The full extent of the diversity and abundance of Earth has been understood only recently due to?

The correct answer highlights the role of advanced molecular techniques in deepening our understanding of Earth's diversity and abundance. These techniques, such as DNA sequencing and metagenomics, allow scientists to explore the genetic material of organisms from various environments with unprecedented precision. By analyzing the genetic information, researchers can identify and classify organisms that were previously unknown or difficult to distinguish through traditional methods.

Furthermore, these molecular methods have revealed the vastness of microbial diversity, showing that microorganisms play critical roles in ecosystems and are essential for nutrient cycling and other ecological processes. This has fundamentally changed our perception of biodiversity, moving beyond observable traits to a deeper understanding based on genetic relationships. As a result, the comprehensive picture of life on Earth that we now have is largely attributable to these advanced techniques.

While historical research studies, increased biodiversity efforts, and environmental legislation all contribute to our understanding and protection of biodiversity, it is the innovations in molecular biology that have most significantly expanded our knowledge in recent years.