5
Evolution and CommunityEcology
Evolution and CommunityEcology
CHAPTER
Black and White, and SpreadAll Over
Black and White, and SpreadAll Over
•Zebra mussels and quagga mussels were accidentallyintroduced into Lake St. Clair in the late 1980s.
•They have since spread throughout the Great Lakessystem and connecting rivers.
•The invasive mussels have a high economic andecological cost.
•Zebra mussels and quagga mussels were accidentallyintroduced into Lake St. Clair in the late 1980s.
•They have since spread throughout the Great Lakessystem and connecting rivers.
•The invasive mussels have a high economic andecological cost.
Talk About It The Great Lakes are home to more than20 native mussel species. Why are the zebra andquagga mussels so much more destructive than thelakes’ native mussels?
Talk About It The Great Lakes are home to more than20 native mussel species. Why are the zebra andquagga mussels so much more destructive than thelakes’ native mussels?
Lesson 5.1 Evolution
Lesson 5.1 Evolution
Scientists have identifiedand describedover 1.5 million species.Millions morehave yet to be discovered.
Scientists have identifiedand describedover 1.5 million species.Millions morehave yet to be discovered.
Evolution and Natural Selection
Evolution and Natural Selection
•Gene: A sequence ofDNA that codes for aparticular trait
•Gene pool: All the genespresent in a population
•Biological evolution:The change in apopulation’s gene poolover time
•Gene: A sequence ofDNA that codes for aparticular trait
•Gene pool: All the genespresent in a population
•Biological evolution:The change in apopulation’s gene poolover time
Lesson 5.1 Evolution
A starting population of fish. Genes controlthe color and pattern of the fish’s scales.
Mechanisms of BiologicalEvolution: Mutation and Migration
Mechanisms of BiologicalEvolution: Mutation and Migration
Mutation
Lesson 5.1 Evolution
Accidental change in DNAthat can give rise tovariation among individuals
Migration (gene flow)
Movement of individuals into(immigration) or out of (emigration)a population
Mechanisms of BiologicalEvolution: Genetic Drift andNatural Selection
Mechanisms of BiologicalEvolution: Genetic Drift andNatural Selection
Lesson 5.1 Evolution
Genetic Drift
Natural Selection
Evolution that occurs by chance
Process by which traits useful forsurvival and reproduction are passed onmore frequently than those that are not
Conditions of Natural Selection
Conditions of Natural Selection
Lesson 5.1 Evolution
(1) Organismsproduce moreoffspring than cansurvive.
(2) Individuals vary incharacteristics, someof which are heritable.
(3) Individuals vary infitness, or reproductivesuccess.
Did You Know? Darwin privately researchednatural selection for two decades beforepublishing On the Origin of Species.
Did You Know? Darwin privately researchednatural selection for two decades beforepublishing On the Origin of Species.
Artificial Selection
Artificial Selection
Lesson 5.1 Evolution
•Selection under human direction
•Throughout history, humans have chosen and bredanimals and plants with beneficial traits.
Speciation
Speciation
Lesson 5.1 Evolution
•Process by whichnew species aregenerated
•Can occur in anumber of differentways; the mostimportant way iscalled allopatricspeciation
•Has resulted in everyform of life on Earth—today and in the past
Allopatric Speciation
Extinction
Extinction
Lesson 5.1 Evolution
•The disappearance ofspecies from Earth
•Generally occurs gradually,one species at a time,when environmentalconditions change morerapidly than the speciescan adapt
•There are five known massextinction events, each ofwhich wiped out a largeproportion of Earth’sspecies.
Did You Know? During the Permo-Triassicextinction 250 million years ago, 70% of allland species and 90% of all marine specieswent extinct.
Did You Know? During the Permo-Triassicextinction 250 million years ago, 70% of allland species and 90% of all marine specieswent extinct.
Trilobites
Marine arthropods that went extinct atthe end of the Permian period.