Topic: Mechanisms of biological evolution

Target group

8th‑grade students of elementary school

Core curriculum

General requirements

I. Knowledge of biological diversity and basic biological phenomena and processes. Student:

2/. explains biological phenomena and processes occurring in selected organisms and in the environment.

Specific requirements

VI. The evolution of life. Student:

2/. explains examples of what natural and artificial selection consists of and the differences between them.

General aim of education

You will learn the basic mechanisms of biological evolution

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to indicate the genetic and ecological factors influencing the formation of the species;

• to explain how the natural selection works;

• to give examples of artificial selection;

• to compare natural selection with artificial selection;

• to explain how the species are formed..

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• exposing

  • exposition.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers.

Lesson plan overview

Before classes

• Students get acquainted with the content of the abstract. They prepare to work on the lesson in such a way to be able to summarize the material read in their own words and solve the tasks themselves.

Introduction

• The teacher explains the aim of the lesson and together with students determines the success criteria to be achieved.

• Then he writes the subject of the lesson on the blackboard or interactive whiteboard. Students write it in notebooks..

Realization

• The teacher asks students to read the abstract themselves, paying particular attention to the illustrations.

• Using the abstract, the lecturer introduces students to the observations and discoveries made by Karol Darwin during a scientific expedition around the world..

• The teacher discusses the mechanism of action of natural selection and the emergence of new species as a result of this process. Then introduces the concept of artificial selection. Using the table „Comparison of natural selection and artificial selection” emphasizes the differences between these mechanisms.

• The lecturer presents the interactive illustration „Results of an intentional selection of livestock” and explains that purposeful breeding treatments have contributed to the creation of many domesticated forms, unheard of at all in the natural environment, often significantly differing in appearance and behavior from wild forms..

• Students, working individually or in pairs, carry out interactive exercises to check and consolidate knowledge learned during the lesson. Selected people discuss the correct solutions for interactive exercises. The teacher completes or corrects the statements of the proteges.

Summary

• At the end of the lesson the teacher asks: If there was going to be a test on the material we have covered today, what questions do you think would you have to answer? If the students do not manage to name all the most important questions, the teacher may complement their suggestions.

Homework

• Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

• Develop a lap book containing issues learned during the lesson and bring your work to the next class.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Mechanisms of biological evolution

One of the first scientists to explain the origins of the great diversity of species on Earth at the moment and in the past, was Charles Darwin. His research, conducted during a scientific expedition around the world, culminated in the coining of the theory of evolution and became the basis for further research.

During his journey, Darwin had the opportunity to study, among other things, animals, plants, fossils and rock formations. His observations concerned such characteristics of organisms, which were adaptations to such diverse environments as the damp forests of Brazil, the grasslands of Argentina and the mighty peaks of the Andes.

During his stay in the Galapagos Islands, Darwin compared plants and animals that inhabited the area with the ones of the land of South America. He noted that despite some similarities, the species of animals from the islands and the mainland are clearly different. He also noticed the differences between the animals living on different islands of the archipelago. One of the groups that attracted his attention were Darwin's finches, that differed between each other, for example, in the shape and size of their beaks, which was a result of the adaptation of these birds to obtain different kinds of food. Based on the structure of the beak, Darwin distinguished, among others, fruit‑eater finches, leaf‑eater finches, insectivorous finches.

While trying to explain the diversity of the Darwin's finches from Galapagos Islands, Darwin assumed that in the remote past, each island was inhabited by birds that had managed to leave the mainland of South America. Slightly different living conditions on the islands meant that the birds had to adapt to the food available there and diversify, giving origin to new species.

Having returned to England, the naturalist worked for many years on the specimens collected during the expedition and analysed the observations. The result of these works was the coining of the theory of natural selection, that explained the causes of evolution, published in the work „On the Origin of Species by Means of Natural Selection” in 1835.

The theory of natural selection created by Charles Darwin and complemented by research on the essence of inheritance is based on facts from observations of the natural world. It is easy to notice that:

• species produce more offspring than can survive in the environment and more than is needed to replace the parents; of the many eggs laid, born individuals or scattered seeds, only a small part will become mature and produce offspring;

• individuals of one species are not identical and many of their characteristics differ, e.g. their size, colour of coating or skin, fitness and susceptibility to diseases

• tens, hundreds and sometimes thousands of descendants appear in the environment. Since its resources are limited, there is a very strong intra‑species competition;

• only the organisms that dispose of the most beneficial features prevail, i.e. those with the most favourable gene composition under given conditions; they also leave more offspring, while genes of the less adapted organisms are eliminated upon their death.

Therefore, environmental conditions cause the selection of individuals, as a result of which, the genes (and adaptations) that remain in the population are favourable in given conditions. The population survives, although the less adapted individuals die or do not pass on their genes to the offspring.

The environment (abiotic and biotic agents) is the selector of organisms. Natural selection is accidental, its effect being the intensified competition of organisms for environmental resources. Changes in populations due to selection result in the consolidation of features facilitating survival in the environment. If individuals of one species are separated by a barrier that is difficult to overcome (e.g. ocean waters or high mountains), populations with slightly different characteristics may emerge. The differences between them may deepen from generation to generation. When separate populations come into contact again, their individuals may be so different that they will not be able to interbreed and produce offspring. They will therefore become separate species.

Observations of the diversification of organisms within the species were made well before Darwin. The first breeders had already noticed that among cattle, for example, each individual was slightly different from the others and so for breeding, they would chose those animals which best met their current needs: which would give more milk or more meat. During the following years, they interbred only those individuals that had the desired traits. This method is called artificial selection and it leads to the reinforcement of a selected characteristic in the population, e.g. more muscular pigs. As a result of an artificial selection, crops and the livestock started to differ from their wild ancestors. Artificial selection can also be used for plants, e.g. for bigger and more juicy fruits.

• Biological evolution happens due to excessive reproduction, single species variability, competition for limited environmental resources and selection of maladjusted organisms.

• Natural selection takes place under the influence of environmental factors - only best adapted individuals, who are able to get the resources necessary for survival, survive and reproduce successfully.

• Artificial selection is used by breeders to select specimens with desired characteristics for breeding , resulting in new animal breeds and plant varieties.

• The emergence of new species is the result of long‑lasting isolation of two or more populations of the same species influenced by natural selection.