Aquatic plants are a heterogeneous assemblage of species that, although surviving in similar habitats, have evolved from very different genetic and ecological backgrounds. However, many aquatics share a number of anatomical, morphological, metabolic and reproductive adaptations, which have arisen independently in remarkable similarities (through convergence and parallelisms) in many unrelated groups. Despite their evolutionary uniqueness, aquatic plants are markedly underrepresented in contemporary biosystematic studies. Moreover, the taxonomic evaluation of numerous aquatic plant groups is intricate due to the strong morphological reduction and a high degree of phenotypic plasticity. This thesis focuses on two notoriously challenging aquatic plant groups, Callitriche and Ranunculus sect. Batrachium. The combination of several approaches (genome size estimation, chromosome counting, sequencing of nrDNA ITS and plastid trnT-trnL regions, examination of herbarium collections) was applied in order to improve our knowledge on principal evolutionary processes such as hybridization, polyploidization and cryptic variation and demonstrate their role on the shaping of overall aquatic plant diversity. The distribution of particular species in the Czech Republic was mapped for the first time. For both groups,...

With global climates changing rapidly, animals must adapt to new environmental conditions with altered weather and phenology. Key to adapting to these new conditions is adjusting the timing of reproduction to have offspring when the conditions are best to maximize growth and survival. Using a long-term dataset on a wild population of yellow-bellied marmots (Marmota flaviventer) at the Rocky Mountain Biological Laboratory (RMBL), we investigated how the timing of reproduction changed with changing spring conditions over the past 50 years. Marmots are hibernators with a four-month active season. It is thus crucial to reproduce early enough in the season to have time to prepare for hibernation, but not too early so as snow cover prevents access to food. Importantly, climate change in this area has increased spring temperatures by 5 °C and decreased spring snowpack by 50 cm over the past 50 years. This directional change in climate may have caused adaptation. Given that adaptation to environmental conditions could arise from either microevolution or phenotypic plasticity, we evaluated how female marmots adjust the timing of their reproduction and estimated the importance of both genetic variance and plasticity in the variation in this timing. We show that, within a year, the timing of reproduction is not as tightly linked to the date a female emerges from hibernation as previously thought. We report a positive effect of spring snowpack but not of spring temperature on the timing of reproduction. There is inter-individual variation in the timing of reproduction but not in its response to changing spring conditions. Genetic variance in the timing of reproduction is low, and heritability was 8%. Earlier pup emergence date increases the number and weighted proportion of pups surviving their first winter, indicative of directional selection on this trait. The same pattern is not found for litter size with no effect of pup emergence date on the number of pups born. Further, all three of these traits are not under stabilizing selection. Taken together, it seems that we should expect some changes in this population with changing climatic conditions, but because of plasticity and not due to natural selection. Further, future studies on the marmots should not operate under the assumption that females reproduce immediately following their emergence.

Unprecedented rates of anthropogenic environmental change have resulted in dramatic decreases in biodiversity worldwide. In order to persist during changes in both the abiotic and biotic environment resulting from anthropogenic stressors such as climate change and habitat degradation, populations must be able to respond or face extirpation. Predicted population-level responses to environmental change include i) range shifts as individuals disperse into more suitable regions, ii) phenotypic plasticity allowing for shifts in the mean phenotype of the population or iii) microevolution resulting from a genetic change within the population. The goal of this thesis is to assess how species within a community respond to a dramatic change in the environment. This study used the sediment record of a Subarctic pond to investigate the impacts of a rapid increase in salinity on two species of the crustacean zooplankton Daphnia. One species, Daphnia tenebrosa, was unable to persist in the high salinity conditions and is believed to have been extirpated from the system. The other species, Daphnia magna, was tolerant of the new environmental conditions and was present throughout the sediment record. To investigate the changes in life history of D. magna, resting eggs from the sediment were hatched to compare iso-female lines from pre- and post-disturbance time periods. No differences were observed between the clone lines, suggesting that phenotypic plasticity allowed D. magna to persist despite the rapidly changing environmental conditions, and that microevolution in salinity tolerance may not have occurred in this population. This study suggests that, in environments with moderate levels of post environmental change, pre-existing phenotypic plasticity may play a greater role than microevolution in species response to environmental changes. However, not all species from a community display the same response to environmental changes, as seen in this study with the extirpation of D. tenebrosa. To better understand how communities will be affected by future environmental change, further investigations need to be made on what factors influence species response. Identifying species response may allow conservation efforts to focus on species that are unlikely to adapt to environmental change, and are most at risk. / Thesis (Master, Biology) -- Queen's University, 2013-09-29 21:54:34.881

