Evolutionary anachronism

Dried examples of "neotropical anachronisms" from Brazil, Peru, and Nicaragua in the herbarium of the New York Botanical Garden.[1]

Evolutionary anachronism, also known as "ecological anachronism",[1] is a term initially referring to attributes of native plant species (primarily fruit, but also thorns) that seemed best explained as having been favorably selected in the past due to their coevolution with plant-eating megafauna that are now extinct. Diminished effectiveness and distance of seed dispersal by fruit-eating mammals inhabiting the same ecosystems today suggest maladaptation. Maladaptation of such fruiting plants will intensify as ongoing climate change shifts the physical and ecological conditions within their current geographic range.[2]

The concept was formulated by Costa Rican-based American ecologist Daniel H. Janzen[3] and carried broadly into scientific awareness when he and his coauthor, paleoecologist Paul S. Martin, published "Neotropical Anachronisms: The Fruits the Gomphotheres Ate" in the journal Science.[4] Among the largest of extinct fruit-eating mammals in the American tropics were the gomphotheres, related to modern elephants, which inspired the title chosen by Janzen and Martin for their 1982 paper. As they explained,

There are prominent members of the lowland forest flora of Costa Rica whose fruit and seed traits can best be explained by viewing them as anachronisms. These traits were molded by evolutionary interactions with the Pleistocene megafauna (and earlier animals) but have not yet effectively responded to its absence.

The Janzen and Martin paper was preceded by a 1977 publication by American ecologist Stanley Temple. Temple attributed the decline of the Mauritius endemic tree tambalacoque to human overharvesting to extinction of a large, flightless bird that had coevolved on the same tropical island: the dodo.[5] It was Janzen who applied the concept to some 18 fruiting plant species or genera in Costa Rica, while Martin took the lead on proposing a distinct seed dispersal syndrome: the "megafaunal dispersal syndrome" by comparing the maladapted neotropical fruits with similar forms in the tropics of Africa and Asia that were documented as dispersed by elephants still inhabiting those continents.[1]

Anachronistic fruits of temperate North America, collected by Connie Barlow.[1] Includes pods of devil's claw (top), honey locust (long and curvy at middle) and mesquite (beige at bottom), along with other fruits of the forests and deserts of the USA.

Two decades after the "neotropical anachronisms" concept was published and named, science writer Connie Barlow aggregated its history and subsequent applications into a popular science book: The Ghosts of Evolution: Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms.[1] In shaping the book's title, Barlow drew upon a 1992 essay by Paul S. Martin titled "The Last Entire Earth".[6] Martin had written:

In the shadows along the trail I keep an eye out for the ghosts, the beasts of the ice age. What is the purpose of the thorns on the mesquites in my backyard in Tucson? Why do they and honey locusts have sugary pods so attractive to livestock? Whose foot is devil's claw intended to intercept? Such musings add magic to a walk and may help to liberate us from tunnel vision, the hubris of the present, the misleading notion that nature is self-evident.[6]

The honey locust mentioned in Martin's excerpt is a native tree of eastern North America. Because it is favored for planting along urban streets and parking lots, Barlow was very familiar with it while she was working on her book in New York City. Its long, curving pods became a prominent part of her book.[1] Later, other writers also popularized its lost partnership with ice age ghosts.[7][8]

One animal-with-animal form of evolutionary anachronism also gained popular attention. As reported in the New York Times, "Pronghorn's Speed May Be Legacy of Past Predators", John A. Byers hypothesized that the antelope-like pronghorn of America's grasslands was still running from a Pleistocene ghost that had been much faster than America's native wolves. This ghost was the American cheetah.[9][10]

  1. ^ a b c d e f Barlow, Connie (2001). The Ghosts of Evolution: Nonsensical Fruit, Missing Partners, and Other Ecological Anachronisms. New York: Basic Books. ISBN 978-0-465-00551-2.
  2. ^ Drew, Liam (26 October 2023). "As the climate changes, plants must shift their ranges. But can they?". Knowable Magazine.
  3. ^ Martin, Paul S (2001). Foreword (in The Ghosts of Evolution) (PDF). New York: Basic Books. pp. ix–xi. ISBN 0-465-00551-9.
  4. ^ Janzen, D. H.; Martin, P. S. (1982). "Neotropical Anachronisms: The Fruits the Gomphotheres Ate" (PDF). Science. 215 (4528). American Association for the Advancement of Science (AAAS): 19–27. Bibcode:1982Sci...215...19J. doi:10.1126/science.215.4528.19. ISSN 0036-8075. PMID 17790450. S2CID 19296719.
  5. ^ TEMPLE, S. A. (1977-08-26). "Plant-Animal Mutualism: Coevolution with Dodo Leads to Near Extinction of Plant". Science. 197 (4306). American Association for the Advancement of Science (AAAS): 885–886. Bibcode:1977Sci...197..885T. doi:10.1126/science.197.4306.885. ISSN 0036-8075. PMID 17730171. S2CID 2392411.
  6. ^ a b Martin, Paul S (1992). "The Last Entire Earth" (PDF). Wild Earth: 29–32. Retrieved 4 April 2023.
  7. ^ Bronaugh, Whit. "The Trees that Miss the Mammoths (2011)". American Forests. Retrieved 17 January 2023.
  8. ^ Boggs, Joe (2 January 2018). "Honeylocusts and Mastodons". Buckeye Yard & Garden Online. Ohio State University. Retrieved 24 March 2023.
  9. ^ Kaesuk Yoon, Carol (24 December 1996). "Pronghorn's Speed May Be Legacy of Past Predators". New York Times. Retrieved 5 April 2023.
  10. ^ Cite error: The named reference Byers was invoked but never defined (see the help page).