It is the discovery of the patterns and processes that describe and explain the diversity, distribution and dynamics of life in the biosphere.
This is a formidable scientific enterprise because there are many more organisms on Earth than there are stars in the Milky Way!
(Apparently there are ~100 billion stars in our galaxy)
All those organisms are split up into many different species each of which is represented by a few hundred populations.
(Our best guess is 10-15 million different species, each with ~200 populations on average)
What motivates much of the science in our lab is the alarming rate at which populations and species are disappearing.
Biodiversity scientists are being challenged to understand the inner workings of the biosphere whilst human society subjects it to new combinations, rates and levels of environmental change.