The altruistic production of public goods is one of most popular puzzles in evolutionary biology, and is most commonly explained by the indirect fitness benefit accrued by producers. I develop our understanding of the ecology and evolution of public good production by considering how inter- and intraspecific interactions can affect indirect fitness benefits, and ultimately, the evolutionary trajectory of public good cooperation in a bacterial public good system: 1) I demonstrate the ability of public good cooperators to adapt to the presence of cheats by reducing their own cooperative output, constraining cheat fitness as a consequence. 2) I examine the relative contributions of inter- (bacteriophage) and intraspecific (social cheats) parasites on shaping bacterial mutation rates, and demonstrate that social cheats can gain a fitness advantage in the presence compared with the absence of interspecific parasites. 3) I formally show for the first time, that siderophore-mediated detoxification can be an altruistic trait, rapidly selecting for the evolution of de novo cheats, and discuss the implications this process may have for community structure and function. 4) I extend (3) to assess the impact the natural microbial community has on the fitness consequences of siderophore-mediated detoxification in a natural soil environment. 5) I discuss the interplay between rapid microbial evolution and community context, and propose the impacts such interplay may have for biotechnological applications.

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Understanding the maintenance of the variation that is typically observed in natural populations has been a central aim of evolutionary biology. In a feral population of Soay sheep on the island of Hirta, St. Kilda there is a phenotypic polymorphism for horns with males growing either normal or reduced (scurred) horns, and females growing either normal, scurred or no (polled) horns, with further variation in horn size within each of the horn types. This thesis examines the potential factors which maintain these polymorphisms. I first present an overview of the literature relating to the factors that potentially maintain variance in traits in natural populations. In chapter two I present an analysis that suggests that polymorphisms in both horn type and horn size may be maintained by trade-offs between allocation to reproductive success and survival in males, and by sexually antagonistic selection between males and females. In chapter three I test the hypothesis that female weaponry may convey an advantage in intrasexual conflicts over resources, rather than just being expressed as a consequence of genetic associations with the male phenotype. Chapter four examines the environmental factors which create variation between individuals in their horn length, revealing that individuals vary in response to the environment. In chapter five I investigate whether the temporally fluctuating environmental conditions of St. Kilda generate fluctuating selection on the horn length of normal-horned males, revealing that this mechanism constrains the evolution of horn length potentially maintaining variance. In chapter six I examine the genetic relationships between morphological traits, revealing that these relationships are dependent upon the environmental conditions experienced during the first year of life. Finally, I discuss the wider implications of these findings for our understanding of the maintenance of trait variation in the wild.

Evolution, physiology and ecology of root-parasitic Rhinanthoid Orobanchaceae was investigated with special emphasis on understanding biology of hemiparasitism. The research was based on a wide range of methods including molecular hylogenetics, cultivation experiments, stable isotope analysis, electron icroscopy, geometric morphometrics and flow-cytometry.

The life strategies of parasites and evolutionary mechanisms forming their diversity are particularly various and become frequent objects of study. The Ph.D. thesis deals with one of the obligate ectoparasitic haematophagous groups of insects, the species of the genus Cimex (Heteroptera: Cimicidae). Unlike in most other ectoparasites, the strategy of cimicids consists of remaining hidden in the shelter of their host. They use the host body only to feed and disperse. The advantage of the lower competition with other ectoparasites is counterbalanced by the need for particularly stable blood source, for which the cimicids choose social hosts living in colonies. The most frequent and the original hosts of cimicids are bats. The host range of particular species of Cimicidae is often rather broad. The morphological analysis of the Cimex pipistrelli species group showed, however, differentiation according to host bat species. This suggests a need for adaptation to particular host species within the usual range. The differentiation was not found reflected in the mitochondrial DNA. It is thus possible that cimicids can exhibit phenotype plasticity. The host associated morphological variability likely caused as many as three species of C. pipistrelli group to be described from Europe, from which two were...

