| Investigating factors that influence species' ranges and the potential consequences arising from expansion is vital in successfully predicting future distributions. Species-habitat associations are considered to be fixed, but if they are variable, inaccurate forecasts may occur. Additionally, hybridization with heterospecifics can affect species' ranges, possibly preventing successful expansion. Here, I used two expanding bird species, Scissor-tailed Flycatcher (Tyrannus forticatus) and Western Kingbird ( T. verticalis), to assess how differential habitat selection and hybridization may influence range expansion. First, I explored variation in habitat selection behavior of Scissor-tailed Flycatchers by comparing habitat selection patterns at the periphery with the historic core of their ranges, and uncovered differential patterns between the regions. Secondly, I genetically documented an undescribed pattern of hybridization involving two sympatric species simultaneously undergoing range expansion. Introgressive hybridization between the two species has occurred across their ranges but I found no negative reproductive consequences of these events. |
