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Morris-Drake A, Cobb B, Kern JM, Radford AN. A positive effect of cumulative intergroup threat on reproductive success. Proc Biol Sci 2023; 290:20231853. [PMID: 37964527 PMCID: PMC10646463 DOI: 10.1098/rspb.2023.1853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 10/27/2023] [Indexed: 11/16/2023] Open
Abstract
Outgroup conflict is a powerful selective force across all social taxa. While it is well documented that individual outgroup contests can have a range of direct and indirect fitness consequences, the cumulative pressure of outgroup threats could also potentially impact reproductive success. Here, we use long-term life-history data from a wild population of dwarf mongooses (Helogale parvula) to investigate how intergroup interaction (IGI) rate might influence breeding and offspring survival. IGI rate did not predict the number of litters produced in a season or the inter-litter interval. Unexpectedly, IGI rate was positively associated with the number of pups alive three months after emergence from the breeding burrow. This was not due to a difference in how many pups emerged but because those in groups experiencing more IGIs had a higher survival likelihood post-emergence. Detailed natural observations revealed that both IGI occurrence and the threat of intergroup conflict led to more sentinel behaviour by adults, probably reducing the predation risk to young. Our results contrast the previously documented negative effects of outgroup interactions on reproductive success and highlight the need to assess cumulative threat, rather than just the impact of physical contests, when considering outgroup conflict as a social driver of fitness.
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Affiliation(s)
- Amy Morris-Drake
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Benjamin Cobb
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Julie M. Kern
- School of Environmental and Rural Science, University of New England, Armidale 2351, New South Wales, Australia
| | - Andrew N. Radford
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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Braga Goncalves I, Morris-Drake A, Kennedy P, Radford AN. Fitness consequences of outgroup conflict. eLife 2022; 11:e74550. [PMID: 35833830 PMCID: PMC9282852 DOI: 10.7554/elife.74550] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 06/27/2022] [Indexed: 12/13/2022] Open
Abstract
In social species across the animal kingdom, conspecific outsiders threaten the valuable resources of groups and their members. This outgroup conflict is recognised as a powerful selection pressure, but we argue that studies explicitly quantifying the fitness consequences need to be broader in scope: more attention should be paid to delayed, cumulative, and third-party fitness consequences, not just those arising immediately to group members involved in physical contests. In the first part of this review, we begin by documenting how single contests can have survival and reproductive consequences either immediately or with a delay. Then, we step beyond contests to describe fitness consequences that can also result from interactions with cues of rival presence and the general landscape of outgroup threat, and beyond single interactions to describe cumulative effects of territorial pressure and elevated outgroup-induced stress. Using examples from a range of taxa, we discuss which individuals are affected negatively and positively, considering both interaction participants and third-party group members of the same or the next generation. In the second part of the review, we provide suggestions about how to move forward. We highlight the importance of considering how different types of outgroup conflict can generate different selection pressures and of investigating variation in fitness consequences within and between species. We finish by discussing the value of theoretical modelling and long-term studies of natural populations, experimental manipulations, and meta-analyses to develop further our understanding of this crucial aspect of sociality.
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Affiliation(s)
| | - Amy Morris-Drake
- School of Biological Sciences, University of BristolBristolUnited Kingdom
| | - Patrick Kennedy
- School of Biological Sciences, University of BristolBristolUnited Kingdom
| | - Andrew N Radford
- School of Biological Sciences, University of BristolBristolUnited Kingdom
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Morris-Drake A, Kennedy P, Braga Goncalves I, Radford AN. Variation between species, populations, groups and individuals in the fitness consequences of out-group conflict. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210148. [PMID: 35369741 PMCID: PMC8977661 DOI: 10.1098/rstb.2021.0148] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Out-group conflict is rife in the natural world, occurring from primates to ants. Traditionally, research on this aspect of sociality has focused on the interactions between groups and their conspecific rivals, investigating contest function and characteristics, which group members participate and what determines who wins. In recent years, however, there has been increasing interest in the consequences of out-group conflict. In this review, we first set the scene by outlining the fitness consequences that can arise immediately to contest participants, as well as a broader range of delayed, cumulative and third-party effects of out-group conflict on survival and reproductive success. For the majority of the review, we then focus on variation in these fitness consequences of out-group conflict, describing known examples both between species and between populations, groups and individuals of the same species. Throughout, we suggest possible reasons for the variation, provide examples from a diverse array of taxa, and suggest what is needed to advance this burgeoning area of social evolution. This article is part of the theme issue 'Intergroup conflict across taxa'.
