Competition over access for mates has led to the evolution of many striking examples of morphological traits and behaviour in animals. The rapid development of the sexual selection field in recent decades have dramatically advanced our understanding of what traits make individuals more successful in attracting mates and how preferences for mates evolve over time. However, till now, research in this field has put less emphasis on the mechanisms that underlie variation in mate choice and sexual behaviour. Cognitive processes could potentially be key drivers of individual variation in mating preferences and sexual behaviours and therefore deserve further investigation. In this thesis, I used guppies artificially selected for relative brain size as the model system to study the association between brain size, cognitive ability and various aspects of mate choice. Previous studies in this model system showed that large-brained individuals of both sexes outperformed small-brained individuals in cognitive tests. Here I quantified their sexual behaviours and mating preferences to provide novel empirical data concerning the association between brain size, cognitive ability and sexual selection. In dichotomous choice preference tests based on visual cues, comparisons between large-brained and small-brained guppies showed important differences in their assessment of mate quality. These results are not driven by pre-existing visual biases caused by the artificial selection since further investigation of the visual capacity of these fish detected no differences between large-brained and small-brained individuals in their sensitivity to colour or in their capacity to resolve spatial detail. I also quantified sexual behaviour in male guppies artificially selected for relative brain size and found no difference in the behaviours of large-brained and small-brained males in a single male-single female non-competitive scenario. On the contrary, in a more complex social setting I found a reduction in large-brained males in the rate of courtship towards females and dominance displays towards other males when exposed to different degrees of predation threat and different numbers of male competitors. However, this reduction in behavioural intensity did not result in a lower access to copulation with females for large-brained males. I likewise evaluated female sexual behaviour and found that large-brained females had higher behavioural flexibility such that they decreased their receptiveness towards males more strongly under higher levels of predation threat. Together, these results provide novel empirical evidence that brain size and cognitive ability are tightly linked to mating preferences and sexual behaviours. These findings suggest that brain size and cognitive ability might be important mechanisms behind variation in mating preferences and in sexually selected traits across and within species. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 5: Manuscript.</p>

<p>Vr&scaron;eno je istraživanje intestinalnih nematoda žutogrlog mi&scaron;a (<em>Apodemus flavicollis&nbsp; </em>Melchior, 1834) uzorkovanog sa 18 lokaliteta na teritoriji Srbije, južno od Save i Dunava, sa ciljem pro&scaron;irenja i upotpunjavanja saznanja o ovoj komponenti parazitofaune glodara u ovom delu Evrope. Fauna nematoda crevnog trakta je analizirana sa vi&scaron;e aspekata: kvantitativnog, aspekta zajednica, biolo&scaron;kog, aspekta biodiverziteta i aspekta polne strukture. Pored toga, ispitan je uticaj odabranih<br />spolja&scaron;njih i unutra&scaron;njih faktora na prevalencu i abundancu parazitske infekcije.</p><p>Zabeleženo je prisustvo devet vrsta intestinalnih nematoda, pri čemu je broj vrsta po lokalitetu varirao od 1 do 7. Ukupna prevalenca infekcije iznosila je 81,6%. Najče&scaron;će vrste u uzorku bile su <em>Heligmosomoides polygyrus </em>i&nbsp;<em> Syphacia stroma</em>, koje su<br />se odlikovale najvi&scaron;im prevalencama i intenzitetima infekcije. Distribucija nematoda unutar domaćina je bila agregirana. Broj vrsta po domaćinu varirao je od 1 do 5, ali su najzastupljenije bile infekcije jednom ili dvema vrstama. Najče&scaron;ća kombinacija<br />vrsta bila je&nbsp;<em> H. polygyrus-S. stroma;</em> međutim, odsustvo podataka iz ranijih istraživanja i adekvatnih polaznih modela sprečava dono&scaron;enje zaključaka o mogućim interakcijama i asocijacijama između vrsta.