During the Cretaceous period on Earth, both large dinosaurs and smaller creatures coexisted, shaping the landscape. The battles between these creatures can still be seen in forests and gardens today.
It was during this time that the first flowering plants emerged. Some insects were attracted to these plants, while others were deterred. Plants eventually discovered a way to fight back indirectly by enlisting ants to repel aggressive beetles, flies, and caterpillars. This defensive tactic dates back to an even earlier period when dinosaurs like Triceratops, T. rex, or Dreadnoughtus roamed the Earth.
A new study suggests that approximately 135 million years ago, plants began bribing ants with sweet nectar to defend them. Jacob Suisa, a plant evolutionary biologist at the University of Tennessee, Knoxville, led this study, exploring how plants have adapted over millions of years.
The study reveals that plants began utilizing ants for defense during the Early Cretaceous period, as published in the Nature Communications journal on May 24.
Attracting Ants with Nectar
While some plants use toxic chemicals or spines to deter herbivores, flowering plants and ferns have evolved to rely on ants for defense. They secrete a sweet sap to attract sugar-hungry ants through nectaries located on various parts of the plant.
Ants primarily come for the nectar reward but inadvertently end up protecting the plant by deterring or consuming herbivores like beetles. Only ferns and flowering plants have nectaries, which evolved around 265 million years after their evolutionary divergence.
Researchers discovered that ants tended to live in trees where flowering plants resided, leading to the evolution of a variety of nectar glands in these plants. Ferns, on the other hand, started on land and later adapted to tree life, resulting in the evolution of different nectaries.
Nectar glands rapidly evolved in flowering plants, attracting ants and shaping their defense mechanisms. Ferns, however, exhibited delayed evolution in their nectar glands, adapting to ant-baiting much later in their history.
Mutualistic Relationship Between Ants and Plants
As flowering plants and ferns began attracting ants for defense, their nectar glands evolved into different shapes. While flowering plants adapted sooner, ferns took longer to develop this defense strategy, surprising researchers.
Ferns, equipped with various defense mechanisms, utilized nectaries as a form of defense when they transitioned to tree living. This interaction between ferns and ants exemplifies mutualism, shedding light on the evolution of plant-animal interactions.
Source: www.snexplores.org
