Final answer:
Closely related species with the same sets of developmentally related genes may take different developmental pathways if gene expression is regulated differently.
Step-by-step explanation:
Closely related species with the same sets of developmentally related genes may take different developmental pathways if gene expression is regulated differently. Developmental genes play a crucial role in determining an organism's body plan and development. However, variations in gene regulation can result in different developmental outcomes, even among closely related species.
For example, the Hox genes are a class of genes that are responsible for directing the organization of major animal body plans. They are strongly homologous across the animal kingdom, meaning they are highly similar among different species. However, variations in the regulation of these genes can lead to the development of different body plans in different species.
Overall, while closely related species may have similar sets of developmentally related genes, variations in gene regulation can lead to different developmental pathways and outcomes.