How Can We Improve Plant Research?

Daintree Rainforest plant diversity. Photo: Australian Geographic

Plants have been researched at great length for a long time and our knowledge of plants is constantly progressing. Nevertheless, there is always room for improvement in how we research things and what factors are considered. Regents Professor Peter B. Reich from the University of Minnesota recently gave a seminar on the use of plant traits to understand global change and the terrestrial biosphere, which provided some suggestions to how we can improve current plant research. 

The Importance of Plant Research

It is first important to understand why plant research is needed. Plants play a crucial role in our ecosystem. We rely on them for clean air which even children’s author Dr. Seuss covered in The Loraxwhere greed led to the disappearance of trees and pollution was rampant. Plants also, provide us with food, shelter, and biodiversity overall. Biodiversity is what helps our ecosystem flourish and preserves the natural resources we need to survive. Researching plants and biodiversity help us understand ecology, various plant relationships, and ways to preserve nature. Although I may not be studying plants, I understand the importance of this research and I can easily see the value in constant improvement with plant research. 

Plant Functional Traits

In Reich’s seminar he expressed the need for studying functional plant traits to help simplify our understanding of ecology, which is quite complex in general. Reich claims that “a few simple traits explain half of all ecology.” These functional traits can include height, specific leaf area, seed size, leaf size, leaf nutrient concentrations (photosynthesis), and many others. Current research has shown plant traits to be useful in understanding organismal function and fitness, community assembly and dynamics, functional biogeography and ecosystem processes. 

Functional traits. Click for source.

For organismal function and fitness, traits were shown to relate to seedling performance in large saplings. This sapling study by Wright used wood density and leaf mass per area (LMA) to explain 40 percent of sapling growth and mortality. In relationship to community assembly, a study of Cedar Creek fire frequency demonstrated that traits are similar between closely related species which helps traits to be conserved over time. Traits assist with functional biogeography and ecosystem processes by demonstrating relationships. Reich referred to his research where photosynthesis in forest canopies was shown to be a function of the canopy nitrogen output percentage, which demonstrates consequences of traits for ecosystems. It is clear that the functional traits of plants can be extremely useful in many aspects of ecology research. 

Improvements for Plant Research

Reich’s research on traits suggests that studies on trait diversity, longitudinal studies, expanding functional trait knowledge, and focus on systems are needed in plant research. 

The productivity dramatically changed in the later 9 years of the experiment. Photo: Reich & Hobbie, 2013

The importance of trait diversity and longitudinal studies is portrayed in a recent study by Reich on the impacts of biodiversity loss. His research showed that having more species diversity, and thereby trait diversity, enhances plant productivity. Additionally, this study showed productivity changed dramatically after four years. This indicates that short-term plant research may have inaccurate data and should be approached with caution.

Parts of a plant. Click for source

Although many functional traits such as height, seed size, and leaf size have been studied at length, there is much to be discovered still in regards to other traits such as roots or hydraulics. Naturally these traits may be more difficult to study, but with improvements in technology there are more opportunities. Some work is already being done to understand tree hydraulics as I discussed in a previous blog regarding Brendan Choat’s research. There may be many more functional traits that we have yet to discover and understand beneath the surface. 

Lastly, Reich feels that researchers should focus more on entire systems. As we look at the whole picture we can consider not just multiple traits of one organism, but also the interactions with other organisms. One good example of these types of interactions is the symbiotic relationship with plants and the fungi mycorrhizae. The fungus and plants help each other to grow, but this relationship may have other roles yet to be discovered. Looking at relationships and whole systems can be applied to every area of research and may provide the largest improvement within research today.  

Conclusion

Plant traits can certainly provide a lot of useful information in many aspects of ecology. Researching more about these traits is just one answer for how we can improve plant research. Ecologists should consider looking at trait diversity, more longitudinal studies, exploring less known traits, and focus on the whole system. 

Further Reading:

Y Evolution: Will Males Disappear?

The X and Y Chromosomes. Click for source.

Men and women are very different, but all of these differences start with one small chromosome. The Y chromosome is what separates the males from the females, but have you ever wondered how it came to be, or how it creates such differences? These are questions that Professor Emeritus Jennifer Graves at La Trobe Institute of Molecular Science has researched at great length. She recently presented a seminar regarding many aspects of sex chromosomes, but Y evolution is of particular interest.

