Question

Investigation of HOX genes indicates that the animal family tree" can be simplified to only how many different types of animals?

Answer 1

Investigations into HOX genes suggest the animal family tree can be simplified based on these highly conserved genetic elements that guide developmental processes. HOX genes are master control genes that impact morphology, and their presence or absence varies among different animal clades, signifying evolutionary relationships.

Step-by-step explanation:

Investigations into HOX genes have revealed that they play a central role in the development of animals. Due to the highly conserved nature of HOX genes across the animal kingdom, from invertebrates with one set, to vertebrates with multiple sets as a result of duplication events, they suggest a simplified animal family tree. Though not directly stated, the implication is that the complexities of the animal family tree can be reduced to a fundamental understanding of genetic and developmental principles.

HOX genes serve as master-control genes that determine the body plan and major developmental processes in animals. If a HOX 13 gene in a mouse was replaced with a HOX 1 gene, the animal's development could be profoundly altered because each HOX gene controls the development of different body segments. Such a swap could result in body parts developing in the wrong position or incorrectly formed structures, significantly influencing the morphology and viability of the animal.

The animal kingdom includes several clades, and not all possess HOX genes. For instance, the Ctenophora and Porifera do not have these genes, while other groups like the Cnidaria and Bilateria do. The Parahoxozoa clade, which includes groups with at least one HOX gene, highlights the diversity in the presence and function of these genes within different animal lineages.

Answer 2

three evolutionary lines

Step-by-step explanation:

The Hox genes are master developmental genes found in animals, which are involved in the regulation of development by specifying the body plan of an embryo along the head-tail axis. Recently, several research groups studied the assortment of the Hox genes in three different marine organisms: 1- a priapulid worm (an unsegmented marine worm), 2- a brachiopod (phylum Brachiopoda), and 3- a polychaete worm (related to earthworms). Then, these research groups combined their research efforts to compare the assortment of the Hox genes observed in these species to those observed in previously studied animals including, among others, mice, fruit flies and sea urchins. From this combined study, researchers concluded that the animal kingdom can be divided into three primary evolutionary lineages.