Interspecific competition affects the expression of personality-traits in natural populations

Lucas A Wauters,Stefan Van Dongen,Damiano G Preatoni,Adriano Martinoli,Maria Vittoria Mazzamuto,Francesca Santicchia

doi:10.1038/s41598-019-47694-4

Lucas A Wauters, Stefan Van Dongen + Show 4 more

Open Access

https://doi.org/10.1038/s41598-019-47694-4

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Journal: Scientific Reports	Publication Date: Aug 1, 2019
Citations: 26	License type: open-access

Affiliation: University of Antwerp, University of Insubria

Abstract

Competition between animal species can cause niche partitioning and shape an individual’s phenotype, including its behaviour. However, little is known about effects of interspecific competition on personality, the among-individual variation in behaviour that is consistent across different spatial and temporal contexts. We investigated whether alien grey squirrels (Sciurus carolinensis) influenced the expression of personality traits in native red squirrels (Sciurus vulgaris). In Italy, alien grey squirrels replaced native reds through competition for food resources and space, reducing breeding and recruitment in the native species. We compared personality of red squirrels in red-only (no interspecific competition) and red-grey (with interspecific competition) sites, using arena-tests. The trait activity was measured by Open Field Test while sociability and avoidance were quantified by Mirror Image Stimulation test. Red squirrels co-occurring with the alien species had higher sociability scores and higher between-individual variation in sociability than in red-only sites. Differences in activity and avoidance were not significant. Personality – fitness relationships were not affected by presence or absence of grey squirrels, suggesting that the expression of sociability in red squirrels was not due to short-term selection, but was likely the result of context-related advantages when co-occurring with the competing species.

Highlights

Intraspecific competition among individuals in a population can be an important driver of natural selection[1,2]
Using arena test (Open Field Test followed by a Mirror Image Stimulation test) we found that red squirrels co-occurring with grey squirrels expressed more the personality trait sociability than in areas without the invasive competitor
The tendency to show less avoidance of the mirror image in red-grey than in red-only areas was weak and non significant, and in contrast with our predictions, we found no difference in the expression of activity between red-grey and red-only areas

Summary

Introduction

Intraspecific competition among individuals in a population can be an important driver of natural selection[1,2]. Intrinsic factors affect the outcome of competition, but spatio-temporal variation in extrinsic environmental conditions can produce extra selective pressures that differ among populations and with time. One of these extrinsic factors is the intensity of interspecific competition with a species that occupies an overlapping ecological niche[3,4,5]. Where it has been shown that spatio-temporal variation in the intensity of intraspecific competition (e.g. differences in population density, food availability, habitat use) can affect the relationship between an animal’s personality and its fitness[14,15,16], only few studies that considered a possible relationships between interspecific competition and the expression of personality traits[3,11,17,18]. Avoidance Sociability Alert Aggressiveness evolutionary issue: behavioural responses can play an important role in the interactions between the native and the alien species and certain personality types might be better adapted than others to cope with the new challenge[7]

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