SRY Gene Pathway. Click for source

How is Sex Determined?

At a young age we learn that if you are a female you have two X chromosomes and males have an X and Y. This Y chromosome in humans is what contains the testis-determining factor that essentially “turns on” the testes to produce the hormones that make a male. This testis-determining factor is called the SRY (Sex-determining Region Y) gene and is what makes the X and Y chromosomes so different. Additionally the Y chromosome is also a lot smaller, with only 45 genes in comparison to the hundreds found on the X chromosome. Together these differences in the Y chromosome are how sex is determined between males and females in humans.

Y Evolution

How did these differences in the X and Y chromosome come about? The evolution of the Y chromosome to its current status has been a process that has taken millions of years. Originally X and Y were an ordinary homologous pair of chromosomes, but they began to differ when one mutated and acquired the male determining gene SRY. This was the beginning of the Y chromosome. Over time, other genes advantageous to males accumulated making the pair even more different.

The evolution of the Y chromosome

The evolution of the Y chromosome. Click for source

A consequence of this evolution led to X and Y not being able to align and recombine as shown in the figure above. As a result, The Y chromosome was slowly degraded to its present state. If the gene deletion and mutation of the Y continues it could result in such degradation as to completely lose function. Graves estimated that the Y chromosome could completely disappear in approximately 4.6 million years.

Is the Y chromosome disappearing?

Spiny Rat. Click for source

Whether or not the Y chromosome is actually disappearing is a matter of some debate among researchers. Graves argues that due to the high variation in the Y, inefficient selection, and drift are continuing to degrade the Y. This has also been shown in other mammals and has actually disappeared in spiny rats. Other researchers have argued that the Y chromosome has been conserved for hundreds of millions of years and has not lost any genes in the last 6 million years. Although Graves believes the Y continues to degrade, she feels the actual disappearance is not likely with our large populations, which prevents drastic genetic drift. Additionally, if the disappearance will take around 4.6 million years it is likely we will not survive that long, especially when considering the overpopulation and overconsumption concerns I described in an earlier blog.

Future Research

The Y chromosome disappearance is still a matter of debate, but future research will hopefully gain even further insights into Y evolution. Much of Graves research has been over a wide variety of species and she is currently working on gene mapping in the Tammar wallaby. By looking at how sex is determined over multiple species we can gain a greater understanding of our own genetics. I have only discussed much of the Y chromosome in humans, but there are many other interesting questions regarding sex determination with other species.

Further Reading

Saving Trees by Understanding Hydraulics

Picture of children posing on an enormous oak tree in Louisiana

Oak tree in Louisiana: Photograph by Edwin L. Wisherd, National Geographic

My favorite trees are the large ones that you can easily climb and perhaps build a tree house in, but what if the tree died due to climate changes and drought? This is definitely a current concern, and recent research may help find answers. Dr. Brendan Choat gave a recent seminar on his research about how trees deal with hydraulic failure. This research can help us understand the resilience of trees to drought, and perhaps ways to help.

The Drought Problem

Photo of the effect of bark beetle and drought on pinon pine in the summer of 2002

Los Alamos before and after drought stress and a bark beetle outbreak. Craig Allen, U.S. Geological Survey

I grew up in Utah where drought is common along with dry and dead trees that sometimes lead to forest fires in summer. However, this is happening all over the world, not just in deserts. A NASA-led study used satellite images to look at severe drought which affected about 30 percent of the Amazon rainforest in 2005. Some of the older trees did not survive, and their decaying wood can lead to an excess release of carbon dioxide, which will affect our ecosystem. Another study did a global assessment of tree mortality due to drought and high temperatures. The study found that various types of forests and trees all over the world can be affected by drought.

White dots indicate documented localities with forest mortality related to climatic stress from drought and high temperatures. Background map shows potential environmental limits to vegetation net primary production (Boisvenue and Running, 2006). Drought and heat-driven forest mortality often is documented in relatively dry regions (red/orange/pink), but also occurs outside these regions. Allen et al., 2010

White dots indicate documented drought related forest mortality locations. Mortality is more common in dry regions (red/orange/pink), but also occurs outside these regions. Allen et al., 2010

Climate changes are definitely affecting tree mortality rates, and the problem is that trees can die a lot quicker than they can grow. As Choat presented, we need to understand more about the mechanisms involved in tree survival and mortality. This information may help us predict, and hopefully prevent, die-off.

