The formation and persistence of species are the subject of much debate among biologists. Many species of Drosophila are behaviourally isolated, meaning that heterospecific individuals are not attracted to one another and do not interbreed. Often, this behavioural isolation is at least in part due to differences in pheromonal preference. Drosophila pheromones are long-chain cuticular hydrocarbons (CHCs). Desaturases are enzymes that are important for the production of CHCs. This thesis investigates the evolution of the gene family across 12 species of Drosophila. Desaturase genes were located in all species. Some genes, those that have previously been shown to have important roles in pheromonal communication, have experienced duplication and loss in several species. Two previously undiscovered duplicates were identified. Generally the desaturase gene family is governed by purifying selection, although following duplication these constraints are relaxed and in some cases duplicated genes show compelling evidence of positive selection. One of the loci under positive selection, the novel duplicate desat1b of the obscura group, was found to have a sex-biased expression pattern and alternative splicing in its 5′ UTR. In RNAi knock-down experiments of desaturase gene function in D. melanogaster, several desaturases were shown to affect CHC profiles of males and females, including some that were previously unlinked to CHC production.

Stunned by the implications of Colage's analysis of the cultural activation of the brain's Visual Word Form Area and the potential role of cultural neural reuse in the evolution of biology and culture, the authors build on his work in proposing a context for the first rudimentary hominin moral systems. They cross-reference six domains: neuroscience on sleep, creativity, plasticity, and the Left Hemisphere Interpreter; palaeobiology; cognitive science; philosophy; traditional archaeology; and cognitive archaeology's theories on sleep changes in Homo erectus and consequences for later humans. The authors hypothesize that the human genome, when analyzed with findings from neuroscience and cognitive science, will confirm the evolutionary timing of an internal running monologue and other neural components that constitute moral decision making. The authors rely on practical modern philosophers to identify continuities with earlier primates, and one major discontinuitysome bright white moral line that may have been crossed more than once during the long and successful tenure of Homo erectus on Earth.

Genetic variation was examined at 19 loci encoding enzymatic and general proteins Notropis lutrensis from the Brazos River in Texas. The thermal regime of the Brazos River below Possum Kingdom Reservoir is altered due to the release of water from the hypolimnion. Summer water temperatures fluctuate as much as 7^oC. Levels of heterozygosity at the malate dehydrogenase-2 locus were correlated with the degree of water temperature fluctuation at each locality. The isozymes from three homozygous patterns of supernatant malate dehydrogenase (Mdh-l, Mdh-2) exhibited different activities at different experimental temperatures.

Spatial and temporal variation in the environment are ubiquitous. Traits are called clinal when they vary along an environmental gradient, and this is often interpreted as the result of spatially varying selection. Drosophila melanogaster is known to have many phenotypic and genotypic clines, replicated in many regions of the world. Recent studies have suggested that most clinal variation could be attributed to neutral, demographic processes. Because the environment varies in similar ways with latitude and across seasons, and seasonal variation is orthogonal to demography, one promising approach is to integrate clinal and seasonal variation to infer selection. Here, we test whether there is a genome-wide relationship between clinal and seasonal variation, and whether the pattern is consistent with selection. Also, we investigate the proportion of the variants that should be under latitudinal and seasonal selection to explain the pattern we uncovered. We estimate allele frequency from pooled samples of flies from eight different locations along the east coast of the US, and 13 samples collected in the spring and in the fall in Pennsylvania. We show that there is a genome-wide pattern of clinal variation mirroring seasonal variation. This pattern is stronger for exonic when compared to intergenic regions, consistent with natural selection. We find that the genome-wide relationship between clinal and seasonal variation could be explained by about 6.6% of our SNPs being under latitudinal and seasonal selection. Our results are consistent with the adaptive hypothesis of clinal variation and, together with other observations, leave little room for the role of demography in maintaining clines in D. melanogaster / Variação espacial e temporal são ubíquas. Caracteres são chamados clinais quando variam ao longo de um gradiente ambiental, e isso é interpretado como resultado de seleção estruturada no espaço. Drosophila melanogaster apresenta clinas em diversos caracteres fenotípicos e genotípicos, as quais são replicadas em diferentes regiões do mundo. Estudos recentes sugeriram que grande parte da variação clinal pode ser atribuída a processos neutros. Como o ambiente varia de maneira similar com a latitude e ao longo do ano, e essa variação sazonal é ortogonal à demografia, uma abordagem possível para inferir seleção natural é integrar variação clinal e sazonal. Neste trabalho, nós testamos se há uma relação entre variação clinal e sazonal ao longo do genoma de D. melanogaster. Também, investigamos a proporção de variantes que deveriam estar sob seleção espacial e sazonal para explicar o padrão encontrado. Estimamos a frequência alélica a partir de amostras de pools de moscas coletadas em diferentes oito localidades ao longo da costa leste dos Estados Unidos e em diferentes estações do ano na Pensilvânia, EUA. Nós encontramos um padrão genômico de variação clinal refletindo variação sazonal. Esse padrão é mais forte para variantes em regiões exônicas do que intergênicas, consistente com a ação de seleção. A relação entre variação clinal e sazonal encontrada pode ser explicada se 6,6% dos polimorfismos estiverem sob seleção espacial e sazonal. Nossos resultados são consistentes com a hipótese adaptativa de variação clinal e, junto com outras observações, revelam que o papel da demografia na manutenção de clinas em D. melanogaster é limitado

