Individual behavior, behavioral stability, and pace of life within and among five shrew species
Phenotypic variation in behavior exists among species and populations, as well as among and within individuals. The pace-of-life syndrome hypothesis predicts covariation between life-history strategies, ranging from slow to fast, and behavior, ranging from shy, inactive, and flexible to bold, active, and less flexible. This covariation is expected to exist at multiple hierarchical levels, from the species down to the individual. We predict that fast-lived species will differ in average levels of behavior, and additionally show lower within-individual and among-individual variation than slow-lived ones. Shrews represent a highly suitable model to test these predictions, as they comprise a range of genera which differ tremendously in life-history strategy and metabolism. We performed repeated tests of boldness and aggression on 155 wild-caught individuals of five species of shrews, two species of the slow-lived genus Crocidura, two of the fast-lived genus Sorex, and one of the intermediate-paced genus Neomys. To compare not only average levels of behavior but also its variance components between those groups, we calculated coefficients of variation at within- and among-individual levels. Our results support our first prediction that, following the framework of pace-of-life-syndromes, fast-lived species should exhibit bolder behavior than slow-lived ones. However, our prediction of lower within- and among-individual variation in fast-lived species was not supported. Instead, our data suggest that other ecological factors might influence the expression of behavioral variation in shrew species, such as the variability in habitat choice and differences in anti-predator strategies.
The behavior and life history of animals are often structured into so-called pace-of-life syndromes (POLS), with slow-lived individuals being rather shy, inactive, and flexible and fast-lived individuals rather bold, active, and less flexible. Comparing the behavior in five species of shrews, we tested if such a gradient can also be found on the species level. While the average levels of species’ behavior indeed matched their pace of life, their individual behavior and behavioral stability did not. It was rather explained by an interplay of ecological and physiological factors, among them the variability in habitat choices and differences in anti-predator strategies. Our study shows that behavioral variation cannot be explained by just one factor like POLS at different hierarchical levels, but rather by a combination of factors including the animals’ life-history and ecological and physiological background.
KeywordsVariance partitioning Personality Shrews Coefficient of variation Behavioral repeatability Life-history strategies
We would like to thank Ana Cerveira, Diogo Barros, Fernando Madeira, Flávio Oliveira, Krzysztof Kowalski, and Pawel Kardynia for the help in the field; Anna Grozelier, Anna Kret, and Karla Bauer for the help in the field and with experiments; and Petri Niemelä for the advice in statistics. Further thanks are given to two anonymous reviewers for their helpful comments on an earlier version of our manuscript. Special thanks are given to Joaquim Tapisso for many fruitful discussions.
This work was supported by a Marie-Curie post-doc fellowship (PIEF-GA-2012-332,331) and an FCT post-doc fellowship (SFRH/BPD/118053/2016) to SvM; the budget of the Department of Systematic Zoology AMU; and CESAM (UID / AMB / 50,017/2019) through national funds by FCT/MCTES. NJD is supported by the German Science Foundation (grant no. DI 1694/1-1).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. Capturing and testing were conducted with approval from the relevant governmental review board of each region: Regionalna Dyrekcja Ochrony Środowiska w Poznaniu (WPN-II.6401.143.2013.AG) for Poznań, Poland; Regierung von Oberbayern (55.1-8642-8-2007) for Starnberg, Germany; Regierungspräsidium Freiburg (35-9185.81/G-14/55) for Konstanz, Germany; and Ministério da Agricultura, do Mar do Ambiente e do Ordenamento do Território (01/2014/CAPT) for Portugal.
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