Sent in by Gary – at https://phys.org/news/2024-07-zooplankton-traditional-views-evolution.html … genetic changes in a naturally isolated population of the water flea – daphnia pulex. This is a tiny crustacean and here it provides us with a unique view of natural selection – and evolution. Daphnia play a crucial role in freshwater ecosystems. When you buy fish food for your goldfish in your pond you are purchasing a goodly number of daphnia pulex.
After ten years of research, followed by publication, using modern generic techniques, the research team discovered the strength of natural selection on individual genes varies significantly, from year to year. The idea was to study the strength of natural selection in order to see how life forms may react to environmental change – not only as a result of global warming but also as a result of polution of the water in which they live in. They found that in a stable environment there is a significant fluctuation in the frequency of gene variants known as alleles at specific chromosomal regions over time. Even if the overall strength 0f selection remains near zero on average over years. This suggests such a genetic variation allows populations to remain adaptable to such environmental changes that might be thrown at them.
Daphnia is a form of zooplankton and plays a crucial role in aquatic ecosystems. They are a food source for fish and help keep algae growth in check. These findings challenge the traditional view that measuring genetic diversity and genetic divergence can easily show how natural selection is overtly operating. Instead, natural selection seems to operate with greater subtlety and complexity than previously allowed. However, the observed patterns of selection on various gene sites provide a mechanism for maintaining genetic diversity – which is essential for rapid adaptations. The study also reveals that genes located near each other in chromosomes tend to evolve in a co-ordinated manner. This allows beneficial continuation of gene variants to be inherited together, potentially accelerating the adaptation process. In addition, the study is said to show evolution is more dynamic and complex than previously appreciated.