The discovery of ancient water striders preserved in amber has provided scientists with a rare glimpse into the mating behaviors of insects from 100 million years ago. Chinese researchers have uncovered these remarkable fossils, shedding light on the sexual dynamics and evolutionary history of these aquatic insects.
A team led by Professor Huang Diying from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences has revealed the mating behavior and potential sexual conflicts of water striders through the first fossil record of Cretaceous specimens in copulation. The amber specimens, originating from northern Myanmar, date back to the mid-Cretaceous period.
Published in the Proceedings of the Royal Society B on April 3, the findings include a specimen containing seven adult water striders, known as Burmogerris rarus, with three paired individuals and a single male, alongside four nymphs enclosed in the amber. Notably, two pairs were captured mid-mating, with smaller males positioned atop the females’ backs.
Professor Huang emphasized the rarity of such a find, stating, “Catching insects during copulation, especially aquatic species, is a rarity in the fossil record. These findings greatly deepen our understanding of behavioral strategies across geological time periods.”
The study also observed that two pairs and a single male were preserved in the same layer near the amber’s upper surface. Research team member Fu Yanzhe speculated, “We believe that the small-sized male Burmogerris rarus is unlikely to be territorial, suggesting a high population density in the Myanmar amber forest.”
Microscopic analysis revealed differences between the males’ and females’ front legs, particularly in a section called the protibia. In males, the protibia is slightly curved and features a comb-like structure absent in females. “By comparing the male’s protibial combs with species in the related family Veliidae, we suggest that this specialized structure functioned as a grasping apparatus, likely an adaptation to overcome female resistance during struggles,” Huang explained.
The researchers propose that these paired fossils represent a stage of precopulatory struggle or postcopulatory contact guarding. Such contact guarding by males could prolong mating, thereby avoiding sperm competition.
The specialized morphology and diverse behaviors of gerromorphans, which include water striders and their relatives, have become prominent topics in evolutionary biology and ecology. These findings not only enhance our understanding of insect evolution but also provide theoretical foundations for the development of biomimetic technology on water surfaces.
This extraordinary discovery offers valuable insights into the behaviors of ancient insects, bridging gaps in our knowledge of evolutionary biology and contributing to interdisciplinary studies that may inspire future technological advancements.
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Chinese researchers reveal mating dynamics of ancient insects in amber
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