Complete question:
Knight used natural differences among ponds in the University of Florida's Ordway-Swisher Biological Station to create a unique field experiment. She selected 8 ponds that were similar in size and depth. Four of the ponds contained fish, but the other four contained no fish.
When fish are present in ponds, they consume the aquatic larvae of dragonflies. Adult dragonflies are voracious predators of other flying insects, including various flies, bees, and butterflies. Flies, bees, and butterflies pollinate a shrub called St. John's wort that grows around all the ponds.
Knight predicted that the presence or absence of fish would cause variation in the abundance of dragonflies, which might influence the abundance of pollinators, thereby affecting the reproductive success of plants that depend on those pollinators, such as St. John's wort.
Drag the pink labels (Shown in the attached files) to indicate which type of interaction occurs between each pair of species. Based on those interactions, drag the blue labels to indicate the population changes Knight predicted for each species in the two different treatments. Labels can be used once, more than once, or not at all.
Answer and Explanation:
Fishes predate over the aquatic larvae of dragonflies, which causes a decrease in its population. As dragonfly feeds on insects larvae, a decrease in the first population means an increase in other flying insects population. These species of flying insects benefit some plant species reproduction, such as St. John's wort, by pollinating them. So, whenever flying insects population increases, plant species are beneficiated, and the plant also benefits the flying insects by giving them a recompense such as nectar. This represents a mutualism relation.
So, when fishes are present, they predate on dragonflies, causing this population to go down. Pollinator insects population goes up in size because they are not eaten by dragonflies. St. John's wort population also goes up in size, because they benefit from pollinators, with whom they create a mutualism relation.
When fishes are not present, the dragonfly population goes up, predating on flying insects and causing their population to go down. The plant species are also affected as they are not pollinated, so these populations also go down.
Open the attached file "relaciones troficas" to see the pink labels and blue labels.
