Science: Copycat Orchids

Did evolution teach this orchid how to get a bee in its bonnet?

Identity theft is the order of the day for many orchids in the Oncidiinae group. This orchid “subtribe,” widespread in tropical America, consists of over 1,700 species. Most depend on animal pollinators but have nothing to offer such visitors, “presumably attracting pollinators through some form of deception.”1 Investigators have learned that, from a bee’s point of view, nearly a third of these orchids look just like the non-orchid “malpighiaceous” flowers that provide an unusual oily reward to bees that come their way.

sea-mammalsAll three of these flowers read “bee-UV-green” to bees. On the left (Trichocentrum ascendens) and right (Rossioglossum ampliatum) are Oncidiinae orchids. To a bee, they can pass for the Malpighiaceae species Stigmaphyllon lindenianum, which produces oil bees favor. Image: A. Papadopulos et al., Proc. R. Soc. B 280 (2013), news.sciencemag.org

Some members of the Malpighiaceae family of flowers produce nutritious oil valued by bees for food and nest-building material. Some Oncidiinae orchids have been suspected of mimicking these oil-producing flowers, but authors of a study published in June write that “evidence for mimicry is anecdotal and floral colours have only been assessed from the perception of humans, rather than of hymenopteran [bees, wasps, or ants] pollinators.”1 They therefore set out to discover how these pretty orchids do it.

It has been known for some time that “bees’ UV [ultraviolet], blue, and green receptors are optimally placed on the wavelength scale for discrimination of flower colors.”2 There are several models for assessing floral color, or reflectance, from a bee’s point of view. Uncertain which bees pollinate the species of orchid they were investigating, the authors chose “a model of bee colour vision that is applicable to a large number of hymenopteran species.”1

Comparing floral reflectance data for 90 Oncidiinae orchid species, 7 Malpighiaceae flowers, and 210 other Costa Rican flowers, they found that 70% of the yellow-flowered Oncidiinae orchids and 5 of the yellow Malpighiaceae species looked green to bees. Specifically, the orchids and the malpighians both look “bee-UV-green,” a “color” which combines the yellow visible light perceived by humans with a UV reflectance detectable by bees.1 Furthermore, comparing the Costa Rican sites where matching orchids and malpighians grew, they found that no other flowers in the area wore “bee-UV-green.”

This delightful botanical scam is widespread. The authors estimate that 500 of the 1,700 known Oncidiinae species are similarly equipped. Thus, these orchids use a sophisticated identity theft system to ensure their reproductive success.

How did the Oncidiinae orchids hack into the malpighian color palette? The investigators propose that this pollination scheme evolved convergently at least 14 times in the Oncidiinae family tree. And that’s not all: More than three-fourths of these bee-UV-green Oncidiinae also have shapes more similar to Malpighiacae than any other local flowers. The authors conclude, “The convergence observed has to be driven by the sensory and cognitive abilities of pollinators.”1

And lest the situation seem too cut and dried, it turns out that a few Oncidiinae orchids also produce nutritious oils similar to those produced by Malpighiacae, revealing “a high degree of biochemical convergence between the oils.”1

But is evolution the clue to this colorful mystery? Nothing in these results suggests that flowers have ever been non-flowers, orchids, non-orchids, or bees, non-bees. No evolution of new kinds of organisms is revealed here. These plant-pollinator dynamics and mimicry result from the interaction and interdependence of variations within created kinds. And we would certainly expect biochemical similarity in the plants created by a common Creator. God created plants just two days before their insect pollinators, not 12 million years or so as many evolutionists suggest. The intricate mechanisms of both pollinator-plant mutualism and mimicry that enhance reproductive success are the logical results of natural selection and other mechanisms acting on the variations available in each created kind of plant and animal.

Biblically, we know that God made all kinds of plants on the third day of Creation week and flying insects on the fifth day. God created plants and animals to reproduce successfully, so we can conclude that He created some organisms capable of forming productive partnerships as those seen between malpighians and their bees as well as additional opportunities for mimicry. The built-in genetic variability and the capacity to vary would enable some organisms to establish new mutualistic partnerships and mimes as conditions change. Thus all that is demonstrated here illustrates the excellent design that still functions in the world God created despite 6,000 years of sin’s curse upon it.

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Footnotes

  1. rspb.royalsocietypublishing.org/content/280/1765/20130960 Back (1) Back (2) Back (3) Back (4) Back (5) Back (6)
  2. L. Chittka, “Does bee color vision predate the evolution of flower color?” Naturwissenschaften 83 (1996):136–138, doi:10.1007/BF01142181. Back