Complex sentence: In the past, "M. sylvestris" was thought to be an important ancestor of the cultivated apples ("M. domestica "), but these have now been shown to have been originally derived from the central Asian species"M. sieversii".
Split into simpler sentences: In the past, "M. sylvestris" was thought to be an important ancestor of the cultivated apples ("M. domestica "). However, one recent study shows the cultivated apple to have been originally derived from the central Asian species"M. sieversii".