EVOLUTION AND COMMON ANCESTry
Iowa Core Alignment:
HS-LS4-1. Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.
HS-LS4-2. Construct an explanation based on evidence that the process of evolution primarily results from four factors: (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment.
HS-LS4-3. Apply concepts of statistics and probability to support explanations that organisms with an advantageous heritable trait tend to increase in proportion to organisms lacking this trait.
HS-LS4-4. Construct an explanation based on evidence for how natural selection leads to adaptation of populations.
HS-LS4-5. Evaluate the evidence supporting claims that changes in environmental conditions may result in (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.
Disciplinary Core Ideas:
Natural selection occurs only if there is both (1) variation in the genetic information between organisms in a population and (2) variation in the expression of that genetic information—that is, trait variation—that leads to differences in performance among individuals.
Genetic information, like the fossil record, provides evidence of evolution. DNA sequences vary among species, but there are many overlaps; in fact, the ongoing branching that produces multiple lines of descent can be inferred by comparing the DNA sequences of different organisms. Such information is also derivable from the similarities and differences in amino acid sequences and from anatomical and embryological evidence.
The traits that positively affect survival are more likely to be reproduced, and thus are more common in the population.
Evolution is a consequence of the interaction of four factors: (1) the potential for a species to increase in number, (2) the genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for an environment’s limited supply of the resources that individuals need in order to survive and reproduce, and (4) the ensuing proliferation of those organisms that are better able to survive and reproduce in that environment.
Natural selection leads to adaptation, that is, to a population dominated by organisms that are anatomically, behaviorally, and physiologically well suited to survive and reproduce in a specific environment. That is, the differential survival and reproduction of organisms in a population that have an advantageous heritable trait leads to an increase in the proportion of individuals in future generations that have the trait and to a decrease in the proportion of individuals that do not.
Changes in the physical environment, whether naturally occurring or human induced, have thus contributed to the expansion of some species, the emergence of new distinct species as populations diverge under different conditions, and the decline–and sometimes the extinction–of some species.
Species become extinct because they can no longer survive and reproduce in their altered environment. If members cannot adjust to change that is too fast or drastic, the opportunity for the species’ evolution is lost.
Minds on Biology (MOBs)
MOB 1: Genetic Variation *
MOB 2: Populations *
MOB 3: Section 17.1
MOC 4: Natural Selection *
MOC 5: Natural Selection in Action
MOB 6: Biological Fitness
MOB 7: Section 16-2 *
MOB 8: Understanding Evolution *
MOB 9: Genetic Makeup of a Population
MOB 10: Allele Frequencies
MOB 11: Speciation
MOB 12: Phylogenetic Trees
MOB 13: Evolutionary Relationships in African Lizards
MOB 14: Critical Reading and Review *
MOB 15: The Evolution Lab * Together in class!
MOB 16: PBS NOVA-What Darwin Never Knew * Together in class!
MOB 17: ACT Prep: Finch Beaks *
MOB 18: ACT Prep: Bacteria and Fish *
MOB 19: Jeopardy
8.1. Without genetic variation, the basic mechanisms of evolution can not operate.
Objectives:
(a.) Describe how mutation and sexual reproduction contribute genetic variation to a species.
Links/Sources:
(Link 1) Genetic Variation (video)
(Link 2) Allele Shuffling (video)
(Link 3) What is a Mutation? (video)
(Link 4) Canine Similarities and Differences
(Link 5) The Outcome of Mutation
(Link 6) How often do mutations happen? (video)
8.2. Evolution results from natural selection acting upon genetic variation within a population.
Objectives:
(b.) Explain and model how allele frequencies in a population are affected by natural selection, mutations, gene flow and sexual selection and how changes to allele frequencies result in evolutionary change.
(c.) Describe the role competition has in natural selection.
(d.) Describe what "survival of the fittest" represents in a population.
Links/Sources:
Sections 17.1, 17.5-17.6
Lab/Claim: Selection in Clip Bird Populations
(Link) Natural Selection
(Link/Video) Recipe for Natural Selection
(Link/Video) Rock Pocket Mice
(Virtual Lab) How Can Natural Selection be Modeled?
8.3. Speciation is the splitting of one ancestral lineage into two or more descendent lineages.
Objective:
(e.) Describe and model how new species arise.
(f.) Determine the number of species of birds in a region.
Links/Sources:
Sections 16-2 and 17-7
Claim: How many species of birds are present in the ecosystem?
(Video/Link) What is a Species?
(Link) Speciation
(Link) Reproductive Barriers
(Link) Causes of speciation
(Link) Reproductive isolation
(Interactive) Sorting Finches
8.4. Present-day species evolved from earlier species and the relatedness of organisms is the result of common ancestry.
Objectives:
(g.) Summarize evidence that supports evolutionary change and common ancestry.
(h.) Create and interpret phylogenetic trees.
(i.) Define biological evolution and identify statements that are true and not true about evolutionary processes.
Links/Sources:
Section 17.11
Claim: Evolutionary Relatedness of Mammals
Link: Guess the Embryo