Analysis of 17,000 Years of Fish Fossil Reveals Rapid Evolution; Cichlid Species Seized Ecological Opportunity To Diversify

In Lake Victoria in the African Great Lakes region, cichlid fishes were not the first colonizers, but they won the speciation race.

A Captivating Tale of Evolution

There is a longstanding assumption among evolutionary biologists that the first organisms to colonize a new environment have an advantage in diversifying into new species. However, a team of researchers has discovered that winning the speciation race takes more than timing.

The recent study examines fish fossils found in East Africa's Lake Victoria, focusing on cichlid species. It challenges the traditional notion and highlights the significance of organisms' adaptability and ability to exploit new ecological niches.

In this study, the scientists investigated the fossilized fish teeth found in four sediment cores extracted from Lake Victoria. These cores provided important information on the history of the lake and allowed for a robust interdisciplinary effort to understand the factors that drive species radiation. In the early period of the lake's history, different fish species, like cyprinoids, dominated the shallow waters. As the lake deepened, cichlids took advantage of the new environment and became the area's most dominant fish.

The cichlids, known for their versatility, were able to adapt to the changing environment of Lake Victoria, leading to their extraordinary diversification. The remarkable burst of evolution resulted in the emergence of 500 new species within a short time frame of approximately 17,000 years.

The rapid radiation within this group is considered the most accelerated event observed among vertebrates. Previous events of adaptive radiation typically took place over millions of years, which makes it challenging to unveil the specific reasons behind the success of the colonizing species.

The study's findings significantly address why certain groups of organisms are more successful at creating multiple species quickly. Furthermore, it emphasizes the significance of opportunity and versatility over primacy in driving species diversification.

What is Adaptive Radiation?

According to Charles Darwin's Theory of Evolution, living organisms tend to change their physical and anatomical structures over a long period of time for better adaptations to their changing environments. As evolution takes place, there could be a point where organisms prefer to exploit a niche and cannot do so with their existing structural component or body design. As a result, they started to split and adapt different versions for better survival.

Adaptive radiation refers to the process in which a lineage of organisms rapidly diversifies from an ancestral species into many new forms, with the newly formed lineages evolving different adaptations.

Various factors can trigger adaptive radiation, each serving as a response to an opportunity. This usually happens when a change in the environment leads to the availability of new resources, when biotic interactions are altered, or when new environmental niches are opened.