- Author: Kathy Keatley Garvey
Yes, if you use the term “personality” to refer to “intraspecific expression of behaviors that are stable over time and consistent across different situations,” says ecologist Richard “Rick” Karban, an international authority on plant communications and a distinguished professor in the UC Davis Department of Entomology and Nematology.
“Individual plants respond differently to alarm calls, just as individual animals do,” says Karban, a 40-year member of the UC Davis faculty who has studied plant communication in sagebrush (Artemisia tridentata) since 1995 on his research site, located east of the Sierra Nevada mountain range.
In a newly published paper in the international peer-reviewed journal, Oecoogia, the UC Davis professor and two colleagues found that when plants tell their neighbors—via volatile cues—that they are under attack by herbivores, the plants showed consistent individual variation in how they perceived and responded to the cues, that is, how effectively they shored up their defenses.
“The gist of the argument here is that animal behaviorists have found it useful to recognize that individual animals show behavioral tendencies that are consistent under different circumstances and repeatable over time,” Karban explained. “So, for instance, some individuals are bolder or shyer in terms of issuing or responding to alarm calls. They have termed these individual tendencies 'personalities.' We have found similar consistent individual differences among sagebrush plants.”
The paper, titled “Consistent Individual Variation in Plant Communication: Do Plants Have Personalities?,” is co-authored by Patrick Grof-Tisza of the University of Eastern Finland and Charline Couchoux of the University of Quebec. Established in 1968, Oecoogia is one of the most cited ecology journals.
“Just as animal biologists have come to consider consistent individual personalities to be an important factor in shaping animal phenotypes, behaviors, and interactions, so, too, should plant biologists include individual variation in plant communication as a significant individual attribute that influences their evolution and ecology,” they noted.
In their abstract, they explained that “When animals sense danger, some individuals will alert neighbors with alarm calls and both calling and responding vary consistently among individuals. Plants, including sagebrush, emit volatile cues when they are attacked by herbivores and neighbors perceive these cues and reduce their own damage.”
They found that 5 percent of the variance in chewing damage “was attributable to the identity of the emitter that provided the cue. This fraction of variation was statistically significant and could not be attributed to the environmental conditions of the receiver. Effective receivers were also relatively effective emitters, indicating consistency across different situations. Pairs of receivers and emitters that were effective communicators in 2018 were again relatively effective in 2019, indicating consistency over time. These results suggest that plants have repeatable individual personalities with respect to alarm calls.”
In their paper, the scientists pointed out that the goal “in discussing plant personalities is not to insinuate that plants are people or are intelligent in a similar way that we are, but to highlight that animal behavior has much to offer the development of plant biology. Recognizing that plants exhibit consistent behaviors that are repeatable in different situations and stable over time (i.e., personalities) has several important consequences.”
First, they said most plant biologists focus on treatment groups instead of individuals. “The idea that individual plants may show consistent tendencies that can be quantified, independent of other treatments, leads to a different research focus. In addition, the existence of plant personalities means that knowledge of an individual's past provides information that can predict its behavior in the future. In Bayesian jargon, the existence of personalities means that informed priors can be used to improve predictive power.”
Tradeoffs. Second, they wrote, “recognition of correlations among different plant behaviors suggests that there may be tradeoffs among important traits that are not independent of one another. For example, a negative correlation between growth of roots and shoots suggests an allocation tradeoff between above and below ground tissues while a positive correlation between growth of roots and shoots suggests that differential access to resources is more important than such an allocation tradeoff. Life-history tradeoffs of this nature are familiar to evolutionary plant biologists and this framework can be applied to other plant behaviors.”
Third, they wrote, “alarm calls that affect herbivory influence plant growth, survival, and reproduction in the few systems where they have been studied. These demographic effects have the potential to shape plant adaptations, population sizes and distributions, ability to respond to natural and human induced changes, and interactions with other species, although potential effects of variation in plant communication have been largely neglected.”
The trio pointed out that “many of these volatile chemicals dissipate rapidly so that they are present in biologically active concentrations over relatively short distances (often less than 1 m). In many instances, cues may be emitted unintentionally, and this process is probably best described as eavesdropping by the receiving plant. These same plant volatile cues have been found to serve other functions in some instances such as repelling herbivores and attracting the predators and parasites of the herbivores.”
