
- SEO/BirdLife - Marine Programme, Delegació de Catalunya, Barcelona, Spain
| | | | - Alejandro Martínez-Abraín
- Grupo de Investigación en Biología Evolutiva, Departamento de Bioloxía, Universidade da Coruña, A Coruña, Spain
| | - Raul Escandell
- SOM (Societat Ornitològica de Menorca), Es Castell, Menorca, Spain
| | - Antonio Sánchez
- Oficina Técnica Devesa-Albufera (Ayuntamiento de Valencia), Valencia, Spain
| | - Beneharo Rodríguez
- SEO/BirdLife - Marine Programme, Delegació de Catalunya, Barcelona, Spain
- Canary Islands' Ornithology and Natural History Group (GOHNIC), Tenerife, Canary Islands, Spain
| | - José M Arcos
- SEO/BirdLife - Marine Programme, Delegació de Catalunya, Barcelona, Spain
| | - Daniel Oro
- IMEDEA (CSIC-UIB), Esporles, Mallorca, Spain
- CEAB (CSIC), Accés Cala Sant Francesc, Blanes,Girona, Catalonia, Spain
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Kiffner C, Rheault H, Miller E, Scheetz T, Enriquez V, Swafford R, Kioko J, Prins HHT. Long-term population dynamics in a multi-species assemblage of large herbivores in East Africa. Ecosphere 2017. [DOI: 10.1002/ecs2.2027] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Christian Kiffner
- Center For Wildlife Management Studies; The School For Field Studies; PO Box 304 Karatu Tanzania
| | - Helena Rheault
- Westfield State University; 577 Western Avenue Westfield Massachusetts 01086 USA
| | | | - Tanner Scheetz
- Department of Biology; Miami University; 501 East High Street Oxford Ohio 45056 USA
| | - Vivien Enriquez
- Department of Anthropology; Beloit College; 700 College Street Beloit Wisconsin 53511 USA
| | - Rachelle Swafford
- Department of Animal Biotechnology and Conservation; Delaware Valley University; 700 East Butler Avenue Doylestown Pennsylvania 18901 USA
| | - John Kioko
- Center For Wildlife Management Studies; The School For Field Studies; PO Box 304 Karatu Tanzania
| | - Herbert H. T. Prins
- Department of Environmental Sciences; Wageningen University; Wageningen The Netherlands
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24
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Lee DE, Kissui BM, Kiwango YA, Bond ML. Migratory herds of wildebeests and zebras indirectly affect calf survival of giraffes. Ecol Evol 2016; 6:8402-8411. [PMID: 28031792 PMCID: PMC5167056 DOI: 10.1002/ece3.2561] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Revised: 09/14/2016] [Accepted: 09/22/2016] [Indexed: 11/24/2022] Open
Abstract
In long‐distance migratory systems, local fluctuations in the predator–prey ratio can exhibit extreme variability within a single year depending upon the seasonal location of migratory species. Such systems offer an opportunity to empirically investigate cyclic population density effects on short‐term food web interactions by taking advantage of the large seasonal shifts in migratory prey biomass. We utilized a large‐mammal predator–prey savanna food web to evaluate support for hypotheses relating to the indirect effects of “apparent competition” and “apparent mutualism” from migratory ungulate herds on survival of resident megaherbivore calves, mediated by their shared predator. African lions (Panthera leo) are generalist predators whose primary, preferred prey are wildebeests (Connochaetes taurinus) and zebras (Equus quagga), while lion predation on secondary prey such as giraffes (Giraffa camelopardalis) may change according to the relative abundance of the primary prey species. We used demographic data from five subpopulations of giraffes in the Tarangire Ecosystem of Tanzania, East Africa, to test hypotheses relating to direct predation and indirect effects of large migratory herds on calf survival of a resident megaherbivore. We examined neonatal survival via apparent reproduction of 860 adult females, and calf survival of 449 giraffe calves, during three precipitation seasons over 3 years, seeking evidence of some effect on neonate and calf survival as a consequence of the movements of large herds of migratory ungulates. We found that local lion predation pressure (lion density divided by primary prey density) was significantly negatively correlated with giraffe neonatal and calf survival probabilities. This supports the apparent mutualism hypothesis that the presence of migratory ungulates reduces lion predation on giraffe calves. Natural predation had a significant effect on giraffe calf and neonate survival, and could significantly affect giraffe population dynamics. If wildebeest and zebra populations in this ecosystem continue to decline as a result of increasingly disrupted migrations and poaching, then giraffe calves will face increased predation pressure as the predator–prey ratio increases. Our results suggest that the widespread population declines observed in many migratory systems are likely to trigger demographic impacts in other species due to indirect effects like those shown here.
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Abstract
Giraffe skin disease (GSD) is a disorder of undetermined etiology that causes lesions on the forelimbs of Masai giraffe ( Giraffa camelopardalis tippelskirchi) in Tanzania, East Africa. We examined soil correlates of prevalence of GSD from 951 giraffe in 14 sites in Tanzania, and estimated mortality using 3 yr of longitudinal mark-recapture data from 382 giraffe with and without GSD lesions, in Tarangire National Park (TNP). Spatial variation in GSD prevalence was best explained by soil fertility, measured as cation exchange capacity. We found no mortality effect of GSD on adult giraffe in TNP. Based on our findings, GSD is unlikely to warrant immediate veterinary intervention, but continued monitoring is recommended to ensure early detection if GSD-afflicted animals begin to show signs of increased mortality or other adverse effects.
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