Первый слайд презентации
COURSE STUDENT MUVAHID Scientific Leader ANNAS ZHUKOVA GENETIC CHARACTRISTIC OF HUMAN POPULATION Medical Academy named after S.I. Georgievsky of Vernadsky CFU DEPARTMENT OF MEDICAL BIOLOGY
Слайд 2: population
population is a group of organisms of the same species that live in the same area How large a population is and how fast it is growing are often used as measures of its health A single individual cannot evolve alone; evolution is the process of changing the gene frequencies within a gene pool. The process of evolution occurs only in populations and not in individuals
Слайд 3: evolution
evolution is the change in the characteristics of a species over several generations and relies on the process of natural selection. The theory of evolution is based on the idea that all species are related and gradually change over time. Evolution by natural selection is one of the best substantiated theories in the history of science, supported by evidence from a wide variety of scientific disciplines
Different characteristics tend to exist within any given population as a result of mutation, genetic recombination and other sources of genetic variation. Evolution occurs when evolutionary processes such as natural selection (including sexual selection ) and genetic drift act on this variation, resulting in certain characteristics becoming more common or rare within a population.
Слайд 5: POPULATION AS THE BASIC UNIT OF EVOLUTION
A population is the smallest unit of living organisms that can undergo evolution.... A peccary population, therefore, can be considered as a "pool" of genes and gene types that reflect the genetic diversity of all the individuals within the group. This "pool-of-genes" is what changes when evolution takes place.
Слайд 6: FACTORS OF EVOLUTION
NON-DIRECTED FACTORS OF EVOLUTION - GENETIC VARIATION IN POPULATION GENE MUTATION RECOMBINATION OF GENES HYBRIDIZATION - POPULATION SIZE - REPRODUCTIVE ISOLATION DIRECTED FACTORS OF EVOLUTION - NATURAL SELECTION
Слайд 7: POPULATION SIZE
In nature all populations have a tendency and a tremendous potential for growth, but remain limited to a relatively constant size due to limitation of resources. It means only a small size of population actually serve as parents for next generation. Normally the individual better adapted to their environment are more likely to survive. But chance is also very important
Слайд 8: genetic characteristics of population
Heterogeneity of population Genetical unity of population If a population is not evolving, the frequencies of each allele remain constant from one generation to the next generation
Слайд 9: Heterogeneity of populations
A given population (as illustrated by different phenotypes) indicates that each individual has a different portion of the genes that exist in the gene pool. Because most species are diploid, each individual member of a population contains only two alleles for each locus. Therefore, a single individual has only some of the genes found in its population gene pool.
Слайд 10: Genetical unity of populations
Each population possesses an iso- lated gene pool, which includes all possible alleles at each locus of each chromosome present in the breeding individuals of the population.
Слайд 11: The Hardy-Weinberg law shows that in large populations, the process of inheritance does not by itself cause changes in allele frequencies, which remain constant from generation to generation
LARGE POPULATION SIZE ISOLATION NO MUTATION NO SELECTION RANDOM MATING
Слайд 12: Most populations have a large reservoir of variability
Heterozygote advantage occurs when the heterozygote has a higher degree of fitness than either homozygote. Both alleles are maintained in the population. In frequency-dependent selection, a genotype’s selective value varies with its frequency of occurrence. Variation that confers no detectable selective advantage is called neutral variation. The neutralist-selectionist controversy is a debate among biologists over the relative importance of selection versus genetic drift in maintaining genetic variability.
Population genetics is a subfield of genetics that deals with genetic differences within and... Haldane also applied statistical analysis to real-world examples of natural selection, such as peppered moth... mutations can eventually cause the genetic assimilation of traits that were previously induced by the environment.
Population genetics began as a reconciliation of Mendelian inheritance and biostatistics models. Natural selection will only cause evolution if there is enough genetic variation in a population. Before the discovery of Mendelian genetics, one common hypothesis was blending inheritance. But with blending inheritance, genetic variance would be rapidly lost, making evolution by natural or sexual selection implausible. The Hardy–Weinberg principle provides the solution to how variation is maintained in a population with Mendelian inheritance. According to this principle, the frequencies of alleles (variations in a gene) will remain constant in the absence of selection, mutation, migration and genetic drift.
Слайд 19: for better understanding
https://www.youtube.com/watch?v=GhHOjC4oxh8 https://www.youtube.com/watch?v=SRWXEMlI0_U https://www.youtube.com/watch?v=hOfRN0KihOU