<p>This study used amplified fragment length polymorphism (AFLP) to detect changes of genetic variation in threespine stickleback exposed to industrial pollution from pulp- and paper mills along the southern east coast of Sweden. A general loss of allelic diversity was associated with exposure (table 3, linear model, F1,4=7.2 [P=0.055]) and exposed populations also displayed a similar pattern of response (fig 5) despite geographic distance, indicating that evolution toward pollution resistant ecotypes of threespine stickleback is occurring in the Baltic Sea. The result suggests that pollution can be regarded as an agent of directional selection, causing a decrease of evolutionary potential of exposed species in the Baltic Sea.</p>

This study used amplified fragment length polymorphism (AFLP) to detect changes of genetic variation in threespine stickleback exposed to industrial pollution from pulp- and paper mills along the southern east coast of Sweden. A general loss of allelic diversity was associated with exposure (table 3, linear model, F1,4=7.2 [P=0.055]) and exposed populations also displayed a similar pattern of response (fig 5) despite geographic distance, indicating that evolution toward pollution resistant ecotypes of threespine stickleback is occurring in the Baltic Sea. The result suggests that pollution can be regarded as an agent of directional selection, causing a decrease of evolutionary potential of exposed species in the Baltic Sea.

The theory of “punctuated equilibrium” suggests that species evolve rapidly during or immediately upon speciation, “punctuating” long periods of little or no morphological evolution. Here I confirm that body size differences within clades of birds and mammals are best explained using a model of punctuated evolution. This allows me to suggest that rates of speciation and extinction are responsible for why there are more small mammals than large, as large mammals likely speciate and go extinct at a higher rate than small mammals, and hence undergo cladogenetic change more often. Likewise, mammals appear to evolve at a higher rate than birds, because mammals, as a whole, speciate and go extinct at a higher rate than birds. Furthermore I show that mass extinctions and competition, i.e. forms of natural selection, do not seem to explain differences in body size between species on a macroevolutionary scale. Taken together, these findings not only contradict the idea that apparently different rates of evolution are due to differential selection intensities, and emphasize the importance of the speciation process in evolution, but raise the intriguing question as to what limits evolution in established species. Here I suggest that phenotypic traits, dependent on one another for development and/or function may constrain evolution by exerting stabilizing selection from within the organism, as opposed to external environmental selection, which has been the main focus of evolutionary studies thus far. / Teorin om "punkterad jämvikt" säger att arter utvecklas snabbt under och omedelbart efter artbildning, vilket "punkterar" långa perioder med lite eller ingen morfologisk föränding. I den här avhandlingen visar jag att skillnader i kroppsstorlek inom klader (grupp med gemensam förfader) hos fåglar och däggdjur förklaras bäst när man använder en modell med punkterad evolution. Detta gör i sin tur att jag kan föreslå att hastigheten var med artbildning och utdöende sker, förklarar varför det finns fler små däggdjur än stora, eftersom stora däggdjur sannolikt bildar nya arter och dör ut med en högre hastighet än små däggdjur. Likaså förefaller däggdjur i sin helhet att evolvera med en högre hastighet än fåglar, detta eftersom däggdjur bildar nya arter och dör ut med en högre hastighet än fåglar. Dessutom visar jag att massutdöenden och konkurrens (naturlig selektion) inte verkar förklara skillnader mellan arter över makroevolutionära skalor (över geologisk tid). Sammantaget motsäger dessa resultat inte bara idén om att skenbart olika hastighet på evolution främst beror på skillnader i selektionstryck utan understryker också vikten av artbildningsprocessen som en viktig faktor som styr evolutionens hastighet. Dessutom leder dessa resultat till frågan om vad som begränsar evolutionen hos redan etablerade arter. Här föreslår jag att fenotypiska karaktärsdrag som är beroende av varandra för sin funktion och utveckling kan begränsa evolutionen genom att utöva stabiliserande selektion inifrån organismen, i motsats till selektion från den omgivande miljön vilket har varit fokus för de flesta evolutionära studier hittills.

