Thanks to wings, birds, bats and insects are one of the most successful animals on Earth. The functions of the wings are many such as feeding, hunting, migrating, dispersing, displaying, etc. Just think about hummingbirds hovering in front a flower, monarch butterflies flying from USA to Mexico, or a peregrine falcon chasing a dove.
The morphology of the wing is very important for flight performance. For example, migrating birds have long and pointed wings, which reduce the energetic costs of flight. I was interested on how wing morphology and its size are related to survival (natural selection) and the success in finding a mate (sexual selection). I investigated this in the damselfly Lestes sponsa (Hansemann, 1823), in a group of ponds in central Sweden (a, b).
We captured every male we found, marked it with a number on a wing, measured it, took a picture of the wings, and released it (b,c). We did this for more than three weeks. We also noted down whether the male was mating or not. This allowed me to estimate survival and mating success.
Interestingly, I found that survival favoured long and slender forewings, but mating success favoured short and broad forewings (d). In addition, survival favoured short and broad hindwings, while mating success favoured narrow-based hindwings. Both survival and mating success favoured males with intermediate size. My results demonstrate that natural (survival) and sexual (mating success) selection can operate in similar directions for some wing traits, that is, wing size, but antagonistically for others, that is, wing shape. This implies that wings are under many evolutionary pressures, and therefore, most likely, wing morphology is never at its optimum. What is best for one strategy (e.g. migrating) can be really bad (in aerodynamic and energetic terms) for other (e.g. defending a territory).
Wanna know more??? http://onlinelibrary.wiley.com/doi/10.1111/evo.12951/full