How is the topic of race relations in the Dominican Republic and in the Caribbean covered in the novel "In the Time of the Butterflies"?
It is not race but class relations that are at issue in Alvarez' novel. The Dominican Republic is ruled by Raphael Trujillo, also known as "El Jefe" (the "Chief"). (Haiti, the other half of the island, was also ruled by a dictator, Papa Doc Duvalier.)
El Jefe and his minions rule land, money, education, religion, and employment. The elite and military ranks, those Trujillo favors, find life easier (mostly by capitulating to his every whim). Initially, the Mirabals are among those on El Jefe's good side. While they do not greatly succeed, neither do they greatly suffer.
But Minerva learns that no one is safe. At a compulsory dance, Trujillo attempts to seduce her. While in high school, her friend Sinita is taken forcibly to become Trujillo's concubine. Prisons are crowded with dissidents. Hunger and poverty are the norm.
A burgeoning awareness of the disparity around them compels Minerva and her sisters (save Dede, until much later) to become a part of the underground Communist movement, introduced to them by Lio. Tired of watching their people suffer for the benefit of a select few, Lio, Minerva, and others join an rouge band who aim to restore power to the people and equalize resources.
Minerva, Maria Teresa, and Patria will give their lives to the cause. Dede will be left behind to ensure that the people never forget their freedom fighters.