In this thesis, I study a radiation of brood-parasitic finch species, the indigobirds and whydahs (genus Vidua), that occur across Africa. Host colonisation is tightly linked to speciation in Vidua because of their remarkable capacity to imprint on their hosts, with mating traits and host preferences being influenced by the parasite's early environment. The challenge of explaining why the radiation has diversified to the extent it has therefore simplifies to understanding why only certain potential host species have been successfully colonised. Following on from the introduction (Chapter 1), I begin by critically examining the logic with which mimicry in the natural world can be conceptually organized (Chapter 2). This creates a “mimicry landscape” in which to situate the mimetic adaptations of hosts exhibited by Vidua. The framework can be used to contrast and draw parallels between these and other mimetic adaptations present in the natural world. In Chapter 3, I review the literature on begging call mimicry and development across all avian brood parasite species. I outline the conditions under which we expect begging call mimicry to evolve, and when we expect it to develop primarily through genetic or environmental cues. This provides clear predictions for what we expect to occur in Vidua finches, which are tested in Chapters 4 and 5. In Chapter 4, I quantify the mimicry of host nestlings by Vidua in detail. I provide the first quantitative evidence that Vidua nestlings mimic the begging calls and show for the first time that Vidua are imperfect mimics of their hosts. In Chapter 5, I simulate the colonisation of a new host by transferring Vidua eggs into the nest of a new host species. I monitor Vidua survival in the foreign host environment and test several hypotheses about what explains differences in chick survival. I find that Vidua survive poorly in the new nest environment and that they do not show adaptive plasticity in begging calls or head movements. This poor survival occurs despite there being minimal differences in the diets each host species feeds their young. Finally, in Chapter 6, I carry out a comparative analysis on the evolution of estrildid mouth markings. Estrildid finches are the hosts of Vidua and so provide the landscape of potential ecological niches that Vidua may colonise and adapt to. I demonstrate that the host family shows strong phylogenetic signal in mouth marking traits, and find no evidence that ecological factors such as light environment or predation pressure has shaped estrildid mouth marking evolution. The work in this thesis highlights how difficult successfully colonising new hosts is for Vidua finches. Vidua must mimic hosts in multiple traits (mouth markings, begging calls, head movements) to obtain sufficient amounts of food from host parents. Overall, habitat filters, the complex and diverse begging displays of estrildid nestlings, the discriminatory behaviour of estrildid parents against mismatching chicks and the lack of adaptive plasticity in begging displays by Vidua together help explain why the Vidua radiation consists of only 19 species rather than many more or fewer.

Phylogenetic studies are providing powerful new insights into the evolution of complex traits. Metal hyperaccumulation is an unusual and complex physiological trait found in about 500 plant species and is associated with an exceptionally high degree of tolerance of metalliferous soils. Alyssum L. (Brassicaceae) is the largest known hyperaccumulator genus, comprising approximately 188 species distributed throughout the Mediterranean region and south-west Asia. Approximately one-quarter of these are largely restricted to areas of serpentine soils and have the ability to accumulate nickel to high concentrations in shoot tissue. This genus provides a good example in which to study the origins of a complex physiological trait, but its phylogeny is currently poorly understood. To produce a well-resolved phylogenetic tree to investigate the number and timing of origins of nickel hyperaccumulation within Alyssum, DNA sequences were generated for four chloroplast regions (matK, rps16–trnK, trnD–T and trnL–F) from 170 of 255 species in the tribe Alysseae. Additional sequencing was carried out for the chloroplast genes ndhF and rbcL and the nuclear gene PHYA. A Bayesian analysis employing a relaxed uncorrelated lognormal molecular clock and multiple fossil-age calibration points was carried out to reconstruct a time-calibrated phylogeny of this tribe using appropriate outgroups. Optimization of the nickel hyperaccumulation trait onto the resulting phylogenetic tree suggests that nickel hyperaccumulation arose twice in the Alysseae in the late Miocene/early Pliocene: 3.3–8.3 Mya in Alyssum and 6.3–8.8 Mya in Bornmuellera. The single origin in Alyssum is strongly associated with a significant acceleration in net species diversification rate, suggesting the ability to hyperaccumulate nickel could have provided a key evolutionary innovation facilitating rapid range expansion and subsequent species diversification. The scattered distribution of nickel hyperaccumulators across small island-like patches of serpentine soil suggests that allopatric speciation may have driven rapid diversification in this clade.

