Topic: Biology

Scientists studied cactus flowers and found that they change shape quickly. This helps new species form fast too.

Cacti are famous for growing slowly, but scientists have discovered that these desert plants are actually evolving at an impressive pace. New research shows that cacti are remarkably quick at forming entirely new species, revealing that deserts are far more dynamic than they may seem.

For decades, biologists believed that pollinators and highly specialized flowers were the main forces behind the development of new plant species. However, researchers at the University of Reading found that cacti follow a different pattern. Instead of flower size or pollinator type driving diversification, the key factor appears to be how rapidly cactus flowers change shape over time.

The research team analyzed flower length data from more than 750 cactus species. Flower sizes varied dramatically, ranging from tiny blooms measuring just 2mm to giant flowers reaching 37cm, representing a 185-fold difference in size. Even with such enormous variation, flower length showed almost no connection to how quickly new cactus species emerged.

What did stand out was the speed of floral evolution. Cactus species whose flowers changed shape most rapidly were also far more likely to branch off into new species. Researchers found this pattern consistently across both recent and ancient evolutionary history.

Why It Matters

Understanding how cacti evolve can help conservation efforts in deserts, which are often seen as harsh and unchanging environments.

Key Facts

• Cacti have over 1,850 known species and are one of the fastest-diversifying plant groups on Earth.
• The study found that flower length is only weakly related to speciation, whereas the rate of flower-length evolution is a strongly positive predictor.
• Flower length and rate of evolutionary change in flower length are only weakly correlated.

Key Terms

Speciation

The process by which a new species forms from an existing one.

Implications

Understanding how cacti evolve can help conservation efforts in deserts, which are often seen as harsh and unchanging environments.