I know that noun adjuncts or attributive nouns (are they the same?) are usually singular. However, I often see native English speakers using plural forms in such nouns. For example, the following sentence. Is not the first sentence below incorrect and the second option should be used instead? I read the first option in scientific papers written by native English speakers very often.
- The population genetics analysis revealed extensive hybridization between the two species.
- The population genetic analysis revealed extensive hybridization between the two species.
Are there particular instances where noun adjuncts or attributive nouns can be plural?