Complex sentence: Without group or team cohesiveness, there is no correlation between leadership and popularity; however, when a group is cohesive, the higher up someone is in the leadership hierarchy, the more popular they are for two reasons.
Split into simpler sentences: Without group or team cohesiveness, there is no correlation between leadership and popularity. However, when a group is cohesive, as you travel up the leadership hierarchy, you tend to become more popular for two reasons.