Effects of domestication in the course of evolution

Domestication is a form of artificial selection where humans selectively breed plants and animals for specific traits that are advantageous for agriculture, companionship, work, or other purposes. This process has profound effects on the species being domesticated, often resulting in genetic, morphological, physiological, and behavioral changes. Here's an overview of the effects of domestication in the course of evolution:

Genetic Diversity
Reduction in Genetic Diversity: Domestication typically involves selecting a few individuals with desirable traits to breed the next generation. This selective breeding can reduce genetic diversity because it often excludes a large portion of the population from reproducing. Reduced genetic diversity can make domesticated species more susceptible to diseases and reduce their ability to adapt to changing environmental conditions.

Founder Effect: Many domesticated species originated from a relatively small ancestral population, which can lead to a pronounced founder effect. This effect occurs when a new population (in this case, domesticated species) is established from a small number of individuals, carrying only a fraction of the genetic diversity of the original population.

Morphological Changes
Size and Shape: Domestication often leads to changes in the size and shape of animals and plants. For example, domesticated animals tend to be larger or smaller than their wild counterparts, depending on the use intended by humans. Similarly, domesticated plants often have larger fruit or seeds than their wild relatives.

Neotenization: Domesticated animals often exhibit juvenile characteristics into adulthood, a process known as neotenization. This can include changes such as floppy ears, smaller jaws, and more docile behavior compared to their wild ancestors.

Physiological Changes
Reproductive Changes: Domesticated species often have higher reproductive rates compared to their wild counterparts. For instance, domesticated animals may breed more frequently or produce more offspring per breeding season. In plants, domestication can lead to a loss of natural seed dispersal mechanisms and an increase in seed yield.

Growth Rates: Enhanced growth rates are common in domesticated species, especially in animals bred for meat production, such as chickens and cattle, and in plants with selected traits for increased biomass or yield.

1. Welcome GROUP B Prashantha, Megha and Brahmesh Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah

2. Man-made selections over natural selections Unintended effects of domestication Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah

3. 1a . Domestication and improvement of crops from wild species is a process of evolution that can be compared to natural selection. In this process, instead of nature being the agent that brings about adaptive changes, it is the human needs and other associated features of cultivation that shape the plant features. In the process, while some changes in plant features are very much intended and visible, there could be a lot of features that get altered unintentionally and may have become invisible . Can you list down at least a set of four such in-intended features that may have undergone changes in crop plants during domestication and explain the direction in which these changes may have taken place . 1b . Also explain how and why you think each of them may have undergone such changes during domestication The question Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah

4. Domestication Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah wild

5. Domestication Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah wild cultivation

6. Why domesticate? Isolate desired characteristics from the wild species. To meet the needs of human beings Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah

7. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah wild So what happens if domesticated?

8. Domestication syndrome Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah wild domesticated

9. The common domestication traits Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Loss of dormancy

10. The common domestication traits Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Larger organ size

11. The common domestication traits Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Reduced seed dispersal and shattering

12. The common domestication traits Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Uniformity in growth

13. The common domestication traits Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Changes to day length sensitivity

14. Where we succeeded Direct effects Increased fruit and seed weight Increased Palatability Changed plant architecture Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1093/pcp/pcac083

15. Traits left behind Indirect effects Reduced sugar content Reduced carotenoids Altered tocopherol and fatty acid content Reduced plant immunity Lower root apical dominance Adaptability Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1093/pcp/pcac083

16. Useful traits left behind A few traits escaped direct selection due to the lack of their perception by humans Loss of innate plant immunity appears to be a common feature associated with domestication in many plant species (Hajjar and Hodgkin 2007) Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah

17. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1007/s10681-007-9363-0 Plus signs indicate number of wild relatives that have contributed beneficial traits to crop varieties in each category of traits

18. Explanation for the losses The reduced frequency or complete loss of resistance alleles due to genetic drift can explain this phenomenon to some extent, especially when resistance is controlled by major gene/s in crop plants Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah

19. Cost of resistance Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah T he wild plants were under continuous pressure from diverse pathogens, and inherent genetic resistance was a necessary defense for their fitness and survival in natural habitats.

