Complex sentence: The still-life category also shades into zoological and especially botanical illustration, where there was a considerable overlap among artists; generally a still life should include a fully depicted background, and have aesthetic rather than illustrative concerns as primary.
Split into simpler sentences: The still-life category also shades into zoological and especially botanical illustration, where there has been considerable overlap among artists. Generally a still life includes a fully depicted background, and puts aesthetic rather than illustrative concerns as primary.