How Trees Get Water

Www Leaves Stoma Function Com

Click for source

Naturally it’s best to start with the basics. Water is pulled up through a tree by negative pressure created from leaf tension. This is very similar to how you drink through a straw. The xylem are the straw-like structures that are dead at maturity (just like plastic straws) and are the vessels through which the water flows (see diagram to the right). However, these vessels have small pits where water can also flow between the xylem. This special hydraulic system can also get clogged through embolism, which is a gas bubble that blocks the water flow (see my diagram below).

Image

Water flows up the xylem, but can be stopped by embolism.

Xylem structures vary a lot between the angiosperms (flowering trees) and the gymnosperms (“naked seeds” like pine cones) as well as between species. Whether they have many thin xylem, or fewer large ones, this variance can definitely affect tree vulnerability and susceptibility to embolism.

Embolism Repair

Can a tree get rid of embolism once it occurs? Choat and his collaborators were able to use x-ray tomography at a synchrotron light source to be able to see not only the occurrence of embolism, but embolism repair. Parenchyma cells near the xylem actually begin to refill the embolism and eventually allow water to continue up the tree. However, this repairing process may not be the same for all species and classes of trees as some, angiosperms in particular, have more parenchyma cells. So, trees may vary widely in their vulnerability to embolism as well as their ability to repair embolism.

Impacts

Understanding more about embolism, and embolism repair over a wide variety of trees species can help to predict species variability during a drought. Additionally, this information may assist us in forming strategies to protect the trees that we can, particularly for droughts. Unfortunately it may be some time before Choat has had the opportunity to study a large sample of trees to make predictions, but that doesn’t mean we can’t work on saving the trees where we can. There are many ways to help save more trees such as recycling, using less paper, planting trees, or joining an organization.

Links to References

Saving Our Future

Researchers Paul and Anne Ehrlich recently gave a seminar on the imminent collapse of global civilization. Their research regarding overpopulation and overconsumption are certainly convincing that in order to save our future, some serious changes need to occur.

Paul and Anne Ehrlich

Click for source

This amazing couple has been working together since 1950’s, received numerous awards, and are currently working in the Department of Biological Sciences at Stanford University. Paul Ehrlich’s book The Population Bomb in 1968 warned that due to overpopulation there would be detrimental effects such as mass starvation by the 1980’s. Much of the estimated predictions in the book did not occur by 1980 leading to a lot of criticism, but it was still influential in opening the world to the problems of overpopulation. Despite the controversy, Paul and Anne have continuously examined and presented their research on the impacts of population growth.

We Are The Problem

Paul and Anne’s work is clear that if we don’t make some serious changes there will be a collapse of global civilization. The problems leading to this collapse include climate disruption, animal and plant extinction, land degradation, global toxification, ocean acidification, and ultimately the overexploitation of the environment. These issues did not just appear overnight, but from our overconsumption and overpopulation. Growing up in the United States I was accustomed to massive food portions while also being taught not to waste food, which results in eating beyond feeling full. According to the American Heart Association, 154.7 million Americans over age 20 are overweight or obese.

overconsumption

Click for source

Paul explains how agriculture is a major source of greenhouse gas, global toxification, and the loss of biodiversity, which is all related to overconsumption issues. One addition to a family leads to another mouth to be fed and more of environmental resources to be used up. According to Paul Ehrlich, having a second child is worse in comparison to four hummers! We are going to be the cause of our own downfall and destruction of our future generations, and the Ehrlich’s are not optimistic we will prevent this collapse.

Are There Solutions?

Of course there are solutions to avoid a global collapse, but will we do them? The Ehrlich’s paper outlines a long list of things to occur to prevent a collapse, but one that may have serious impact is to increase women rights and gender equity throughout the world. A longitudinal study in the U.S. following a group of women in college over 50 years saw that although original expectations were for the women to focus on a family, most ended up in the workforce (George & John, 2011). Had this study included a wider ethnic and economic group of women the results may have been different.

click for source

Not all women may desire to work, but shouldn’t they all have the choice? Paul described a conversation with group of women that expressed their dislike of the limitations placed on them based on gender. These views are likely shared between women all over the world (click here for the story about an Indian woman named Rai). This isn’t just about women being able to work, but for them to be able to have a voice. What happens when incredible women throughout the world finally get to express their opinions about how many children they want? What if we had more women in politics? I am not suggesting that women have all the answers, but gender equity can easily assist in helping overpopulation concerns which in turn assists in overconsumption.

