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Bio Lectures.docx

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University of Guelph
BIOL 1070
Wright& Newmaster

September 14 2011 What is biodiversity? - Biodiversity is the variety of genes, species and ecosystems. - Shaped by billions of years of evolutionary history of life forms interactions with each other and their environment. - Altered by human activity with lasting impacts at large scales that are difficult to predict. What is evolution? - Descent with modification from common ancestors. Can only occur if there is variation. - Evolution evolves in change of proportions of variants in population. What factors contribute to threats to native freshwater mussel biodiversity? - Habitat destruction - Human impacts / Overfishing - Agriculture runoff - Chemicals in water - Invasive species - Water temperature fluctuations List of characteristics of Unionids & Dreissenids Unionids Dreissenids What is the larval form? Glochidia Veligers Does it need a host? Host-dependant Not host-dependant. Can attach to any solid surface. What type of larval dispersal? Larvae dispersed by host Dispersed in water Freshwater bivalves develop in 3 ways 1. By producing veligers larvae (Dreissena Polymorphall) 2. By releasing ully developed young mussels (rare) 3. By passing early development as a parasitic stage on a host (Unionids)  Unionid larvae  Glochidia – Can’t swim or crawl – Attach to host fish grills Strategies for infecting fish hosts 1. Conglutinates – Glochidia enclosed in membranous capsules that mimic host prey. 2. Lures – Modified mantle tissue, mimics fish or invertebrate prey item to attract fish host. Host capture - Mussel may physically grip host and pump glochidia over the gills. September 19 2011 Biological Variation - Variation occurs in all species - A well sampled population = A normal distribution What causes the variation? - Genotypic variation - Phenotypic variation Agent Definition Effect on Genetic Variation Mutation A heritable change in DNA Introduces new genetic flow Gene Flow Change in allele frequencies May introduce genetic variation from another as individuals join a population population and reproduce Genetic Drift Random changes in allele Reduces genetic variation, especially in small frequencies caused by chance populations; can eliminate alleles events Natural Selection Differential survivorship or One allele can replace another or allelic variation reproduction of individuals can be preserved with different genotypes What is a gene? - A molecular unit of heredity in a living organism. - It is made up of stretches of DNA and RNA that may code for a type of protei
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