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Affiliation(s)
- Amy Morris-Drake
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Patrick Kennedy
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Ines Braga Goncalves
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Andrew N Radford
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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Grindstaff JL, Beaty LE, Ambardar M, Luttbeg B. Integrating theoretical and empirical approaches for a robust understanding of endocrine flexibility. J Exp Biol 2022; 225:274311. [PMID: 35258612 PMCID: PMC8987727 DOI: 10.1242/jeb.243408] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
There is growing interest in studying hormones beyond single 'snapshot' measurements, as recognition that individual variation in the endocrine response to environmental change may underlie many rapid, coordinated phenotypic changes. Repeated measures of hormone levels in individuals provide additional insight into individual variation in endocrine flexibility - that is, how individuals modulate hormone levels in response to the environment. The ability to quickly and appropriately modify phenotype is predicted to be favored by selection, especially in unpredictable environments. The need for repeated samples from individuals can make empirical studies of endocrine flexibility logistically challenging, but methods based in mathematical modeling can provide insights that circumvent these challenges. Our Review introduces and defines endocrine flexibility, reviews existing studies, makes suggestions for future empirical work, and recommends mathematical modeling approaches to complement empirical work and significantly advance our understanding. Mathematical modeling is not yet widely employed in endocrinology, but can be used to identify innovative areas for future research and generate novel predictions for empirical testing.
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Affiliation(s)
| | - Lynne E Beaty
- School of Science, Penn State Erie - The Behrend College, Erie, PA 16563, USA
| | - Medhavi Ambardar
- Department of Biological Sciences, Fort Hays State University, Hays, KS 67601, USA
| | - Barney Luttbeg
- Department of Integrative Biology, Oklahoma State University, OK 74078, USA
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Abstract
Linking cognitive performance with fitness outcomes, measured using both reproductive and survival metrics, of free-living animals is crucial for understanding the evolution of cognition. Although there is increasing evidence showing a link between cognitive traits and reproductive success metrics, studies specifically exploring the link between cognition and survival are scarce. We first explore which cognitive traits related to survival have been investigated in free-living animals. We also discuss the challenges associated with investigating the links between cognition and survival. We then review studies that specifically consider survival of animals of known cognitive abilities that are either free-living or in captivity and later released into the wild. We found nine studies exploring cognitive traits in wild populations. The relationships between these cognitive traits and survival were equivocal. We found a further nine studies in captive-reared populations trained to predator cues and later released into the wild. Training to recognize predator cues was correlated with increased survival in the majority of studies. Finally, different individual intrinsic characteristics (i.e., age, body condition, personality, sex) showed varied effects between studies. We argue that finding ecologically relevant cognitive traits is crucial for gaining a better understanding of how selection impacts certain cognitive traits, and how these might contribute to an individual’s survival. We also suggest possible standardized, easy to implement, cognitive tests that can be used in long-term studies, which would generate large sample sizes, take into account intrinsic characteristics, and provide an opportunity to understand the mechanisms, development and evolution of cognition.
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Morris-Drake A, Linden JF, Kern JM, Radford AN. Extended and cumulative effects of experimentally induced intergroup conflict in a cooperatively breeding mammal. Proc Biol Sci 2021; 288:20211743. [PMID: 34875195 PMCID: PMC8651417 DOI: 10.1098/rspb.2021.1743] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 11/17/2021] [Indexed: 12/05/2022] Open
Abstract
Conflict between rival groups is rife in nature. While recent work has begun exploring the behavioural consequences of this intergroup conflict, studies have primarily considered just the 1-2 h immediately after single interactions with rivals or their cues. Using a habituated population of wild dwarf mongooses (Helogale parvula), we conducted week-long manipulations to investigate longer-term impacts of intergroup conflict. Compared to a single presentation of control herbivore faeces, one rival-group faecal presentation (simulating a territorial intrusion) resulted in more within-group grooming the following day, beyond the likely period of conflict-induced stress. Repeated presentations of outsider cues led to further changes in baseline behaviour by the end of the week: compared to control weeks, mongooses spent less time foraging and foraged closer to their groupmates, even when there had been no recent simulated intrusion. Moreover, there was more baseline territorial scent-marking and a higher likelihood of group fissioning in intrusion weeks. Consequently, individuals gained less body mass at the end of weeks with repeated simulated intrusions. Our experimental findings provide evidence for longer-term, extended and cumulative, effects of an elevated intergroup threat, which may lead to fitness consequences and underpin this powerful selective pressure.
