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Kairomones are infochemicals that benefit a heterospecific receiver. Chaoborus spp. release a kairomone from their gut when feeding on Daphnia spp. Daphnia respond to kairomone by shifting life history parameters or producing neonates with induced morphological defenses, increasing their chance of survival. When laboratory-cultured Daphnia are exposed to environmentally-relevant metal concentrations, a kairomone response is not induced, increasing predation vulnerability. Currently Daphnia live in metal-contaminated lakes in Sudbury, ON. It is possible the extant population is tolerant of relatively high copper (Cu) concentrations and can still induce a kairomone response. In comparison, it is hypothesized clones found in lakes isolated from anthropogenic sources of metal-contamination would be less tolerant as they have not been exposed to high Cu concentrations. The purpose of this study was to examine how multiple clones of D. pulicaria obtained from lakes along a Cu gradient respond to kairomone in the absence and presence of copper. Several different clones from Ontario lakes located in the Canadian Shield were exposed to environmentally-relevant Cu concentrations and Chaoborus kairomone. Neonates were collected and measured to assess predator-induced defenses. Results indicate that kairomone-mediated responses and Cu-tolerance vary among D. pulicaria clones. Clones from the Sudbury area were able to induce a response to kairomone when exposed to Cu, indicating a Cu-tolerance. However, this was not true for all Sudbury clones. In contrast, most clones from clean lakes did not respond to kairomone when exposed to Cu; while some clones exhibited a Cu-tolerance. Clones that were not tolerant of Cu were affected at concentrations much lower than those predicted by the Biotic Ligand Model (BLM) that induce acute toxicity. Predictions generated by the BLM can be conservative making them useful when creating water quality criteria; however, my results indicate these predictions can also be under-protective. Chemosensory cues mediate vital life processes that are essential for survival. Populations may be devastated if metals interfere with chemosensory cues. Overall, the results of my study suggest that genetic variation is important for population establishment and maintenance, specifically when exposed to multiple stressors, and that directional selection may result in stress tolerance. / Thesis (Master, Biology) -- Queen's University, 2009-12-23 09:50:46.152

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Tests for adaptation to three different soils inhabited by subspecific taxa within Phacelia dubia and for preadaptation to a serpentine soil were conducted to examine the plausibility of an endemic-to-endemic evolutionary pathway. Each taxon performed optimally on its home soil, demonstrating edaphic specialization. None survived on the serpentine. Hydroponic assays for tolerance to two serpentine factors, elevated magnesium: calcium and elevated nickel, were conducted on population samples and maternal half sib families. Performance was estimated by root length and rosette diameter while leaf dissection served as an indicator of developmental maturity. Both nickel and magnesium: calcium of typical serpentine inhibited all three taxa. However, the granite outcrop endemic var. georgiana tolerated higher magnesium: calcium than other taxa, its tolerance exceeded that found on its home soil, and there was developmental variation among sibships. The tolerance uncovered in the endemic var. georgiana suggests that a specialized endemic taxon may encompass variation that could lead to preadaptation to a novel habitat and therefore serve as the raw material for speciation rather than represent an evolutionary dead end.

Four populations of Deschampsia caespitosa (L.) Beauv (a Poaceae species), growing on disturbed and undisturbed sites at Climax, Colorado, were examined for metal tolerances (Zn, Cu, Pb, Al). Root growth assessments on parent plant and offspring material for each population were conducted using nutrient solutions containing elevated levels of Zn, Cu, Pb, or Al. Seed germination and seedling survival tests for each population were conducted on both alpine topsoil and mine spoil material. Evidence is presented that supports the hypothesis that ecotypic variation exists within Deschampsia caespitosa and that this variation has allowed certain Deschampsia populations to become successfully established on alpine mine spoils. Acid mine spoil populations showed significantly less root growth retardation in the presence of zinc, copper or aluminum.

Contamination from various sources has a huge impact on soil health and microbial community composition. Metal contamination of soil in mining scenarios is of concern and is not adequately addressed, particularly with respect to the microbial community. The mining industry is one of the largest contributors to heavy metal contamination of soil in South Africa, especially since the country is one of the major mining countries in the world. Platinum mining is of special importance, since the largest percentage of the world’s reserves of platinum group metals are found and mined in South Africa. Metals from mining activities become irreversibly immobilized in soil systems because they cannot be degraded and has a huge impact on soil systems. In this study, bacteria was isolated from soil samples collected from a platinum mine tailings dam outside Rustenburg. During the warm sampling season (March 2006) most isolates were found, especially in sites 3 and 4. During the colder and drier season (May 2006) there were less isolates. Most of the isolated cultures also displayed a wide temperature growth range, mostly between 24°C - 37°C. Paenibacillus lautus and Bacillus subtilus DN-10 had a growth range between 5°C - 40°C. Culturable metal tolerant bacteria were isolated, purified and identified using 16S rDNA sequences. Nine different species were found namely Paenibacillus lautus strain DS19, Paenibacillus lautus, Paenibacillus sp. C15, uncultured Paenibacillaceae, Bacillus subtilis strain DN-10, Bacillus sp. KDNB5, Bacillus cereus, Stenotrophomonas maltophilia and Alcaligenes sp. DJWH 146-2. The ability of these strains to tolerate metal concentrations were explored by determining their minimum inhibitory concentrations for a selection of metals e.g. aluminum, barium, cobalt, chromium, cadmium, copper, iron, lead, manganese, nickel and mercury. Most isolates were able to tolerate >5mM of the Al\Ni alloy and cobalt. Transmission electron microscopy was used to determine the location of metals inside bacterial cells and electron dispersive X-ray analysis was used to determine the levels of metals inside microbial cells. Bacillus subtilis DN-10 (LDK0306) showed a high MIC (>5mM) for most metals used, except Hg. This strain also had a high percentage (10.26%) of Pb detected in its cells by EDX. This was the highest percentage detected. Plasmids were extracted from the identified strains and can help gain a better understanding of metal tolerance mechanisms used by these isolates. / Thesis(MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013