The Evil Quartet described by Jared Diamond does not include fission.

Jared Diamond, in his book "Collapse: How Societies Choose to Fail or Succeed," discusses the various factors that contribute to the decline and collapse of civilizations throughout history. He identifies a set of interrelated and mutually reinforcing problems that he calls the "Evil Quartet." These problems are significant drivers of societal collapse and include:

1. Introduction of Invasive Species:
The introduction of non-native species into an ecosystem can have devastating effects. Invasive species often lack natural predators and can outcompete native species for resources, leading to the decline or extinction of native flora and fauna. They can also disrupt ecosystem processes and alter the balance of the entire ecosystem.

2. Fragmentation:
Fragmentation refers to the breaking up of natural habitats into smaller, isolated patches. This process often occurs due to human activities such as deforestation, urbanization, and infrastructure development. Fragmentation disrupts ecological connectivity, making it difficult for species to migrate, find mates, and access resources. It can also lead to genetic isolation and an increased risk of extinction.

3. Overharvesting:
Overharvesting occurs when the exploitation of natural resources exceeds their ability to replenish. This can include the unsustainable extraction of fish, timber, water, minerals, and other valuable resources. Overharvesting can lead to resource depletion, ecosystem degradation, and the collapse of industries and economies dependent on these resources.

4. Introduction of Invasive Species:
Fission is the process of splitting a group or society into smaller, separate entities. While fission can have social and political consequences, it is not typically considered one of the key drivers of societal collapse. Instead, Diamond focuses on factors such as resource depletion, environmental degradation, and social, economic, and political factors as the primary causes of collapse.

In conclusion, the Evil Quartet described by Jared Diamond includes the introduction of invasive species, fragmentation, and overharvesting as significant drivers of societal collapse. Fission, on the other hand, is not considered one of the key factors in his analysis.