G. Tyler Miller’s Living in the Environment 13 th Edition Evolution and Biodiversity: Origins, Niches, and Adaptations Chapter 5 Evolution and Biodiversity: Origins, Niches, and Adaptations Chapter 5

Evolution and Adaptation Natural selection Process in by which individuals of a population acquire genetically based traits that increase their chances of survival and their ability to produce offspring.Process in by which individuals of a population acquire genetically based traits that increase their chances of survival and their ability to produce offspring. Adaptation (n.) Adaptation (n.) –A heritable trait that enables an organism to better survive and reproduce under a given set of environmental conditions Artificial selection Humans select one or more desirable genetic traits in the population of a plant or animal.Humans select one or more desirable genetic traits in the population of a plant or animal.

Natural Selection Conditions necessary for natural selection: –variability –heritability –differential reproduction Fig. 5-5 p. 101

Climate Change and Natural Selection Changes in climate throughout the earth’s history have shifted where plants and animals can live.Changes in climate throughout the earth’s history have shifted where plants and animals can live. Figure 4-6

Limits on Adaptation through Natural Selection A population’s ability to adapt to new environmental conditions through natural selection is limited by its gene pool and how fast it can reproduce.A population’s ability to adapt to new environmental conditions through natural selection is limited by its gene pool and how fast it can reproduce. –Humans have a relatively slow generation time (decades) and output (# of young) versus some other species.

Evolution and Adaptation Co-EvolutionCo-Evolution –Populations of two different species interacting over a long period of time –Changes in the gene pool of of one species changes the gene pool of another species Predator-Prey RelationshipsPredator-Prey Relationships Plant defense mechanismsPlant defense mechanisms

Ecological Niches and Adaptation Ecological nicheEcological niche –Total way of life or functional role of a species in an ecosystem. HabitatHabitat –Physical location of a species Occupation Address

Ecological Niches and Adaptation Fundamental nicheFundamental niche –Full potential range of the physical, chemical, and biological factors a species can use if there were no direct competition from other species. Realized nicheRealized niche –Part of a species fundamental niche that are actually used.

Broad and Narrow Niches Generalist speciesGeneralist species –Species with a broad ecological niche. Live in many different places.Live in many different places. Eat a variety of food.Eat a variety of food. Tolerate a wide range of environmental conditions.Tolerate a wide range of environmental conditions. (flies, mice, deer, catfish, humans) Specialist speciesSpecialist species –Species with a narrow ecological niche. Live only in one type of habitatLive only in one type of habitat Use only a few types of foodUse only a few types of food Tolerate only a narrow range of climatic and other environmental conditions.Tolerate only a narrow range of climatic and other environmental conditions. (tiger salamander, red-cockaded woodpecker, spotted owls, pandas)

Generalist and Specialist Species: Broad and Narrow Niches Generalist species tolerate a wide range of conditions.Generalist species tolerate a wide range of conditions. Specialist species can only tolerate a narrow range of conditions.Specialist species can only tolerate a narrow range of conditions.

Speciation, Extinction, and Biodiversity Speciation - formation of two species from one species because of divergent natural selection 1)Geographic isolation – groups of the same species become physically separated

Geographic Isolation …can lead to reproductive isolation, divergence of gene pools and speciation.

Speciation, Extinction, and Biodiversity 2)Reproductive Isolation – isolated populations become so genetically different they cannot...  Interbreed, or  produce live, fertile offspring

Extinction: Lights Out Extinction occurs when the population cannot adapt to changing environmental conditions.  The golden toad of Costa Rica’s Monteverde cloud forest has become extinct because of changes in climate. Figure 4-11

Extinction: Lights Out 99.9 % of all species that ever existed are now extinct Figure 4-11

How do speciation and extinction affect biodiversity? Speciation – Extinction = Biodiversity

Effects of Humans on Biodiversity The scientific consensus is that human activities are decreasing the earth’s biodiversity.The scientific consensus is that human activities are decreasing the earth’s biodiversity.