</p><p>Monoksene nematode su bile brojnije i imale veću prevalencu od heteroksenih nematoda, &scaron;to oslikava&nbsp; razlike u njihovim životnim ciklusima. Među monoksenim nematodama, geohelminti u užem smislu su se odlikovali najvećim prevalencama, a ageohelminti najvećom abundancom, u skladu sa životnim strategijama koje teže ka disperziji ili akumulaciji.&Scaron;enonov indeks diverziteta cele uzoračke populacije iznosio je 1,44 &scaron;to je visoka vrednost u odnosu na one iz drugih delova Evrope. Nije uočena značajna negativna korelacija između udaljenosti lokaliteta i vrednosti Sorensenovog indeksa,ukazujući da je prostorni faktor značajan u strukturiranju zajednica intestinalnih nematoda i na lokalnom nivou. Odnos polova je bio neravnomeran, uglavnom u korist ženki, u skladu sa podacima drugih autora. Ženke su ujedno bile krupnije od mužjaka, saglasno sa ranijim nalazima za parazitske nematode. Nadmorska visina nije uticala na abundancu intestinalnih nematoda. Pol domaćina je uticao na prevalencu dve vrste: prevalenca&nbsp; <em>S. stroma</em>&nbsp; je bila veća kod mužjaka, a prevalenca<em> Trichuris muris</em>&nbsp; kod ženki. Kao značajan faktor uticao je na abundancu samo kod vrste&nbsp;<em> Aonchotheca annulosa</em>; abundanca ove vrste bila je veća kod mužjaka. Rezultati sugeri&scaron;u da je uticaj pola domaćina na nivo parazitske infekcije izuzetno kompleksan fenomen.&nbsp; Prevalenca i abundanca infekcije intestinalnim nematodama je bila veća kod domaćina sa B hromozomima.&nbsp; Lokalitet je bio značajan faktor u variranju abundance nematoda. Uzrast i prisustvo drugih vrsta nematoda su&nbsp; takođe ispoljavali značajan efekat. Povećanje abundance nematoda sa uzrastom&nbsp; se vezuje za dužu izloženost starijih jedinki parazitima. Iako je registrovan uticaj abundance jedne vrste na abundancu druge, on ne predstavlja čvrst dokaz za postojanje interakcija između vrsta.</p> / <p>A study of intestinal nematode parasites was conducted on the yellow-necked mouse (<em>Apodemus flavicollis&nbsp;</em> Melchior, 1834) sampled from 18 sites from Serbia south of the Sava and Danube rivers. The aim of the study was to broaden and enrich the data on this category of rodent parasites in this part of Europe. The nematode fauna of the gastrointestinal tract was analysed from quantitative, community, biological, biodiversity and sex ratio aspects. In addition, selected extrinsic and intrinsic factors were tested for their influence on the prevalence and abundance of infection.</p><p>Nine species of&nbsp; intestinal nematodes were noted, 1 to 7 per site. Total sample prevalence was 81.6%. <em>Heligmosomoides polygyrus</em>&nbsp; and&nbsp; <em>Syphacia stroma</em> were the most common species, with the highest prevalence and intensity values. Nematodes were aggregated within their hosts. Infracommunity richness varied from 1 to 5, but infections with one or two species were most common. The most frequent<br />combination&nbsp; of species was <em>H. polygyrus-S. stroma</em>, but in absence of prior research and adequate null models, conclusions of possible interactions and associations between species could not be drawn.</p><p>Monoxenous nematodes were more abundant and prevalent than heteroxenous species, reflecting the differences in their life cycles. Of the monoxenous nematodes, geohelminths<em> sensu stricto</em> had the highest prevalence values, whereas ageohelminths were most abundant, with respect to their life strategies that favour either dispersal or accumulation. Shannon&rsquo;s diversity index for the total sample was 1.44, a high value compared to those from other European based studies. A significant negative correlation between site distance and Sorensen index values was not found, implying that spatial factors have an important role in structuring intestinal nematode communities on a local scale. Sex ratio was generally female-biased, in agreement with data from other authors. In addition, females were larger than males, congruent with previous findings for parasitic nematodes.</p><p>Elevation did not significantly influence intestinal nematode abundance. Host sex influenced the prevalence of two species: for <em>S. stroma</em> prevalence was higher in males, and for <em>Trichuris muris</em> in females. Influence of host sex on abundance was found only for <em>Aonchotheca annulosa</em>, with abundances of this parasite higher in male mice. The results suggest that the effectof host sex on parasite infection levels is a highly complex phenomenon.