Maternal thyroid hormones enhance hatching success but decrease nestling body mass in the rock pigeon ( Columba livia )

Journal of Avian Biology

Doligez

Gustafsson

et al. 2019

Self Cite

Maternal thyroid hormones (THs) have been proven crucial for embryonic development in humans, but their influence within the natural variation on wild animals remains unknown. So far the only two studies that experimentally investigated the potential fitness consequences of maternal THs in birds found inconsistent results. More studies are thus required to assess the general effects of maternal THs and their influences on more behavioral and physiological parameters. In this study, we experimentally elevated yolk TH content in a wild migratory passerine species, the collared flycatcher Ficedula albicollis, to investigate the effects on hatching success, nestling growth and oxidative stress. We found that TH‐injected eggs had a higher hatching success, and the nestlings hatched from TH‐injected eggs were heavier and larger than control nestlings, but only during the early postnatal period. These differences vanished by fledging. Nestlings from TH‐injected eggs exhibited lower activity of the glutathione‐s‐transferase, a major antioxidant enzyme, than control nestlings at day 12, a few days before fledging, but they did not differ in oxidative damage and overall intracellular oxidative state. These results suggest that the early growth‐enhancing effects incurred no observable oxidative stress. We hypothesize that such a transient growth‐enhancing effect might be adaptive in advancing the development and maturation of the offspring so they are well‐prepared in time for the upcoming migration. Further studies investigating whether such advancing effects can influence long‐term fitness, will be more than valuable.

Section: Discussioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 84%

Transient growth‐enhancing effects of elevated maternal thyroid hormones at no apparent oxidative cost during early postnatal period

Journal of Avian Biology

Doligez

Gustafsson

et al. 2019

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“…In the great tits, 446 yolk TH elevation did not influence nestling RMR before fledging (Ruuskanen et al 2016a). In the 447 rock pigeons, similar yolk TH elevation raised the RMR in female nestlings but reduced it in males on 448 the hatching day, a pattern that was consistent with the effects on plasma T4 concentrations (but 449 not T3) at day 14 after hatching (in the middle of the nestling phase, Hsu et al 2017). Although in the 450 pigeon study, elevated yolk THs showed consistent effects on nestling RMR and plasma T4, the sex-451 specific pattern remains unexplained.…”

Section: No Size-independent Associations Between Maternal Ths and Pamentioning

confidence: 54%

“…THs reported inconsistent effects of yolk TH on nestling traits across species (Ruuskanen et al 2016a; 69 Hsu et al 2017Hsu et al , 2019a. Such species differences intrigue us to consider the possibility that maternal 70 yolk THs might have co-evolved with life-history differences and therefore species respond to 71 elevated yolk THs differently.…”

Section: Introduction 38mentioning

confidence: 99%

Maternally-transferred thyroid hormones and life-history variation in birds

Pakanen

Boner

et al. 2019

Preprint

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19Animals' life-history traits vary largely along many continuums across species and several 20 physiological parameters have been proposed as possible mediators that drive the life-history 21 variation, such as metabolic rates, glucocorticoids, and oxidative stress. Interestingly, thyroid 22 hormones (THs), despite closely interacting with these physiological parameters, have never been 23 considered as such mediators. Because of the crucial effects on embryonic development, THs can 24 also induce transgenerational plasticity when transferred into developing offspring, for instance, via 25 egg yolks in birds. In this study, we compiled a unique data set of maternal yolk THs in 34 bird 26 species across 17 families and 6 orders and analysed them with data of life-history traits along 27 several life-history continuums. Our phylogenetic mixed models estimated higher deposition of the 28 two most important forms of THs -T3 and T4 --in both concentrations and total amounts in 29 migratory species than resident species, and larger total amounts of T3 in precocial species than in 30 altricial species. However, maternal THs did not show clear associations with any traits of the pace-31 of-life syndrome. When taking environmental factors into account, we found that captive species 32 also deposited higher TH concentrations and larger amounts in the egg yolks than wild species. 33These findings suggest that THs are likely involved in the evolution of life-history variation or vice 34 versa. Accordingly we proposed many angles for further studies. 35 36 Key words: life histories, birds, maternal thyroid hormones, phylogenetic comparative analysis 37 Chastel, O., Lacroix, A., Kersten, M. (2003). Pre-breeding energy requirements: thyroid hormone, 595 metabolism and the timing of reproduction in house sparrows Passer domesticus.

“…Third, previous research has studied the effects of T 3 only (Fini et al, 2012;Raine et 91 al., 2004;Walpita et al, 2007) or a combination of T 3 and T 4 (Hsu et al, 2017;Hsu et al, 92 2019;Ruuskanen et al, 2016), where the effects of the two forms cannot be separated. 93…”

Section: Introduction 39mentioning

confidence: 99%

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

Sarraude

Groothuis

et al. 2019

Preprint

Self Cite

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.