Populações nativas da América do Sul apresentam diversidade genética reduzida em relação às demais populações do mundo e alta diferenciação interpopulacional dentro do continente. As pressões seletivas sobre a região cis-reguladora do CCR5 geram uma assinatura de diversidade oposta àquela esperada com base na história demográfica, reduzindo a variação interpopulacional e contribuindo para uma elevação das taxas de polimorfismo. No presente estudo investigamos a interação entre esses processos micro-evolutivos, analisando o polimorfismo da região cis-reguladora de ameríndios da América do Sul e comparando os resultados com aqueles obtidos em outras regiões do mundo. Sequenciamos 927 pares de base (pb) da região controladora do CCR5 em 7 tribos indígenas da região amazônica. Em ameríndios, nenhum haplótipo exclusivo foi encontrado em ameríndios e os dois haplogrupos mais comuns foram de diferentes clusters filogenéticos. A diversidade nucleotídica (&#960;) para a amostra total, foi a mais alta dentre todas as regiões do mundo já estudadas (&#960;=0,0027). A estimativa da diversidade genética populacional para ameríndios, baseada no número de sítios polimórficos (&#952;s), foi similar aos valores encontrados para as populações não-africanas, sendo que em africanos o valor foi praticamente o dobro. Conseqüentemente, foi observado um valor de D de Tajima positivo e estatisticamente significativo (D=2,82, p<0,01), maior do que aquele visto para outras regiões do mundo. Através de comparações empíricas e de simulações coalescentes verificamos que o alto valor de D de Tajima encontrado para ameríndios não é explicável por um recente modelo demográfico de evolução humana. O teste Ewens-Watterson indicou para a amostra ameríndia uma taxa de heterozigose maior do que esperada para um população neutra. O valor de Fst observado para comparação envolvendo asiáticos e ameríndios foi mais baixo que 1000 valores de Fst calculados a partir de 783 microssatélites genotipados em amostras de mesmo tamanho de regiões geográficas similares. Essas caraterísticas corroboram a hipótese de seleção balanceadora na região cis-reguladora do CCR5 de ameríndios da região amazônica brasileira. No presente estudo demonstramos também a existência de uma associação estatisticamente significativa (p<0,01) entre os alelos mantidos em freqüências intermediárias na população humana e regiões ativadoras de splicing localizadas em exons (ESEs). Finalmente, nós acreditamos que um modelo demográfico de evolução humana, complementar ao utilizado neste trabalho, deve ser testado para se refutar a hipótese de que a forte assinatura de seleção balanceadora observada em ameríndios não foi causada por seleção natural que atuou em população ancestral à de indígenas americanos / Native american populations show lower genetic diversity and higher interpopulational genetic differences than populations from other continents. Within South America groups from the non-andean geographic region shows extremely high genetic differentiation. The strong signature of balancing selection observed for 5\' cis-regulatory region of the CCR5 gene at the worldwide scale represents an opposite pattern of genetic variation to that expected by demographic process which acted in Amerindians. To evaluate the impact of complex demographic history on the 5\' cis-regulatory region of CCR5 we resequenced 927 bp of this locus in 62 individuals from different native groups located in the Brazilian Amazonian region. No new haplotype was detected and the two most common haplogroups observed were from different phylogenetic clusters, according with the pattern observed for other human populations. The level of heterozigosity of the total sample, measured by nucleotide diversity (&#960;) was the highest yet described for human populations (&#960;=0,0027) while values based on polymorphic sites (&#952;s) were similar among Amerindians and non-Africans populations. Consequently we observed a positive and significant Tajima\'s D value (D=2,82, p <0,01). This value was higher than all D values observed for the other human populations. Observed summary statistics (&#960; and D) were significantly higher than same statistics estimated from 2000 simulated samples assuming a recently proposed demographic model of human evolution. We also found significant deviations in Ewens-Watterson homozygosity test toward an excess of heterozygosity for Amerindian sample. Another striking feature of CCR5 cis-regulatory region was the low Fst value among populations. The Fst among Asians and Amerindians was an outlier among 1000 Fst values estimated by 783 microssatelites of samples from similar geographic regions and with the same sample sizes as those of the CCR5 5\' cis-regulatory data. These features corroborates the strong signature of balancing selection described for CCR5 5\'cis regulatory region. We also contributed to discussion about functional aspects of CCR5 cis-regulatory region demonstrating a significant association between intermediate frequency SNPs and exonic splicing enhancers (ESEs) regions (p<0,01). Finally, we believe that improved models of demographic human evolution must be tested to refute the hypothesis that the strong signature of balancing selection observed in Amerindians was not caused by a selection pressure which occurred in an ancestral population.