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Yes / Background In the context of advanced immunosuppression, M. tuberculosis is known to cause detectable mycobacteremia. However, little is known about the intra-patient mycobacterial microevolution and the direction of seeding between the sputum and blood compartments. Methods From a diagnostic study of HIV-infected TB patients, 51 pairs of concurrent blood and sputum M. tuberculosis isolates from the same patient were available. In a previous analysis, we identified a subset with genotypic concordance, based on spoligotyping and 24 locus MIRU-VNTR. These paired isolates with identical genotypes were analyzed by whole genome sequencing and phylogenetic analysis. Results Of the 25 concordant pairs (49 % of the 51 paired isolates), 15 (60 %) remained viable for extraction of high quality DNA for whole genome sequencing. Two patient pairs were excluded due to poor quality sequence reads. The median CD4 cell count was 32 (IQR; 16–101)/mm3 and ten (77 %) patients were on ART. No drug resistance mutations were identified in any of the sequences analyzed. Three (23.1 %) of 13 patients had SNPs separating paired isolates from blood and sputum compartments, indicating evidence of microevolution. Using a phylogenetic approach to identify the ancestral compartment, in two (15 %) patients the blood isolate was ancestral to the sputum isolate, in one (8 %) it was the opposite, and ten (77 %) of the pairs were identical. Conclusions Among HIV-infected patients with poor cellular immunity, infection with multiple strains of M. tuberculosis was found in half of the patients. In those patients with identical strains, whole genome sequencing indicated that M. tuberculosis intra-patient microevolution does occur in a few patients, yet did not reveal a consistent direction of spread between sputum and blood. This suggests that these compartments are highly connected and potentially seed each other repeatedly.

Body size is one of the most fundamental quantifiable traits of living or fossil organisms, and understanding it in various temporal and spatial contexts can offer key insights into the process of evolution. This volume examines body size of eukaryotes and its correlates in various temporal and spatial contexts in three distinct studies. The first study investigates the relationship between parasitism and body size of modern bivalve hosts. Individuals of Protothaca staminea were extensively parasitized (86%) by two types of trace-producing parasites. The only significant relationship between parasitism and body size was that spionid mudblister infested clams from one environment were slightly, yet significantly, smaller than their non-infested counterparts. The most obvious pattern regarding body size was that clams from a lagoon were significantly larger than clams from a tidal creek. This size discrepancy could be related to environmental stress, durophagous predators, differing hydrodynamic conditions, or the comparison of differing cohorts. Even though there was no discernible impact of trematode parasitism on bivalve body size, their traces were abundant and easy to identify. Investigators of body size in the fossil record should be aware of these organisms and their possible ramifications for body size studies. The second study, using Quaternary terrestrial gastropods from the Canary Islands, tests the hypothesis of limiting similarity, the idea that two closely related species will alter their size/morphology in order to minimize competition. By integrating amino acid geochronology, stable isotope estimates, and morphometric techniques I was able to more adequately test whether limiting similarity is an evolutionary process or a transient ecological phenomenon. The first prediction of limiting similarity, character displacement, was confirmed. The second prediction of limiting similarity, character release, was not confirmed. It appears that changing climate at the end of the Pleistocene may be responsible for the body size trends, but intraspecific competition likely played a secondary role in the evolution of body size of Theba. The third study addressed the history of body size and morphological disparity of the first 1.3 billion years of acritarch history. The results reject the idea that acritarch body size increased monotonically through the Proterozoic; in fact they displayed non-directional fluctuation. Acritarch body size decreased significantly following the first appearance of Ediacara organisms and gradually rose during the Cambrian. Morphological disparity increased a half billion years before the first taxonomic radiation. Morphological disparity decreased significantly during the snowball earth events and upon the first appearance of Ediacaran organisms suggesting multiple events of selective extinction in the Proterozoic biosphere. Disparity then increased in step with the diversification of acritarch and metazoans through the Cambrian suggesting ecological links between the two groups. Ecological processes, whether extrinsic abiotic processes or biotic interactions, influence the body size and evolution of organisms at wide range of spatial and temporal scales. / Ph. D.