&nbsp; Infection prevalence and abundance was higher in hosts that carried B chromosomes. Site was a significant factor in explaining variations in nematode abundance. Hostage and presence of other nematode species&nbsp; also exibited effects.&nbsp; An increase in nematode abundance with host age&nbsp; is explained by prolonged exposure to parasites in older host individuals. Although results indicate that the abundance of one species influences the abundance of another, this is not firm evidence of the existence of species interactions.</p>

Migration occurs among many animal species for the purpose of, among other things, finding food or to reproduce. Spawning migration is a form of migration that occurs among many fish species where they move to another site for reproduction. The movement can be obstructed by migration barriers like road culverts. Barriers to migration pose one of the greatest threats to biodiversity and ecosystem functions in freshwater. They impair the connectivity of watercourses and may prevent fish from improving reproductive success or completing their life histories altogether. There are both benefits and costs with migration, benefits such as increased survival for the adults and offspring, and costs such as increased energy consumption and increased mortality. The costs are often dependent on the morphological traits of the individual, like body shape and size. In this study, the spawning migration of two species of fish of the family Cyprinidae, ide (Leuciscus idus) and roach (Rutilus rutilus) was investigated. Few studies have been made on ide or on roach compared to other cyprinids and salmonids. This study might therefore enhance the overall knowledge of these two species. The overall aims of this project are to study and compare phenotypic correlates of spawning migration behaviour of ide and roach. The field studies were performed in Oknebäcken, Mönsterås (SE632310-152985), Sweden in March and April 2020. To describe the watercourse and define the location and characteristics of different potential migration barriers, a simplified biotope mapping method was used. The fish were caught in a hoop net and then measured, weighted, sexed, and injected with passive integrated transponder using the bevel down method. In order to register in stream movement of fish, reading stations with antennas were placed, at two locations upstream from the marking station and one downstream at the estuary. The sex ratio differed from the expected 1:1 with a majority of females for both species. This might be a result of fluctuations in survival of spawn coupled with different age-at-maturity between sexes. We found that individuals that arrived early to the stream were larger for both study species, as other studies also reported. Also, male ide was both larger and arrived before female ide. There might be an energy cost associated with early arrival to the stream and therefore, larger individuals arrive first. For roach, there was no difference in arrival time between the sexes although female roach were larger. There was no difference in the time spent in the stream between the species. For ide, females stayed for a longer period of time in the stream than males. However, the opposite was true for roach. This may be because male roach might benefit from more fertilization events when staying longer. There might therefore be a trade-off between the energy cost in staying in the stream and the increased fitness advantage in fertilization events. We found no correlation between any of the morphological traits and migration distance. However, since very few individuals were registered at the upstream reading stations, there might be an effect of migration barriers on the spawning migration. The mortality after spawning was higher for roach than for ide. For ide, a larger proportion of females than males died. For roach, individuals that arrived early was classified as alive to a greater extent than those who arrived late. Both similarities and differences between the species were discovered in this study which concludes that even closely related species might differ substantially from each other.

