Respuesta :
Flies only have a single pair of functional wings, but their ancestors had two pair of wings. Thus, having two pairs of wings is ancestral trait.
Ancestral trait an evolutionary trait that is homologous within groups of organisms (see homology) that are all descended from all common ancestor in which the trait first evolved.
Flies are considered as the insects of the order Diptera, the name being derived from the Greek word "two", and pteron as "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into the advanced mechanosensory organs called as halteres, which act as high-speed sensors of the rotational movement and allow dipterans to perform advanced aerobatics.
Dipterans are considered as large order containing around 1,000,000 species including the horse-flies, crane flies, hoverflies and others, although only about 125,000 species have been described till now.
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(Complete question) is:
Flies only have a single pair of functional wings, but their ancestors had two pair of wings. Thus, having two pairs of wings is _______ trait.
