EVOLUTION
EVOLUTION OF A POPULATION
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Question
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Only some animals that have been tested have Hox genes, suggesting that Hox genes have no function and only evolved recently.
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Hox genes are regulatory genes that determine body plans of animals.
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Similarities among Hox genes suggest that they all arose from a single ancestral gene that duplicated many times.
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Hox genes provide information about evolutionary relationships.
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Detailed explanation-1: -Researchers used DNA sequencing techniques to find similarities of Hox genes in roundworms, arthropods, mollusks, echinoderms, cephalochordates, and vertebrates. Hox genes are regulatory genes that determine body plans of animals. Hox genes provide information about evolutionary relationships.
Detailed explanation-2: -Hox genes play a key role in animal body plan development. These genes tend to occur in tightly linked clusters in the genome. Vertebrates and invertebrates differ in their Hox cluster number, with vertebrates having multiple clusters and invertebrates usually having only one.
Detailed explanation-3: -It is now well known that Hox genes play a fundamental role in the body patterning of bilaterian organisms as diverse as worms, insects, vertebrates, and echinoderms [2–7], and putatively in non-bilaterian animals [8].
Detailed explanation-4: -The presence of similar Hox genes in different species reflects their common ancestry: a Hox gene cluster was likely already present in a common ancestor of mice, flies, humans, and other animal groups.
Detailed explanation-5: -Vertebrate Hox genes confer axial positional information to emerging embryonic tissues from the three germ layers. Loss-of-function mutations in individual mouse Hox genes have been found to alter the identity of tissues located within the expression domain of the genes, most often in the rostral part of that domain.