The evolution and maintenance of multiple phenotypes within populations is an interesting evolutionary and ecological question, and is becoming increasingly important for the restoration and conservation of partially migratory species. In particular, why individuals adopt a particular phenotype has been the focus of numerous research efforts. In the partially migratory species Oncorhynchys mykiss (commonly known as steelhead and rainbow trout), I found that sex plays a strong role in whether an individual adopts an anadromous or resident life history. I observed a higher frequency of females adopting the anadromous tactic throughout the species range, and I attributed this to the relationship between body size and reproductive success in females that is not present in males. I did not observe differences in female bias along gradients of latitude or migration distance, and I hypothesize that while the frequency of tactics among populations may change along these gradients, either the change is equal between males and females, or an interaction of latitude and migration distance may control changes. I did not observe a corresponding male bias in the one resident population I sampled, and suggest that this is the result of a high frequency of residents in that population. I propose that sex ratios could be a valuable metric for measuring frequency of life-history tactics in populations and could facilitate the investigation into the controls of life-history tactics across broad scales. / Graduation date: 2013

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Background: In 1999, The International Study of Asthma and Allergies in Childhood (ISAAC) Phase One reported the prevalence of eczema symptoms in 715,033 children from 154 centers in 56 countries by using standardized epidemiologic tools. Objective: To update the world map of eczema prevalence after 5 to 10 years (ISAAC Phase Three) and include additional data from over 100 new centers. Methods: Cross-sectional surveys using the ISAAC questionnaire on eczema symptoms were completed by adolescents 13 to 14 years old and by parents of children 6 to 7 years old. Current eczema was defined as an itchy flexural rash in the past 12 months and was considered severe eczema if associated with 1 or more nights per week of sleep disturbance. Results: For the age group 6 to 7 years, data on 385,853 participants from 143 centers in 60 countries showed that the prevalence of current eczema ranged from 0.9% in India to 22.5% in Ecuador, with new data showing high values in Asia and Latin America. For the age group 13 to 14 years, data on 663,256 participants from 230 centers in 96 countries showed prevalence values ranging from 0.2% in China to 24.6% in Columbia with the highest values in Africa and Latin America. Current eczema was lower for boys than girls (odds ratio, 0.94 and 0.72 at ages 6 to 7 years and 13 to 14 years, respectively). Conclusion:ISAAC Phase Three provides comprehensive global data on the prevalence of eczema symptoms that is essential for public health planning. New data reveal that eczema is a disease of developing as well as developed countries. / Revisión por pares

Im Zeitraum 1989 bis 2005 sind per Saldo 1,6 Millionen Menschen aus den neuen in die alten Bundesländer gezogen. Die Mehrheit dieser Binnenwanderer war zwischen 18 und 29 Jahre alt und die Mehrheit war weiblich. Als Ergebnis dieser anhaltenden geschlechtsselektiven Wanderung ist in den neuen Bundesländern eine stark unausgewogene Geschlechterproportion in der Wohnbevölkerung entstanden. In der Altersgruppe der 18- bis 29-Jährigen lag die Geschlechterproportion in den neuen Bundesländern (einschließlich Berlin) im Jahr 2005 nur bei 90 Frauen zu 100 Männern und sank in zahlreichen Landkreisen auf Werte von weniger als 85 zu 100. Eine so unausgewogene Geschlechterproportion ist auch im europäischen Maßstab ungewöhnlich und kommt in keinem ähnlich großen und dicht besiedelten Gebiet vor. Als eine wesentliche Ursache der disproportionalen Wanderung wird ein erhebliches Bildungsgefälle zwischen jungen Frauen und Männern in den neuen Bundesländern identifiziert. Das hohe Bildungsniveau von Frauen ist dabei nicht nur als ökonomischer Faktor für den Fortzug zu sehen: Da Frauen Partnerschaften mit geringer gebildeten Partnern meiden, werden auch Paarbeziehungen mit westdeutschen Männern und damit das Verbleiben in Westdeutschland wahrscheinlicher. Als Ursache für die Auseinanderentwicklung des Bildungsniveaus von Frauen und Männern in den neuen Bundesländern sieht die Studie die Kollision eines Geschlechterarrangements, das