Why were tenant farmers in western Ireland especially vulnerable to the Great Famine?

Tenant farmers in western Ireland were especially vulnerable to the Great Famine due to a combination of extreme economic precariousness and an over-reliance on a single food source.

• Subsistence Dependence: By the early 1840s, the rural poor—particularly in the west—depended almost exclusively on the potato for their diet. A typical family consumed about eight pounds of potatoes per person daily, providing roughly 80 percent of their caloric intake.1
• Lack of Genetic Diversity: Farmers relied on one or two high-yielding potato varieties. Because these crops were propagated from tubers rather than seeds, there was virtually no genetic diversity, making the entire crop susceptible to the late blight pathogen (Phytophthora infestans).21
• Economic Hardship: Many farmers lived at a subsistence level on small allotments of land. While they produced other goods, they often lacked the money to purchase the food their own farms produced, as they were required to supply the British market with cereal crops to pay their rents.1
• Systemic Fragility: When the blight destroyed the potato crop, these farmers lost both their food supply and their ability to pay rent, leading to mass evictions by landlords who were also struggling under the financial burden of the crisis.321