Flexibilidade comportamental é a capacidade de ajustes comportamentais que permitem aos indivíduos responderem a um novo desafio ambiental podendo ser, ou pela modificação de suas respostas, ou por desenvolver novas estratégias diante de um novo estímulo. Esse novo comportamento pode ser alvo da seleção natural, apesar de não ser hereditário. O que é transferida para as próximas gerações, é a capacidade de ajustar o comportamento. Assim, é plausível assumir a existência de uma associação entre capacidades cognitivas e o desafio do ambiente. Neste contexto, espera-se que indivíduos territoriais exibam capacidades cognitivas associadas ao seu habitat específico. Estudos têm frequentemente focado em diferenças nas capacidades de resolução de problemas em animais de espécies e populações distintas. No entanto, o presente estudo compara capacidades de resolução de problemas de lagartos Tropidurus torquatus de uma mesma população que utilizam dois tipos de territórios, os quais diferem no grau de desafio: muros, ambientes desafiadores, e árvores, ambientes permissíveis. Essa espécie exibe um comportamento territorial em que machos dominantes e fêmeas associadas possuem uma fidelidade evidente aos seus territórios. Lagartos foram observados no campo para a caracterização do território e, posteriormente, realizaram testes de resolução de problemas no laboratório. Os resultados demonstraram que lagartos de ambientes desafiadores obtiveram um desempenho superior aos de ambientes permissíveis nos testes de resolução de problemas, e foram mais propensos em exibir uma inovação comportamental durante a resolução dos testes. As interpretações para esses resultados consistem em duas possíveis explicações. Lagartos de muros podem se beneficiar de capacidades cognitivas avançadas, pois a seleção natural teria agido na flexibilidade comportamental e selecionaria indivíduos que poderiam lidar com problemas de uma ambiente desafiador. Alternativamente, é possível que a maioria dos lagartos Tropidurus torquatus apresentem melhores capacidades de resolução de problema, porém esta característica estaria críptica, e apenas a interação entre o indivíduo e a vivência em ambientes desafiadores (muros) induziria o surgimento de melhores capacidades cognitivas. Os resultados desse estudo provavelmente indicam que diferenças nas capacidades de resolução de problemas e habilidades cognitivas entre indivíduos poderiam estar sob efeitos de regimes seletivos antes mesmo de ocorrer alguma segregação populacional. / Behavioral flexibility is the ability of behavioral adjustments that allow individuals to respond to a new environmental challenge by either modifying their responses or developing new strategies when facing novel stimuli. This new behavior may be target of natural selection, despite not being heritable. What is transferred to the next generation is the capacity to adjust behavior. Thus, it is plausible to assume the existence of an association between cognitive capabilities and environmental severity. In this context, it is expected that territorial individuals exhibit cognitive capabilities associated with their specific habitat. Studies have often been focused on differences of problem-solving capabilities in animals from different species and populations. Nevertheless, the present study compares problem-solving abilities of Tropidurus torquatus lizards from the same population that use two types of territories that differ in the level of harshness: house walls, a harsh environment, and trees, a mild environment. This species exhibits a territorial system where dominant males and associated females have an evident fidelity to their territories. Lizards were observed in the field for territory characterization and then performed problem-solving tests in the laboratory. The results show that lizards from harsh environments outperformed those from mild environments in the problem-solving tasks and were more likely to show a behavioral innovation when solving the task. Interpretations for these results resides on two possible explanations. Lizards from walls might benefit from enhanced cognitive capabilities because natural selection acted on behavioral flexibility and selected individuals that can deal with problems of a harsh environment. Alternatively, it is possible that the majority of Tropidurus torquatus lizards exhibit enhanced problem-solving capability, but this characteristic might be cryptic, and only the interaction between the individual and living in a harsh environment (walls) induces the emergence of enhanced cognitive capabilities. These findings probably indicate that differences in problem-solving and cognitive capabilities might be exposed to specific selective regimes even before population segregation occurs.

