Variation in Reproductive Success Across Captive Populations: Methodological Differences, Potential Biases and Opportunities

Our understanding of fundamental organismal biology has been disproportionately influenced by studies of a relatively small number of model\u27 species extensively studied in captivity. Laboratory populations of model species are commonly subject to a number of forms of past and current selection that may affect experimental outcomes. Here, we examine these processes and their outcomes in one of the most widely used vertebrate species in the laboratory - the zebra finch (Taeniopygia guttata). This important model species is used for research across a broad range of fields, partly due to the ease with which it can be bred in captivity. However despite this perceived amenability, we demonstrate extensive variation in the success with which different laboratories and studies bred their subjects, and overall only 64% of all females that were given the opportunity, bred successfully in the laboratory. We identify and review several environmental, husbandry, life-history and behavioural factors that potentially contribute to this variation. The variation in reproductive success across individuals could lead to biases in experimental outcomes and drive some of the heterogeneity in research outcomes across studies. The zebra finch remains an excellent captive animal system and our aim is to sharpen the insight that future studies of this species can provide, both to our understanding of this species and also with respect to the reproduction of captive animals more widely. We hope to improve systematic reporting methods and that further investigation of the issues we raise will lead both to advances in our fundamental understanding of avian reproduction as well as to improvements in future welfare and experimental efficiency

Interaction of climate change with effects of conspecific and heterospecific density on reproduction

We studied the relationship between temperature and the coexistence of great titParus majorand blue titCyanistes caeruleus, breeding in 75 study plots across Europe and North Africa. We expected an advance in laying date and a reduction in clutch size during warmer springs as a general response to climate warming and a delay in laying date and a reduction in clutch size during warmer winters due to density-dependent effects. As expected, as spring temperature increases laying date advances and as winter temperature increases clutch size is reduced in both species. Density of great tit affected the relationship between winter temperature and laying date in great and blue tit. Specifically, as density of great tit increased and temperature in winter increased both species started to reproduce later. Density of blue tit affected the relationship between spring temperature and blue and great tit laying date. Thus, both species start to reproduce earlier with increasing spring temperature as density of blue tit increases, which was not an expected outcome, since we expected that increasing spring temperature should advance laying date, while increasing density should delay it cancelling each other out. Climate warming and its interaction with density affects clutch size of great tits but not of blue tits. As predicted, great tit clutch size is reduced more with density of blue tits as temperature in winter increases. The relationship between spring temperature and density on clutch size of great tits depends on whether the increase is in density of great tit or blue tit. Therefore, an increase in temperature negatively affected the coexistence of blue and great tits differently in both species. Thus, blue tit clutch size was unaffected by the interaction effect of density with temperature, while great tit clutch size was affected in multiple ways by these interactions terms.Peer reviewe

The great tit HapMap project: a continental‐scale analysis of genomic variation in a songbird

A major aim of evolutionary biology is to understand why patterns of genomic diversity vary within taxa and space. Large-scale genomic studies of widespread species are useful for studying how environment and demography shape patterns of genomic divergence. Here, we describe one of the most geographically comprehensive surveys of genomic variation in a wild vertebrate to date; the great tit (Parus major) HapMap project. We screened ca 500,000 SNP markers across 647 individuals from 29 populations, spanning ~30 degrees of latitude and 40 degrees of longitude – almost the entire geographical range of the European subspecies. Genome-wide variation was consistent with a recent colonisation across Europe from a South-East European refugium, with bottlenecks and reduced genetic diversity in island populations. Differentiation across the genome was highly heterogeneous, with clear ‘islands of differentiation’, even among populations with very low levels of genome-wide differentiation. Low local recombination rates were a strong predictor of high local genomic differentiation (FST), especially in island and peripheral mainland populations, suggesting that the interplay between genetic drift and recombination causes highly heterogeneous differentiation landscapes. We also detected genomic outlier regions that were confined to one or more peripheral great tit populations, probably as a result of recent directional selection at the species' range edges. Haplotype-based measures of selection were related to recombination rate, albeit less strongly, and highlighted population-specific sweeps that likely resulted from positive selection. Our study highlights how comprehensive screens of genomic variation in wild organisms can provide unique insights into spatio-temporal evolutionary dynamics

