The phylogeny (V1), showing estimated speciation rate variation in one method (BAMM).
Contrary to half a century of creationist assurances that biologists are about to abandon ‘Darwinism’ and adopt creationism, two biologists from the School of Biological Sciences, University of Reading, UK, have done what scientists actually do: they used evolutionary theory to investigate why cacti have speciated so rapidly. Their conclusion was not that supernatural magic was involved, but that the tempo of evolution itself appears to be a major factor.
Taking their cue from a line of thinking that goes back to Charles Darwin’s work on orchids — including his famous prediction that a then unknown moth, with an exceptionally long proboscis would be found to pollinate a highly specialised Madagascan orchid (subsequently discovered and named Xanthopan praedicta) — botanists had reason to expect cactus diversification to follow a similar pattern. If specialised flowers drive speciation, then cactus speciation should correlate with flower length, especially where long, tubular flowers are associated with particular pollinators.
But that is not what Dr Jamie B. Thompson and Professor Chris Venditti found. They studied flower-length data for more than 750 cactus species in 107 genera, covering a 185-fold range in size, from just 2 mm to 37 cm. Despite that extraordinary variation, flower length itself was only weakly related to how fast cactus lineages split into new species. What mattered was not having a particular flower size, but how rapidly floral morphology — measured here through flower length — was evolving. In other words, faster-speciating cacti had faster-evolving flowers. Their findings have recently been published in the Royal Society’s Biology Letters.
The research was made possible by a new Open Access database called CactEcoDB, created by Jamie Thompson and ten colleagues. This database brings together cactus traits, spatial distributions, environmental variables, range estimates, speciation rates and evolutionary relationships for more than 1,000 cactus species. The result is a major new resource for studying cactus ecology, evolution, biogeography and conservation, and reflects seven years of work compiling and checking data on one of the world’s most distinctive and threatened plant families.
Background: What Are Cacti? Cacti are flowering plants in the family Cactaceae, part of the order Caryophyllales. They are mostly native to the Americas, from Canada to Patagonia, with particularly high diversity in Mexico and other arid or seasonally dry regions. One unusual exception is Rhipsalis baccifera, a mistletoe cactus whose native range also includes parts of tropical Africa and Sri Lanka. [1]The two papers are accompanied by a news release from Reading University:
Although cacti are often thought of simply as “desert plants”, the family is much more varied than that. Some are the familiar columnar or barrel-shaped plants of deserts and semi-deserts; others are sprawling prickly pears, small globular species, tree-like forms, or epiphytes that grow on trees in tropical forests. What unites them is not just succulence, but the presence of specialised structures called areoles — the tiny pads from which spines, flowers and new shoots arise. These are a defining feature of true cacti, and help distinguish them from unrelated succulent plants that may look cactus-like because they have evolved similar adaptations to dry conditions.
Most cacti have greatly reduced or absent leaves. Instead, their thick green stems have taken over the job of photosynthesis, while also storing water. The spines are modified leaves and serve several purposes: they discourage herbivores, reduce air movement close to the plant surface, provide a little shade, and in some species may help condense moisture from fog or dew. Many cacti also have shallow, wide-spreading roots, allowing them to absorb water quickly from brief or infrequent rainfall. [2])
A key adaptation in many cacti is crassulacean acid metabolism, or CAM photosynthesis. Instead of opening their stomata during the heat of the day, when water loss would be greatest, CAM plants open them mainly at night, take in carbon dioxide, and store it chemically until daylight, when photosynthesis can proceed with the stomata closed. This is a highly effective water-saving strategy, although it usually comes at the cost of slower growth. [3]
Cactus flowers are often large, showy and highly specialised. Depending on the species, they may be adapted for pollination by bees, moths, bats, birds or other animals. This close relationship between floral form and pollinator behaviour has long made cacti an attractive group for studying evolutionary diversification. The new work from Reading University adds an important refinement: it is not simply the possession of longer or shorter flowers that appears to matter most, but the speed at which floral traits evolve.
Cacti are also a useful reminder that spectacular evolutionary success does not make a group secure. A global assessment found that 31% of evaluated cactus species were threatened with extinction, with pressures including habitat loss, agriculture, development and illegal collection for the horticultural trade. So this is a family that illustrates both evolutionary innovation and modern vulnerability. [4]
The cactus on your desk is an evolution speed machine
The cactus on your windowsill may grow slowly, but new research shows that cacti are surprisingly fast at creating new species.
Biologists have long thought that pollinators and specialised flowers drive the formation of new plant species. But scientists at the University of Reading found that in cacti, the secret lies in how quickly flowers change shape, rather than how big the flowers grow or which animal pollinates them.
