ecology
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Adaptive Evolution is driven by natural selection. Natural selection is not "survival of the fittest," but rather "reproduction of the fittest." Evolution can occur at many different speeds based on the strength of the selection driving it. These types of selection can result in directional, stabilizing, and disruptive outcomes. They can be driven by frequency-dependent selection and sexual selection, in addition to more standard types of ...more
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Breeding strategies differ both among males and females of the same species as well as among different species. The difference in breeding strategies among members of the same species can usually be linked to frequency dependence. If the species is at evolutionary equilibrium, the relative fitnesses of these different strategies will be identical. Differing strategies have been found at the level of the gamete as well as at the level of di...more
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Genetic transmission is the mechanism that drives evolution. DNA encodes all the information necessary to make an organism. Every organism's DNA is made of the same basic parts, arranged in different orders. DNA is divided into chromosomes, or groups of genes, which code for proteins. Asexually reproducing organisms reproduce using mitosis, while sexually reproducing organisms reproduce using meiosis. Both these mechanisms involve duplicat...more
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This lecture provides an overview of the physical aspects of earth's biomes. Temperature, water, latitude, and altitude all come into play. Regions with similar levels of these climatic features tend to have similar life-forms living there. These same climatic features can also affect weather patterns, which in turn affect life by altering habitats and ecosystems. On a large enough scale, such as El Niño, these weather patterns can affect ...more
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Coevolution happens at many levels, not just the level of species. Organelles such as mitochondria and chloroplasts serve as good intracellular examples. Other living things make up a crucial component of an organism's environment. Coevolution can occur in helpful ways (symbiosis) and in harmful ways (parasitism). Many factors can influence coevolution, such the frequency and degree of interaction.
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We can use methods of genetic analysis to connect phylogenic information to geographical histories. Human migration has left genetic traces on every continent, and allows us to trace our roots back to Africa. Molecular genetic methods allow us to determine whether or not trait states were ancestral, which can have profound implications for fundamental biological ideas.
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The idea of ecological communities has changed tremendously over the past forty years. The classical view stated that there were so many different species because evolution packed them tightly into the available niches. The modern view emphasizes the idea of trophic cascades, or top-down control in food chains. This emphasized the importance of predation in ecology, although it downplayed the significance of food webs, which showed the int...more
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There are several ways to examine the behaviors of organisms when they forage or hunt for food or mates. These behaviors become more complex in higher organisms, such as primates and whales, which can hunt in groups. Foragers and hunters have been shown to examine the marginal cost and marginal benefit of continuing an action and then adjust their behaviors accordingly. They are also able to handle risk by hoarding resources.
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The movement of matter and energy around the planet is very important, and its study draws on geology, and meterology in addition to chemistry. Energy tends to flow upwards from plantlike producers to herbivores to carnivores before being decomposed by detritovores and cycling back into energy usable by producers, in addition to the photosynthesis or chemosynthesis used by producers to produce energy. Like energy, compounds vital to life s...more
