lecture 13

How organisms interact with each other and with their environment

• Came up with the idea of endosymbiotic theory • Eukaryotic cells originate because of ancient symbiosis Host cell engulfed a bacterial cell then evolved into mitochondria

• is not equally distributed across the tree of life • 70 to 90 percent are bacteria

• Model organisms represent vertebrates, invertebrates and plants - Mice models for vertebrates Fruit fly models for invertebrates Arabidopsis thaliana models for plants

• all the individual of the same species in one place at one time (all the zebras in a savanna)

• all the species living together in one place at one time (all zebras, giraffes, plants and insects in a savanna)

• all the species and non living environment (the entire savanna)

• Understand where plants and animals can grow because they provide food, wood,etc • Predict what will happen to biodiversity as climate change • Predict how biodiversity will respond to habitat destruction, pollution, etc

• Dispersal: If the species can get there • Abiotic conditions: It has to be able to tolerate the climate and nutrients • Species interactions: The interactions between species (competition, predation and mutualism) can help them survive better or limit where they can live

• Dispersal: If species can’t get there, it limits them from going there - Inexhaustible resources: (climate, temperature) If the climate is too hot or too cold, some species can’t live there Exhaustible resource (nutrients, space, etc) Lack of food, nutrients, or space limits how far species can spread Species interactions: the interactions between species (competition, predation and mutualism) can help them survive better or limit where they can live

How many species are in a space Some species are very abundant Abundant species are pests

When numbers of species become low, it risks extinction The worst case is when there’s only 1 individual left and cant reproduce

Population cant grow faster than the resource that supports it Numbers of individuals must be kept low by competition for resource