Biology subjects

Thomson, R. L.

Publications and source records attributed to Thomson, R. L..

3 recordsLinked to original sources

bioRxiv2024

Common cuckoo female host selection is not determined by host quality but can affect cuckoo nestling growth when parasitising Common redstarts

Common cuckoo (Cuculus canorus) females lay their eggs in the nests of other avian hosts, relying on parental care provided by parasitised hosts. Therefore, it would benefit cuckoo females to target high-quality individual hosts, able to provide optimal parental care. Attempts at testing cuckoo female host selection have so far shown mixed results. However, this might be because studies have rarely considered the host nests that are available in space and time during each cuckoo egg-laying event, as well as the implications of host choice on the cuckoo nestling growth. Here we combined long-term monitoring data with an experiment to test whether cuckoo females parasitising Common redstarts (Phoenicurus phoenicurus) target individual hosts to optimise their nestling[s] growth. Making use of data collected between 2013 and 2022 from 350+ nest boxes in Oulu (Finland), we first explored whether there is a range of available host nests for the cuckoo female to choose from. Second, we tested if hosts are targeted according to individual quality (using clutch size as a proxy). And third, we investigated the outcomes of cuckoo female host-selection on nestling growth (mass, tarsus length, and wing length) between 2014 and 2019. We conducted a cross-fostering experiment where we either left cuckoo eggs to hatch and be raised in the nest their mother originally chose for them or moved cuckoo eggs to non-parasitised nests. Additionally, we conducted an exploratory analysis to test the quality of the parents caring for the cross-fostered cuckoo nestlings. After accounting for how many host nests were available to the cuckoo female to choose from, we found that nests with bigger clutches were not more likely to be parasitised, and cross-fostering did not affect mass and tarsus length growth. However, both in the wing length growth and in our exploratory analysis of host parental care on cuckoo nestling growth we found that cuckoo nestlings that grew in the nest selected by their mothers, reached higher asymptotic growth at a slower rate. This suggests that while cuckoos may not choose redstart hosts based on their individual quality when parasitising common redstarts, cuckoo female host selection might improve cuckoo nestling growth and thus, have an adaptive significance.

animal behavior and cognition↗

bioRxiv2021

Population differences in the length, early-life dynamics, and heritability of telomeres among European pied flycatchers

Telomere length and shortening rate are increasingly used as biomarkers for long-term costs in ecological and evolutionary studies because of their relationships with survival and fitness. Both early-life conditions and growth, and later-life stressors can create variation in telomere shortening rate. Studies on between- population telomere length and dynamics are scarce, despite the expectation that populations exposed to varying environmental constraints would present divergent telomere length patterns. The pied flycatcher (Ficedula hypoleuca) is a passerine bird breeding across Eurasia (from Spain to western Siberia) and migrating through the Iberian Peninsula to spend the non-breeding period in sub-Saharan Africa. Thus, different populations show marked differences in migration distance. We studied the large-scale variation of telomere length and early-life dynamics in the pied flycatcher by comparing six European populations across a north- south gradient (Finland, Estonia, England, and Spain) predicting negative effect of migration distance on adult telomere length, and of nestling growth on nestling telomere dynamics. There were clear population differences in telomere length, with English birds from mid-latitudes having the longest telomeres. Telomere length did not thus show consistent latitudinal variation and was not linearly linked to differences in migration distance. Early-life telomere shortening rate tended to vary between populations. Fast growth was associated with shorter telomeres in the early life, but faster nestling growth affected telomeres more negatively in northern than southern populations. While the sources of between-population differences in telomere-related biology remain to be more intensively studied, our study illustrates the need to expand telomere studies at the between-population level.

zoology↗

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↗