20. Cost of resistance Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah In domesticated habitats, the extra care in agronomic measures and later, the application of chemicals slowly eliminated the need for natural pathogen immunity in cultivated plants. The loss of immunity during domestication should also be considered under the ‘ cost of resistance ’ hypothesis

21. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1086/285938

22. Fitness cost Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah keeping resistance genes may have associated fitness costs on desirable traits under selection during the plant domestication process

23. RPM1 codes for a peripheral plasma membrane protein that confers the ability to recognize Pseudomonas syringae. Susceptible individuals lack the entire coding region of RPM1, so there is a single susceptible allele at this locus Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1038/nature01588

24. RPM1+ individuals suffered a 9% decrease in total seed production relative to their RPM1- counterparts Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1038/nature01588

25. Fitness cost Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah For instance, certain metabolic compounds such as s teroidal glycoalkaloids (SGAs), guaiacol and methyl salicylates provide chemical defense and contribute to systemic plant immunity against diverse pathogens These metabolites are also associated with undesirable fruit flavor in tomato and increase in fruit palatability by selecting against these compounds might have inadvertently compromised the host plant immunity

26. Fitness cost Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah A direct negative selection against fruit bitterness decreased the concentrations of 45 out of 46 SGA metabolites in domesticated compared to wild tomato accessions. https://doi.org/10.1016/j.cell.2017.12.019

27. Fitness cost Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah S election against seed dormancy, increased storability and dispersal, the seed carotenoid content inadvertently decreased in several widely consumed legumes including soybean, pea, common bean, peanut and chickpea

28. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1186/s12870-014-0385-1

29. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1186/s12870-014-0385-1

30. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1186/s12870-014-0385-1 The percentage of variation during domestication is also shown [% Δ = (D-W)/W.100] for both carotenoids and tocopherols

31. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1186/s12870-014-0385-1

32. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1186/s12870-014-0385-1

33. Root traits In a similar way, other unperceived plant traits shall most likely illustrate the undesirable impacts of artificial selection. Among them, root traits were neglected during the domestication of desirable above-ground plant parts, yet they differ significantly between wild and domesticated populations in different crops Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah

34. Wild plants are a source of key root traits that are important for adaptation under marginal conditions. For instance, wild common beans display a relatively high root apical dominance than the domesticated plants, which is an important trait under water stress conditions Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Root traits

35. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1104/pp.18.01509

36. Root traits Statistical comparisons of wild and cultivated accessions revealed highly significant differences (P < 0.01) in the RSA of young seedlings Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah

37. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1104/pp.18.01509 Principal component analysis (PCA) of root traits clearly shows that wild and domesticated genotypes form distinct clusters, suggesting selective forces applied during domestication significantly altered size and RSA

38. A change in soil habitats and direct selection of above-ground plant parts may have caused these differences in roots of these two groups. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Root traits - reason for loss

39. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.1093/aob/mcy221

40. Domesticated types achieved lower root depth per unit of biomass (i.e. root exploration efficiency), indicating that the root system of domesticated forms was more spreading than that of wild types. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Root traits - shift of focus

41. The domesticated types increased the depth of roots relatively more per unit of root biomass than wild types. Yet even under this drought stress the root depth per biomass unit was 60 % greater in the wild than in the domesticated types. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Root traits - shift of focus

42. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.15252/embj.2019103256

43. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.15252/embj.2019103256

44. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah https://doi.org/10.15252/embj.2019103256 TS-21 / TS-422 - wild (PIM type) TS-577 /670 - domesticated (BIG type)

45. Wild tomatoes appear to be less sensitive to salt stress than their domesticated counterparts. These traits could have been less important for domesticated plants to adapt to fertile and well-irrigated soils during the start of domestication, which led to their reduced phenotypic expression in them. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah Root traits - wild vs domesticated

46. Prashantha V Megha S Sogalad Brahmesh Reddy BR Unintended Effects of Domestication Department of Genetic and Plant Breeding GPB 607 (3+0) - Dr. K N Ganeshaiah open discussion