Human impacts on ecosystems have been ongoing since the beginning of human evolution. As human needs increase daily, agricultural and industrial activities have become significant tools that have altered the magnitude of ecological changes.
The loss of biodiversity presents serious consequences that may take prolonged periods to address. Genetic diversity changes over time and space and often reflects environmental patterns, suggesting adaptation to prevailing conditions.
Due to its agricultural importance, genetic erosion must be treated with urgency. Therefore, this article presents the effects of genetic erosion and outlines management strategies.
Proper management requires timely and appropriate procedures to sustain genetic variability, and these methods are provided within this context.
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Effects of Genetic Erosion on Agricultural Systems
1. Inbreeding and Stress Response in Crops and Livestock
Inbreeding negatively affects most fitness-related traits. However, the degree of inbreeding depression varies significantly depending on species, population, traits, and environmental conditions, often revealing additional harmful genetic loci.
Genetic erosion caused by fragmentation reduces both individual and population fitness, while increasing sensitivity to stress. The environmental dependency of inbreeding depression implies that human-induced environmental changes such as climate change strongly and negatively impact biological fitness.
Species that have recently experienced habitat fragmentation and have become inbred may be more vulnerable to such environmental stress than those in large, diverse populations.
3. Inbreeding and Phenotypic Plasticity in Genetically Eroded Populations
Genetically eroded populations tend to exhibit reduced genetic variability and lower evolutionary potential. Consequently, survival might rely more on the ability of organisms to respond to environmental challenges through phenotypic plasticity.
Such plastic responses can enhance population persistence in a changing environment. Since phenotypic plasticity has a genetic basis, genetic erosion may reduce the capacity for plastic responses.
Furthermore, plasticity can be energetically demanding. Inbreeding increases the energy required for maintenance, leaving less energy for critical functions like plastic adaptation.
4. Population Size and Genetic Variation Levels in Agricultural Biodiversity
Genetic diversity is essential for adaptive evolution. A population can only persist if its evolutionary rate matches or exceeds the rate of environmental change. In cases of abrupt change, demographic processes become more significant alongside evolutionary responses.
Genetic drift reduces genetic diversity in small populations at a rate proportional to size, as confirmed by the loss of neutral variation in experimental and natural populations.
5. Population Size and Agricultural Adaptability
As adaptive variation decreases with reduced population size, and the ability to respond to selection depends on existing genetic variation, small populations subjected to genetic erosion display diminished adaptive potential. Several researchers have explored how genetic bottlenecks and inbreeding affect the selection response of quantitative traits.
A decrease in genetic variance for many traits supports expectations about additive variation. For example, selection responses in Drosophila melanogaster showed a consistent decline over generations of inbreeding, indicating that prolonged genetic erosion leads to lower adaptability.
6. Other Notable Effects of Genetic Erosion
Genes from potential parent plants may be absent in seeds due to random factors, such as phenological differences, plant distance, weather conditions affecting pollen dispersal, plant mortality, embryo abortion, and higher extinction risks.
Management Strategies for Genetic Erosion in Agricultural Context
1. Assessing Crop Distribution and Identifying Priority Regions
Effective conservation strategies require knowledge of crop distribution and identification of regions for targeted conservation efforts. Prioritization is based on high genetic diversity, community interest in unique diversity, lack of previous conservation work, and imminent erosion threats.
2. Ex Situ Conservation of Agricultural Genetic Resources
Ex situ conservation involves preserving biological diversity outside natural habitats. Historically, this practice has supported agriculture’s expansion and global spread. Traditional agricultural stocks from gene centres regions rich in wild relatives of crops are essential resources for developing modern cultivars or initiating new crop evolution pathways.
With the rise of scientific breeding and increased human populations, modern varieties replaced landraces, making formal ex situ storage vital.
3. Ex Situ Conservation Techniques for Diverse Crop Types
Seed storage is the most practical method for conserving plant genetic resources long-term. Seeds are typically dried to low moisture and stored at low temperatures.
However, tropical and sub-tropical species with recalcitrant seeds lose viability quickly, making seed storage impractical. These species require field gene banks or botanical gardens, though challenges like high costs and disaster vulnerability exist. As a result, in vitro conservation techniques are being developed.
Botanical gardens also use in vitro conservation to propagate rare species, offering pest and disease protection. Despite being costly and labor-intensive, it is effective for special materials.
Advances in biotechnology now allow germplasm conservation through tissue culture, cryopreservation, pollen storage, and DNA banking.
The success of ex situ conservation relies on seed longevity. Most species produce orthodox seeds that maintain viability longer with reduced humidity and temperature.
4. In Situ Conservation and On-Farm Agricultural Biodiversity
In situ conservation maintains genetic resources in their natural or cultivated environments, allowing continued evolution under natural and farmer-driven selection.
While backup seed collections are valuable, they cannot replace evolutionary changes occurring in fields. On-farm populations often harbor rare alleles and diverse genotypes, which gene banks may miss.
This dynamic conservation method acknowledges farmers’ roles in maintaining and selecting genetic diversity. Farmers influence evolution through their seed choices, retaining a portion of harvests for replanting each season.
5. Nursery Management and Genetic Integrity
Effective nursery management considers genetic variation in seed traits, germination, and growth. Such awareness helps prevent unintended selection and minimizes impacts on original genetic diversity.
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Understanding Genetic Vulnerability in Agricultural Production
While genetic erosion reflects diversity loss over time, genetic vulnerability highlights the dangers of uniform genetic deployment across space. Crop populations become vulnerable when they lack diversity needed to adapt to stress or environmental change.
For example, monocultures spanning large regions may succumb uniformly to a new disease or climate condition due to shared susceptibility genes.
True genetic vulnerability arises when other varieties possessing tolerance or resistance exist but are excluded from cultivation. Hence, the concept includes genotype × environment interactions, where some genotypes from other regions may resist threats better than the local population.
Indicators of genetic vulnerability consider both genetic uniformity and environmental responsiveness.
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