Chapter 1There is somewhere between 1.5 million and 2 million species that have been named on earthParticularly diverse groups of species include beetles, insects in general and flowering plantsApproximately how many species of vertebrates, insects and plants are thereVertebrates: 50,000Insects: 950,000Plants: 300,000Biodiversity can refer to habitat diversity, species diversity and genetic diversitySpecies are often defined by the ability to interbreedSpecies richness refers to the number of species, while species diversity incorporates both number and relative abundanceBiodiversity is not evenly spread out across the world and tropical areas typically have more species than temperate areasA genome is all the genes of an individualThe source of genetic variation among individuals is having different alleles for particular genesThe 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 ecosystemA diversity of organisms is necessary to provide ecosystems with all the services neededBiodiversity refers to the variety of lifeGenotype: set of genes carried by an individual vs. phenotype: the expression of the trait in an individualThe most important discovery of a unifying principle of life was the theory of evolution by natural selection by Charles Darwin and Alfred WallaceMany species are not know by scientists, specialists known as taxonomists or systematics are trained to find and identify new speciesLinnaean 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 yearsEukarya included all forms of multicellular lifeThe 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 onesBiophila: attraction to elements of the natural worldWe 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 orderMass 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 changesChapter 2Charles Darwin learned about biodiversity by travelling on the Beagle to South America and the GalapagosAlfred 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 bookDarwin’s work consisted of two major ideas: descent with modification (tree thinking) and natural selectionMajor pieces of evidence for evolution/ speciationLife on islands: the finches from Galapagos had colonized the islands from South AmericaHomology (comparative anatomy): different species that have shared evolutionary history are genetically similarFossil record: show us that different forms of life existed in the past and that they go extinct and new forms appearSelective breeding: peppered moth went from being light to commonly darkStandard deviation is a measure of the amount of variation in a populationVariation among individuals in a population is the fundamental basis of Darwin’s ideasPopulation variance can make the link between cause (smoking) and effect (cancer) less than straightforwardSpecies are most commonly formed through geographic isolationThere are three types of natural selection: directional, stabilizing and disruptiveStabilizing: the individuals with characteristics close to the mean are the most successful and have the most offspringThe population tends to stay at the same mean value but becomes less variableDirectional: 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 areaMany 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 inhabitBates developed idea of mimicry: that animals and plants evolve patterns to resemble other species to avoid being eatenNatural selection has acted to delay the start of old age in different species until after individual of that species normally die in natureHabitats 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 occursChapter 3Areas of the world with similar climates have similar habitats (biomes)Temperature, moisture and seasonality all play a role in determining habitatsSeasonality is important in distinguishing the desert and Mediterranean habitatsEcological 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 occursThree main types of species interaction: predation, competition and mutualismAn ecological community is all the species in an area while an ecosystem consists of the community plus the non-living environmentPredation includes eating plants, parasites and parasitoidsPredator- prey relationship can be summarized in a food webDisturbance results in ecological succession and intermediate levels of disturbance result in the highest diversityAreas with low levels of disturbance have low diversityA limited amount of disturbance increases the range of environments and niches available thus leading to higher diversityOnly plants can bring energy into ecosystemsNitrogen fixing bacteria are required to supply
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