西安建筑科技大学：《环境学 Environmentology》双语课程电子课件_Unit 5 生物多样性问题 Biodiversity Issues Biodiversity Issues

Biodiversity Issues Unit5:生物多样性问题 Human Influence wilderness WIlderness Addition of foreign species 00950= Managed forests rangelands, and lakes Agriculture and Extinction aquaculture Degree of human influence

Biodiversity Issues Biodiversity Issues Unit 5: Unit 5: 生物多样性问题 生物多样性问题

Biodiversity Loss and Extinction Two basic terms Biodiversity: a broad term used to describe the diversity of genes, species, and ecosystems in a region Extinction: the death of a species, the elimination of all the individuals of a particular kind Biodiversity is lost when a species becomes extinct Extinction is a major consequence of human domination of the earth Complete extinction: all the individuals of a species are eliminated Local extinction: the future of the species is not encouraging

Biodiversity Loss and Extinction • Two basic terms – Biodiversity Biodiversity: a broad term used to describe the diversity of genes, species, and ecosystems in a region. – Extinction Extinction: the death of a species, the elimination of all the individuals of a particular kind. • Biodiversity is lost when a species becomes extinct. • Extinction is a major consequence of human domination of the Earth. – Complete extinction Complete extinction: all the individuals of a species are eliminated. – Local extinction Local extinction: the future of the species is not encouraging

Causes of extinction Probability of becoming extinct Most Likely to become Extinct Least Likely to Become Extinct Low population density High population density Found in small area Found over large area Specialized niche Generalized niche Low reproductive rates High reproductive rates

Causes of Extinction • Probability of becoming extinct

Extinction as a result of human Activity At one time, a human was just another consumer somewhere in the food chain -just like other animals Human fell prey to predators Human died as a result of disease and accident As human population grew, and as their tools became more advanced, the impact that a single man could have on his surroundings increased tremendously Purposeful use of fire -to change ecosystems Wood was harvested for fuel and building materials Human displaced other kinds of organisms

Extinction as a Result of Human Activity • At one time, a human was just another consumer somewhere in the food chain – just like other animals. – Human fell prey to predators. – Human died as a result of disease and accident. • As human population grew, and as their tools became more advanced, the impact that a single man could have on his surroundings increased tremendously. – Purposeful use of fire – to change ecosystems. – Wood was harvested for fuel and building materials. – Human displaced other kinds of organisms

Changes in the ability of humans to modify their world

Changes in the ability of humans to modify their world

Describing Biodiversity Genetic Diversity: the number of different kinds of genes present in a population or a specles High genetic diversity -many different kinds of genes, individuals within the population having different structures and abilities Low genetic diversity -nearly all the individuals in the population having the same characteristics

Describing Biodiversity • Genetic Diversity: the number of different kinds of genes present in a population or a species. – High genetic diversity High genetic diversity – many different kinds of genes, individuals within the population having different structures and abilities. – Low genetic diversity Low genetic diversity – nearly all the individuals in the population having the same characteristics

Describing Biodiversity Several things influence the genetic diversity of a population Mutations are changes in the genetic information of an organism Migration of individuals of a species from one population to another alters the genetic diversity of a population Sexual reproduction generates new genetic combinations superior to those of other members of the population Population size is a very important factor related to genetic diversity Selective breeding eliminates undesirable characteristics and selects for desirable ones

Describing Biodiversity • Several things influence the genetic diversity of a population – Mutations Mutations are changes in the genetic information of an organism. – Migration Migration of individuals of a species from one population to another alters the genetic diversity of a population. – Sexual reproduction Sexual reproduction generates new genetic combinations superior to those of other members of the population. – Population size Population size is a very important factor related to genetic diversity. – Selective breeding Selective breeding eliminates undesirable characteristics and selects for desirable ones

Describing biodiversity Species Diversity-a measure of the number of different species present in an area Two kinds of species diversity Species richness: number of different kinds of species In an area Taxonomic richness: the number of different taxonomic categories of the species present in an area Species diversity is influenced by climatic events ntroduction of new species size of the area, and human activities

Describing Biodiversity • Species Diversity – a measure of the number of different species present in an area. – Two kinds of species diversity ™ Species richness Species richness: number of different kinds of species in an area. ™ Taxonomic richness Taxonomic richness: the number of different taxonomic categories of the species present in an area. – Species diversity is influenced by climatic events, introduction of new species, size of the area, and human activities

Numbers of Described Species by Taxonomic Group Taxonomic Group Approximate Number of Described Species Insects 751.000 Plants 248428 Noninsect Arthoropods(mites, spiders 123.151 crustaceans, etc.) Mollusks 50.000 46,983 Protozoa 30.800 Algae 26.900 Flat 12,200 Roundworms 12.000 Earthworms and related organisms 12.000 Birds 9.040 Jullyfish, corals, comb jellies 9.000 Reptiles 6300 Starfish, sea urchins, sand dollars, etc 6,100 Sponges 5000 Bacteria, blue-green algae 4.760 Amphibians 4.184 Mammals 4.000 Total 1380,902

Numbers of Described Species by Taxonomic Group Taxonomic Group Approximate Number of Described Species Approximate Number of Described Species Insects 751,000 Plants 248,428 Noninsect Arthoropods (mites, spiders, crustaceans, etc.) 123,151 Mollusks 50,000 Fungi 46,983 Protozoa 30,800 Algae 26,900 Fish 19,056 Flatworms 12,200 Roundworms 12,000 Earthworms and related organisms 12,000 Birds 9,040 Jullyfish, corals, comb jellies 9,000 Reptiles 6,300 Starfish, sea urchins, sand dollars, etc. 6,100 Sponges 5,000 Bacteria, blue-green algae 4,760 Amphibians 4,184 Mammals 4,000 Total 1,380,902 1,380,902

Describing biodiversity Ecosystem Diversity-a measure of the number of kinds of ecosystems present in an area Many regions of the world appear to be quite uniform in terms of the kinds of ecosystems present Desert with similarities of low rainfall, thorny woody plants, animals that can survive on little water Natural events such as hurricanes fires, floods or volcanic eruptions may have destroyed the original vegetation, resulting in patches of early successional stages ocal topographic conditions may create patches of the landscape that differ from the prevailing type

Describing Biodiversity • Ecosystem Diversity – a measure of the number of kinds of ecosystems present in an area. – Many regions of the world appear to be quite uniform uniform in terms of the kinds of ecosystems ecosystems present. ™ Desert with similarities of low rainfall, thorny woody plants, animals that can survive on little water. – Natural events Natural events such as hurricanes, fires, floods, or volcanic eruptions may have destroyed the original vegetation, resulting in patches of early successional stages. – Local topographic conditions Local topographic conditions may create patches of the landscape that differ from the prevailing type