A comprehensive analysis of over 4,000 ant specimens collected over the last decade has unveiled a complex evolutionary history of Fijian ants.
The Origins of Colonization
The process of piecing together the history of these ant populations involves meticulous comparisons of individual genetic sequences and extensive computer simulations. “We examined multiple individuals from each population,” said researcher Mikheyev. “A population with low genetic diversity indicates a recent descent from a small number of individuals, while high diversity hints at long-term stability.”
Armed with DNA data, the research team simulated the evolutionary trajectories of ant populations over thousands of years. They focused on scenarios that best aligned with their findings on genetic diversity. “We identified numerous colonization events that shaped the Fijian ant fauna over different periods,” Mikheyev noted, revealing that there were at least 65 instances of colonization.
The earliest ants are believed to have reached Fiji millions of years ago, giving rise to 88 endemic species. These ants likely evolved from a single ancestor, diverging from their mainland counterparts. Additionally, 23 more colonization events introduced ant species from a broader Pacific region. The research indicated that these species included both naturally migrating ants and those brought by the Lapita people, the first human settlers who arrived approximately 3,000 years ago.
This introduction of humans coincided with the initial declines in native Fijian ant species.
Impact of Human Activity
“In hindsight, these declines are quite understandable,” Mikheyev commented. While the early Fijian settlers had a lower population density, they engaged in practices such as slash-and-burn agriculture, which involved clearing forests for farming. “Certain ants are not suited for open fields, particularly those that evolved in forest environments,” he added. However, the decline of endemic Fijian ant species intensified significantly following early European contact.