seine Wurzeln in der DDR-Geschichte hat, mit den ökonomischen und gesellschaftlichen Veränderungen nach der Wiedervereinigung. Das Rollenbild von Frauen, gekennzeichnet durch hohe Wertschätzung ökonomischer Selbstständigkeit und Orientierung auf Tätigkeiten im qualifizierten Dienstleistungsbereich, erweist sich im wirtschaftlichen und gesellschaftlichen Strukturwandel als prinzipiell anpassungsfähiger als jenes der Männer, deren klassische Tätigkeiten in Industrie und Handwerk eine tief greifende Entwertung erfahren haben. / Between the fall of the Berlin Wall in 1989 and the year 2005, 1.6 million people have migrated from East Germany (the former German Democratic Republic – GDR) to West Germany. The majority of these migrants were female and between the ages of 18 and 29. This unbalanced migration has caused a disproportionate sex ratio in the East German population. The sex ratio (in the age group between 18 and 29) in 2005 was only 90 women per 100 men and in many remote counties the ratio was less than 85 to 100. In such a large and densely populated area this phenomenon is unique within Europe. This study identifies the development of a considerable discrepancy in educational levels between women and men in Eastern Germany as one important cause for the disproportionate sex ratio in migration. The higher educational level of women is not only an economic factor: Since women generally prefer partners with at least the same educational level, relationships between East German women and West German men has become much more likely than the opposite. As a cause for the discrepancy in educational levels the study highlights a clash between gender roles rooted in GDR history and structural changes that took place after German reunification. The role model of women – a high valuation of economic independence and orientation towards professions in the service sector – proves to be more adaptable to the economic and social changes in East Germany than the role model of men, whose classical vocations in industry and crafts experience a considerable devaluation.

Postcopulatory sexual selection—sperm competition and cryptic female choice—has become a major area of research over the past 40 years. Within this field there are many outstanding questions at every level of analysis, from proximate to ultimate. The fitness consequences for both sexes in the period after copulation and before fertilization are considerable, but are obscured within the female reproductive tract. Our understanding of postcopulatory mechanisms is especially sparse in taxa other than birds and insects. Nearly nothing is known in reptiles except that multiple paternity is common and widespread, and often results from long-term sperm storage across breeding seasons. We present some of the very first data on the determinants of fertilization success in the context of sperm competition in reptiles, a group that accounts for 30% of terrestrial vertebrates. In the first chapter, "Asymmetric gametic isolation between two populations of red-sided garter snakes", we discuss the use of between-population crosses to reveal gametic isolation. The effect of population density and operational sex ratios on mating systems and the speciation process has fueled theoretical debate. We attempted to address these issues using two populations of red-sided garter snakes (Thamnophis sirtalis parietalis) from Manitoba, Canada. Our study populations differ markedly in their density mating aggregations, with a 10-fold difference between them. Using microsatellite markers for paternity analysis of litters produced from within and between population crosses. We found that the population with highest aggregation density, and presumably with the highest level of sexual conflict (i.e., when the evolutionary interests of the sexes differ) over mating, was also the population that exhibited homotypic sperm precedence. The less dense population showed a distinct postcopulatory male-size advantage. We also demonstrated that sperm stored within the female over hibernation can father 20-30% of offspring in a litter. In the second chapter, "Sperm competition and mate-order effects in red-sided garter snakes", we test whether females use mate-order effects to ensure that a larger (fitter) male will sire her offspring. Does that second male should have precedence in sperm competition? We tested for second-male precedence using singly-mated females that mated with a second male. Average proportion of paternity was shared equally among the first (P₁, i.e., proportion of offspring from a litter fathered by