505 research outputs found

    Patterns and process during the diversification of the cichlid fishes in Lake Malawi, Africa

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    The 500-1000 cichlid species endemic to Lake Malawi constitute one of the most rapid and extensive radiations of vertebrates ever discovered. The objective of this dissertation was to test the assumptions and predictions of several recently published models of cichlid speciation. First, a novel assay of female choice was used to evaluate the role of visual cues during conspecific recognition. The results of this experiment demonstrate that females are able to identify conspecific mates using only visual cues. Second, the assumptions of a recent model of speciation via intrasexual selection were tested by comparing aggressive behavior during territorial contests among five closely related cichlid species from Lake Malawi. I found that interactions between conspicuously heteromorphic males tend to be less aggressive than between those of homomorphic males. Third, I used transect data to evaluate the intrinsic and extrinsic factors that have affected the dispersal of 17 closely related cichlid species introduced to Thumbi West Island in Lake Malawi. A quarter of a century after their initial introduction, I found that the translocated cichlid community around Thumbi West Island is still in a state of flux, as many species continue to spread around the island. Next, I evaluated the patterns of divergence predicted by three competing speciation models that differ in the temporal action of natural and sexual selection by using AFLP to reconstruct the evolutionary relationships among 20 species of the ubiquitous rock dwelling subgenus Pseudotropheus tropheops. I found that cladogenesis is associated with numerous unambiguous changes in male color states. A geometric morphometric analysis of the lower jaw of these taxa revealed that the repeated differentiation of jaw morphology is associated with species habitat preference. Finally, I used AFLP data to reconstruct the evolution of species within three genera of sand dwelling cichlids that construct elaborate male display platforms. I found that sister taxa with distinct bower morphologies, and that exist in discrete leks separated by only 1-2m of depth, are divergent in both sexually selected and ecological traits. These phylogenies suggest that the forces of sexual and ecological selection have been intertwined during the speciation of these groups

    English literacy as a barrier to healthcare information for deaf people who use Auslan

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    Background: This study sought to gain insight into how Deaf Australians who use Auslan as their primary language perceive their English literacy and if they feel that they can sufficiently access preventative and ongoing health care information, and to explore their views in regards to accessing information in Auslan. Method: A phenomenological, inductive study, with data collected through 72 semi-structured interviews with Deaf Auslan users identified through non-probabilistic, purposeful and network sampling. Data was thematically analysed for identification of issues related to healthcare information access through English. Results: Deaf people experience barriers in accessing healthcare information because of limited English literacy and a lack of information being available in Auslan, apart from when Auslan interpreters are present in health care appointments. Conclusion: Many Deaf people in Australia lack consistent access to preventative and ongoing health care information. It is important to be aware of the English literacy levels of patients. More funding is needed for the provision of interpreting services in other healthcare contexts and the translation of materials into Auslan.4 page(s

    Repeated Parallel Evolution of Parental Care Strategies within Xenotilapia, a Genus of Cichlid Fishes from Lake Tanganyika

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    The factors promoting the evolution of parental care strategies have been extensively studied in experiment and theory. However, most attempts to examine parental care in an evolutionary context have evaluated broad taxonomic categories. The explosive and recent diversifications of East African cichlid fishes offer exceptional opportunities to study the evolution of various life history traits based on species-level phylogenies. The Xenotilapia lineage within the endemic Lake Tanganyika cichlid tribe Ectodini comprises species that display either biparental or maternal only brood care and hence offers a unique opportunity to study the evolution of distinct parental care strategies in a phylogenetic framework. In order to reconstruct the evolutionary relationships among 16 species of this lineage we scored 2,478 Amplified Fragment Length Polymorphisms (AFLPs) across the genome. We find that the Ectodini genus Enantiopus is embedded within the genus Xenotilapia and that during 2.5 to 3 million years of evolution within the Xenotilapia clade there have been 3–5 transitions from maternal only to biparental care. While most previous models suggest that uniparental care (maternal or paternal) arose from biparental care, we conclude from our species-level analysis that the evolution of parental care strategies is not only remarkably fast, but much more labile than previously expected

    Case reports and the fight against cancer

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    Some of the earliest case reports describing individual patients afflicted with cancer can be traced all the way back to the papyrus records of Ancient Egyptian medicine of approximately 1600 B.C.. Throughout the centuries physicians have continued the practice of writing case reports. Case reporting has provided significant advances in the knowledge of cancer on several fronts. It is without question that case reports do not replace well designed randomized clinical trials in advancing medical knowledge about cancerous diseases. However, case reports have their unique role in evidence-based medicine and often constitute the first line of evidence. This editorial reviews the many useful aspects of case reports and describes specific reports known to have revolutionized cancer management. Journal of Medical Case Reports is committed to publish well written case reports from around the world and be a source of inspiration for clinicians and scientists about newer research directions

    Evaluating the Sampling Design of a Long-Term Community-Based Estuary Monitoring Program

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    Community-based monitoring programs (CBMPs) are a cost-effective option to collect the long-term data required to effectively monitor estuaries. Data quality concerns have caused some CBMP datasets, which could fill knowledge gaps for aquatic ecosystems, to go unused. The Community Aquatic Monitoring Program (CAMP) is a CBMP that has collected littoral nekton assemblage data from estuaries in the southern Gulf of St. Lawrence since 2003. Concerns with the CAMP sampling design (station placement and numbers) have prevented decision-makers from using the data to inform estuary health assessments. This study tested if CAMP’s sampling design that accommodates volunteer participation provides similar information as a scientific sampling approach. Six CAMP stations and six stations selected using a stratified random design were sampled at ten estuaries. A permutational-MANOVA revealed nekton assemblages were generally not significantly different between the two sampling designs. The current six CAMP stations are sufficient to detect the larger differences in species abundances that may indicate differences in estuary condition. The predicted increase in precision (2%) with twelve stations is not substantive enough to warrant an increased sampling effort. CAMP’s scientific utility is not limited by station selection bias or numbers. Furthermore, well-designed CBMPs can produce comparable data to scientific studies.Department of Fisheries and Oceans’ Gulf Fisheries Centre|| Prince Edward Island estuaries||CAM
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