Phenotypic traits that vary geographically within species are commonly assumed to represent local adaptations to different environments. In order for local adaptation to evolve by natural selection, three conditions must be met: (1) traits must vary geographically, (2) local variants of traits must provide a fitness advantage (increased survival or reproductive success) within the local environment, and (3) local variants of traits must be heritable. In chapter two, we review evidence for local adaptation in birds. Geographic variation among populations is nearly ubiquitous, yet experimental tests of the fitness advantages of local trait variants are rare among populations of birds, presumably because of the difficulties in transporting individuals between populations. Thirty-seven studies have tested the heritability of among population variation in traits. Thirty-three of the 37 studies found some degree of heritability of variation among populations, consistent with traits diverging in response to natural selection. In chapter three, we experimentally test the fitness consequences of divergent nest morphologies of Yellow Warblers (Dendroica petechia) using reciprocal nest transplant experiments between a temperate and subarctic site in Canada. Yellow Warblers breeding at our subarctic site build larger nests constructed with more insulative materials than Yellow Warblers breeding at our temperate site, and these differences are the result of different nest building behaviours. Temperate nests transplanted to subarctic sites experienced significantly colder temperatures, and tended to suffer higher egg and nestling mortality due to climatic conditions (cold temperatures), than locally transplanted subarctic nests. Adult females breeding in subarctic sites that received temperate nests changed their incubation behaviours by taking shorter recesses than females who received locally transplanted subarctic nests. In contrast, subarctic nests transplanted to our temperate site showed no changes in nest temperature, fledgling success, or parental behaviour during incubation. We suggest that divergent selective pressures acting on Yellow Warblers in subarctic and temperate environments results in different nest building behaviours. Cold temperatures in our subarctic site likely favour increased investment in larger, insulative nests, whereas warmer temperatures at our temperate sites likely favour reduced investment in nest building, and consequently smaller nests. / Thesis (Master, Biology) -- Queen's University, 2010-09-28 13:16:38.686

In this thesis, I combine molecular analyses, common-garden and field experiments to examine how evolutionary and ecological processes influence patterns of genetic variation among and within populations of the declining, insect-pollinated, self-incompatible, perennial herb Primula farinosa. More specifically I examined 1) whether genetic diversity at neutral marker loci was related to habitat fragmentation and habitat stability, 2) whether floral display and flowering time were more strongly differentiated among populations than were putatively neutral marker loci, 3) whether adaptive population differentiation could be detected on a local spatial scale, and 4) whether floral display differentially affected male and female reproductive success. Genetic diversity at neutral marker loci was lower within fragmented populations on the Swedish mainland than within the more densely occurring populations on the island Öland, SE Sweden. On Öland, fluctuations in population size were more pronounced on thin than on deep soils, but genetic diversity was not related to soil depth. Among-population genetic differentiation in scape length and flowering time was stronger than that of neutral marker loci, which is consistent with divergent selection acting on these traits. Water availability should influence the length of the growing season and thus the time available for fruit maturation, but flowering time in a common-garden experiment was not related to estimates of water availability at sites of origin. In a reciprocal transplant experiment conducted among four populations separated by up to a few kilometres and growing in environment differing in water availability and grazing intensity, no evidence of local adaption was observed. Finally, in a field experiment, interactions with pollinators and antagonists differentially affected selection on floral display through male and female function. Taken together, the results indicate that habitat connectivity and environmental heterogeneity contribute to high neutral and adaptive genetic variation in Primula farinosa on the island Öland, SE Sweden, and illustrate that effects on both male and female reproductive success need to be considered to understand fully the evolution of floral display.

<p>The evolution of selfing from outcrossing is one of the most frequent mating system transitions in angiosperms. Plants that are highly selfing typically exhibit a suite of morphological traits termed a "selfing syndrome," including reduced corollas and reproductive structures, loss of corolla pigmentation, little anther-stigma separation, and a low pollen/ovule ratio. The overall consensus among scientist is that the morphological changes that accompany the transition to selfing are adaptive and thus a product of natural selection. Few attempts, however, have been made to determine whether traits of the selfing syndrome are truly an operation of natural selection or if genetic drift could be the acting force. My dissertation examines the roles that natural selection and genetic drift played in the evolution of the selfing syndrome in Ipomoea lacunosa. With the use of field observations, crossing data, and molecular analyses, I show that I. lacunosa has evolved increased selfing ability, decreased anther-stigma distance and smaller, white flowers, compared to its closest relative I. cordatotriloba. Furthermore, using a standard QST - FST comparison, I evaluated the relative importance of selection and drift in the evolution of the selfing syndrome in I. lacunosa. I also identified the genetic basis of flower color divergence between I. lacunosa (white) and I. cordatotriloba (purple) and examined patterns of variation to determine if selection or genetic drift caused the divergence. Analyses revealed that the traits of I. lacunosa characteristic of the selfing syndrome have evolved as a product of natural selection, not genetic drift.</p> / Dissertation

<p>Changes in the expression and function of genes active during metazoan development have played a critical role in the evolution of morphological differences between species and phyla, yet the origins of these changes remain poorly understood. What roles do positive and negative selection play in the evolution of development? How do evolutionary changes accumulate given the degree to which organisms are able to buffer the effects of environmental and genetic perturbations during development? The crucial insight of the Modern Evolutionary Synthesis was that divergence between species arises from variation within populations. Following this principle, I have made use of tools from quantitative and population genetics to investigate three central questions: 1) How much genetic variation is there in the networks of genes that underlie metazoan development? 2) What affect does developmental buffering have on the accumulation of selectable genetic variation? 3) To what extent does selection act to shape patterns of genetic variation among different kinds of genes and at different stages of development? I show that developmental systems can harbor extensive levels of genetic variation, and that the amount of genetic variation in individual genes at different stages of development is related to the extent to which variation in those genes is buffered by genetic interactions. I also show that while selection plays an active role in shaping genetic variation in development, the extent to which variation in a gene is visible to selection depends in predictable ways on a) the biological function of that gene and b) whether the mutations in question influence gene expression or protein function. My results as a whole demonstrate the utility of population level approaches to the study of the evolution of development, and provide key insights into the role that selection plays in generating developmental variation.</p> / Dissertation

The colour of guppies (Poecilia reticulata) evolves as a compromise between sexual selection (favouring conspicuousness) and natural selection (favouring crypsis). However, guppies live in a variety of habitats and with a variety of predators and consequently in a variety of selective environments. I investigated how habitat and predator's visual systems affect the evolution of colour. I used regressions to assess the importance of habitat features on the evolution of colour for 29 guppy populations. I then quantified the colour of guppies living in the presence and absence of two predators. The prawn predator is insensitive to orange light while the fish predator is insensitive to ultraviolet light. Habitat explained some variation in colour, but not in a consistent manner. Guppies living with the prawn were more orange and guppies living with the fish had more ultraviolet reflectance, providing evidence for the use of these aspects of colour as private signals.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2006. / Härtill 5 uppsatser.

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

Diss. (sammanfattning). Umeå : Sveriges lantbruksuniv. / Härtill 6 uppsatser.

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 93-102). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.