sentences:  The eclipse of Alasdair Óg's line—the senior branch of Clann Domhnaill—may explain the rise of Aonghus Óg's line.If Ruaidhrí of Islay indeed represented the line of Alasdair Óg, his forfeiture evidently paved the way for the rise of Eóin Mac Domhnaill.In fact, before the end of Robert I's reign, this son of Aonghus Óg appears to have administered Islay on behalf of the Scottish Crown, and eventually came to be the first Clann Domhnaill dynast to bear the title "" ("Lord of the Isles").