He is an expert in comparative linguistics.

Computational linguistics is the study of analyzing human language with computers.

She is majoring in clinical psychology.

He is an expert in psychiatry.

He is known as an expert in population genetics.

He is an expert in theoretical physics.

He is an expert in phytopathology, making a significant contribution to agriculture.

He is an expert in ethology, and his research is highly regarded worldwide.

He is an expert in algebraic geometry.

He is an expert in topology.