the first male to mate) and second males (P₂) to mate, and stored sperm (P[subscript ss]). This may be a case where last male precedence breaks down with more than two males. All females were spring virgins (they had not mated that spring, but may have stored sperm from fall matings); thus sperm stored presumably from fall matings is important in this system. As the interval between matings increased P₁ increased at the expense of P[subscript ss]. As the second male to mate's copulation duration increased, P₁ also increased at the expense of P₂. This last result may indicate female influence over sperm transfer during coerced matings. Copulatory plugs (CPs) are found in many taxa, but the functional significance is debated. Male garter snakes produce a gelatinous copulatory plug during mating that occludes the opening of the female reproductive tract for approximately two days. In chapter three, "Not just a chastity belt: the role of mating plugs in red-sided garter snakes revisited", we experimentally tested the role of the CPs. In snakes, sperm are produced in the testes and delivered through the ductus deferens, and the copulatory plug is thought to be produced by the sexual segment of the kidney and conveyed through the ureter. We manipulated the delivery of the two fluids separately by ligating the ducts. We confirmed that the CP is not formed in ureter-ligated males and that sperm leaks out immediately after copulation. The CP is analogous to a spermatophore. The protein matrix contains most of the sperm which are liberated as the plug dissolves within the female's vaginal pouch. One of the fundamental principles in sperm competition is that increased sperm numbers increase the odds of winning in competitions for fertilization success and males will adjust their ejaculate relative to competition and the quality of his mate. In chapter four, "Sperm depleted males and the unfortunate females who mate with them", we detect significant among-male variation in the number of sperm ejaculated, and that male mate-order reduces sperm numbers. Male sperm numbers drop significantly from one mating to the next, and this has implications for sperm competiveness, as Thamnophis sirtalis exhibits a disassociated reproductive tactic, in that sperm stores are produced outside the breeding season, and thus cannot be replenished after mating. Interestingly, however, the on average the mobility of the sperm increased for a male's second mating. Therefore, increased sperm quality may compensate for reduced numbers in a competitive context. Further, females increase their remating rate when mating with males that are unable to deliver sperm. In chapter five, "Sexual conflict during mating in red-sided garter snakes as evidenced by genital manipulation", we revisited the CP in the context of sexual conflict. Sex-differences in optimal copulation duration can be a source of conflict, as increased copulation duration may be advantageous for males as it delays female remating. Males of many species actively guard females to prevent them from remating, and in some cases males produce copulatory plugs to prevent remating. If precopulatory choice is limited at the time of her first mating, conflict may be especially onerous to a female. The size of the plug is influenced by the copulation duration. We experimentally tested the contribution of male and female control over copulation duration. We ablated the largest basal spine on the male's hemipene and found a reduction in copulation duration and an increase in the variation of plug mass. Further, we anesthetized the female's cloaca and found copulation duration increased, which suggests that males benefit from increased copulation duration while females actively try to reduce copulation duration. Therefore, sexual conflict is manifest in divergent copulation duration optima for males and females. / Graduation date: 2013

Les plumes d'oiseaux abritent de nombreux microorganismes qui pourraient être acquis dans l'environnement, ces microorganismes pouvant exercer une sélection intense sur leurs hôtes en réduisant leur fécondité et leur survie. Plusieurs taxons bactériens qui vivent sur des plumes ont la capacité de dégrader la kératine des plumes et causent des dommages à leur structure et peuvent modifier aussi leur coloration. Les oiseaux utilisent des signaux visuels tels que des couleurs vives ou des ornementations exagérées pour la communication socio-sexuelle ainsi que la reconnaissance des espèces. Seuls les individus en bonne santé sont capables de produire des caractères sexuels secondaires exagérés et