Biology subjects

Eens, M.

Publications and source records attributed to Eens, M..

4 recordsLinked to original sources

bioRxiv2026

City and forest great tits respond differently to artificial light at night: insights from a common garden study

Artificial light at night (ALAN) disrupts the natural light-dark cycle, which is the most important cue for synchronizing circadian clocks. If populations most exposed to ALAN adapt to get less disturbed by it, we expect forest and city populations to differ genetically. We tested this prediction in a common garden experiment using a songbird, the great tit (Parus major), originating from forest and city populations. We simulated ALAN exposure during the breeding season by keeping the birds in pairs under ALAN or dark nights for three months and then repeated the experiment in the following year with the same pairs under the opposite treatment. The advancement of daily onset under ALAN disappeared over time for city birds, but not for their forest counterparts. For these same birds, we measured their onset of daily activity under constant dim light and shift in activity in response to light pulses and showed that the city/forest difference in behavioural response was not reflected in any clock property measured. This indicates that city and forest birds differ genetically in the downstream behavioural response to ALAN, and not in the circadian clock. Thus, urbanization is unlikely to select for divergence in circadian clock properties in songbirds.

evolutionary biology↗

bioRxiv2022

Within-flock differences in exploratory tendency and flock performance in a highly gregarious bird

How individual differences translate into group outcomes is a timely and debated issue. Recent studies, especially in social arthropods and fish, focus on diversity of personality traits. These studies suggest that the phenotypic group assortment by personality type of an animal group, including the presence of "keystone" individuals, leads to group-level personality differences and can strongly impact both group and individual outcomes. However, little attention has been given to the variation of a given trait within a group. Theory predicts that phenotypic homogeneity rather than heterogeneity yields the optimal group performance, especially in an anti-predatory context, but the experimental support includes mainly morphological traits, e.g. body size or colouration. Here, we focus on personality and group level differences in a highly gregarious bird, the European starling (Sturnus vulgaris). We investigated how different degrees of within-flock variation in exploration affect flock outcomes in exploratory behaviour and in escape response after a frightening stimulus. First, we established consistent individual differences in exploration. Then, flocks of 4 birds were formed to obtain gradual differences in mean and in variation of exploration scores among flocks. Flocks underwent an exploration test and a perturbation test. More exploratory individuals entered the test arena earlier, tended to start flying more rapidly and also stopped flying sooner upon frightening. Flocks with a more homogeneous distribution with respect to this personality trait were significantly faster to enter the test room, but no effect on the escape response emerged. The mean exploration tendency of the flock or the maximum exploration tendency of purported key individuals within groups did not play a notable role in explaining such differences in group performance. Our results indicate that it is not the individual that predicts/drives the flock outcome, but rather a group feature, namely phenotypic variation within the group.

animal behavior and cognition↗

bioRxiv2021

Using historical museum samples to examine divergent and parallel evolution in the invasive starling

1.During the Anthropocene, Earth has experienced unprecedented habitat loss, native species decline, and global climate change. Concurrently, greater globalisation is facilitating species movement, increasing the likelihood of alien species establishment and propagation. There is a great need to understand what influences a species ability to persist or perish within a new or changing environment. Examining genes that may be associated with a species invasion success or persistence informs invasive species management, assists with native species preservation, and sheds light on important evolutionary mechanisms that occur in novel environments. This approach can be aided by coupling spatial and temporal investigations of evolutionary processes. Here we use the common starling, Sturnus vulgaris, to identify parallel and divergent evolutionary change between contemporary native and invasive range samples and their common ancestral population. To do this, we use reduced-representation sequencing of native samples collected recently in north-western Europe and invasive samples from Australia, together with museum specimens sampled in the UK during the mid-19th Century. We found evidence of parallel selection on both continents, possibly resulting from common global selective forces such as exposure to pollutants (e.g. TCDD) and food carbohydrate content. We also identified divergent selection in these populations, which might be related to adaptive changes in response to the novel environment encountered in the introduced Australian range. Interestingly, signatures of selection are equally as common within both invasive and native range contemporary samples. Our results demonstrate the value of including historical samples in genetic studies of invasion and highlight the ongoing and occasionally parallel role of adaptation in both native and invasive ranges.

evolutionary biology↗

bioRxiv2020

Bird populations most exposed to climate change are less responsive to climatic variation

The phenology of many species shows strong sensitivity to climate change; however, with few large scale intra-specific studies it is unclear how such sensitivity varies over a species range. We document large intra-specific variation in phenological sensitivity to temperature using laying date information from 67 populations of two European songbirds covering a large part of their breeding range. Populations inhabiting deciduous habitats showed stronger phenological sensitivity compared with those in evergreen and mixed habitats. Strikingly, however, the lowest sensitivity was seen in populations that had experienced the greatest change in climate. Therefore, we predict that the strongest phenological advancement will not occur in those populations with the highest sensitivity. Our results show that to effectively assess the impact of climate change on phenology across a species range it will be necessary to account for intra-specific variation in phenological sensitivity, climate change exposure, and the ecological characteristics of a population.

ecology↗