Photosynthesis is responsible for fixing approximately 111 – 117 Pg of CO₂ into organic carbon each year, of which about half is performed by algae in the oceans. Over geological timescales, photosynthesis by algae was instrumental in transforming Earth’s atmosphere. Despite the integral role algae play in the carbon cycle, the interaction and feedbacks between CO₂ fixation by algae and atmospheric CO₂ is poorly understood. This thesis expands upon our current knowledge by tracing the evolution of the key enzyme of photosynthesis, Rubisco, in algae through geological history. It was found that Rubisco underwent adaptation during distinct periods corresponding with falling atmospheric CO₂. The pattern of adaptation hints at physiological adaptation to varying concentrations of atmospheric CO2 and possibly indicates the emergence of carbon concentrating mechanisms (CCMs). This adaptation was probed further within the red and chromist algae, identifying key residues within the Rubisco protein sequence that may influence its kinetic properties. This research also provided new measurements of Rubisco CO2 affinity within the haptophyte algae. Finally, the importance of HCO₃- use by phytoplankton in the modern ocean was explored. HCO₃- utilisation was modelled through signals retained within stable carbon isotopes of organic matter estimate the response to anthropogenic increases of CO₂. The results indicate that phytoplankton utilise a large proportion HCO₃- which shows little sensitivity to anthropogenic increases of CO₂, even when model predictions are extended to 2100. This thesis demonstrates how algae can respond to CO₂ levels over geological and anthropogenic time scales.

C4 photosynthesis is an advanced complement to the more ancestral and more commonpathway refereed to as C3. C4 metabolism has evolved in several taxa, and it is theorized thatit worked as an adaptation to the low CO 2 levels characteristic of late geological time. Theadaptation also carries with it some resistance to the negative effects brought on by hightemperatures and drought. C4 metabolism is, however, not free, meaning that underconditions of lower temperature and higher CO2-levels, C3 photosynthesis is still moreviable. This makes it interesting to study how C4-species might shift their ranges in responseto climate change, as it implies both elevated CO 2 levels and higher mean temperatures inmost parts of the world. In this report, I develop a model based on the CO 2/O2 specificity of Rubisco from Spinach(Spinacia oleracea) at different temperatures, using data found in literature on the subject.The resulting model has some success in describing the current distribution of C4 species,using temperature and CO2 concentration as explanatory variables.

A range-wide collection of Juglans regia seeds was undertaken in autumn 1997 from 12 countries, including 25 provenances and 375 half-sib progenies. 2200 seedlings were produced using innovative nursery techniques. The seedlings were planted in three provenance trials in southern England in 1999, the largest of which acted as a combined provenance/progeny trial. After one growing season, survival was 98.9 %, mean height growth 35 cm, and mean stem diameter increment 5 mm. Provenance differences for both height and stem diameter increment were highly significant (p<0.001). There were no significant genotype × environment interactions. Flushing assessments revealed few significant differences between provenances and flushing was complete by early April. Family heritability for tree height was 0.19 at one site and, with combined selection, genetic gain was estimated at 8 %. The effects of three types of treeshelter and a stumping treatment on walnut establishment were tested over three growing seasons. Treeshelters were found beneficial to height increment. However, 120 cm tall shelters promoted early flushing, and consequent risk of increased frost damage, and caused more stem die-back than 75 cm shelters. Stumping promoted rapid early height increment but gave no longer-term benefit. The crown (cd) and stem (dbh) diameter at breast height relationship of open growing trees in Britain was assessed and was highly significant (r2 = 0.96, p<0.001). The regression equation (cd = 2.71 + 17.6dbh) permitted the estimation of suitable planting densities for the provenance trials and the calculation of a thinning regime. Isozyme analysis of the 375 genotypes identified 20 loci in 15 enzyme systems with seed embryo extracts. Using young leaf extracts, the polymorphic locus Pgm-1 indicated low expected heterozygosity of 0.06 both within populations and at the species level. FST and GST estimates, both 0.05, indicated high uniformity among populations. Genetic distance estimates did not identify significant clustering consistent with geographic origin.