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

This is the final version. Available on open access from Wiley via the DOI in this recordThe data and the R code used to produce the results of this study are available from the Dryad Digital Repository: https://doi.org/10.5061/dryad.547d7wmb5.1. In vertebrates, thyroid hormones (THs) play an important role in the regulation of growth, development, metabolism, photoperiodic responses and migration. Maternally transferred THs are important for normal early-phase embryonic development when embryos are not able to produce endogenous THs. Previous studies have shown that variation in maternal THs within the physiological range can influence offspring phenotype. 2. Given the essential functions of maternal THs in development and metabolism, THs may be a mediator of life-history variation across species. 3. We tested the hypothesis that differences in life histories are associated with differences in maternal TH transfer across species. Using birds as a model, we specifically tested whether maternally transferred yolk THs co-vary with migratory status, developmental mode, and traits related to pace-of-life (e.g. basal metabolic rate, maximum lifespan). 4. We collected un-incubated eggs (n = 1-21 eggs per species, median = 7) from 34 wild and captive bird species across 17 families and 6 orders to measure yolk THs (both triiodothyronine, T3 and thyroxine, T4), compiled life-history trait data from the literature, and used Bayesian phylogenetic mixed models to test our hypotheses. 5. Our models indicated that both concentrations and total amounts of the two main forms of THs (T3 and T4) were higher in the eggs of migratory species compared to resident species, and total amounts were higher in the eggs of precocial species, which have longer prenatal developmental periods, than in those of altricial species. However, maternal yolk THs did not show clear associations with pace-of-life related traits, such as fecundity, basal metabolic rate, or maximum lifespan. 6. We quantified interspecific variation in maternal yolk THs in birds and our findings suggest higher maternal TH transfer is associated with the precocial mode of development and migratory status. Whether maternal THs represent a part of the mechanism underlying the evolution of precocial development and migration or a consequence of such life histories is currently unclear. We therefore encourage further studies to explore the physiological mechanisms and evolutionary processes underlying these patterns.Academy of FinlandAcademy of FinlandCape Horn International Center, Chil

Data from: Within-clutch variation in yolk testosterone as an adaptive maternal effect to modulate avian sibling competition: evidence from a comparative study

The data package contains three datasets: -Sources for yolk testosterone used in this study. Mean yolk testosterone concentrations in core eggs, marginal eggs and the difference in yolk testosterone between core and marginal eggs. Marginal eggs represent the later-laid, asynchronously-hatching eggs and were identified by dividing the hatching spread by the laying interval between subsequent eggs (app. C). If these calculations produced non-integers, we rounded the values up. Core eggs represent the early-laid, synchronously-hatching eggs and were identified by subtracting the number of marginal eggs from the average clutch size. Yolk testosterone concentrations for core and marginal eggs were averaged to produce mean core T concentrations and mean marginal T concentrations, respectively. In our analyses, we included mean marginal T minus mean core T as a response variable and mean core T as a covariate that corrects for differences in average clutch T values across species as well as assay differences. * indicates the species excluded from analyses containing initial size asymmetries between core and marginal chicks as a predictor (n=28 species included). **indicates the species excluded from analyses containing hatching spread and logistic growth rate constant as a predictor (n=25 species included). -Data on egg size and their sources. Data on within-clutch variation in egg size used in this study. Marginal eggs represent the later-laid, asynchronously-hatching eggs and were identified by dividing the hatching spread by the laying interval between subsequent eggs. If these calculations produced non-integers, we rounded the values up. Core eggs represent the early-laid, synchronously-hatching eggs and were identified by subtracting the number of marginal eggs from the average clutch size. Sizes of core eggs and marginal eggs were averaged to produce mean core egg size and mean marginal egg size, respectively. In our statistical models, we included proportional difference in egg size between core and marginal eggs as a covariate. This was calculated by dividing the difference in egg size between core and marginal eggs (mean marginal size minus mean core size) by mean core egg size. -Data on life history variables and their sources. Data on life-history variables used in this study (data in bold, reference codes not in bold). Hatching spread represents the number or days between the hatching of the first egg and the last egg of a clutch. Days between eggs represents the time interval between the laying of subsequent eggs. Logistic growth rate constant represents the rate of mass increase in a sigmoid curve fitted to chick growth curves. % size difference was calculated as the mass of the core nestlings (estimated from their growth curves) at the time the last marginal chick hatched (hatching spread), divided by the size of a newly hatched chick. This represents the initial proportional size advantage of core chicks over marginal chicks

Data from: Organizing effects of adverse early-life condition on body mass, compensatory growth and reproduction: Experimental studies in rock pigeons

This set contains behavioural and survival data for the article "Organizing effects of adverse early-life condition on body mass, compensatory growth and reproduction: experimental studies in rock pigeons" Early‐life food conditions can have profound impact on adult behavioural performance. In song birds, early‐life food conditions affect adult physiology and cognitive performance such as song learning and spatial learning. However, effects on reproductive behaviour other than song, such as visual courtship display, pair formation, and egg laying, which are all important determinants of fitness, received hardly any attention. In this study, rock pigeons Columba livia were raised either in a food ad‐libitum or at impoverished (quality) and restricted (quantity) food conditions, in which the latter was applied for either 26 or 8 d after hatching and in slightly different severity. Their growth and reproductive behaviour in adulthood was analysed under semi‐natural conditions. Impoverished and restricted food (IRF) negatively affected adult body mass, pair‐bonding behaviour, courtship (males) and being courted (females), and induced incomplete compensatory growth. Further analyses suggest that the effects of IRF on behaviour could result from the strong effects on body mass, and perhaps also from detrimental effects of compensatory growth. These results provide evidence that adverse early‐life condition can negatively impact on reproductive success, as suggested by the significant effect on egg production, which will very likely lead to a lower life‐time fitness. The detrimental effects on male courtship indicate that IRF can affect sexual displays via other pathways than by impaired cognition as has been suggested for bird song, since courtship in the pigeons is not learned

