Topic: Genetic diversity

Target group

High school / technical school student

Core curriculum

General requirements

V. Reasoning and applying the acquired knowledge to solving biological problems. Student:

1. interprets information and explains causal relationships between processes and phenomena, formulates conclusions.

Specific requirements

XI. Biodiversity, its threats and protection. Student:

1 . presents types of biodiversity: genetic, species and ecosystem.

General aim of education

Students explain the importance of genetic diversity.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• describe the importance of genetic diversity in adapting organisms to local living conditions;

• explain what the evolutionary arms race is all about and what genetic diversity has in it;

• explain the causes and effects of the decline in genetic diversity.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• 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 gives the topic, the goals of the lesson in a language understandable for the student, and the criteria of success.

Realization

• The teacher uses the text of the abstract for individual work or in pairs, according to the following steps: 1) a sketchy review of the text, 2) asking questions, 3) accurate reading, 4) a summary of individual parts of the text, 5) repeating the content or reading the entire text.

• Participants familiarize themselves with the content presented in the interactive illustration. Then the teacher discusses the issues with the students.

• The teacher initiates a discussion about the impact of man on the genetic diversity of organisms. During the discussion, the importance of adaptation of the heterozygosity of the population on selected examples of plants and animals is discussed.

• Students perform exercises and commands. The teacher checks and supplements the answers, providing students with the necessary information. Provides feedback..

Summary

• The teacher briefly presents the most important issues discussed in class. He answers the additional questions of the proteges and explains all their doubts. Students complete notes.

Homework

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

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Genetic diversity

Genetic diversity (intra‑species) is the diversification of alleles of genes in pools of genes of the population of a given species.

High genetic diversity makes it possible for species to create various adjustments (adaptations), for example to fight with predators and pathogens (viruses, pathogenic microorganisms, parasites).

There is a continuous evolutionary arms race in nature between the hosts and parasites, and between predators and preys, which is a sign of coevolution. By shuffling within pool of genes and appearing of new mutations in genotypes the adaptations appear which enable specific species to achieve superiority over the enemy species, which is reflected in their better adaptation to living conditions in changing environmental conditions.

„Individuals which are more immune produce more offspring and at least some of the individuals from the offspring inherit genes determining increased immunity. As a consequence, the appearance of mutated genes in a given population is more frequent. Analogically, when it comes to pathogens, new mutations increase the efficacy of infecting the hosts, e.g. by breaking their natural defence mechanisms. Pathogens which acquired the ability to infect the host more efficiently multiply more intensively, and therefore they spread in the host’s population more effectively.

The direct cause of decrease in genetic diversity is the decrease in number of individuals in a population. Genes are transferred from one generation to another randomly. The bigger number of individuals has specific allele, the more probable it is that it will be passed onto next generation and it will be strengthened in a population. However, if a specific allele appears in a population occasionally, there is high probability that it will disappear from the pool of genes. Therefore, only properly high population number guarantees passing diversified genetic material onto the next generations. High number of individuals also mean more chances for the appearance of mutations and obtaining new alleles of genes of adaptational importance.

An important cause of the decrease in genetic diversity is extinction of local subspecies or varieties of wild organisms, as well as the appearance of more and more selected, genetically homogeneous varieties of crop plants and breeds of farm animals. With the extinction of wild varieties, all unique alleles, which were in their genotypes and determined the adaptation to local environmental conditions, disappear.

One of the method of preserving a feature desired by a human is inbreeding, which means crossbreeding of closely related organisms, resulting in the increase in homozygosity in offspring. Individual offspring are very similar to each other in terms of genes, and in the case of crop plants they are sometimes clones. In this way, the pool of genes is depleted gradually in next generations. The use of inbreeding in plants contributes to increase in yields, but it also leads to a situation when new varieties are more susceptible to the attack of various pathogens. In animals, it may lead to increased meatiness of pigs or milkness of cows, but it also reduces the immunity of these animals to diseases.

Thanks to selective breeding people obtained many varieties and breeds of plants and animals. There are thousands of varieties especially for ornamental plants, e.g. roses, which were crossed and selected due to numerous desired characteristics: size of flowers, their colour, scent, ability to climb on supports, production of many thorns or lack of thorns, tree or miniature type, winter hardiness. Due to that they maintained many alleles of genes. Similarly to roses, the species of domestic dog, represented by many breeds, still maintains high genetic diversity.

• Genetic diversity enables the adaptation of a species to environmental changes.

• Mutations, by enriching the pool of genes of a population, may give the organisms the advantage reflected by their better accommodation to living conditions in changing environmental conditions.