In the Garden | Major contributions on species

 

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Last Tuesday marked the 210th birthday of the famous botanist and naturalist Charles Darwin, who is most well-known for his groundbreaking work on the science of evolution.

In 1859, Darwin published his most noteworthy book, "On The Origin of Species by Means of Natural Selection, or Preservation of Favoured Races in the Struggle for Life," which was a foundational work that defined our current understanding of evolutionary biology.

In this book, Darwin describes how all species on Earth have descended from common ancestors over time, which has become a foundational concept in science, now known as evolution.

In "On the Origin of Species," Darwin discusses past concepts of speciation on Earth, which primarily assume that species are static, unchanging mainstays of the biological world. Darwin's work, through personal observation and scientific experiment, uncovered a whole new understanding of how taxa on Earth developed over the eons. We learned that species are not static, but rather ever changing in concert with environmental factors and competition from other biota.

Darwin's professional career began with a five-year voyage by sea, primarily to South America but circumnavigating the globe, aboard the HMS Beagle from 1831-1836. During this expedition, Darwin explored land and sea, amassing collections of plant and animal specimens and carefully observing geology.

The primary goal of this expedition was to map the South American coastline with Darwin joining the effort to document geology and collect specimens for further scientific investigation by experts back in England.

Throughout the course of this journey, Darwin kept a detailed journal of his observations that became the basis for much of his life's work.

Darwin is considered a naturalist because much of his early work, which gained him notoriety and launched his career as a scientist, was based on wide-ranging topics, from geology and fossils to taxonomy of both plants and animals.

However, Darwin's work as a botanist has interested me most, providing some very important discoveries that all gardeners use regularly to this day.

The continual publication of Darwin's findings from the HMS Beagle expedition fueled his early career as a scientist and writer. To break up the monotony of writing, Darwin constantly had other field data collection and experiments in the works.

He regularly corresponded with a wide range of collaborators around the world that assisted in his research efforts. His alma mater, The University of Cambridge, has a large online collection of Darwin's letters, which offer a fascinating look into Darwin's own evolution as a scientist and the network of others that assisted in data collection and discussion of hypotheses.

Perhaps his most interesting work related to botany was in the study of orchids. For many years, Darwin meticulously researched orchids native to England, as well as exotic specimens that he collected himself or others sent him. A primary focus of much of his research on these beautiful flowering plants centered on their pollination.

At the time, Victorian science did not understand the close relationship between plants and pollinating insects. The majority of botanists accepted the prevailing thought that most plants were self-pollinated by wind or other means. Few understood the great services that pollinating insects (and other animals) provide in plant reproduction.

Darwin carefully studied orchids by observing the presence, or absence, of pollen masses on orchid flowers. As pollinating insects visit the plants in search of nectar, they maneuver flower parts to access nectar and are forced to come in contact with pollen masses near the nectar causing pollen to detach and adhere to the insect.

As the insect visits multiple flowers for nectar, cross-pollination is accomplished, which introduces heterogeneity in the gene pool among individuals in a species, thus fueling the process by which the best genes for survival are perpetuated and handed down to future generations resulting in gradual change over time, or evolution.

Darwin also studied the co-evolution of insects and flowers, carefully observing how flower parts have evolved to ensure that insects in search of nectar encounter pollen. He also observed that some insects have developed special adaptations to retrieve nectar from specific flowers.

In 1862, Darwin published a book titled "On the Various Contrivances by Which British and Foreign Orchids are Fertilised, and on the Good Effects of Intercrossing." This work thoroughly explored the relationship between orchid flower and pollinator, forever changing the global understanding of plant pollination and co-evolution of species.

Today, plant enthusiasts around the world owe Darwin homage for defining the very important relationship between plants and pollinating animals, not to mention his most important work on the theory of natural selection. Take a minute this weekend to honor the "Father of Evolution" and to marvel at his ever inquisitive drive to carefully study nature and draw practical conclusions across multiple disciplines.

Ryan Pankau is a horticulture educator with the University of Illinois Extension, serving Champaign, Ford, Iroquois and Vermilion counties.