[Truncated abstract] Despite the costs associated with mating, females of many taxa solicit multiple mates during a single reproductive event (polyandry). Polyandry is clearly adaptive when females gain direct benefits from males at mating. However, polyandry has also been shown to increase female fitness in the absence of direct benefits. Thus, a number of genetic benefit hypotheses have been developed to account for the origin of this behaviour. Although not mutually exclusive, a distinction lays between genetic benefits that propose defense against reproductive failure (nonadditive genetic effects), and those that propose benefits from intrinsic sire effects (additive genetic effects). Nonadditive genetic benefits of polyandry have been documented in a number of species; by soliciting multiple mates females can avoid inbreeding and other forms of incompatibility between parental genotypes. Polyandry may also increase female reproductive success when genetically superior males have greater success in sperm competition, and produce better quality offspring. An inevitable consequence of polyandry is that sperm from rival males will overlap in the female reproductive tract and compete to fertilise the ova. The outcome of sperm competition is typically determined by bias in sperm use by the females, interactions between parental genotypes, and ejaculate characteristics that provide a fertilisation advantage. Thus, sperm competition is recognised as a persuasive force in the evolution of male reproductive traits. Comparative analyses across species, and competitive mating trials within species have suggested that sperm competition can influence the evolution of testis size and sperm production, and both sperm form and sperm function. ... After six generations of selection I observed phenotypic divergence in litter size - litter size increased in the polyandrous lines but not in the monandrous lines. This result was not attributable to inbreeding depression, or environmental/maternal effects associated with mating regime. Genetic benefits associated with polyandry could account for this result if increased litter size were attributable to increased embryo survival. However, males from the polyandrous lineages were subject to sperm competition, and evolved ejaculates with more sperm, suggesting that evolutionary increases in litter size may in part be due to improved male fertility. Finally, Chapter Five is an investigation of the natural variation in levels of polyandry in the wild, and the potential for sperm competition to drive macroevolutionary changes in male reproductive traits among geographically isolated island populations of house mice. I sampled seven island populations of house mice along the coast of Western Australia and, by genotyping pregnant females and their offspring, determined the frequency of multiply sired litters within each population. I applied the frequency of multiple paternity as an index of the risk of sperm competition, and looked for selective responses in testis size and ejaculate traits. I found that the risk of sperm competition predicted testis size across the seven island populations. However, variation in sperm traits was not explained by the risk of sperm competition. I discuss these results in relation to sperm competition theory, and extrinsic factors that influence ejaculate quality.

The aim of this thesis project was to elucidate patterns and processes associated with the biotic interactions in a natural plant–herbivore–parasitoid food web characterized by spatial and temporal heterogeneity with regard to species composition. The system examined is based on island populations of the perennial herb Meadowsweet (Filipendula ulmaria, Rosaceae), located in the Skeppsvik Archipelago. The area is subject to isostatic rebound, amounting to 0.85 cm per year; this makes it possible to calculate the age of the rising islands. Meadowsweet colonizes new islands when they are about 100 years old. Meadowsweet is consumed by two major herbivores in the study area: Galerucella tenella and Altica engstroemi (Coleoptera: Chrysomelidae). Both herbivores overwinter in the topsoil and successful colonization occurs when the islands reach a height that prevents the beetles from being removed or killed as a result of wave wash during the winter. I found that both herbivores significantly reduced individual plant fitness and population growth rate. A “cafeteria experiment” with Galerucella showed that this beetle discriminated between plants from different islands, avoiding plants from old islands which contained high concentrations of putative defence compounds, while readily accepting plants from younger islands which contained lower concentrations of these chemicals. Further, the plant species exhibited a trade-off between growth and production of the putative defence compounds. Taken together, these results were interpreted as providing evidence of herbivore-driven evolution of resistance in Meadowsweet. Further, laboratory studies suggested that Galerucella gradually includes a less preferred host plant (Rubus arcticus, Rosaceae) in its diet as Meadowsweet resistance increases. This implies that Galerucella drives its own host-breadth enlargement by selectively inducing a ‘rent rise’ in the original host, Meadowsweet. In a number of field studies I showed that the oligophagous parasitoid Asecodes mento (Hymenoptera: Eulophidae) has a strong positive effect on Meadowsweet seed set by removing large numbers of G. tenella larvae. This top-down effect is, however, altered by the presence of a close relative of G. tenella, namely G. calmariensis, which is monophagous on Purple loosestrife (Lythrum salicaria, Lythraceae). G. tenella experiences associational susceptibility when coexisting with G. calmariensis since the latter supports a higher and more fit pool of shared parasitoids and because Meadowsweet attracts a higher proportion of the shared parasitoid females than Purple loosestrife. This implies that G. tenella densities are very low in coexisting populations and that Meadowsweet experiences associational resistance and produces more seeds when co-occurring with Purple loosestrife. Thus, selection for increased resistance in Meadowsweet is likely to be relaxed in populations mixed with Purple loosestrife. I conclude that the evolution of plant resistance is likely to depend on the length of time and intensity of selection. When Meadowsweet colonizes new islands it experiences a period of enemy-free space; followed by a midlife and ageing with selection by herbivores. The intensity of this selection does, however, depend on the presence of additional plant and herbivore species.