Spread the Word

We have an obligation to take care of the world that we live in, and right now we are not doing our part. It is imperative that we help share the word that our habits need to change, women should have a voice, and that this needs to happen now! Being passive and ignoring these current issues will certainly lead to a global collapse of civilization and the destruction of life as we know it.

References

Caterpillar Death: an Example of Niche Construction

Last Wednesday I attended a seminar by Dr. Steven Hamblin, a behavioral ecologist that uses economic approaches, who is currently delving into viral niche construction. The terms niche construction refer to any type of process by which an organism changes or manipulates their environment. There are many of examples of this all around us.

As humans we often change our environments to suit our wants and needs. We may build elaborate houses or relocate to be closer to different careers or environments. Other great examples are the birds and the bees. Birds are fantastic examples of nest-building, but also many species are migratory and will travel incredibly long distances for a better climate. Bees are also nest-builders which can vary from very small to incredibly large nests that easily help them to fit into many types of environments. In my opinion, spiders have the largest variety of methods to witch they manipulate their environment with

spectacular webs and traps. I once ran into a long string from an orb spider web in Namibia that was so thick and strong I thought it was string. Even string-like webs are perfect examples of how even the type of construction material is a part of how an organism manipulates the environment.

Hamblin did not of course discuss any of these examples, but the significantly smaller and less discussed example of niche construction: viruses. Currently he has been looking at Baculoviridae which is a type of virus that dramatically changes their host. This virus infects caterpillars and modifies them both behaviorally and internally.

The infected caterpillar becomes awakened and suddenly compelled to move to the very top of it’s tree to wait and die, then the virus liquefies the caterpillar into a goo,

and so ends the life of the caterpillar. The fact that the virus kills its poor unsuspecting host isn’t surprising, but Hamblin investigated why they manipulate their host so dramatically. 

The possible answers are quite fascinating. Hamblin used fancy mathematical models and diagrams to assist in finding the effects of these two traits and their relationship with the virus genetics. These Baculoviridae that cause the dramatic caterpillar death have two specific traits called zombie and gooey which also are related to three specific genes, so basically it is in the virus genetics to create this effect. Hamblins findings also demonstrate that this process is for the viruses own benefit. Although it would seem beneficial for

viruses to grow extremely fast, this can cause death too quickly to the host, some mutated viruses and other errors. Additionally the virus wants to be placed somewhere so it can easily find a new host. The result is an optimal growth rate for the virus in a location that allows it to be easily transmitted leading to a zombie-like and gooey caterpillar.

Niche construction is an interesting concept, but I am certainly intrigued by gaining further knowledge in viral niche construction. For example, why don’t all viruses kill their host? I would think there would be more benefits for a virus to live without having to make so many dramatic changes.

Here are some related articles worth reading:

http://ww.explorelifeonearth.org/cursos/dayetalnicheconstruction.pdf

http://lalandlab.st-andrews.ac.uk/niche/Ecology.html

Creanza, N., Fogarty, L., & Feldman, M. W. (2012). Models of Cultural Niche Construction with Selection and Assortative Mating. PLoS ONE, 7(8), e42744. doi:10.1371/journal.pone.0042744
Harrison, N. M., & Whitehouse, M. J. (2011). Mixed-species flocks: an example of niche construction? Animal Behaviour, 81(4), 675–682. doi:10.1016/j.anbehav.2011.01.013
Okano, K., Vanarsdall, A. L., Mikhailov, V. S., & Rohrmann, G. F. (2006). Conserved molecular systems of the Baculoviridae. Virology, 344(1), 77–87. doi:10.1016/j.virol.2005.09.019
At this point in time I am also disovering other great science blogs, here are some links to websites or blogs I like so far:
http://www.pandasthumb.org/  – a wide variety of short topics and ideas
http://scienceblog.com/  – this has many different scientific topics you can choose from
http://drsophiayin.com/blog  – thoughts from an animal behaviourist
http://www.biology-blog.com/  – mostly biology related blog topics