restent résistants aux parasites débilitants. Le paon (Pavo cristatus) est une espèce polygame qui a plusieurs décorations exagérées, les caractères sexuels secondaires les plus remarquables du paon sont leur traîne décorée avec des ocelles magnifiques qui contiennent trois couleurs irisées différentes. Grâce à une technique basée sur la culture, j'ai isolé la communauté bactérienne des plumes de différentes parties colorées des ocelles de la traîne du paon. L'étude révèle qu'il y a eu une répartition hétérogène des bactéries parmi les différentes parties colorées des ocelles. L'abondance et la prévalence des taxa bactériens spécifiques étaient liées au degré de dégradation des plumes, à l'expression de différents caractères sexuels secondaires, à des changements dans la coloration des ocelles et à l'augmentation de la croissance quotidienne des plumes. En outre, nous avons constaté un petit effet de l'expression de caractères sexuels secondaires sur la proportion sexuelle des couvées avec un biais en faveur des individus masculins. Les travaux présentés dans cette thèse fournissent des preuves que les ocelles de plumes peuvent être considérés comme un signal fiable de la diversité et de l'abondance de bactéries chez le paon. En conséquence, ils représentent une indication pour la qualité individuelle, ce qui permet aux femelles de choisir des mâles avec une communauté bactérienne spécifique. / Bird feathers harbour numerous microorganisms that could be acquired from the surrounding environment, these microorganisms may exert intense selection on their hosts by reducing fecundity and survivorship. Several bacterial taxa that live on feathers have the ability to degrade feather keratin and cause damage to feather structure and may alter the feather colouration. Birds use visual signals such as bright colours or exaggerated ornamentation for socio-sexual communication as well as species recognition. Only healthy individuals are able to produce exaggerated secondary sexual characters and still remain resistant to debilitating parasites. Peacocks (Pavo cristatus) is a polygamous species that have different exaggerated ornamentation, the most notable secondary sexual characters of the peacock are their long-decorated trains that comprise the magnificent ocelli which contain three different iridescent colours. Through a culture based technique we isolate feather bacterial community from differently coloured parts of the ocelli of the peacock’s train. The study reveals that there was a heterogeneous distribution of bacteria among the differently coloured parts of ocelli. The abundance and prevalence of specific bacterial taxa was related to the degree of feather degradation, expression of different secondary sexual character, changes in ocelli colouration and daily growth increment. Furthermore, we found a small effect of the expression of secondary sexual characters on biasing of brood sex ratio towards production of more sons than daughters. The work presented in this thesis provide evidence that feather ocelli may consider as a reliable signal of the diversity and the abundance of bacteria in peacock and in consequence indication for the individual quality and that allowing the choosy females to pick males with a specific bacterial community.

The variability of egg-size within a bird species reflects different reproductive investments and, besides the intrinsic constraints and particular female quality, it can be affected by environmental factors, too. Moreover, the egg-size predetermines the chick performance. The knowledge of factors influencing precocial chick survival is crucial for better understanding of life-history strategies as well as for endangered species conservation. The Northern Lapwing (Vanellus vanellus) represents a suitable model species for investigation of climate variables effects on egg-size and also to study factors influencing chick survival. Eggs in a total of 714 nests were measured during 13 breeding seasons over period 1988-2014 in South Bohemia and 293 lapwing chicks from 100 broods in 37 localities were monitored in 2013-2014. The mean egg-size through the whole season is positively affected by March precipitation, March clutches also negatively by minus temperatures in March. The higher intensity of rainfall there is during March, the bigger eggs are laid in March and the steeper is slope of decline in mean egg-size during season. This decline is more profound with lower rainfall in April. The effect of habitat is not significant. The body mass and condition of hatchlings is positively correlated with the...

