G. Tyler Miller’sLiving in the Environment 13th Edition

G. Tyler Miller’sLiving in the Environment 13th Edition

Evolution and Biodiversity:Origins, Niches, and Adaptations

Chapter 5

Evolution and Biodiversity:Origins, Niches, and Adaptations

Chapter 5

Evolution and AdaptationEvolution and Adaptation

Natural selectionNatural selection• Process in by which individuals of a population acquire Process in by which individuals of a population acquire

genetically based traitsgenetically based traits that that increaseincrease their their chances of chances of survivalsurvival and their and their ability to produce offspringability to produce offspring..

Adaptation (n.)Adaptation (n.)– A heritable trait that enables an organism to better A heritable trait that enables an organism to better

survive and reproduce under a given set of survive and reproduce under a given set of environmental conditionsenvironmental conditions

Artificial selectionArtificial selection• Humans select one or more desirable genetic traits in Humans select one or more desirable genetic traits in

the population of a plant or animal.the population of a plant or animal.

Natural SelectionNatural Selection

Conditions necessary for natural Conditions necessary for natural selection:selection:– variabilityvariability– heritabilityheritability– differential reproductiondifferential reproduction

Fig. 5-5 p. 101Fig. 5-5 p. 101

Climate Change and Natural SelectionClimate Change and Natural Selection

• Changes in climate throughout the earth’s history Changes in climate throughout the earth’s history have shifted where plants and animals can live.have shifted where plants and animals can live.

Figure 4-6Figure 4-6

Limits on Adaptation through Natural SelectionLimits on Adaptation through Natural Selection

• A population’s ability to adapt to new A population’s ability to adapt to new environmental conditions through environmental conditions through natural selection is natural selection is limited by its limited by its gene poolgene pool and and how fast it can how fast it can reproducereproduce..– Humans have a relatively slow Humans have a relatively slow

generation time (decades) and output generation time (decades) and output (# of young) versus some other species.(# of young) versus some other species.

Evolution and AdaptationEvolution and Adaptation

• Co-EvolutionCo-Evolution– Populations of two Populations of two differentdifferent species species

interactinginteracting over a long period of time over a long period of time

– Changes in the gene pool of of one species Changes in the gene pool of of one species changes the gene pool of another specieschanges the gene pool of another species

• Predator-Prey RelationshipsPredator-Prey Relationships• Plant defense mechanismsPlant defense mechanisms

Ecological Niches and AdaptationEcological Niches and Adaptation

• Ecological nicheEcological niche– Total way of life or functional role of a Total way of life or functional role of a

species in an ecosystem.species in an ecosystem.

• HabitatHabitat– Physical location of a speciesPhysical location of a species

Occupation

Address

Ecological Niches and AdaptationEcological Niches and Adaptation

• Fundamental nicheFundamental niche– Full potential range of the physical, chemical, Full potential range of the physical, chemical,

and biological factors a species can use if and biological factors a species can use if there were there were nono directdirect competitioncompetition from other from other species.species.

• Realized nicheRealized niche– Part of a species fundamental niche that are Part of a species fundamental niche that are

actually used.actually used.

Broad and Narrow NichesBroad and Narrow Niches

• Generalist speciesGeneralist species– Species with a Species with a broadbroad ecological niche. 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)(flies, mice, deer, catfish, humans)

• Specialist speciesSpecialist species– Species with a Species with a narrownarrow ecological niche. 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 Tolerate only a narrow range of climatic and other

environmental conditions.environmental conditions.(tiger salamander, red-cockaded woodpecker, (tiger salamander, red-cockaded woodpecker, spotted owls, pandas)spotted owls, pandas)

Generalist and Specialist Species: Broad and Narrow NichesGeneralist and Specialist Species: Broad and Narrow Niches

• Generalist Generalist species species tolerate a tolerate a wide range of wide range of conditions.conditions.

• Specialist Specialist species can species can only tolerate a only tolerate a narrow range narrow range of conditions.of conditions.

Speciation, Extinction, and BiodiversitySpeciation, Extinction, and Biodiversity

Speciation - Speciation - formation of formation of two species two species from onefrom one species because of species because of divergent divergent natural selectionnatural selection

1)1) Geographic isolation – Geographic isolation – groups groups of the same species become of the same species become physically separatedphysically separated

Geographic IsolationGeographic Isolation

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

Speciation, Extinction, and BiodiversitySpeciation, Extinction, and Biodiversity

2)2) Reproductive IsolationReproductive Isolation – isolated – isolated populations become so genetically populations become so genetically different they cannot . . . different they cannot . . .

Interbreed, orInterbreed, orproduce live, fertile offspringproduce live, fertile offspring

Extinction: Lights OutExtinction: Lights Out

• Extinction occurs when the population cannot adapt to changing environmental conditions.

The golden toad of Costa Rica’s The golden toad of Costa Rica’s Monteverde cloud forest has Monteverde cloud forest has become extinct because of become extinct because of changes in climate.changes in climate.

Figure 4-11Figure 4-11

Extinction: Lights OutExtinction: Lights Out

• 99.9 % of all species that ever existed are now extinct

Figure 4-11Figure 4-11

How do speciation and extinction affect biodiversity?

How do speciation and extinction affect biodiversity?

Speciation – Speciation – Extinction = Extinction = BiodiversityBiodiversity

Effects of Humans on BiodiversityEffects of Humans on Biodiversity

• The scientific consensus is that The scientific consensus is that human activities human activities are decreasing the earth’s biodiversityare decreasing the earth’s biodiversity..