Biology subjects

Landler, L.

Publications and source records attributed to Landler, L..

5 recordsLinked to original sources

bioRxiv2026

Applying advanced circular statistics: magnetic orientation of green toad larvae

Many animals use the Earths magnetic field as a directional reference. Among those are amphibians, which can be trained to orient towards magnetic directions. We used mixed-effects models, controlling for individual and test round effects in the random structure, to analyse a dataset exploring magnetic orientation in green toad larvae. We used control simulations with uniform circular to assess whether the modelling approach produced inflated false-positive rates. Traditional approaches applied to average individual bearings, namely the Rayleigh test and Hotellings test, did not detect significant deviations from uniformity. However, the linear mixed-effects models (LMMs) applied to sine and cosine components suggested orientation components consistent with a trained magnetic response, as well as a geographic component. Model predictions suggested changing directional responses during the two-minute trial and with the larvaes activity. Larvae oriented geographically northward at the beginning of trials and when activity was high, whereas the trained magnetic response became more pronounced towards the end of trials. Our study represents a first attempt to use recently developed circular adaptations of LMMs with complex random-effects structures to better capture animal orientation strategies, potentially increasing statistical power and providing more nuanced insight into orientation behaviour.

animal behavior and cognition↗

bioRxiv2022

Land-use preferences of the European green toad (Bufotes viridis) in the city of Vienna (Austria): the importance of open land in urban environments

Urban areas are increasing worldwide, which poses treats to animal wildlife. However, in certain cases cities can provide refuges for endangered animals. The European green toad (Bufotes viridis) is one of such examples, which is known from cities throughout their distribution. In contrast, considerable areas of their former (primary) habitats have been degraded. The primary habitats of this species include steppes and wild river floodplains, both characterized by dynamic changes and the presence of open areas. We used available green toad observation data (2007-2020) to model the effects of land-use types on occurrence probability in the city of Vienna. Forest and densely populated areas were highly significantly negatively associated with green toad presence, while transformation/construction site areas showed a strong positive effect. Such occurrence pattern might be characteristic for early succession species, which depend on stochastic environmental disturbances (e.g., droughts and floods) in their primary habitats. We argue that urban landscape planning should appreciate the potential ecological value of open land in cities which is either in a transition phase or a permanent wasteland. Ecological managing of such landscape could vastly increase urban biodiversity.

ecology↗

bioRxiv2021

Comparing two circular distributions: advice for effective implementation of statistical procedures in biology

Many biological variables, often involving timings of events or directions, are recorded on a circular rather than linear scale, and need different statistical treatment for that reason. A common question that is asked of such circular data involves comparison between two groups or treatments: Are the populations from which the two samples drawn differently distributed around the circle? For example, we might ask whether the distribution of directions from which a stalking predator approaches its prey differs between sunny and cloudy conditions; or whether the time of day of mating attempts differs between lab mice subject to one of two hormone treatments. An array of statistical approaches to these questions have been developed. We compared 18 of these (by simulation) in terms of both abilities to control type I error rate near the nominal value, and statistical power. We found that only eight tests offered good control of type I error in all our test situations. Of these eight, we are able to identify Watsons U2 test and MANOVA based on trigonometric functions of the data as offering the best power in the overwhelming majority of our test circumstances. There was often little to choose between these tests in terms of power, and no situation where either of the remaining six tests offered substantially better power than either of these. Hence, we recommend the routine use of either Watsons U2 test or MANOVA when comparing two samples of circular data.

animal behavior and cognition↗

bioRxiv2018

Revised testing procedures do not elicit magnetoreceptive behavior in C. elegans

A diverse range of species is known to rely on the Earths magnetic field for spatial information. Vidal-Gadea et al. claimed that C. elegans are magneto-sensitive, exploiting the magnetic field to guide their burrowing behavior [1]. Our attempts to replicate their findings were unsuccessful [2], which Vidal-Gadea attributed to the satiety of the animals and the environment in which they were raised. Here, we report our repeated experiments, having adopted several suggestions proposed by Vidal-Gadea et al. [3]. We find that shortening the length of the behavioral assay and raising the animals in a Faraday cage does not result in magnetotactic behavior. We reluctantly conclude that the assays employed by Vidal-Gadea are not robust or C. elegans are not magneto-sensitive.

animal behavior and cognition↗

bioRxiv2017

Are Caenorhabditis elegans magnetoreceptive?

A diverse array of species on the planet employ the Earths magnetic field as a navigational aid. As the majority of these animals are migratory, their utility to interrogate the molecular and cellular basis of the magnetic sense is limited. Vidal-Gadea and colleagues recently argued that the worm C. elegans possesses a magnetic sense that guides their vertical movement in soil. In making this claim they relied on three different behavioural assays that involved magnetic stimuli. Here, we set out to replicate their results employing blinded protocols and double wrapped coils that control for heat generation. We find no evidence supporting the existence of a magnetic sense in C. elegans. We further show that the Vidal-Gadea hypothesis is problematic as the adoption of a correction angle and a fixed trajectory relative to the Earths magnetic inclination does not necessarily result in vertical movement.

neuroscience↗