Introduction to Bioinformatics Online Course: IBT s2
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Introduction to Bioinformatics online course: IBT
Practical assignment #1
Module topic: Molecular Evolution & Phylogenetics Contact session title: historical perspective, mechanisms of molecular evolution and speciation Trainer: JB Domelevo Entfellner Participant:
Darwin’s finches of the Galápagos Islands
Introduction
In the Pacific Ocean, approximately 1,000km west of Ecuador’s coastline, lies the volcanic archipelago of the Galápagos Islands. During his long journey on the HMS Beagle, Charles Darwin stopped on these islands to make observations pertaoning to the geology of the islands, but also to capture flora and fauna specimen. Since then, the finches (small birds, 10 to 20cm long) of these islands have become a classic of evolution.
Tools used in this session
Use the files you will find online on the IBT website: map of the Galápagos Islands images of finches results by Lack (1947) on the distribution on beak depths on various islands
Please note
Hand-in information for those formally enrolled in the IBT course, please upload your completed assignment to the Vula ‘Assignments’ tab. Take note of the final hand-in date for each assignment, which will be indicated on Vula.
Task 1: Predicting the distribution of finches in different habitats
Task 1: instructions Darwin observed that each of the islands had similar types of finches, iguanas and tortoises, but that each was different to make the most of local conditions. Drawing from the information given on the map of the Galápagos and on the description of the various
Introduction to Bioinformatics online course: IBT finches, try and predict the distribution of the finches on the various islands (write a ‘cross’ in the relevant cells wherever you believe a given finch may be present on a given island).
Task 1: participant’s answer z a e a a a a a l l s z u F n n
e o i e r a a l a b n d v C e t
P a a r n o n a s r p a n t I a s o n e n S l E r a G F e S F
Large Ground Finch Cactus Finch
Small Tree Finch
Small Ground Finch
Vegetarian Finch
Large Tree Finch
Warbler Finch
Task 2: Physical characteristics of the bills
Task 2: instructions The bills are the mouthparts of the birds, also called beaks. From a careful observation of the images of the various finches, try and summarize the characteristics of the bills that make them appropriate to feed from seeds, cactus, insects or buds. Try and be as accurate as possible. You may also find relevant information browsing the internet.
Task 2: participant’s answer
Task 3: What if... the seeds on Española started to increase in size?
3.1 What would you expect to see happen to the population over the next 20 years?
3.2 What would you expect to happen immediately to the population of Small Ground Finches?
3.3 What would happen if the size of the seeds decreased again in the future?
Task 4: Variations in the depth of the beaks
In 1947, Lack measured the beak sizes of the three different species of Ground Finch (genus Geospiza) in the Galápagos Islands. His data is recorded in the graphs below (also available in the file online): Introduction to Bioinformatics online course: IBT
4.1 Describe the pattern shown in the beak depth distribution for the birds on Pinta and Marchena.
4.2 What happens to the beak depth of G. fulignosa on Los Hermanos when there is no other competition?
4.3 What happens to the range in beak depth of G. fortis on Floreana and San Cristobal compared to Pinta and Marchena? What may this indicate about the size of seeds available on these islands?
4.4 Darwin only observed one type of finch on the mainland - similar to the Galapagos Small Ground Finch.He proposed that all finches evolved from the one species that lived on the mainland. How could the data from Daphne and Los Hermanos be used to support Darwin’s theory that all Finches evolved from a common ancestor?