Serpentine ecosystems shed light on the nature of plant adaptation and speciation

Mar 10, 2014
This is the American Journal of Botany cover image; the issue contains the article by Brian Anacker on serpentine endemism. Credit: Image credit: Sylwia Oleszczuk.

Plants that live in unusual soils, such as those that are extremely low in essential nutrients, provide insight into the mechanisms of adaptation, natural selection, and endemism. A seminal paper by Arthur Kruckeberg from 1951 on serpentine plant endemism has served as a solid bedrock foundation for future research on the link between natural selection and speciation. A recent article in the American Journal of Botany focuses on how this paper has influenced subsequent research on local adaptation, evolutionary pathways, and the relationship between climate, soils, and endemism.

In the latest in a series of AJB Centennial Review papers, AJB Anacker (University of California, Davis) examines the impact that Kruckeberg's 1951 AJB paper has had on our subsequent understanding of plant evolution and ecology.

Kruckeberg's classic paper reported on reciprocal transplant experiments, in which he made several generalizations about plant competition, local adaptation, and speciation. Kruckeberg showed that the strong selective pressures of —characterized by low amounts of and water, and high in heavy metals—can lead to the formation of ecotypes (genetically distinct plant varieties), representing a possible first step in the evolution of serpentine endemism (e.g., plants that are only found on serpentine type soils). These important initial findings spurred subsequent research on determining plant traits (from molecular to organismal) that underlie serpentine adaptation.

Anacker draws attention to a second significant contribution of Kruckeberg's paper—researching the historic origins of endemic species, such as those found in serpentine soils. Anacker explains that endemic species are thought to originate in two ways: neoendemics are species that have formed relatively recently via nearby progenitor taxa, and paleoendemics are species that formed following habitat-specific population extirpation. Kruckeberg viewed serpentine ecotypes as representing the first step along the path of paleoendemism. While this stimulated much research in this area, Anacker points out that several serpentine endemics appear to have arisen from nearby progenitor taxa, and thus the neoendemic pathway is also likely important.

Interestingly, Kruckeberg's experiments also showed that many serpentine ecotypes actually performed better on the non-serpentine soils than on serpentine soils, which begs the question of why serpentine-adapted are not also found on non-serpentine soils. Anacker points out that Kruckeberg was one of the first to indicate that competition may play a key role in serpentine specialization. He also highlights recent research indicating that serpentine species are typically slow-growing stress tolerators rather than fast-growing competitive dominants, and their adaptations for being more drought-tolerant puts them at a disadvantage in soils where water and nutrients are not limiting.

While serpentine ecosystems are special and unique environments, Kruckeberg and subsequent researchers have shown how important these systems are for shedding light on broader aspects of plant ecology and evolution.

Explore further: Wrangling flow to quiet cars and aircraft

More information: Anacker, Brian L. 2014. The nature of serpentine endemism. American Journal of Botany 101(2): 219-224. www.amjbot.org/content/101/2/219.full.pdf+html

add to favorites email to friend print save as pdf

Related Stories

Measuring calcium in serpentine soils

Aug 19, 2008

Serpentine soils contain highly variable amounts of calcium, making them marginal lands for farming. Successful management of serpentine soils requires accurate measurement of the calcium they hold. Research published this ...

The benefits of stress ... in plants

Nov 19, 2009

Chronic stress in humans has been implicated in heart disease, weight gain, and diabetes, among a host of other health problems. Extreme environments, a source of chronic stress, present a challenge even for the hardiest ...

Wrangling flow to quiet cars and aircraft

Oct 18, 2013

Plasmas are a soup of charged particles in an electric field, and are normally found in stars and lightning bolts. With the use of high voltage equipment, very small plasmas can be used to manipulate fluid ...

Change in geometry improves aerodynamics

Dec 23, 2013

Kids and dogs understand the force of air, when they stick their hands and heads out of moving cars only to feel them pushed back. It may be invisible, but air is like a see-through net dragging a vehicle back as it strains ...

Phosphorus threatens existence of endangered plants

Nov 20, 2013

Plant species that persist in areas with low availability of phosphorus invest little in sexual reproduction. Due to the increase of phosphorus in their habitats and the fragmentation of low-phosphorus areas, these plant ...

Recommended for you

For legume plants, a new route from shoot to root

Sep 19, 2014

A new study shows that legume plants regulate their symbiotic relationship with soil bacteria by using cytokinins—signaling molecules— that are transmitted through the plant structure from leaves into ...

Controlling the transition between generations

Sep 18, 2014

Rafal Ciosk and his group at the FMI have identified an important regulator of the transition from germ cell to embryonic cell. LIN-41 prevents the premature onset of embryonic transcription in oocytes poised ...

User comments : 0