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Affiliation(s)
- Amy Morris-Drake
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Jennifer F. Linden
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Julie M. Kern
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
| | - Andrew N. Radford
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
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Rochais C, Hotte H, Pillay N. Seasonal variation in reversal learning reveals greater female cognitive flexibility in African striped mice. Sci Rep 2021; 11:20061. [PMID: 34625648 PMCID: PMC8501043 DOI: 10.1038/s41598-021-99619-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 09/27/2021] [Indexed: 11/09/2022] Open
Abstract
Cognitive flexibility describes the ability of animals to alter cognitively mediated behaviour in response to changing situational demands, and can vary according to prevailing environemental conditions and individual caracteristics. In the present study, we investigated (1) how learning and reversal learning performance changes between seasons, and (2) how cognitive flexibility is related to sex in a free-living small mammal. We studied 107 African striped mice, Rhabdomys pumilio, in an arid semi-desert, 58 during the hot dry summer with low food availability, and 49 during the cold wet winter with higher food availability. We used an escape box task to test for learning and reversal learning performance. We found that learning and reversal learning efficiency varied seasonally by sex: females tested in summer were faster at solving both learning and reversal tasks than males tested in winter. Performance varied within sex: males tested in winter showed faster learning compared to males tested in summer. During reversal learning, females tested in summer were more efficient and solve the task faster compared to females tested in winter. We suggest that seasonal cognitive performance could be related to sex-specific behavioural characteristics of the species, resulting in adaptation for living in harsh environmental conditions.
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Affiliation(s)
- Céline Rochais
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa.
| | - Hoël Hotte
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa.,ANSES, Plant Health Laboratory - Nematology Unit, Domaine de la Motte Au Vicomte, BP 35327, 35653, Le Rheu Cédex, France
| | - Neville Pillay
- School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Seasonal changes in problem-solving in wild African striped mice. Anim Cogn 2021; 25:401-413. [PMID: 34591197 DOI: 10.1007/s10071-021-01559-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 08/20/2021] [Accepted: 09/04/2021] [Indexed: 10/20/2022]
Abstract
Innovative problem-solving ability is a predictor of whether animals can successfully cope with environmental changes. These environmental changes can test the limits of animals, for example when energy availability decreases seasonally and, hence, problem-solving performance decreases because less energy is available for cognitive processes. Here, we investigated: (1) how problem-solving performance changed between seasons that differed significantly in food availability; (2) whether these changes were related to environmentally induced physiological changes in blood glucose and ketone levels, indicators of energy availability; and (3) whether individual variation in problem-solving was related to sex differences. We studied 99 free-ranging African striped mice, Rhabdomys pumilio, in the Succulent Karoo, South Africa, 55 during the hot dry summer with low food availability and 44 during the cold wet winter with higher food availability. We measured their problem-solving abilities using a food extraction task and found no seasonal differences in problem-solving success. However, mice solved the problem faster in summer versus winter. In summer, food availability was reduced and blood ketones increased but there was no seasonal difference in blood glucose levels. There were no correlation between problem-solving performance and blood glucose or ketone levels. Overall, more males solved the task than females. It appears that in striped mice cognitive functions can be maintained under harsh environmental conditions.
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Rimbach R, Pillay N, Schradin C. Prolonged growth during the food-restricted dry season in a small African mammal. J Mammal 2021. [DOI: 10.1093/jmammal/gyaa169] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Studying how different environmental parameters, such as resource availability and ambient temperature, affect growth rates aids to understand the evolution of different growth strategies. Low levels of food availability restrict growth, and high ambient temperature can constrain growth via trade-offs between body temperature maintenance and heat produced during digestion. We studied growth of African striped mice (Rhabdomys pumilio), a small mammal living in a seasonally arid habitat. Striped mice are born during spring with high food availability and low ambient temperature, and typically enter the food-restricted dry season before reaching adulthood. We predicted low food availability and high ambient temperature would negatively affect growth. We therefore expected an extended period of slow growth during the long dry season. We repeatedly measured body length of 369 free-living individuals, examined how ambient temperature and food availability influenced growth rate, and seasonal changes in growth rate. In addition, we investigated whether mice (N = 27) born in summer (atypical breeding season) have slower growth rates than those born in spring. Growth rate increased with increasing food availability and decreased with increasing ambient temperature. Individuals born in summer grew slower than those born in spring. Sexes reached asymptotic body length at 258 days (females) and 285 days (males), which is an unusually long growth period compared with other small rodents. As most striped mice live for less than 1 year, this period encompasses the entire life for most individuals, but stops at old age, which could indicate senescence. Our results demonstrate a positive influence of food availability on growth, a relationship mediated by ambient temperature. We conclude that striped mice enter the food-restricted dry season before postnatal growth is terminated, and early exposure to harsh environmental conditions during the long dry season likely explains the prolonged growth period in striped mice.