Data from: Differential maternal testosterone allocation among siblings benefits both mother and offspring in the Zebra Finch Taeniopygia guttata

Parents are selected to preferentially invest in the offspring with highest reproductive value. One mechanism to achieve this is the modification of competitive asymmetries between siblings by maternal hormones. In many organisms, offspring value varies according to birth position in the brood, which determines survival chances and competitive advantage over access to resources. In birds, variation in yolk androgen allocation over the laying sequence is thought to modulate dominance of senior chicks over junior brood mates. We tested this hypothesis in zebra finches, which show a natural decreasing pattern of within-clutch testosterone allocation. We abolished these within-clutch differences by experimentally elevating yolk testosterone levels in eggs 2-6 up to the level of the egg 1, and assessed fitness measures for junior (eggs 2-6) and senior (egg 1) offspring, and their mothers. T-injected eggs hatched later than control eggs. Junior but not senior chicks in T broods attained poorer phenotypic quality compared with control broods, which was not compensated by positive effects on seniors. Mothers were generally unaffected by clutch treatment. Thus, naturally decreasing within-clutch yolk testosterone allocation appears to benefit all family members, and does not generally enhance brood reduction by favoring senior chicks, in contrast to widely held assumption. The data package contains one dataset: -Boncoraglio et al database Dryad file Original data collected in the lab. File created with Excel 2003. No abbreviations used for column headings

Experimental Evidence for Genetic Heritability of Maternal Hormone Transfer to Offspring

In many animal species, embryos are exposed to maternal hormones that affect their development. Maternal hormone transfer varies with environmental conditions of the mother and is often interpreted as being shaped by natural selection to adjust the offspring to prevailing environmental conditions. Such hormone transfer requires genetic variability, which has not yet been experimentally demonstrated. Our study reports direct evidence for additive genetic variance of maternal androgens through a bidirectional selection on yolk testosterone (T) levels in Japanese quail. Lines selected for high egg T (HET) and low egg T (LET) concentration differed in yolk levels of this androgen, resulting in high realized heritability (h^2 = 0.42). Correlated responses to selection on other gonadal hormones indicated that selection specifically targeted biologically active androgens. Eggs of HET quail contained higher androstenedione and lower estradiol concentrations than did those of LET quail, with no line differences in yolk progesterone concentration. Plasma T concentrations in adult females were not affected by selection, seriously challenging the hypothesis that transfer of maternal hormones to offspring is constrained by hormone levels in a mother’s circulation. Our results suggest that transfer of maternal T represents an indirect genetic effect that has important consequences for the evolution of traits in offspring.

Data from: Differential survival between visual environments supports a role of divergent sensory drive in cichlid fish speciation

Identifying the selective forces that initiate ecological speciation is a major challenge in evolutionary biology. Sensory drive has been implicated in speciation in various taxa, largely based on phenotype-environment correlations and signatures of selection in sensory genes. Here, we present a reciprocal transplant experiment revealing species differences in performance in alternative visual environments, consistent with speciation by divergent sensory drive. The closely related cichlids Pundamilia pundamilia and P. nyererei inhabit different visual environments in Lake Victoria and show associated differences in visual system properties. Mimicking the two light environments in the laboratory, we find a substantial reduction in survival of both species when reared in the other species' visual environment. This implies that the observed differences in Pundamilia colour vision are indeed adaptive, and substantiates the implicit assumption in sensory drive speciation models that divergent environmental selection is strong enough to drive divergence in sensory properties. The data package contains one dataset: - Maanetal2016_AmNat Excel file containing 1) 6-month and 12-month survival data; 2) spectrometry data from field and lab

Replication Data for: Testing the Darwinian function of lateralization. Does separation of workload between brain hemispheres increase cognitive performance?

This dataset consists of an Excel file "Data_for_repository_neuropsychologia.xlsx" with two tabs: Tab 1 "data" contains all responses and variables used for analysis; tab 2 "legend and labels" contains the names/explanations of the variables and the names coded values. The file "Syntax_for_repository_neuropsychologia.sps" is an SPSS script (syntax), which was used to perform the analyses

Replication Data for: Is imitational learning a driving factor for the population bias in human hand preference?

One Excel-file containing the handedness and imitation performance data used for analysis in sheet 1, and the explanation of the data labels in sheet 2. One exemplary instruction movie of four in total, that were shown to the participants. The sequence shows: granny knot (right-handed demonstration), bowstring knot (left-handed demonstration), artillery loop (right-handed demonstration), bowline (left-handed demonstration)

Dataset of maternal thyroid hormones transfer in Pied flycatchers

This is the dataset of an experiment conducted on Pied flycatchers (Ficedula hypoleuca) in which we manipulated thyroid hormones in the mother's circulation. This dataset contains all the responses measured in this experiment

Habitat fragmentation induces rapid phenotypic 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