Final answer:
Biodiversity is measured in various ways, none of which can be singularly considered the best due to life's complexity. Species richness is a common measure but must account for additional factors. DNA barcoding provides a modern method for cataloging species, aiding in identifying and conserving biodiversity.
Step-by-step explanation:
When it comes to determining biodiversity on Earth, there isn't a singular "best" method as the complexity of life is vast and varies across different ecosystems. The term biodiversity itself covers a multitude of different aspects and scales of life, from genetic diversity to the diversity of species and ecosystems. Measures of biodiversity often involve organism-based metrics that count the number of species within a defined area, known as species richness. However, this can be complicated by factors such as relative abundance, uniqueness, and spatial scale.
To bridge the gap in quantifying biodiversity, conservation biologists use indices that stem from information theory. Despite the various methods, it's crucial to consider the cost-benefit ratio and the practicality of data collection over time and space. Techniques such as DNA barcoding are used to catalog species using the sequence of certain genes, allowing for the identification of species, including previously undescribed ones. Approximately 200,000 species have been barcoded as of the mid-2010s, with numbers increasing as the method advances.