In this study, buckwheat (Fagopyrum esculentum Moench) and alyssum (Lobularia maritima (L.)) flowers were used to examine the effect of floral resources on the efficacy of the leafroller parasitoid Dolichogenidea tasmanica (Cameron) in vineyards. This was done by assessing the influence of these flowers on parasitoid abundance and parasitism rate, and by investigating the consequences of this for leafroller abundance. In laboratory experiments, alyssum flowers were used to investigate the effect of floral food on the longevity, fecundity and sex ratio of D. tasmanica. Dolichogenidea tasmanica comprised more than 95 % of parasitoids reared from field collected leafrollers in this study. The abundance of D. tasmanica during the 1999-2000 growing season was very low compared with previous studies, possibly due to the very low abundance of its leafroller hosts during the experiment. The number of males of this species on yellow sticky traps was increased (although not significantly) when buckwheat flowers were planted in a Marlborough vineyard; however, the number of female D. tasmanica on traps was no greater with flowers than without. The abundance of another leafroller parasitoid, Glyptapanteles demeter (Wilkinson)(Hymenoptera: Braconidae), on traps was also not significantly affected by the presence of buckwheat flowers, although females of this species were caught in greater numbers in the control than in buckwheat plots. Naturally-occurring leafrollers were collected from three vineyard sites in Marlborough, and one in Canterbury during the 2000-2001 season to assess the effect of buckwheat and alyssum flowers on parasitism rate. Parasitism rate more than doubled in the presence of buckwheat at one of the Marlborough vineyards, but alyssum had no effect on parasitism rate in Canterbury. A leafroller release/recover method, used when naturally-occurring leafrollers were too scarce to collect, was unable to detect any effect of buckwheat or alyssum on parasitism rate. Mean parasitism rates of approximately 20 % were common in Marlborough, although rates ranged from 0 % to 45 % across the three vineyard sites in that region. In Canterbury in April, mean parasitism rates were approximately 40 % (Chapter 4). Rates were higher on upper canopy leaves (40-60 %) compared with lower canopy leaves and bunches (0-25 %). Leafroller abundance was apparently not affected by the presence of buckwheat in Marlborough, or alyssum in Canterbury. Buckwheat did, however, significantly reduce the amount of leafroller evidence (webbed leafroller feeding sites on leaves or in bunches) in Marlborough, suggesting that the presence of these flowers may reduce leafroller populations. Leafrollers infested less than 0.1 % of Cabernet Sauvignon leaves throughout the 1999-2000 growing season, but increased in abundance in bunches to infest a maximum of 0.5 % of bunches in late March in Marlborough. In Pinot Noir vines in the 2000-2001 season, leafroller abundance was also low, although sampling was not conducted late in the season when abundance reaches a peak. In Riesling vines in Canterbury, between 1.5 % and 2.5 % of bunches were infested with leafrollers in April. In the laboratory, alyssum flowers significantly increased the longevity and lifetime fecundity of D. tasmanica compared with a no-flower treatment. However, daily fecundity was not increased by the availability of food, suggesting that the greater lifetime fecundity was related to increases in longevity. Parasitoids were also able to obtain nutrients from whitefly honeydew, which resulted in similar longevity and daily fecundity to those when alyssum flowers were present. The availability of food had a significant effect on the offspring sex ratio of D. tasmanica. Parasitoids reared from naturally-occurring leafrollers produced an equal sex ratio, assumed to be the evolutionarily stable strategy (ESS) for this species. In the laboratory, this ESS was observed only when parasitoids had access to alyssum flowers. Without food, or with honeydew only, sex ratios were strongly male-biased. In the field, floral resources affected the sex ratio of D. tasmanica only when this species was reared from leafrollers released and recovered in Marlborough. In that experiment, buckwheat shifted the sex ratio in favour of female production from the equal sex ratio found in control plots. No firm explanations can be given to account for these results, due to a lack of research in this area. Possible mechanisms for the changes in sex ratio with flowers are discussed. This study demonstrated that flowers are an important source of nutrients for D. tasmanica, influencing the longevity, fecundity and offspring sex ratio of this species. However, only some of the field experiments were able to show any positive effect of the provision of floral resources on parasitoid abundance or parasitism rate. More information is needed on the role these parasitoids, and other natural enemies, play in regulating leafroller populations in New Zealand vineyards, and on how they use floral resources in the field, before recommendations can be made regarding the adoption of this technology by growers.