Since water has a strong surface tension, what do you think would happen if water had weak surface tension

Surface tension is the property of the surface of a liquid which allows it to resist an external force. It is due to the cohesive nature (stickiness and clumpability) of the water molecules. Since water has a strong surface tension:

1)      The surface tension of water provides the necessary wall tension for the formation of bubbles with water

2)      It is responsible for the shape of liquid droplets, too

3)      Small objects will "float" on the surface of a fluid, as long as the object cannot break through and separate the top layer of water molecules

If surface tension is weak, the reverse happens. Bubbles will come from round to spherical, small objects will not float, water will fall as it is, without forming spherical droplets and will not immediately spread. 

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.