西安建筑科技大学：《环境学 Environmentology》双语课程电子课件_Unit 3 环境、生物与生态系统 Environments, Organisms and Ecosystems

Environments, Organisms and Ecosystems Unit3:环境、生物与生态系统 Physical Fi environment/Ecosystems Light Interactions energy thesis Organisms eco Organic molecules Heat energy Atoms

Environments Environments, Organisms and , Organisms and Ecosystems Ecosystems Unit 3: Unit 3: 环境、生物与生态系统 环境、生物与生态系统

Ecological Concepts Ecology: Study of how organisms interact with each other and with their non-living surroundings Environment: Everything that affects an organism during its lifetime biotic: living component abiotic: non -living component

Ecological Concepts • Ecology: Study of how organisms interact with each other and with their non-living surroundings. • Environment: Everything that affects an organism during its lifetime. – biotic: living component – abiotic: non-living component

Biotic environment Abiotic environment (physical) Levels of Organization in Commun Energy Ecology Climate Population of species 2 Weather The study of Minerals ecology can take 合 Water place at several interaction p different levels as population of Population of species 3 Salinity shown in the Temperature gure. Sunlight Population of Individual oms an

Levels of Organization in Ecology The study of ecology can take place at several different levels as shown in the figure

Ecological Concepts Limiting Factors: Any factor whose shortage or absence restricts species success Habitat: Space an organism inhabits-defined by biological requirements of each particular organism Niche: Includes all ways an organism affects organisms with which it interacts as well as how it modifies its physical surroundings Species: Category of organisms in which individuals within the group can potentially interbreed and produce viable offspring

Ecological Concepts • Limiting Factors: Any factor whose shortage or absence restricts species success. • Habitat: Space an organism inhabits - defined by biological requirements of each particular organism. • Niche: Includes all ways an organism affects organisms with which it interacts as well as how it modifies its physical surroundings. • Species: Category of organisms in which individuals within the group can potentially interbreed and produce viable offspring

Moss habitat The habitat of mosses is typically cool, moist and shady. Mosses must also have a thin layer of water present

Moss Habitat The habitat of mosses is typically cool, moist, and shady. Mosses must also have a thin layer of water present

Ecological Niche The ecological niche of an organism Is a complex set of interactions between an organism and its surroundings For example, a beaver's ecological niche includes building dams and flooding forested areas, killing trees providing habitat for the ducks and other animals, serving as food for predators

Ecological Niche The ecological niche of an organism is a complex set of interactions between an organism and its surroundings. For example, a beaver’s ecological niche includes building dams and flooding forested areas, killing trees, providing habitat for the ducks and other animals, serving as food for predators

The Niche of a dandelion a dandelion serves as food to various herbivores, supplies nectar to bees, and can regrow quickly from its root if its leaves are removed

The Niche of a Dandelion A dandelion serves as food to various herbivores, supplies nectar to bees, and can regrow quickly from its root if its leaves are removed

Role of natural selection and evolution Genes, Populations, and Species: Three interrelated concepts Genes: Genes are distinct pieces of DNA (deoxyribonucleic acid) that determine the characteristics an individual displays Population: a population is considered to be all the organisms of the same kind found within a specific geographic region Species: A species is a population of all the organisms potentially capable of reproducing naturally among themselves and having offspring that also reproduce An individual organism is not a species but a member of a species

• Genes, Populations, and Species: Three interrelated concepts – – Genes: Genes are distinct pieces of DNA (deoxyribonucleic acid) that determine the characteristics an individual displays. – Population: A population is considered to be all the organisms of the same kind found within a specific geographic region. – Species: A species is a population of all the organisms potentially capable of reproducing naturally among themselves and having offspring that also reproduce. ™ An individual organism is not a species but a member of a species. Role of Natural Selection and Evolution

Natural selection Natural Selection: Process that determines which individuals within a species will reproduce and pass their genes to the next generation Evolution: The changes in the genes and the characteristics displayed by successive generations of a population of organisms over time Natural selection is the mechanism that causes evolution to occur Conditions Involved in the process of natural Selection: Individuals within a species show variation Organisms within a species typically produce huge numbers of offspring most of which die

Natural Selection • Natural Selection: Process that determines which individuals within a species will reproduce and pass their genes to the next generation. • Evolution: The changes in the genes and the characteristics displayed by successive generations of a population of organisms over time. – Natural selection is the mechanism that causes evolution to occur. • Conditions Involved in the Process of Natural Selection: – Individuals within a species show variation. – Organisms within a species typically produce huge numbers of offspring, most of which die

Natural selection Conditions Involved in the process of natural Selection Excess number of individuals results in a shortage of specific resources Due to individual variation some individuals have a greater chance of obtaining needed resources and thus have a greater likelihood of survival and reproduction As time passes, percentage of individuals showing favorable variations will increase and percentage showing unfavorable variations will decrease

Natural Selection • Conditions Involved in the Process of Natural Selection: – Excess number of individuals results in a shortage of specific resources. – Due to individual variation, some individuals have a greater chance of obtaining needed resources and thus have a greater likelihood of survival and reproduction. – As time passes, percentage of individuals showing favorable variations will increase and percentage showing unfavorable variations will decrease