Biology subjects

Groothuis, T. G. G.

Publications and source records attributed to Groothuis, T. G. G..

6 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↗

bioRxiv2020

Co-evolved maternal effects selectively eliminate offspring depending on resource availability

Many plants and animals adaptively downsize the number of already-produced propagules if resources become insufficient to raise all of them. In birds, mothers often induce hatching asynchrony by incubating first eggs before last eggs are laid, creating an age/size hierarchy within broods which selectively eliminates the smallest chicks in poor food conditions. However, mothers also deposit more testosterone into late-laid eggs, which boosts competitive abilities of younger chicks, counteracts the competitive hierarchy, and ostensibly creates a paradox. Since testosterone also carries costs, we hypothesized that benefits of maternally deposited testosterone outweigh its costs in good food conditions, but that testosterone has a net detrimental effect in poor food conditions. We found experimental evidence that elevated maternal testosterone in the egg caused higher chick mortality in poor food conditions but better chick growth in good food conditions. These context-dependent effects resolve the paradox, suggesting co-evolution of two maternal effects, and explain inconsistent results of egg hormone manipulations in the literature.

evolutionary biology↗

bioRxiv2019

Inter-specific variation of maternal thyroid hormones associate with migration, mode of development, and captivity: a phylogenetic comparative analysis

Life-history traits vary largely across species and several physiological parameters have been proposed to be associated with life-history variation, such as metabolic rates, glucocorticoids, and oxidative stress. Interestingly, the association between thyroid hormones (THs) and life history variation has never been considered, despite a close interaction between THs and these physiological traits. Because of the crucial effects on embryonic development, THs can also induce transgenerational plasticity when transferred to developing offspring, for instance, via egg yolks in birds. In this study, we compiled a unique data set of maternal yolk THs in 34 bird species across 17 families and 6 orders, and tested for associations with various life-history traits. Our phylogenetic mixed models indicated that both concentrations and total amounts of the two most important forms of THs (T3 and T4) were higher in the eggs of migratory species than in those of resident species, and that there were higher total amounts of T3 in the eggs of precocial species than in those of altricial species. However, maternal THs did not show clear associations with any traits of the pace-of-life syndrome, such as developmental duration, growth rate, or lifespan. When taking environmental factors into account, we found that captive species deposited higher TH concentrations and larger amounts in the egg yolks than wild species. These findings suggest that maternal THs are likely involved in the evolution of life-history variation, or vice versa.

evolutionary biology↗

bioRxiv2019

Elevated exposure to prenatal thyroid hormones affects embryonic mortality but has no effects into adulthood

Maternal thyroid hormones (THs) are known to be crucial in embryonic development in humans, but their influence on other, especially wild, animals remains poorly understood. So far, the studies that experimentally investigated the consequences of maternal THs focused on short-term effects, while early organisational effects with long-term consequences, as shown for other prenatal hormones, could also be expected. In this study, we aimed at investigating both the short- and long-term effects of prenatal THs in a bird species, the Japanese quail Coturnix japonica. We experimentally elevated yolk TH content (the prohormone T4, and its active metabolite T3, as well as a combination of both hormones). We analysed hatching success, embryonic development, offspring growth and oxidative stress as well as their potential organisational effects on reproduction, moult, and oxidative stress in adulthood. We found that eggs injected with both hormones had a higher hatching success compared with control eggs, suggesting conversion of T4 into T3 by the embryo. We detected no other clear short-term or long-term effects of yolk THs. These results suggest that yolk thyroid hormones are important in the embryonic stage of precocial birds, but other short- and long-term consequences remain unclear. Research on maternal thyroid hormones will greatly benefit from studies investigating how embryos use and respond to this maternal signalling. Long-term studies on prenatal THs in other taxa in the wild are needed for a better understanding of this hormone-mediated maternal pathway.

physiology↗

bioRxiv2019

Prenatal thyroid hormone exposure increases growth but not oxidative stress in a wild passerine species

Hormones transferred from mothers to their offspring are thought to be a maternal tool for mothers to prepare their progeny for expected environmental conditions, thus increasing fitness. Thyroid hormones (THs) are crucial across vertebrates for embryonic and post-natal development and metabolism. Nevertheless, the studies that investigated the consequences of maternal hormones have mostly focused on steroid hormones and ignored maternally-derived thyroid hormones. In this study, we experimentally elevated yolk thyroid hormones in a wild population of a migratory passerine, the European Pied flycatcher Ficedula hypoleuca. We injected eggs with a mixture of T4 and T3 within the natural range of the species to assess its effects on hatching success, nestling survival, growth and oxidative status (antioxidant enzyme activity, lipid peroxidation and oxidative balance). We found no effects of yolk THs on egg hatchability or nestling survival. Yolk THs increased nestling growth during the second week post hatching, but this potentially beneficial effect did not incur any costs in terms of oxidative stress. The results should stimulate more research on thyroid hormone mediated maternal effects, further studies into the underlying mechanistic pathways for these effects and how they translate into adulthood and fitness.\n\nSummary statementThyroid hormones have been overlooked in the context of hormone-mediated maternal effects. We found that yolk thyroid hormones in a wild bird species increase growth without incurring oxidative stress.

physiology↗

bioRxiv2018

Visual adaptation and microhabitat choice in Lake Victoria cichlid fish

When different genotypes choose different habitats to better match their phenotypes, adaptive differentiation within a population may be promoted. Mating within those habitats may subsequently contribute to reproductive isolation. In cichlid fish, visual adaptation to alternative visual environments is hypothesised to contribute to speciation. Here, we investigated whether variation in visual sensitivity causes different visual habitat preferences, using two closely related cichlid species that occur at different but overlapping water depths in Lake Victoria and that differ in visual perception (Pundamilia sp.). In addition to species differences, we explored potential effects of visual plasticity, by rearing fish in two different light conditions: broad-spectrum (mimicking shallow water) or red-shifted (mimicking deeper waters). Contrary to expectations, fish did not prefer the light environment that mimicked their typical natural habitat. Instead, we found an overall preference for the broad-spectrum environment. We also found a transient influence of the rearing condition, indicating that assessment of microhabitat preference requires repeated testing to control for familiarity effects. Together, our results show that cichlid fish exert visual habitat preference, but do not support straightforward visual habitat matching.

evolutionary biology↗