Natural Selection (15.3) State Standard SB5D. Relate natural selection to changes in organisms

Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance Natural Selection Nature acts to select the individuals that are best adapted for survival and reproduction in a particular environment

Principles of Natural Selection Chapter 15 Evolution Principles of Natural Selection Natural selection takes place when… Individuals in the population show variations. The variations are inheritable. Members of the population have more offspring than can survive on available resources (overproduction). Variations that increase reproductive success have a greater chance of being passed on.

Industrialization & the peppered moths 15.3 Natural Selection-Speciation-Resistance Industrialization & the peppered moths

Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance Stabilizing selection operates to eliminate extreme expressions of a trait when the average expression leads to higher fitness. Ex: Peppered Moths before the Industrial Revolution

Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance Directional selection makes an organism more fit by selecting against one extreme. Ex: Pollution from the Industrial Revolution caused directional selection in the peppered moths.

Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance Disruptive selection is a process that splits a population into two groups. Ex: Different rock types in the same biome will favor different coat varieties of these mice

Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance Sexual selection operates in populations where males and females differ significantly in appearance. Qualities of sexual attractiveness appear to be the opposite of qualities that might enhance survival.

Can occur in a relatively short time when one species gives rise to Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance Adaptive Radiation – AKA Divergent Evolution/Speciation Can occur in a relatively short time when one species gives rise to many different species in response to the creation of new habitat or some other ecological opportunity

Associated with mutualism Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance Coevolution The relationship between two species might be so close that the evolution of one species affects the evolution of the other species. Associated with mutualism

Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance Convergent Evolution Unrelated species evolve similar traits because of similar environmental pressures.

Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance Rate of Speciation Evolution proceeds in small, gradual steps according to a theory called gradualism. Punctuated equilibrium explains rapid spurts of genetic change causing species to diverge quickly.

Chapter 15 Evolution 15.3 Natural Selection-Speciation-Resistance

directional evolution divergent evolution Chapter 15 Evolution 15.3 Formative Questions Which evolutionary pattern is represented by the similarities between these two organisms that live on separate continents? coevolution convergent evolution directional evolution divergent evolution A B C D FQ 14

The divergent evolution of these cichlid fish is Chapter 15 Evolution Chapter Assessment Questions The divergent evolution of these cichlid fish is an example of what type of speciation? coevolution mutation adaptive radiation convergent evolution A B C D CAQ 2

What tempo of evolution does this model represent? Chapter 15 Evolution Chapter Assessment Questions What tempo of evolution does this model represent? gradual elevated sequential punctuated A B C D CAQ 3

Standardized Test Practice Chapter 15 Evolution Standardized Test Practice Within a population of squirrels, those that live higher in the mountains where it is cooler have long fur. Squirrels that live in the foothills where it is warmer have short fur. The original population is believed to have had intermediate fur length. Which graph represents this type of natural selection? A B C STP 5