Question

Biosynthesis of nectar and nutrient-rich pollen is energetically very expensive for a plant. Yet, plants funnel large amounts of energy into animal pollination. What are the evolutionary advantages that offset the cost of attracting animal pollinators?

Short answer

Animal pollination increases the genetic variation in plants and promotes cross-pollination. In comparison to wind pollination, the chances of successful pollination through animal pollination is higher.

Step-by-step solution

Introduction

Pollen grains are transferred from the anther to the stigma during pollination in seed plants. This leads to fertilization and reproduction.

Explanation

Pollination is carried out by various agents, such as water, wind, insects and other animals. There are two types of pollination, namely cross-pollination and self-pollination.

• In self-pollination pollen is transferred from anther to the stigma of the same flower or to another flower of the same plant.
• In cross-pollination pollen is transferred from the anther of one flower to the stigma of another flower in another plant of the same species or other species.

Explanation

Insects are responsible for pollination in more than 80% of the angiosperms. As a result, they evolved various adaptations to attract the pollinators.

• One such adaptation is the production of nectar, a sweet sugar-rich liquid that is produced by flowers pollinated by birds and insects. Nectar is an important source of energy for the pollinators. As birds and insects collect the nectar the pollen grains get stuck to the them and they carry it to other flowers.
• Along with nectar they also produce an abundance of pollen, both fertile and non-fertile, that is nutritious for birds and insects.
• Another adaptation is the flowers having ultraviolet reflectance pattern, that is designed for insects and birds that can detect ultraviolet light. This aids them to to reach the flower's core easily.

Explanation

Cross-pollination evolved to provide evolutionary benefits to the plants that outweighed the cost of attracting the pollinators. These are:

• The produced offsprings are healthier than the previous generation.
• Cross-pollination between two different species or two different variants of the same species can result in the emergence of new species.
• Production of fertile and abundant seeds.