Evan Rehm, a former graduate student with FIU Department of Biology and ICTB (currently a postdoc at Colorado State University), and Dr. Kenneth Feeley have published a new article in the open-access journal Frontiers of Biogeography.  The article is entitled “Many species risk mountaintop extinctions long before they reach the top“.  In their article, Rehm and Feeley discuss the importance of ecotones, such as the alpline treeline, in setting current and future species’ distributions.  They highlight the fact that many species’ range boudaries are set by ecotones and that these ecotones may not shift concurrently with climate change – potentially resulting in rapid range compressions and elevated extinction risks.

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Fall 2016 in Colombia

Ken Feeley has been awarded a Fulbright Research Fellowship.  With the support of the Fulbright Fellowship, Ken will spend the Fall 2016 semester on a sabbatical leave at the National University of Colombia in Medellin working on a collaborative study with Dr. Alvaro Duque. Ken’s research will build off of previous work that he and Alvaro conducted looking at climate-driven changes in the composition of Andean forests (published in the Proceedings of the National Academy of Sciences: http://www.pnas.org/content/112/34/10744.abstract).  Ken and Alvaro will now look at how the observed changes in composition relate to species’ functional traits and climatic tolerances.

transplants help to reveal the complex factors setting high Andean treeline

Evan Rehm, a former biology grad student at FIU, and Ken Feeley have published a new article in the journal Oecologia entitled “Seedling transplants reveal species-specific responses of high-elevation tropical treeline trees to climate change” (http://link.springer.com/article/10.1007/s00442-016-3619-0).  The article is based on a study transplanting seedling of high-elevation Andean tree species across an elevational gradiant and under experimental heating and shading treatments. The study revealed that tree species responded differently to the environmental manipulations and that warming decreased survivorship in the most common species (Weinmannia fagaroides).  These results highlight the need for species specific studies and models to predict the effects of climate change in this biodiversity hotspot.

 

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Thermal trouble in the tropics

Tim Perez, James Stroud and Ken Feeley published a new Perspectives article in Science Magazine entitled “Thermal  Trouble in the Tropics”.  The article explains why tropical species are at extra risk of extinction under climate change compared to their temperate counterparts.  They also discuss the need for additional studies of tropical plant species and their climatic tolerances. A copy of the article is available HERE.

Ken Feeley discussed the article during a radio interview with John Batchelor.  A podcast of the interview is available to download or listen to HERE.

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Priority effects in a changing climate

A new publication from the Feeley Lab in Frontiers in Ecology and Evolution addresses the importance of priority effects on species range shift. The publication is a comment to a paper published in Nature by Alexander et al (2015).

Commentary: Novel competitors shape species´ responses to climate change

Belen Fadrique and  Kenneth Feeley

There is a growing appreciation of the need to understand the effects of climate change on species interactions and how changes in interactions can influence the ability of species to persist in the face of climate change (Araújo and Luoto, 2007; Thuiller et al., 2008; Svenning et al., 2014). However, empirical or experimental studies investigating species interactions under climate change remain extremely scarce. Alexander et al. (2015) use experimental transplants of European alpine plant species and communities to provide valuable insight into some of the novel competitive interactions that may emerge as species migrate upslope to keep pace with rising temperatures. More specifically, they look at performance of plant species under simulated upslope migrations into preexisting higher-elevation plant communities as well as the performance of plant species that fail to migrate and find themselves competing with new suites of species migrating into their community from below. This is a useful approximation of some of the scenarios that are already being created by the unequal responses of species to climate and the creation of novel communities.

One limitation of the study by Alexander et al. (2015) is the omission of the earliest phases of establishment when processes such as dispersal and germination are crucial in the encroachment of initial populations of migrant species into the new locations (Hampe, 2011). In particular, the experimental set up fails to account for one of the potentially most important drivers of community assembly—priority effects. Priority effects refer to the observation that early colonists will often inhibit, or alternatively facilitate, the establishment of subsequent colonizers (Connell and Slatyer, 1977).

Keep on reading HERE.

OTS leftovers: Does leaf pH influence herbivory?

My research focuses on how species have adapted to environmental variation and how these adaptations influence species’ niche breadths and geographic distributions. Although IUntitled focus on tropical plants, and insect herbivores are a substantial biotic selection pressure, herbivory is not a topic I actively pursued until I participated in an OTS course last summer. On my OTS course I was able to investigate an array of topics from plant defense to plant-mediated tri-trophic interactions, all of which are documented in our 2015 OTS coursebookOf all the projects I participated in, the last project of the course remains my favorite because it has provoked new questions, some of which have informed my thesis research.

In this last project, my classmate and I were following-up a previous study in which we investigated the ability of leaf pH to predict herbivory in plants. Literature suggested that low pH values deter herbivores in the sub-arctic where ungulates, not insects, are the dominant herbivores. Consequently, the influence of leaf pH on herbivory in tropical to sub-tropical regions where insects are the dominant herbivores is unclear. In our first project, my classmate and I found no effect of leaf pH on standing herbivore damage in the 5 Piper species we measured. For our follow-up project we were interested in determining the sources of variation that may have influenced leaf pH, and thus, the results of our previous study. Ultimately, we decided to investigate diurnal and ontogenic changes in leaf pH for two Piper species. 

