Biology subjects

Nicolaus, M.

Publications and source records attributed to Nicolaus, M..

4 recordsLinked to original sources

bioRxiv2022

Mesocosm experiments reveal the loss of migratory tendencies in a recently isolated population of three-spined sticklebacks

In the 1970s, water management in the Netherlands resulted in numerous isolated populations of three-spined sticklebacks, which can no longer migrate from freshwater to the sea. We tested whether [~]50 years of isolation resulted in reduced migratory tendencies in these resident sticklebacks. Lab-based individual testing showed behavioural divergence between residents and migrants, but also produced counter-intuitive results, especially with regards to movement tendencies. To detect differences in migration tendencies, we set up a semi-natural mesocosm, consisting of connected ponds, where movements of numerous individuals could continually be tracked at larger spatial scales. We found that wild-caught residents and migrants exhibited no differences in movement tendencies within ponds, but residents moved significantly less between ponds than migrants. Between-pond movements were consistent and the observed differences were robust across contexts (changes in water flow and group size). Our study reveals that larger-scale movement tendencies can diverge over short time scales in response to human-induced isolation, and highlights the importance of observing behaviour in ecologically relevant setups that bridge the gap between lab and field studies.

animal behavior and cognition↗

bioRxiv2021

Does genetic differentiation underlie behavioral divergence in response tomigration barriers in sticklebacks? A common garden experiment

Water management measures in the 1970s in the Netherlands have produced a large number of resident populations of three-spined sticklebacks that are no longer able to migrate to the sea. This may be viewed as a replicated field experiment, allowing us to study how the resident populations are coping with human-induced barriers to migration. We have previously shown that residents are smaller, bolder, more exploratory, more active, more aggressive, exhibited lower shoaling and lower migratory tendencies compared to their ancestral migrant counterparts. However, it is not clear if these differences in wild-caught residents and migrants reflect genetic differentiation, rather than different developmental conditions. To investigate this, we raised offspring of four crosses (migrant [male] x migrant [female], resident [male] x resident [female], migrant [male] x resident [female], resident [male] x migrant [female]) under similar controlled conditions and tested for differences in morphology and behavior as adults. We found that lab-raised resident sticklebacks exhibited lower shoaling and migratory tendencies as compared to lab-raised migrants, retaining the differences in their wild-caught parents. This indicates genetic differentiation of these traits. For all other traits, the lab-raised sticklebacks of the various crosses did not differ significantly, suggesting that the earlier-found contrast between wild-caught fish reflect differences in their environment. Our study shows that barriers to migration can lead to rapid differentiation in behavioral tendencies over contemporary timescales ([~]50 generations), and that part of these differences reflects genetic differentiation. Significance statementMany organisms face changes to their habitats due to human activities. Much research is therefore dedicated to the question whether and how organisms are able to adapt to novel conditions. We address this question in three-spined sticklebacks, where water management measures cut off some populations, prohibiting their seasonal migration to the North Sea. In a previous study, we showed that wild-caught resident fish exhibited markedly different behavior than migrants. To disentangle whether these differences reflect genetic differentiation or differences in the conditions under which the wild-caught fish grew up, we conducted crosses, raising the F1 offspring under identical conditions. As their wild-caught parents, the F1 of resident x resident crosses exhibited lower migratory and shoaling tendencies than the F1 of migrant x migrant crosses, while the F1 of hybrid crosses were intermediate. This suggests that [~]50 years of isolation are sufficient to induce behaviorally relevant genetic differentiation.

evolutionary biology↗

bioRxiv2021

Habitat fragmentation induces rapid divergence of migratory and isolated sticklebacks

The adaptive capacity of many organisms is seriously challenged by human-imposed environmental change, which currently happens at unprecedented rates and magnitudes. For migratory fish, habitat fragmentation is a major challenge that can compromise their survival and reproduction. Therefore, it is important to study if fish populations can adapt to such modifications of their habitat. Here, we study whether originally anadromous three-spined stickleback populations (Gasterosteus aculeatus; migrants) changed in behavior and morphology in response to human-induced isolation. We made use of a natural field-experiment, where the construction of pumping stations and sluices in the 1970s unintendedly created replicates of land-locked stickleback populations ( resident) in the Netherlands. For two years, we systematically tested populations of residents and migrants for differences in morphology and behavioral traits (activity, aggressiveness, exploration, boldness and shoaling) in lab-based assays. We detected differences between migrant and resident populations in virtually all phenotypic traits studied: compared to the ancestral migrants, residents were smaller in size, had fewer and smaller plates and were significantly more active, aggressive, exploratory and bolder and shoaled less. Despite large ecological differences between 2018 and 2019, results were largely consistent across the two years. Our study shows that human-induced environmental change has led to the rapid and consistent morphological and behavioral divergence of stickleback populations in about 50 generations. Such changes may be adaptive but this remains to be tested. Lay summaryThe adaptive capacity of many organisms is seriously challenged by human-imposed environmental changes. For example, migratory fish encounter man-made barriers that impede their movements and force them to adopt a resident lifecycle. Here we study whether and how populations of three-spined sticklebacks diverged in response to human-induced isolation. We show that about 50 generations of isolation were sufficient to induce substantial morphological and behavioral differentiation between land-locked populations ( residents) and their migratory ancestors ( migrants).

ecology↗

bioRxiv2020

DNA metabarcoding successfully quantifies relative abundances of arthropod taxa in songbird diets: a validation study using camera-recorded diets

O_LIEcological research is often hampered by the inability to quantify animal diets. Large-scale changes in arthropod diversity, abundance and phenologies urge the need to understand the consequences for trophic interactions. Diet composition of insectivorous predators can be tracked through DNA metabarcoding of faecal samples, but to validate the quantitative accuracy of metabarcoding, validation using free-living animals for which their diet can be approximated, is needed. C_LIO_LIThis validation study assesses the use of DNA metabarcoding in quantifying diets of an insectivorous songbird. Using camera footage, we documented food items delivered to nestling Pied Flycatchers Ficedula hypoleuca, and subsequently sequenced the Cytochrome Oxidase subunit I (COI) in their faeces. Our special interest was to retrieve the relative contribution of arthropod taxa with a PCR-based protocol. C_LIO_LIAssessment of taxonomic coverage of the invertebrate COI primers LCO1490 and HCO1777, previously applied in insectivorous songbirds, demonstrated that COI barcodes were predominantly assigned to arthropod taxa, however, substantial amounts of reads (2-60%) were assigned to flycatchers. Modified primers reduced vertebrate reads to 0.03%, and yielded more spider DNA without significant changing the recovery of other arthropod taxa. C_LIO_LITo explore digestive biases, contents of stomachs and lower intestines were compared in eight adult male flycatchers, victims of competitors for nest boxes. Similarity in arthropod community composition between stomach and intestines confirmed limited digestive bias. C_LIO_LIWith nest box cameras in 2013, 2015 and 2016, size-adjusted counts of prey items fed to nestlings were recorded, to approximate provided biomass of arthropod orders and families which allowed comparison with abundance of COI barcode reads in nestling faeces. The relative abundances of size-adjusted prey counts and COI reads correlated at R = 0.85 (CI:0.68-0.94) at order level and at R=0.75 (CI:0.67-0.82) at family level. Each common order and all common taxa within Lepidoptera, Diptera and Coleoptera were retrieved in similar proportions, while the taxonomic resolution was higher in barcodes than in camera records. C_LIO_LIThis DNA metabarcoding validation demonstrates that quantitative arthropod diet analyses is possible in songbirds. We discuss the ecological application of our approach in approximating the arthropod diets in insectivorous birds. C_LI

ecology↗