who wrote a book ___(explain) how animals and plants develop

explaining 分词结构做定语,修饰的名词与后面的动词是主动关系,用ing形式,如果是动宾关系,用ed形式.

Who wrote a book __EXPLAINING_(explain) how animals and plants developed as the environment changed? --------------分词结构做定语
===Who wrote a book THAT EXPLAINED how animals and plants developed as the environment
changed.?-------------从句做定语 / 定语从句

explaining，动名词短语做定语，起到解释说明的作用