Variation in clutch size in relation to nest size in birds

Peer reviewe

Maternal Age-Related Depletion of Offspring Genetic Variance in Immune Response to Phytohaemagglutinin in the Blue Tit (Cyanistes caeruleus)

Studies examining age-specific patterns in genetic variance have focussed primarily on changes in the genetic variance within cohorts. It remains unclear whether parental age may affect the genetic variance among offspring. To date, such an effect has been reported only in a single study performed in a wild bird population. Here, we provide experimental evidence that the additive genetic variance (V-A) observed among offspring may be related to parental age in a wild passerine-the blue tit (Cyanistes caeruleus). To separate genetic and environmental components of phenotypic variance in nestling body size and immune function we cross-fostered nestlings between pairs of broods born to young and old mothers and used an animal model to estimate V-A. We show that the genetic variance in immune response to phytohaemagglutinin (PHA) and body weight among offspring depends on maternal age. V-A in response to PHA appeared to be lower among nestlings of older mothers. Such a tendency was not observed for tarsus length. We argue that the lower V-A may result either from depletion of additive genetic variation due to selection acting on parents across age classes or from environmental effects confounded with parental age. Thus, our study suggests that parental age may significantly affect estimates of quantitative genetic parameters in the offspring

Benefits of extra-pair mating may depend on environmental conditions-an experimental study in the blue tit (Cyanistes caeruleus)

Extra-pair mating constitutes a relatively common reproductive strategy in many socially monogamous bird species. This strategy may considerably improve reproductive success of males, but female benefits from extra-pair matings still remain unclear and empirical evidence is scarce. This may be because genetic benefits of extra-pair mating are not always revealed. It is possible that they are shown only in unfavourable environmental conditions and hence problems arise with detecting differences between within- and extra-pair offspring whose performance is measured under favourable conditions. In order to test this prediction, we manipulated environmental conditions by altering brood sizes of blue tits and compared phenotypic characteristics of within- and extra-pair offspring in mixed-paternity broods. We found that extra-pair young exhibited a higher response to phytohemagglutinin in comparison to within-pair young, but this was only observed among nestlings from experimentally enlarged broods. These results indicate that genetic benefits may interact with the environment, and thus benefits of extra-pair mating are likely to become visible only when conditions are relatively unfavourable

Low Cross-Sex Genetic Correlation in Carotenoid-Based Plumage Traits in the Blue Tit Nestlings (Cyanistes caeruleus)

In some bird species, both adult and juvenile individuals are often brightly coloured. It has been commonly assumed that identical plumage colouration present in both sexes results from strong intersexual genetic correlations in colour-related traits. Here, we aimed at testing this hypothesis in juvenile individuals and looked at genetic parameters describing carotenoid-based colouration of blue tit nestlings in a wild population. To separate genetic and environmental sources of phenotypic variation we performed a cross-fostering experiment. Our analyses confirmed the existence of sexual dichromatism in blue tit nestlings and revealed a significant, although low, genetic component of carotenoid-based colouration. However, genetic effects are expressed differently across sexes as indicated by low cross-sex genetic correlations (r(mf)). Thus our results do not support the prediction of generally high rmf and suggest that intersexual constraints on the evolution of colouration traits may be weaker than expected. We hypothesise that observed patterns of genetic correlations result from sex-specific selective pressures acting on nestling plumage colouration

Heterozygosity-fitness correlations in blue tit nestlings (Cyanistis caeruleus) under contrasting rearing conditions

