Biodiversity SG 12 05 2012 Chapter 1 There is somewhere between 1 5 million and 2 million species that have been named on earth Particularly diverse groups of species include beetles insects in general and flowering plants Approximately how many species of vertebrates insects and plants are there Vertebrates 50 000 Insects 950 000 Plants 300 000 Biodiversity can refer to habitat diversity species diversity and genetic diversity Species are often defined by the ability to interbreed Species richness refers to the number of species while species diversity incorporates both number and relative abundance Biodiversity is not evenly spread out across the world and tropical areas typically have more species than temperate areas A genome is all the genes of an individual The source of genetic variation among individuals is having different alleles for particular genes The two parts of a species name are the genus homo and species sapiens An ecosystem service is something such as oxygen fresh water or food that is provided by an ecosystem A diversity of organisms is necessary to provide ecosystems with all the services needed Biodiversity refers to the variety of life Genotype set of genes carried by an individual vs phenotype the expression of the trait in an individual The most important discovery of a unifying principle of life was the theory of evolution by natural selection by Charles Darwin and Alfred Wallace Many species are not know by scientists specialists known as taxonomists or systematics are trained to find and identify new species Linnaean system of classification highest rank is the kingdom there are 5 now there s an even higher one domain which is bacteria Achaea and eukarya Bacteria and Archaea are microscopic forms of life that evolved independently for billions of years Eukarya included all forms of multicellular life The ultimate explanation for biological diversity is evolution change in genetic nature of living things over time Evolution typically follows a branching pattern known as a phylogeny Evolution typically does not result in one species replacing another but one species becoming two different ones Biophila attraction to elements of the natural world We can learn about the details of biological function using diversity using the comparative method this is part of the field of genomics DNA sequence consists of a particular set of molecules called nucleotides that are strung along the DNA in a particular order Mass extinction events over the last 450 million years the world has seen five periods in which biodiversity dramatically declined the last extinction being the dinosaurs We are in our sixth mass extinction estimated 30 of land birds may be extinct by 2100 because of human caused changes Chapter 2 Charles Darwin learned about biodiversity by travelling on the Beagle to South America and the Galapagos Alfred Russell Wallace learned about biodiversity through his travels to the Amazon and Southeast Asia Know how the interaction between Darwin and Wallace led to the publication of Darwin s book Darwin s work consisted of two major ideas descent with modification tree thinking and natural selection Major pieces of evidence for evolution speciation cid 224 Life on islands the finches from Galapagos had colonized the islands from South America Homology comparative anatomy different species that have shared evolutionary history are genetically similar Fossil record show us that different forms of life existed in the past and that they go extinct and new forms appear Selective breeding peppered moth went from being light to commonly dark Standard deviation is a measure of the amount of variation in a population Variation among individuals in a population is the fundamental basis of Darwin s ideas Population variance can make the link between cause smoking and effect cancer less than straightforward Species are most commonly formed through geographic isolation There are three types of natural selection directional stabilizing and disruptive Stabilizing the individuals with characteristics close to the mean are the most successful and have the most offspring The population tends to stay at the same mean value but becomes less variable Directional individuals at one end of the distribution are more successful than the ones at the other end the population mean tends to shift in the direction of selection Disruptive one way of producing to forms of life from one requires specific set of conditions and not common individuals at the extremes have to do better than those in middle Population groups of individuals of the same species living in the same area Many people think typologically they assign things to categories and expect them to fit into those categories Wallace came up with idea of natural selection and developed the idea that the geographic distributions of plants and animals are determined by the geological history of the areas they inhabit Bates developed idea of mimicry that animals and plants evolve patterns to resemble other species to avoid being eaten Natural selection has acted to delay the start of old age in different species until after individual of that species normally die in nature Habitats that once were big are now small and tend to isolate population from one another and may lead to formation of new species Reset if extinction occurs 12 05 2012 Chapter 3 Areas of the world with similar climates have similar habitats biomes Temperature moisture and seasonality all play a role in determining habitats Seasonality is important in distinguishing the desert and Mediterranean habitats Ecological niche the ecological role of a species each type of organism is a species and each species has a particular set of environmental condition in which is normally occurs Three main types of species interaction predation competition and mutualism An ecological community is all the species in an area while an ecosystem consists of the community plus the non living environment Predation includes eating plants parasites and parasitoids Predator prey relationship can be summarized in a food web Disturbance results in ecological succession and intermediate levels of disturbance result in the highest diversity Areas with low levels of disturbance have low diversity A limited amount of disturbance increases the range of environments and niches available thus leading to higher diversity Only plants can bring energy into ecosystems Nitrogen fixing bacteria are
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