Landmark Book. Karban is the author of the landmark book, Plant Sensing and Communication (University of Chicago Press, 2015). He is a fellow of the Ecological Society of America (ESA) and the American Association for the Advancement of Science, and the recipient of the 1990 George Mercer Award from ESA for outstanding research.
The UC Davis ecologist is featured in the Dec. 23-30, 2013 edition of The New Yorker in Michael Pollan's piece, The Intelligent Plant: Scientists Debate a New Way of Understanding Plants. Zoe Schlanger featured him in a Nov. 21, 2020 Bloomberg Quint article titled The Botanist Daring to Ask: Do Plants Have Personalities?
Karban, who holds a doctorate in biology from the University of Pennsylvania, Philadelphia, joined the UC Davis faculty in 1982.
- Author: Kathy Keatley Garvey
The honor is awarded to those scholars “whose work has been internationally recognized and acclaimed and whose teaching performance is excellent.”
The UC Davis Department of Entomology now has a total of nine distinguished professors: six current faculty--Bruce Hammock, Frank Zalom, Lynn Kimsey, James R. Carey, Jay Rosenheim, and Richard Karban--and three emeriti faculty--Harry Kaya, Howard Ferris and Thomas Scott. (In addition, emeritus professor/chair Robert E. Page Jr. is a UC Davis distinguished emeritus professor, as was the late Robbin Thorp, who died in 2019.)
Karban, whose research interests include the population regulation of animal species and the interactions between herbivores and their host plants, currently focuses his research on two main projects: volatile communication between sagebrush plants that affects resistance to herbivory and factors that control the abundance and spatial distribution of wooly bear caterpillars.
Karban has researched plant communication in sagebrush (Artemisia tridentata) on the east side of the Sierra since 1995. His groundbreaking research on plant communication among kin, published in February 2013 in the Proceedings of the Royal Society B: Biological Sciences, drew international attention. In that study, Karban and his co-researchers found that kin have distinct advantages when it comes to plant communication, just as “the ability of many animals to recognize kin has allowed them to evolve diverse cooperative behaviors.”
On his website, he explains his research on volatile communication: “When sagebrush is experimentally clipped, it releases volatile cues that undamaged branches on the same plant, on different sagebrush plants, and on some other plant species respond to. These volatile cues cause many changes in neighboring plants and some of these changes make the undamaged neighbors better defended against their herbivores. We currently know little about the nature of these cues.
“Blocking air contact between branches makes responses undetectable, indicating the involvement of airborne cues. Methyl jasmonate has the ability to serve as the signal although it remains unclear if it acts in this capacity in nature. I would like to understand the costs and benefits of releasing volatiles cues and of responding to them. I am examining the multiple consequences of emitting cues. For example, cues affect neighboring plants, nearby herbivores, as well as predators and parasites of those herbivores. I am currently examining the long-term fitness consequences for sagebrush of responding to volatile cues.”
On his research on the abundance and distribution of caterpillars, Karban writes: “Many workers define ecology as the science that explains the abundance and distribution of species. Despite a century of work on these questions, our field has only a rudimentary grasp on the factors that are important. I have been censusing populations of wooly bear caterpillars at Bodega Bay for 30 years and have relatively little understanding of the factors that produce patterns in abundance and distribution. The ‘usual suspects' all have relatively little explanatory power: weather, food limitation, and parasitoids all fail to provide much insight. Indeed, caterpillars often recover from the attacks of their tachinid parasitoids and alter their diets when parasitized to increase their chances of surviving. Including a more complete food web in our analysis does not appear to provide more resolution although ants may be unappreciated as predators and food quality may also be important. I am collaborating with Perry de Valpine to attempt to develop new analytical techniques that will account for more of the variance in abundance data. I am collaborating as well with Marcel Holyoak to examine spatial patterns of abundance.”
Karban is the author of landmark book, Plant Sensing and Communication. He is a fellow of the Ecological Society of America (ESA) and the American Association for the Advancement of Science, and the recipient of the 1990 George Mercer Award from ESA for outstanding research.
