SlideServe
Télécharger Obtenir Pro
Menu
Accueil Pro
Préférences
ApparenceLight Aide et commentaires
© SlideServe · v2026

Understanding Natural Selection and the Hardy-Weinberg Principle in Evolution

myles-barrett avatar
myles-barrett
18 diapositives · 355 Views · Dec 01, 2014

Natural selection is a fundamental mechanism of evolution where organisms with advantageous traits reproduce more successfully, leading to a gradual change in populations. Key concepts include reproductive fitness, genetic variation, adaptation, and the Hardy-Weinberg principle, which predicts allele frequencies in a population under specific conditions. This principle helps analyze genetic disorders and allele frequencies over generations. By studying extinct species like Phoberomys pattersoni, we can apply these principles to understand past populations and their genetic dynamics.

Understanding Natural Selection and the Hardy-Weinberg Principle in Evolution - slide 1
01 / 18Understanding Natural Selection and the Hardy-Weinberg Principle in Evolution
1 / 17

Télécharger la présentation

Understanding Natural Selection and the Hardy-Weinberg Principle in Evolution
Une image / un lien ci-dessous est fourni (tel quel) pour télécharger la présentation

Politique de téléchargement : le contenu du site vous est fourni TEL QUEL pour votre information et votre usage personnel ; il ne peut être vendu, concédé sous licence ni partagé sur d’autres sites sans l’accord de son auteur.Le contenu vous est fourni TEL QUEL, pour votre information et votre usage personnel uniquement. Téléchargez la présentation en cliquant sur ce lien. Lors du téléchargement, si vous ne parvenez pas à télécharger une présentation, l’éditeur a peut-être supprimé le fichier de son serveur.Pendant le téléchargement, si vous ne parvenez pas à obtenir une présentation, le fichier a peut-être été supprimé par l’éditeur.

F I N

Plus de contenu associé

Transcription de la présentation

  1. Unit IEvolution Learning Goal 1 Natural Selection is a major mechanism of evolution

  2. Natural Selection is a major mechanism of evolution Natural Selection – in a population, organisms with a genetic trait that increases the chance of having offspring will pass on their genes to the next generation more than those without. Reproductive Fitness – relative ability to survive and leave offspring

  3. Requirements • More offspring born than can survive to adulthood • Competition for resources • Genetic variation/diversity within the population • Some varieties have an increased chance to survive long enough to reproduce.

  4. Genetic variation and mutation play roles in natural selection. A diverse gene pool is important for the survival of a species in a changing environment.

  5. Environments can be more or less stable or fluctuating, and this affects evolutionary rate and direction; different genetic variations can be selected in each generation.

  6. An adaptation is a genetic variation that is favored by selection and is manifested as a trait that provides an advantage to an organism in a particular environment.

  7. In addition to natural selection, chance and random events can influence the evolutionary process, especially for small populations.

  8. Mathematical approaches are used to calculate changes in allele frequency, providing evidence for the occurrence of evolution in a population. This can be done using the Hardy-Weinberg Principle

  9. The Hardy-Weinberg Principle The Hardy-Weinberg law is an algebraic formula to estimate the frequency of a dominant or recessive gene in a population based on the frequency with which the trait or condition is found in a population.

  10. A population with: • A large number of individuals • No migration • No mutations • Random mating • No natural selection Is said to be in Hardy-Weinberg equilibrium and no evolution can occur.

  11. The equation is p2 + 2pq + q2 = 1 where: p = the frequency of the dominant allele q = the frequency of the recessive allele p2 = the frequency of the homozygous dominant genotype 2pq = the frequency of the heterozygous genotype. p2 = the frequency of the homozygous recessive genotype.

  12. Cystic fibrosis is a genetic disorder in homozygous recessives that causes death during the teenage years. If 4 in 10,000 newborn babies have the disease, what are the expected frequencies of the three genotypes in newborns, assuming the population is at Hardy- Weinberg equilibrium? Why is this assumption not strictly correct?

  13. The allele y occurs with a frequency of 0.8 in a population of clams. Give the frequency of genotypes YY, Yy, and yy. Show your work!

  14. In the year 2374, humans finally developed the technology necessary for time travels. You are a scientist interested in the population genetics of extinct animals. Taking advantage of this technological advance, you decide to go to the past 8 million years to conduct a field work in Venezuela to study a population of Phoberomys pattersoni*, the world’s largest extinct rodent weighing approximately 700 kg (1500 lb) and looking vaguely like a giant guinea pig. The coat color of this rodent varies between tan (dominant) and brown (recessive). Assume the population is in Hardy-Weinberg equilibrium. You observed 336 tan Phoberomys and 64 brown Phoberomys during your study.

  15. What is the frequency of the homozygous recessive genotype? b) What is the allelic frequency of the dominant (tan) allele in the population? c) Of the animals you observed, how many were heterozygous?

  16. You make another trip to Venezuela and this time you observe 650 animals. d) How many of the 650 animals would you expect to be tan, assuming the population is still in Hardy-Weinberg equilibrium? e) How many of these tan animals are homozygous for the dominant allele? f) How many of these 650 animals would you expect to be brown, assuming the population is still in Hardy-Weinberg equilibrium?

  17. Key Vocabulary • Biological Evolution • Natural Selection • Reproductive Fitness • Competition 5. Variation 6. Adaptation 7. Hardy-Weinberg Principle 8. Genetic equilibrium 9. Hardy-Weinberg Conditions 10. Hardy-Weinberg Equation