Secrets in the Seaweed

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Ancient Secrets in the Seaweed: Climate Change and Evolution

Elephant Seal in Bull Kelp Photo Ceridwen Fraser

Allan Wilson Centre Post Doctoral Fellow Ceridwen Fraser has recently completed her PhD, which saw her spend three years unravelling a story of the impact of climate cycles that is hidden in the DNA of Southern Bull Kelp (Durvillaea antarctica). Using modern biotechnologies to analyse DNA from Bull Kelp samples collected from the coastline of New Zealand, Southern Chile and Sub‐Antarctic Islands, Ceridwen has discovered evidence that in the last ice age the sea ice was more extensive than previously thought, and that this has affected the distribution of populations of Kelp that we see today.

This Ancient Secrets in the Seaweed Seminar includes these resources to assist your learning :

Download the Seminar Paper and questions
Review the Pre-Seminar Discussion Paper.
Watch the seminar and discuss the questions with your teacher and school group
Answers the seminar challenge questions.
If you would like to ask a question about the seminar paper click here.

The Seminar Paper and Questions

Download the Ancient Secrets in the Seaweed Seminar Paper and read this in preparation for your in-school workshop prior to the seminar.

Answers the seminar challenge questions below:

1. The genus Durvillaea (commonly known as Southern Bull‐Kelp) contains a number of species, of
which Durvillaea antarctica is one.
(a) Define genus and species.
Biologists have different ways of defining species. Three of the most common are the biological, morphological and phylogenetic species concepts.
(b) Explain the differences between each, including a description of its limitations.Add your answer here.

2. Figure 1 shows a phylogenetic tree illustrating genetic variation within the single species Durvillaea antarctica. Explain what the diagram tells you about
the variation shown within the species.
Do you think this bull‐kelp should be treated as one, or several, species? (Do you feel you have enough information to make this decision, and if not, what other information might you require?) Add your answer here.

3. Ceridwen and the team analysed the samples from the populations using molecular biotechnologies. The evidence allowed them to infer what had happened to the populations in the last glacial period. What does the term infer mean and why is it used in this context? Add your answer here.

4. Mitochondrial DNA is used in the analysis of the samples because it is abundant and easily accessible. However there are other advantages of using mitochondrial DNA over using nuclear DNA. Discuss possible reasons for these advantages. Add your answer here.

5. Discuss the potential mechanisms and role of climate change in causing genetic variation within Durvillaea antarctica. Use the data from Fig 8 and Fig 9 (on page 5 of the seminar paper), to explain why the evidence suggests that the subantarctic populations of Durvillaea antarctica have colonised this area recently (in terms of geological time). Explain what would have to occur in order for new species to evolve from the variants currently seen within the population? Add your answer here.

6. Discuss the potential mechanisms and role of climate change in causing genetic variation within Durvillaea antarctica. Use the data from Fig 8 and Fig 9 (on page 5 of the seminar paper), to explain why the evidence suggests that the subantarctic populations of Durvillaea antarctica have colonised this area recently (in terms of geological time). Explain what would have to occur in order for new species to evolve from the variants currently seen within the population? Add your answer here.

If you have any questions that you would like answered post them on the Question page.

The Seminar Multi Media

A copy of the seminar powerpoint is available here.

Click here to download the video of this seminar.

Links to your school programme

This seminar links to NCEA Level 3 Achievement Standards:

AS 90716 Describe animal behaviour and plant responses in relation to environmental factors
AS 90717 Biology 3.5 Describe processes and patterns of evolution
AS 90718 Describe applications of biotechnological techniques

A list of objectives from your Year 13 programme that link into the seminar can be found on page 2 of the Pre-seminar Questions and Discussion.

About the Presenters

Jacquie Bay| Ceridwen Fraser | Hamish Spencer

Ceridwen grew up in Canberra, Australia, and early in high school decided she wanted to become a marine biologist. Many tried to discourage her, saying there were few jobs in marine science, so Ceridwen did a university degree in art conservation—but she eventually had to admit that biology was still her dream, jobs or no jobs. She started a degree in Marine Science at James Cook University in tropical northern Australia, finished it off at Macquarie University in Sydney, worked for a year in the marine invertebrate research group at the Australian Museum, and then began a PhD in the Department of Zoology at the University of Otago, New Zealand, which she completed in 2009. Crid is now a postdoctoral research fellow at The Biological control and Spatial Ecology Lab. within the Université Libre de Bruxelles. Since starting her degree in marine biology, she has never looked back, and instead looks forward to an exciting career filled with discovery and adventurous fieldwork.