The Mouse-colored Tyrannulet (Phaeomyias murina) is a species complex that includes the Cocos Flycatcher (Nesotriccus ridgwayi), an island form that underwent a population bottleneck.

Simultaneous examination of evolutionary history in island forms and closely related mainland relatives can provide reciprocal insight into the evolution of island and mainland faunas. The Cocos Flycatcher (Nesotriccus ridgwayi) is a small tyrant flycatcher (Tyrannidae) endemic to Cocos Island, an oceanic island in the eastern Pacific Ocean. We first established its close relationship to the mainland species Mouse-colored Tyrannulet (Phaeomyias murina) using a phylogeny from genome-wide ultraconserved elements and exons.