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Affiliation(s)
- Rebecca Rimbach
- School of Animal, Plant, and Environmental Sciences, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein 2001, Johannesburg, South Africa
| | - Neville Pillay
- School of Animal, Plant, and Environmental Sciences, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein 2001, Johannesburg, South Africa
| | - Carsten Schradin
- School of Animal, Plant, and Environmental Sciences, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein 2001, Johannesburg, South Africa
- Université de Strasbourg, CNRS, UMR 7178, Institut Pluridisciplinaire Hubert Curien, Département Écologie, Physiologie et Éthologie, 23, rue Becquerel, F-67000 Strasbourg, France
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Hill DL, Pillay N, Schradin C. Glucocorticoid levels predict subsequent social tactic in females of a facultatively social mammal. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Davina L. Hill
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Johannesburg South Africa
- Institute of Biodiversity, Animal Health and Comparative Medicine College of Medical, Veterinary and Life Sciences University of Glasgow Glasgow UK
| | - Neville Pillay
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Johannesburg South Africa
| | - Carsten Schradin
- School of Animal, Plant and Environmental Sciences University of the Witwatersrand Johannesburg South Africa
- Université de StrasbourgCNRSIPHC UMR 7178 Strasbourg France
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Criscuolo F, Pillay N, Zahn S, Schradin C. Seasonal variation in telomere dynamics in African striped mice. Oecologia 2020; 194:609-620. [DOI: 10.1007/s00442-020-04801-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 11/05/2020] [Indexed: 02/08/2023]
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Schradin C, Drouard F, Lemonnier G, Askew R, Olivier CA, Pillay N. Geographic intra-specific variation in social organization is driven by population density. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-020-02896-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Rimbach R, Blanc S, Zahariev A, Robin JP, Pillay N, Schradin C. Fat content of striped mice decreases during the breeding season but not during the food-restricted dry season. ACTA ACUST UNITED AC 2019; 222:jeb.208504. [PMID: 31727761 DOI: 10.1242/jeb.208504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 11/07/2019] [Indexed: 10/25/2022]
Abstract
Individuals that are capable of accumulating appropriate fat stores are assumed to have selective advantages when food becomes scarce. Similarly to species from temperate zones, some species inhabiting arid areas accumulate fat stores prior to periods of food limitation. Yet, we have little knowledge concerning seasonal variation in body composition and the relationship between fat store size and disappearance risk in species from arid habitats. Using the water dilution method, we examined the body composition of African striped mice (Rhabdomys pumilio) living in a seasonal habitat with a long food-restricted dry season. We tested for seasonal changes in body composition (N=159 measurements of 113 individuals) and whether dry season survival was related to fat mass (N=66 individuals). Fat stores were similar in size at the onset and the end of the dry season, but surprisingly smaller at the onset of the moist breeding season. Fat stores showed a negative relationship with food availability. Individual variation in fat stores was not associated with disappearance risk, but there was a positive association of disappearance risk with body mass. Increased disappearance risk of heavy individuals suggests elevated dispersal rates in competitive individuals. This study suggests that non-breeding philopatric striped mice do not accumulate large fat stores prior to the food-limited dry season but that they might mobilize fat stores at the onset of the breeding season to satisfy the energetic demands of reproduction and/or to decrease costs associated with larger fat stores, such as increased predation risk.
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Affiliation(s)
- Rebecca Rimbach
- School of Animal, Plant & Environmental Sciences, University of the Witwatersrand, Private Bag 3, WITS 2050, Johannesburg, South Africa
| | - Stéphane Blanc
- Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France
| | | | | | - Neville Pillay
- School of Animal, Plant & Environmental Sciences, University of the Witwatersrand, Private Bag 3, WITS 2050, Johannesburg, South Africa
| | - Carsten Schradin
- School of Animal, Plant & Environmental Sciences, University of the Witwatersrand, Private Bag 3, WITS 2050, Johannesburg, South Africa.,Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France
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14
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How does cognitive performance change in relation to seasonal and experimental changes in blood glucose levels? Anim Behav 2019. [DOI: 10.1016/j.anbehav.2019.10.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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