Understanding the relation between genetic variation and fitness remains a key question in evolutionary biology. Although heterozygosity has been reported to correlate with many fitness-related traits, the strength of the heterozygosity-fitness correlations (HFCs) is usually weak and it is still difficult to assess the generality of these associations in natural populations. It has been suggested that HFCs may become meaningful only under particular environmental conditions. Moreover, existing evidence suggests that HFCs may also differ between sexes. The aim of this study was to investigate correlations between heterozygosity in neutral markers (microsatellites) and fitness-related traits in a natural population of blue tits (Cyanistes caeruleus). Additionally, we tested whether sex and environmental conditions may influence the magnitude and direction of HFCs. We found a positive relationship between heterozygosity and body mass of 14 days post-hatching nestlings, but only among females. Our results suggest that the correlation between heterozygosity and nestling body mass observed among female offspring could be attributed to within-brood effects. We failed to find any evidence that environmental conditions as simulated by brood size manipulation affect HFCs

Entrance strategy of SANO Ltd. in the Finaland's energy consumer market.

Bakalaura darba tēma ir SIA “SANO” ieiešanas stratēģija Somijas energoresursu uzskaites tirgū. Bakalaura darba mērķis ir pamatojoties uz Somijas energoresursu tirgu, SIA “SANO” uzņēmuma darbību, kā arī dažādu uzņēmumu pieredzi un ekspertu viedokļiem par Somijas tirgu analīzi noteikt piemērotāku ieiešanas stratēģiju SIA “SANO” Somijas energoresursu tirgū un izstrādāt priekšlikumus, lai attiecīgā stratēģija tiktu veiksmīgi sasniegta. Pētījuma rezultāti liecina, ka uzņēmumam ir iespējas ieiet Somijas energoresursu uzskaites tirgū, jo ir izpildīti priekšnosacījumi veiksmīgam eksportam: ir pietiekami liels vadības zināšanu līmenis, uzņēmums ir konkurētspējīgs, ir brīva ražošanas jauda, ko nav iespējams realizēt vietējā tirgū, un ir pieprasījums pēc pakalpojuma Somijas tirgū. Bakalaura darba izstrādē ir izmantoti 86 informācijas avoti, tā apjoms ir 77 lappuses. Diplomdarbā ir izmantoti 20 attēli, 9 tabulas un 2 pielikumi. Atslēgvārdi: starptautiskā uzņēmuma attīstība, eksports, tirgū ieiešanas stratēģijas, SIA SANO, Somijas energoresursu uzskates tirgus, viedie skaitītāji, uzņēmuma pārstāvju, eksperta intervijas.Theme of the thesis is SIA “SANO” strategy for entering in Finland energy resource meter market. The aim of the thesis is to determine the best possible market entering strategy of SIA “SANO”, based on Finland energy resource market, SIA “SANO” current experience, the experience of other companies and expert opinions. The aim also includes defining proposals for achieving the strategy. Research results show that SIA “SANO” has possibilities to enter Finland’s energy resource market because all the prerequisites for successful export have been fulfilled – The knowledge level of the current management is high, company can be competitive, Finish market shows demand for this type of product and there is empty production capacity, that can not be fulfilled in local market. The results of the research indicate that the company has the opportunity to enter the Finnish energy resource market, as the preconditions for successful export are met: there is sufficient level of management knowledge, the company is competitive, there is free production capacity that is not realizable in the domestic market and there is demand for the service On the market in Finland. At the international level, not all companies are developing, although any product can be found on an export market or establish a branch abroad. There are several prerequisites for international development, which, according to the author, will not be possible expansion. One of the prerequisites is management knowledge and the decision to further develop the company beyond national boundaries. In the diploma paper are 86 sources of information, and 77 pages. Diploma paper includes 20 pictures, 9 tables and 2 annexes. Keywords: international business development, export, market entry strategies, SIA SANO, Finnish energy resource market, smart meters, business representatives, expert interview