Diversity of Organisms

(IB Topic A3.1)

Essential Idea(s): Organisms exhibit intricate variation and diversity in traits, driving speciation.

Unit Length: 3 Lessons (+2 AHL)

  Guiding Questions

◊ What is a species?

◊ What patterns are seen in the diversity of genomes within and between species?

Materials:

Self-Teaching Slides (SL) / Self-Teaching Slides (AHL) Quizlet Vocab Set (SL) / Quizlet Vocab Set (AHL)
Teaching Slides (SL) Notes Template (SL) / Notes Template (AHL)

 

IB Statement(s) and Objective(s)

 

A3.1.1:  Variation between organisms as a defining feature of life

  • Define variation
  • Explain the utility of variation for survival and adaptation of populations
  • Define taxonomy and taxonomist

 

A3.1.2:  Species as groups of organisms with shared traits

  • Outline the original morphological concept of the species as used by Linnaeus

 

A3.1.3:  Binomial system for naming organisms

  • Define binomial nomenclature
  • State the rules of binomial nomenclature formatting

 

A3.1.4:  Biological species concept

  • Define species according to the biological species concept
  • Outline a competing definition for the term “species”

 

A3.1.5:  Difficulties distinguishing between populations and species due to divergence of non- interbreeding populations during speciation

  • Describe limitations of the biological species concept
  • Define speciation
  • Define population
  • Describe the process of gradual speciation
  • Define gradualism
  • Identify gradualism from graphs of morphology changes over time

 

A3.1.6:  Diversity in chromosome numbers of plant and animal species

  • Define chromosome
  • Explain why diploid chromosomes come in pairs
  • Outline the formation of a diploid cell from two haploid gametes

 

A3.1.7:  Karyotyping and karyograms

  • Describe the process of creating a karyogram
  • Evaluate the evidence that chromosome 2 in humans arose from the fusion of chromosomes 12 and 13 with a shared primate ancestor
  • NOS Concept: Students should be able to distinguish between testable hypotheses and non-testable statements 
  • Give 2 examples of non-testable hypotheses for the origin of chromosome 2 in humans

 

A3.1.8:  Unity and diversity of genomes within species

  • Define gene
  • Define genome
  • State the number of genes in the human genome
  • State the size in base pairs of the human genome
  • Define single-nucleotide polymorphism
  • Explain genome variation between different organisms of the same species

 

A3.1.9:  Diversity of eukaryote genomes

  • Describe the relationship between the number of genes in a species and the species complexity 

 

A3.1.10:  Comparison of genome sizes

  • Use the GenBank Database to search for a given gene
  • Compare sizes of genomes of various species based on GenBank search results

 

A3.1.11:  Current and potential future uses of whole genome sequencing

  • Define “sequence” in relation to genes and/or genomes
  • Define whole genome sequencing
  • State the aim of the Human Genome Project
  • Define personalized medicine
  • Outline the potential uses of personalized medicine
  • Outline the technological improvements that have sped the DNA sequencing process
  • Outline current and potential future uses of whole genome sequencing

Additional Higher Level Topics

A3.1.12:  Difficulties applying the biological species concept to asexually reproducing species and to bacteria that have horizontal gene transfer

  • Explain why the species concept does not work well with asexually breeding organisms
  • Describe the structure and function of plasmid DNA
  • Define horizontal gene transfer
  • Explain why the species concept does not work well with organisms that can do horizontal gene transfer

 

A3.1.13:  Chromosome number as a shared trait within a species

  • State that chromosome number and type is a distinguishing characteristic of a species
  • Explain why the typical number of chromosomes in a species is an even number

 

A3.1.14:  Engagement with local plant or animal species to develop a dichotomous key

  • Explain the use of a dichotomous key in the identification of a specimen
  • Create a dichotomous key given a sample of known specimens

 

A3.1.15:  Identification of species from environmental DNA in a habitat using barcodes

  • Define DNA barcoding
  • Define environmental DNA (eDNA)
  • Explain how barcodes and eDNA allow biodiversity of habitats to be investigated rapidly

Activities: ⓟ = podcast / ⍰ = inquiry 5 / ⓦ = Write it /  Ӕ = The academy  / Ⓡ = Read it

(Required) Lab! ⓟ/ⓦ/Ӕ/⍰: Exploring Lizard Phylogeny with DNA  (💁 [written] / 👭 [podcast only] max 3)

Jump into the Caribbean to see how anole lizards have been evolving to local climates for millions of years. There are 4 modules to this virtual lab – you may pick any one of them and answer the questions that align with them, either as a podcast or a written assignment. Alternatively, you can come up with your own inquiry questions, and treat this as an inquiry task. Work your way through this document as you go. You might need the following documents to complete your module:

 

Lab! ⓟ/ⓦ: What is a Species? (💁 / 👭 [podcast only] max 3)

How do animals know who to choose as a mate and who is a member of their own species? A subfamily of fish called darters contains over 200 species – and how one species recognizes another can blur the definition of species. Read about an experiment that collected data on darter behavior, then draw conclusions. Complete any one of the student activities on this page, and answer the accompanying questions either as a podcast or a written assignment.

 

Ӕ: The Academy: Biodiversity  (💁)

Create a Khan Academy-style video to explain the biodiversity that results from the speciation of life. Include the following key points: 

  • The concept of variation as an essential component of life
  • The definition of a “species” and limitations of this definition
  • The current system used to name species
  • How new species arise from previous ones (e.g. gradualism)
  • What the future of classification might look like in light of DNA discoveries and technology

You choose how to present this (e.g. screencast, class lesson), but this is a good topic to use pictures from the internet to support your explanations.

 

⍰: “Inquiry 5″: Q&A on Speciation (💁/ 👭 max 2)

Create a list of 5 inquiry questions related to speciation. Remember that good inquiry questions are conceptual / open-ended, 

SUCH AS: “How is speciation different from evolution?; 

NOT: “What is a gene pool?” 

If working solo, write out answers to your own questions; if working in pairs, record yourselves asking each other your 5 questions.

 

ⓡ/ⓟ/ⓦ (+NOS): What’s in a Name? How DNA Sequencing Makes It Harder to Tell Species Apart  (💁)

“DNA Barcoding” is changing the way we classify living organisms. Read the following two articles about the ways DNA barcoding is changing the way we classify life…

…then come up with a list of thoughtful, insightful questions to discuss. Here are some suggested questions to get you started: 

  • Who was Carolus Linnaeus, and what was his contribution to taxonomy?
  • Since the time of Linnaeus, how have we typically classified new organisms?
  • What is DNA barcoding, and how/why is it changing the outlook for taxonomy and classification?
  • How the advancement of DNA sequencing is an example of the Nature of Science (e.g. how technology begets discovery; how science theories can change over time, etc).