Genetics and Evolution- Evolution - Evidences For Evolution
Slide 1:
- Introduction to Evidences for Evolution
- Evolution is supported by a variety of evidences including fossil records, anatomical structures, and molecular evidence.
Slide 2:
- Fossil Records
- Fossils provide evidence of life on Earth from millions of years ago.
- Fossils can show the progression and transformation of species over time.
Slide 3:
- Anatomical Structures
- Homologous structures are similar structures found in different organisms, indicating a common ancestor.
- Analogous structures are similar structures found in organisms with different ancestors, suggesting convergent evolution.
Slide 4:
- Comparative Embryology
- Similarities in embryonic development suggest a common ancestor.
- Embryos of different species display shared characteristics during development.
Slide 5:
- Biochemical and Molecular Evidence
- DNA and protein sequences can be compared between different species.
- Similarities in sequences indicate common ancestry.
Slide 6:
- Artificial Selection
- Selective breeding by humans has led to the development of new breeds of plants and animals.
- This demonstrates that traits can be modified and manipulated over generations.
Slide 7:
- Biogeography
- The study of the distribution of plants and animals suggests evolution.
- It explains the similarities and differences in species found in different geographical regions.
Slide 8:
- Vestigial Organs
- Vestigial organs are structures that have no known function in an organism.
- These organs are remnants of structures that were once functional in ancestral species.
Slide 9:
- Convergent Evolution
- Convergent evolution occurs when unrelated species develop similar traits.
- This is often seen in species living in similar environments.
Slide 10:
- Direct Observations
- Examples of evolution can be seen in real-time.
- For example, the development of antibiotic resistance in bacteria and the adaptation of insects to pesticide exposure.
Slide 11:
- Homology
- Similarities in characteristics among different species suggest a common ancestry.
- For example, the similar bone structure seen in the forelimbs of vertebrates, including humans, bats, whales, and birds.
Slide 12:
- Comparative Anatomy
- Similar anatomical structures in different species can indicate common evolutionary origins.
- Such as the presence of wings in bats, birds, and insects, even though they come from different lineages.
Slide 13:
- Molecular Clock
- The molecular clock hypothesis uses DNA or protein sequences to estimate the time of divergence between different species.
- It assumes that mutations accumulate at a relatively constant rate over time.
Slide 14:
- Transitional Fossils
- Fossils that exhibit characteristics of both ancestral and derived organisms are called transitional fossils.
- An example is the fossil of Archaeopteryx, which has characteristics of both dinosaurs and birds.
Slide 15:
- Patterns of Speciation
- Speciation is the formation of new species from existing ones.
- Different patterns, such as allopatric, sympatric, and adaptive radiation, can occur during this process.
Slide 16:
- Genetic Variation and Natural Selection
- Genetic variation within a population allows for natural selection to act upon individuals with advantageous traits.
- Over time, the frequencies of certain traits may increase or decrease, leading to evolutionary change.
Slide 17:
- DNA Sequencing
- Advances in DNA sequencing techniques have provided more detailed evidence for evolution.
- Whole genome sequencing allows for a comprehensive understanding of genetic relationships between species.
Slide 18:
- Molecular Phylogenetics
- Molecular phylogenetics is the study of evolutionary relationships using genetic data.
- Tools such as phylogenetic trees can depict the relationships between species based on their genetic similarities.
Slide 19:
- Convergent vs Divergent Evolution
- Convergent evolution occurs when unrelated species develop similar adaptations due to similar environments.
- Divergent evolution is the opposite, where closely related species evolve different adaptations due to occupying different environments.
Slide 20:
- Evolutionary Arms Race
- The co-evolution of two species, where each develops advantageous traits to counter the other, is known as an evolutionary arms race.
- Examples can be seen in predator-prey relationships, such as the struggle between cheetahs and gazelles.
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Slide 21:
- Hardy-Weinberg Equilibrium
- The Hardy-Weinberg principle describes a population in the absence of evolutionary pressures.
- The equation p^2 + 2pq + q^2 = 1 represents the genotype frequencies in a population.
- p represents the frequency of the dominant allele, q represents the frequency of the recessive allele, and pq represents the frequency of heterozygotes.
- The Hardy-Weinberg equilibrium is maintained when the allele frequencies remain constant over generations.
Slide 22:
- Genetic Drift
- Genetic drift refers to the random fluctuations in allele frequencies in a small population.
- It can lead to the loss of rare alleles or fixation of certain alleles.
- The founder effect and bottleneck effect are two examples of genetic drift.
- The founder effect occurs when a small group of individuals migrates and establishes a new population, resulting in reduced genetic diversity.
- The bottleneck effect occurs when a population undergoes a drastic reduction in size, leading to a loss of genetic diversity.
Slide 23:
- Gene Flow
- Gene flow is the transfer of genetic material between populations through migration and interbreeding.
- It can introduce new alleles into a population or decrease genetic differentiation between populations.
- Gene flow can counteract the effects of genetic drift and promote genetic diversity.
Slide 24:
- Natural Selection
- Natural selection is the process by which individuals with favorable traits are more likely to survive and reproduce, leading to changes in allele frequencies.
- It can result in adaptations that enhance an organism’s fitness in its environment.
- There are three types of natural selection: directional selection (favoring one extreme phenotype), stabilizing selection (favoring intermediate phenotypes), and disruptive selection (favoring two or more extreme phenotypes).
- Examples of natural selection include the evolution of antibiotic resistance in bacteria and the adaptation of camouflage in prey species.
Slide 25:
- Sexual Selection
- Sexual selection is selection based on an individual’s ability to attract mates.
- It can lead to the evolution of traits that enhance reproductive success, such as elaborate ornaments or behaviors.
- There are two types of sexual selection: intersexual selection (mate choice by one sex) and intrasexual selection (competition between members of the same sex).
- Examples include the peacock’s tail and the fighting behaviors of male deer during the rutting season.
Slide 26:
- Artificial Selection
- Artificial selection is the intentional breeding of plants or animals by humans to produce desired traits.
- Selective breeding has led to the development of various crop plants, domesticated animals, and ornamental plants.
- Examples include the breeding of different dog breeds or the improvement of crop yield through selective breeding.
Slide 27:
- Evolutionary Fitness
- Evolutionary fitness refers to an individual’s ability to survive and reproduce in its environment.
- Fitness is measured in terms of the number of offspring an individual produces that survive to reproductive age.
- It is influenced by factors such as genetic traits, behavior, and environmental conditions.
Slide 28:
- Coevolution
- Coevolution occurs when two or more species evolve in response to each other.
- Examples include the coevolution between predators and prey or between plants and their pollinators.
- Coevolution can lead to the development of specialized traits and interactions between species.
Slide 29:
- Evolutionary Development
- Evolutionary development, or evo-devo, is the study of how changes in developmental processes contribute to evolutionary changes.
- It explores the genetic and molecular mechanisms underlying the development of different organisms.
- Evo-devo has provided insights into the evolution of novel traits and the diversification of body plans.
Slide 30:
- Recap
- Evolution is supported by various evidences, including fossil records, anatomical structures, molecular evidence, and direct observations.
- Fossils provide a record of past life forms and the changes over time.
- Homologous structures indicate a common ancestry, while analogous structures suggest convergent evolution.
- Molecular evidence, such as DNA and protein sequences, reveals genetic relationships between species.
- Evolutionary mechanisms include natural selection, sexual selection, genetic drift, and gene flow.
- Coevolution and evolutionary development are also important factors in shaping the diversity of life on Earth.