Researchers studied flower length data for more than 750 cactus species, covering a 185-fold range in size from just 2mm to 37cm. Despite this variation, flower length had almost no relationship with how fast a species split into new ones. Instead, species whose flowers were evolving most rapidly were also the most likely to branch into new species, an effect that held across both recent and deep evolutionary history.
Their study, published today (Wednesday, 18 March) in Biology Letters, challenges ideas going back to Charles Darwin, who studied orchids and suggested that specialised flower forms drove the creation of new plant species.
People may think of cacti as tough, slow-growing plants, but our research shows that the cactus family is one of the fastest-evolving plant groups on Earth. Knowing how fast cacti evolve reveals that deserts, often seen as harsh and unchanging, are actually hotbeds of rapid natural change. We expected cacti with longer, more specialised flowers to be the ones creating the most new species. Instead, flower size made almost no difference. What matters is how quickly flowers change shape. Cacti whose flowers evolve rapidly are far more likely to split into new species than those whose flowers stay the same, however elaborate they are.
This result has real implications for conservation. Since flower evolution has helped generate cactus species over millions of years, evolutionary pace should become part of conservation efforts. Although being able to rapidly evolve does not guarantee resilience, especially as the planet is changing faster than most cacti can keep up, it could help predict which species need the most help. Rather than searching for a single trait that predicts which cacti are most at risk, conservationists may need to look at how fast a species is evolving instead.
Dr. Jamie B. Thompson, lead author
School of Biological Sciences
University of Reading
Reading, Berkshire, UK.
Mapping the cactus family tree
The cactus family contains around 1,850 species and is one of the fastest-expanding plant groups on Earth, spreading across the Americas over the past 20 to 35 million years.
This research was made possible by anew Open Access database called CactEcoDB, created by lead author Jamie Thompson and developed in collaboration with ten coauthors from three continents, including six from the University of Reading. Published this month in Nature Scientific Data, it brings together seven years of work compiling cactus traits, habitats, and evolutionary relationships. With nearly a third of cacti threatened with extinction, the database provides a shared resource for scientists worldwide, to study their biodiversity, conservation and future under climate change, for the first time.
Publications:Jamie B. Thompson, Chris Venditti
Faster speciating cacti have faster evolving flowers. Biol Lett 1 March 2026; 22 (3): 20250834. https://doi.org/10.1098/rsbl.2025.0834
Thompson, J.B., Martinez, C., Avaria-Llautureo, J. et al.
CactEcoDB: Trait, spatial, environmental, phylogenetic and diversification data for the cactus family.
Sci Data 13, 623 (2026). https://doi.org/10.1038/s41597-026-06936-7
Here, then, is another example of science doing what creationism cannot do: taking observable facts, testing expectations, and refining understanding in the light of evidence. The expectation that cactus speciation might be driven simply by flower length was reasonable. It was based on real evolutionary thinking, on known relationships between flowers and pollinators, and on a Darwinian tradition of using natural selection to make testable predictions. But when the evidence showed that flower length itself was not the main factor, the scientists did not discard evolution. They used it to ask a better question.
And the answer was still an evolutionary one. The important factor was not a fixed floral form, but the rate at which floral traits were changing. That is exactly the kind of result evolutionary biology is equipped to explain: variation, ecological interaction, selection, divergence, and the splitting of lineages over time. Cacti did not diversify because an invisible designer tinkered with them in ways that conveniently left no evidence of design. They diversified through natural processes acting on inherited variation, shaped by ecology, geography, pollinators, climate, and time.
Creationism, by contrast, contributes nothing to this understanding. It could not have predicted this result, cannot explain why closely related cactus lineages differ in their rates of floral evolution, and offers no useful framework for investigating why some groups diversify rapidly while others do not. “The designer did it” is not an explanation; it is the abandonment of explanation. It tells us nothing about mechanisms, makes no useful predictions, and provides no research programme.
What this research shows instead is the continuing strength of evolutionary theory. More than 160 years after Darwin, it is still the framework that enables scientists to make sense of life’s diversity — not as a set of disconnected miracles, but as the result of natural processes that can be investigated, measured and understood. The cactus on the windowsill, far from being a token of supernatural manufacture, is part of a vast evolutionary story: one in which changing flowers, changing environments and changing lineages have produced one of the most distinctive plant families on Earth.
Advertisement
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
Amazon
All titles available in paperback, hardcover, ebook for Kindle and audio format.
Prices correct at time of publication. for current prices.
No comments :
Post a Comment
Obscene, threatening or obnoxious messages, preaching, abuse and spam will be removed, as will anything by known Internet trolls and stalkers, by known sock-puppet accounts and anything not connected with the post,
A claim made without evidence can be dismissed without evidence. Remember: your opinion is not an established fact unless corroborated.