Question

Orchids (plants) typically supply nectar (a food source) to pollinating insects. As they collect nectar, the insects move pollen among the plants. Nectar is energetically expensive to produce, so "cheater" plants sometimes evolve. These cheaters have empty nectaries, so the insects disperse the pollen, but get nothing in return. Assume that a few insects in the pollinator population can tell the plants with true nectaries apart from the cheaters.

(9 pts) Describe the 3 conditions necessary for natural selection to act on the insects; explain how each condition would be met for the insects living with orchids.
A.
i. Genetic Variation among Insects
ii. Differential Reproductive Success
iii. Heritability of Traits

Answer 1

Natural selection could potentially act on insects around orchids if there is genetic variation allowing some insects to identify nectar-producing plants, if this trait leads to differential reproductive success, and if the trait is heritable.

Step-by-step explanation:

Conditions Necessary for Natural Selection in Insects Pollinating Orchids

To explain how natural selection might act on insects that can discern between orchids with true nectaries and cheater plants, we must consider three crucial conditions:

1. Genetic Variation among Insects: There must be differences in the genetic makeup of the pollinating insects that allow some of them to identify the cheater orchids. This variation is crucial because without it, there would be no traits to select for or against.
2. Differential Reproductive Success: Insects that can avoid the cheater orchids and focus on those providing nectar will have more energy for reproduction and, as a result, will likely have more offspring than those that visit cheater orchids. The valuable trait enabling them to identify rewarding flowers will lead to greater reproductive success.
3. Heritability of Traits: The ability of the insects to distinguish between true and cheater orchids must be heritable. This means that the trait is passed from parents to offspring through genes. If the trait cannot be inherited, it cannot be acted upon by natural selection.

In the ecosystem of orchids and insects, these conditions set the stage for natural selection to potentially favor insects that can avoid being duped by cheater plants. Over time, we might expect these insects to become more common, as their successful foraging strategies are passed on to future generations.