Evolution in our time (the lesson)
Categorie(s): Food for Mankind, thematic lessons
Thinking of evolution people mostly think of processes of millions of years and exotic and extinct animals like dinosaurs. But evolution happens all the time, maybe even more than before. There are more and more cases showing that we humans are accelerating the evolution of species around us. That we make more species extinct (also an aspect of evolution) is well known, but changing species happens all the time too. The best known cases are bacteria turning resistent against antibiotics and insects against insecticides.
Read the texts Smaller Fish – The Decade’s Most Underreported Story? and As humans change lanscapes brains of some animals change too and answer the questions below. Try to find more examples of evolution caused by humans.
Questions:
1. Species like cod and halibut used to be so big that one helping was no more than a slice of the fish. Nowadays you see half of a cod as a one-persons’ portion. And the big ones are very rare today. Which type of selection made these fishes on average so much smaller?
2. There are strict rules for the fishing nets, meant to prevent extinction.
a. What is the idea behind the minimum mesh size of fishing nets?
b. What is the evolutionary effect?
3. Explain exactly how variation and natural selection work in this case.
4.Try to find people who can tell how big cod and halibut (and maybe other fishes) used to be, maybe your grandparents, of some old fisherman, of fish monger, or somebody working in a museum of natural history. Such people can often tell much more about changes in animals in the populations, etc. and the way people used to catch them.
5. What should the fishing industry change to prevent not only extinction of the species, but also this type of change in the fenotype in the future?
6 .From other studies (old wood but also old texts) we know that until ca 1800 there were many more old big trees (like oaks) in Europa and North America . Is this also a form of evolutionary change in the oak? Explain! If not what is the cause?
7. Hunters say that hunting is necessary to maintain the populations, because there are no longer enough wild predators . Which hunting rules are meant to keep the populations of boar, elk, deer etc alive?
8. a. Would it be better tot stop the hunt completely to keep the population healthy and intact?
b. Also some other species of animals hunted by humans do not get so big anymore as before. How can you explain that?
c. If hunting will not be forbidden, how should the rules be changed to stop the evolution to smaller forms?
9. In urban settings small animals like mice and voles must be smarter than in the countryside – even if you would think there is more food for them in the cities. Why is it nevertheless more difficult to find enough food and survive in the city – if you are a small rodent?
10. Other studies have shown that singing birds in the city sing louder and in higher pitch than the same species in the countryside. Which (natural) selection is working here?