The UC Davis ecologist is featured in the Dec. 23-30, 2013 edition of The New Yorker in Michael Pollan's piece, The Intelligent Plant: Scientists Debate a New Way of Understanding Plants. Zoe Schlanger featured him in a Nov. 21, 2020 Bloomberg Quint article titled The Botanist Daring to Ask: Do Plants Have Personalities?
Karban received his bachelor's degree in environmental studies from Haverford (Penn.) College in 1977 and his doctorate in biology from the University of Pennsylvania, Philadelphia, in 1982. He served as a lecturer at Haverford College for six months before joining the UC Davis faculty in May 1982 as an assistant professor. He advanced to associate professor in 1988 and to full professor in 1994.
- Author: Kathy Keatley Garvey
Yes, they can.
And now UC Davis ecologist Richard “Rick” Karban's research is “talking” in TED-Ed Original Lessons and drawing international attention from thousands of teachers, their students and other Internet viewers.
Karban's work on plant communication is featured in an interactive lesson plan where "words and ideas of educators are brought to life by professional animators.” Teachers can customize the lesson plan to engage their students.
Plants can eavesdrop, sense danger in the environment, and can distinguish friend from foe, says Karban, a professor in the UC Davis Department of Entomology and Nematology, who recently published a 250-page comprehensive book, Plant Sensing and Communication (University of Chicago Press), hailed as a landmark in its field.
A plant under a predatory attack will emit volatile chemical cues, enabling its neighboring plants to adjust their defenses to better protect themselves.
Nearly 130,000 have accessed the lessons, with nearly 2000 questions answered. In the TED-ED lessons, teachers can interact with their students, quizzing them on:
- What are some characteristics of the language of plants?
- Why do plants communicate? What advantages might they get from communicating that increase their chances of survival and reproduction?
- In what ways are communication systems between plants similar to communication systems between animals? In what ways are they different?
The creators of the plant communication lesson are Karban, educator; Yukai Du, director; Angus MacRae, composer; Eleanor Nelson, script editor; and Jiaqi Wang, animator.
Karban has researched plant communication in sagebrush (Artemisia tridentata) on the east side of the Sierra since 1995. His groundbreaking research on plant communication among kin, published in February 2013 in the Proceedings of the Royal Society B: Biological Sciences, drew international attention. In that study, Karban and his co-researchers found that kin have distinct advantages when it comes to plant communication, just as “the ability of many animals to recognize kin has allowed them to evolve diverse cooperative behaviors.”
“Plants responded more effectively to volatile cues from close relatives than from distant relatives in all four experiments and communication reduced levels of leaf damage experienced over the three growing seasons,” they wrote.
In other words, if you're a sagebrush and your nearby kin is being eaten by a grasshopper, deer, jackrabbit, caterpillar or other predator, communication is more effective if you're closely related. Through volatile cues, your kin will inform you of the danger so you can adjust your defenses.
Karban likened this kind of plant communication to eavesdropping.” Plants “hear” the volatile cues of their neighbors as predators damage them.
The most basic form of communication? When a plant is being shaded, it senses the diminished light quality caused by a competitor and responds by moving away, Karban says.
What are 10 things to know about plant sensing and communication? According to Karban:
- Plants sense their environments and respond.
- Although they lack central nervous systems, they process information and appear to "behave intelligently."
- They sense the position of competitors and "forage" for light.
- They sense the availability of water and nutrients in the soil and "forage" for these resources.
- Their decisions are influenced by past experiences, akin to memory.
- The respond to reliable cues that predict future events, allowing them to "anticipate."
- Plants respond differently to cues that they themselves produce, allowing them to distinguish self from non-self.
- They respond differently to close relatives and strangers.
- Plants that are prevented from sensing or responding experience reduced fitness.
- By understanding the "language" of plant responses, we can grow healthier and more productive plants.
The most basic form of communication? When a plant is being shaded, it senses the diminished light quality caused by a competitor and responds by moving away, Karban says.
Karban is a fellow of the American Association for the Advancement of Science (AAAS) and has published more than 100 journal articles and now, three books.
Karban is featured in the Dec. 23-30, 2013 edition of The New Yorker in Michael Pollan's piece, “The Intelligent Plant: Scientists Debate a New Way of Understanding Plants."
Related Link:
Rick Karban: Kin Recognition Affects Plant Communication and Defense