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Figure 1: Ontogenic changes in leaf pH of P. multiplinervum & P. hispidum

Interestingly, our immature leaves exhibited the lowest pH values (Fig 1), and immature leaves have previously been shown to be the most palatable to insect herbivores. Compared to mature leaves, immature leaves tend to receive more insect herbivory because they are softer, are higher in nutrients, but also produce more chemical defense compounds. Therefore, leaf acidity may be correlated with leaf age and linked to chemical defenses that deter herbivores. If so, leaf pH could be an easily-measured trait used to understand the susceptibility of plants to insect herbivory.

In addition to ontogeny, leaves also exhibited diurnal changes in their chemistry (Fig 2). We found that both immature and mature leaves that were measured in the morning (~9am) had lower pHs than leaves measured in the the afternoon (~4pm). These diurnal fluctuations may have resulted from changes in carbonic acid and cytoplasmic proton gradients throughout the day. However, given the potential relationship of pH to chemical defenses, it is easy to speculate that some chemical defenses could fluctuate throughout the day in addition to ontogenic phase. 

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Figure 2: Diurnal changes in leaf pH of P. multiplinervum & P. hispidum

Since our first study did not properly measure herbivore damage, the effect of pH on insect herbivory remains an unanswered question. The observations from our follow-up study indicate pH is probably correlated with ontogeny, which has been shown to influence the production of chemical defenses that deter herbivory. pH was also observed to fluctuate diurnally, and may indicate diurnal changes in herbivore deterrence.

What I think is exciting about these results is that if pH does influence herbivory, insects may feed upon leaves according to temporal differences in leaf chemistry. In turn, these short-term temporal feeding preferences could promote co-existence of insect species, which greatly outnumber plant species, and are likely to overlap in diet-breadth. There are many unanswered questions that this project has induced that warrant further investigation before any concrete conclusions can be made about the influence of pH on insect herbivory. 

My uncharacteristic foray into plant-insect interactions has led me to a new understanding of niche-breadth and coexistence theories through concepts such as the storage effect that incorporate temporal niche partitioning – a topic of great relevance to my thesis. Moreover, my newfound interest in herbivory highlights the benefit of stepping outside the territory of your own research in order to gain a better understanding of it. 

Now that I am in Florida, where Pipers are introduced and rare,  I’ve been
gathering information on the native species Psychotria nervosa to address some of the questions I developed while on my OTS course. I’m currently collecting and identifying insects that feed on P. nervosa, and have already quantified ontogenic changes in leaf nutrients. As my course-load dwindles and the resources at the International Center for Tropical Botany 
become available, I hope to dedicate more time to understanding how leaf chemistry influences insect herbivory in the sub-tropics as a side-project…so stay tuned.

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Me (Tim Perez) happily collecting Piper cenocladum at La Selva Biological Station, Costa Rica.

P.E.O. ayudando a la educación superior de las mujeres

(see below for English version)

En la mayoría de los casos, el camino hasta llegar a los estudios de postgrado, y especialmente si es un postgrado en ecología tropical, no es barato.

Después de mis estudios de licenciatura, me encontré realizando actividades que definitivamente me iban a ayudar a desarrollar mis habilidades, enriquecer mi experiencia y mi curriculum, pero también a empobrecer mi cuenta bancaria. Fui voluntaria en laboratorios, en expediciones de campo, realicé prácticas en el otro lado del mundo y me apunté a varios cursos de inglés para tener varios certificados. Solía decir que todas estas actividades eran INVERSIONES. Cuando comencé mi doctorado pensé que todas esas inversiones por fin se veían recompensadas. Y sí, era verdad, estaba en un buen grupo de investigación, estudiando lo que yo quería. Sin embargo, muy pronto me di cuenta de que el doctorado era otra inversión. Tuve que hacer malabares para poder pagar las tasas, la renta, la comida, el seguro, el coche y todo lo necesario para empezar una vida en Miami.

Afortunadamente, mi compañera de laboratorio Catherine Bravo me animó a solicitar la International Peace Scholarship, ofrecida por la hermandad P.E.O. (Philanthropic Educational Organization). Esta beca apoya a mujeres internacionales que realizan estudios de postgrado en los Estados Unidos y Canada. Durante este año académico, P.E.O. me ha proporcionado apoyo para pagar las tasas y algún otro gasto, lo que ha hecho mi vida mucho más fácil y amena.

P.E.O. fue fundada en 1869 por siete estudiantes de Iowa Wesleyan College en Mount Pleasant, Iowa. El objetivo era promover oportunidades de educación para mujeres. La hermandad ha crecido y ahora está presente en los 50 estados de Estados Unidos y en seis provincias de Canadá. Hay más de 250.000 miembros de P.E.O. en el mundo. Más de 90.000 mujeres se han beneficiado de P.E.O. a través de becas, préstamos, premios, proyectos especiales y Cottey College.

Recientemente, tuve el honor de acudir a una comida en conmemoración de la fundación de P.E.O. por siete mujeres valientes, que desafiaron el mundo de su tiempo. Conocí a mujeres increíbles de diferentes capítulos de Broward County, Florida. Me mostraron un increíble entusiasmo por mi investigación, mis objetivos y el impacto que yo misma y otras mujeres podemos tener en la sociedad.

Fue una experiencia increíble y me gustaría agradecer a P.E.O. no solo por la beca, que es muy útil, sino por el apoyo emocional y social que me proporcionan.