Coevolution: Honeycreepers and Tubular Corollas

Coevolution and Pollination

• Coevolution is responsible for the long, curved beaks of honeycreepers, which insert their beaks into tubular flowers to obtain nectar.
• Long tubular corollas of flowers that honeycreepers visit also developed through co-evolution.

Agents of Pollination

• Wind pollination is used by gymnosperms and some flowering plants, such as grasses and trees.
• Wind pollination is not a very efficient method, as it relies on chance and can be wasteful.
• Examples of wind pollination include hazel staminate flowers releasing clouds of pollen grains.

Animal Pollinators

• Insects: bees, wasps, flies, butterflies, and moths
• Birds: hummingbirds, honeycreepers
• Mammals: bats, mice, monkeys
• Some reptiles and amphibians also act as pollinators

Coevolution and Attraction of Pollinators

• Flowering plants have evolved distinct visual cues, such as bright colors, stripes, and patterns, to attract specific pollinators.
• Examples: blue and ultraviolet colors for insects, red and orange for birds.
• Scent is also used to attract pollinators, with the scent becoming stronger and closer to the plant.
• This is metabolically more expensive for the plant, as pollen is rich in protein and nectar is composed of carbohydrates.

Plant Mimicry

• Some plants take advantage of the sex drive of insects, such as certain orchids that look and smell like female insects.
• Male insects try to mate with the flower, resulting in pollination.

Fertilization

• Fertilization occurs through the union of female and male gametes.
• Parts of a flower include: petal, anther, stamen, filament, receptacle, ovary, and ovule.

Agents of Cross-Pollination

• Water (hydrophily) is used by certain plants, such as those in the families of Naiadaceae, Ceratophyllaceae, and Potamoghentonaceae.
• Pollination takes place either underwater (hypohydrogamous) or on the water surface (epihydrogamous).

Alteration of Generation

• The alteration of generation refers to the sequence of sexual and asexual phases in an organism's life cycle.

Pollination and Reward

• Animals pollinate plants in exchange for food, such as nectar.
• Nectar is a sugary solution produced in special flower glands called nectaries.
• Nectar concentration matches the energy requirements of the pollinator.
• Pollen is high in protein and some bees and beetles eat it.

Floral and Extra-Floral Nectaries

• Floral nectaries are found in flowers and produce nectar.
• Extra-floral nectaries are found outside of flowers and produce nectar.

Getting the Attention of Pollinators

• Colors: bees see blue, yellow, and UV, while birds see red and yellow. Bats do not see well, so flowers are often white.
• Nectar or honey guides: visual cues for pollinators to locate the reward.
• Aromas: can also be carrion or dung smell, guiding pollinators to the reward.
• Edible decoy stamens: some flowers do not produce nectar, so pollinators eat part of the stamens and pollen instead.