There is considerable evidence that pollinator shifts can explain many differences in flower morphology between closely related plant species, but the extent to which pollinator shifts can explain the maintenance of among-population variation in floral traits within species is poorly known. In this thesis, I combined comparative and experimental approaches to examine the evolution of floral traits in the moth-pollinated orchid Platanthera bifolia. More specifically, I investigated (1) the relationship between flower and pollinator morphology, (2) phenotypic selection on morphology and phenology in populations in contrasting environments, (3) components of prezygotic reproductive isolation among divergent populations, and (4) the adaptive and functional significance of two correlated floral traits. A study of Scandinavian of P. bifolia populations revealed that spur length was positively correlated with proboscis length of local pollinators, which suggests that variation in spur length reflects adaptive evolution in response to geographically variable pollinator-mediated selection. A phenotypic selection study on Öland, SE Sweden, suggested that disruptive selection on spur length contributes to the maintenance of a bimodal distribution of spur length in mixed habitats, but provided very limited evidence of divergent selection on plant morphology and flowering phenology in grassland and woodland habitats. Field experiments revealed strong reproductive isolation between divergent populations on Öland, due to differences in spatial distribution, flowering phenology, and pollinators, and among-population incompatibility. The results suggest that prezygotic reproductive isolation contributes to the maintenance of population differentiation in floral traits in P. bifolia. A field manipulation experiment demonstrated that spur length but not perianth size affects pollination success and seed production. This suggests that among-population differentiation in perianth size may be the result of a genetic correlation with spur length. Taken together, the results of this thesis suggest that pollinator-mediated selection can shape the evolution of intraspecific floral variation.

The fitness function developed in this thesis directly links the physicochemical properties of an enzyme to evolutionary fates in a quantitative and predictive manner through a comparative study of empirical and simulated data. The success or failure of organisms during evolution is dictated by changes in molecular structure that give rise to changes in fitness revealed by evolutionary dynamics within a population. While the conceptual link between genotype, phenotype and fitness is clear, the ability to relate these in a quantitative manner remains difficult. I show here that predicting success during adaptation can depend critically upon enzyme kinetic and folding models. We used a 'weak link' method to favor mutations to an essential, but maladapted adenylate kinase gene within a microbial population that resulted in the identification of five mutants that arose nearly simultaneously and competed for success. The unique catalytic role of adenylate kinase in vivo is to maintain adenylate homeostasis by catalyzing the reaction: ATP + AMP [imaginary] ADP. The stabilizing substitutions retained this essential function and were shown to be necessary for viability at higher temperatures. Physicochemical characterization of these mutants demonstrated that, although steady-state enzyme activity is important, success within the population is critically dependent on resistance to denaturation and aggregation thus emphasizing the importance of proper folding in adaptation. In vitro activity is a product of critical catalytic and folding pathways, and hence is a valuable proxy for fitness. A fitness function relating in vitro measurements of enzyme activity and reversible and irreversible unfolding to growth rate must impose an activity threshold above which there is no added fitness benefit in order to reproduce in vivo evolutionary fates in an in silico population. The fitness function thereby links organismal adaptation to the properties of a single gene. Understanding the physical basis for adaptation of an organism is the first step in the development of approaches that can accurately model, and someday predict, the manner in which organisms would respond to new antibiotics and improve upon the current clinical regimens.