Minions

       Bryce Rauterkus (2013) Bryce was key to the success of the field season in 2013.  We planted seeds in the field in 4 Sierra Nevada sites from maternal families selectively bred for traits associated with autogamy, early flowering and low herkogamy.  Bryce assisted in data collection with a keen eye to flower phenology and a steady hand while holding the IRGA.  Here, he can be seen taking night time fluorescence measurements (at about 2 in the morning).  He also started his own independent project, investigating effects on natural pollen deposition of our selected lines.  He is currently analyzing the data using path analysis in R.

       Joel Kirksey (2013) Joel worked in the field of the Sierra Nevada in one of the driest seasons on record. This was Joel's first experience in the field, but he adapted quickly.  He assisted greatly with a common garden experiment using selection lines from greenhouse propagated maternal families of early flowering and low herkogamy lines.  He is currently working in education outreach.

       Bridget Bedsaul (REU 2012) Bridget worked with us to test whether sex allocation (the pollen:ovule ratio) is associated with early flowering in outcrossing Clarkia taxa? Specifically, she will test whether (1) Lineages of Clarkia unguiculata and C. xantiana selected for early flowering exhibit lower pollen:ovule ratios than their corresponding Control lines (in which mating is at random and there is no selection).  In other words, is their a significant positive genetic correlation that exists between the age at first flower (the number of days between germination and the production of the first open flower) and the mean pollen:ovule ratio exhibited by an individual’s flowers.  (2) Lineages of Clarkia unguiculata and C. xantiana selected for low herkogamy (which facilitates selfing) will exhibit lower pollen:ovule ratios than their corresponding Control lines. Specifically, we predict that lineages with low herkogamy will exhibit lower pollen:ovule ratios than Control lineages.  Bridget has collected hundreds of flower buds, dissected them into ovary and anther and has started counting pollen.   These buds are from greenhouse-raised selection lines for which we have artificially selected early flowering and low herkogamy for three generations of C. xantiana ssp. xantiana.

Alberto Carreño (INSET 2010) Alberto worked on a project very similar to Sandro Roman (see below).  Here, Alberto examined the relationship between a specific physiological trait, WUEi and fruit production.  In his own words "Plants are under constant risk of dessication. How plants deal with this risk may be influenced by or influence their mating system. Because of this, we are exploring whether selfing plants differ from outcrossing plants. In Clarkia, endemic to the western United States, previous work has shown different physiological rates between the selfing species Clarkia exilis and the outcrossing close relative Clarkia unguiculata such as a higher photosynthetic rate in the selfers. Additionally, selfers go through their life cycle at an accelerated rate compared to their outcrossing sister taxa, which flower later on in the season. Consequently, outcrossing plants experience lower water availability that could negatively affect reproductive fitness. We examine how efficient C. exilis and C. unguiculata are at using water (Water use efficency, WUE) and correlate this to a component of fitness, fruit set. With this study, we predict to find that selfing plants have lower WUE than their outcrossing sister taxa.  Furthermore, we should see a positive correlation between WUE and fruit set in the outcrossing species, while we may see no relationship or even perhaps a negative one in the selfing species." Alberto has since transferred from his 2 year institution to a 4 year one, here at UCSanta Barbara.

Josh Haddox (REU 2011) Josh worked with us testing the possibility that architectural and developmental mechanisms may contritbute to the accelerated and compressed life cycle of autogamously selfing Clarkia taxa.  Specifically, he tested two hypotheses.   Hypothesis I, Plant architectural mechanisms for the evolution of early flowering:  early-flowering genotypes achieve their accelerated life cycle by initiating flowering at earlier nodes (i.e., a node lower on the primary stem) than late-flowering genotypes and/or by exhibiting synchronous flowering among multiple stems. Similarly, architectural attributes of early-flowering genotypes of the outcrossing C. xantiana ssp. xantiana are similar to those observed by randomly sampled genotypes of its selfing derivative, C. xantiana ssp. parviflora.  Hypothesis II, Accelerated and/or synchronous flowering contribute to compressed flowering phenology: early-flowering genotypes achieve their more compressed life cycle by accelerating the rate of flower production and thereby increasing the synchrony among blooming flowers.  Independently or together, these mechanisms will shorten the duration of lifetime flower production without decreasing total flower production. Similarly, flowering patterns exhibited by early-flowering genotypes of the outcrossing C. xantiana ssp. xantiana are similar to those observed by randomly sampled genotypes of its selfing derivative, C. xantiana ssp. parviflora.  This work was done in the greenhouse using selection lines of C. for which we had artificially selected early flowering and low herkogamy for two generations of C. xantiana ssp. xantiana. Josh has since graduate and is awaiting his girlfriends graduation to think about his next step.

       Kristen Klinefelter (REU 2009)  Kristen worked in our lab beginning in her freshman year and continuing until graduation.  She excelled at presenting her work to others.  One of her posters presented at a local venue is to the right.  She worked on multiple projects but took the lead in the greenhouse selection experiment.  She put together a data set looking at the responses to selection that we had imposed in the greenhouse.  In her own words her project was based on the "Genetically correlated traits of early flowering and the tendency to self-fertilize in Clarkia xantiana ssp. xantiana.  The evolution of selfing from outcrossing has occurred repeatedly in the genus Clarkia.  Sefling taxa tend to grow in drier warmer areas than their outcrossing counterparts and tend to flower earlier.  Earlier flowering is also thought to be a drought avoidance strategy.  By using an artificial selection experiment, we examine whether early flowering is genetically correlated with the tendency to self-fertilize.  We use an outcrossing, native California wildflower, Clarkia xantiana ssp xantiana and selected for maternal families that flower early.  During the first generation of selection for two field-derived populations, anther-stigma distance (key to self-fertilization) increased with the number of days to first flower. These results support the hypothesis of a genetic correlation between self-fertilization and early flowering in Cxx."  Kristen in now at her first pick graduate school at University College, Dublin Ireland.

       Anthony Linarez (REU 2009, UCLEADS 2009) Anthony has been with us since his freshman year and will be graduating this Spring.  He plans on taking a year off while applying to grad schools in the area of ecology.  His main project has been working on understanding the complex interactions among physiological rates with their effects on fitness.  In his own words "In wild plant species, there are few studies that have directly linked physiological rates to fitness. Here, we explore relationships between plant physiology and plant fitness in two wild annual species in the family Clarkia, Clarkia unguiculata and Clarkia xantiana. Physiological rates, photosynthesis and transpiration, were measured twice in the field, once during the vegetative stage (pre-flowering) and once during the reproductive stage (during flowering). Because fruits are carbon sinks, we expect that plants that are photosynthesizing at higher rates would have higher fitness. In addition, because there is a morphological constraint in which stoma that control carbon uptake also permits water loss, plants that have higher photosynthetic rates are expected to have higher transpiration rates. Therefore, higher transpiration rates should also be correlated with higher fitness. The ratio of carbon gain to water loss is an indicator of how efficient plants are with their water (WUE_i). WUE is a little more difficult to predict because there are two plausible scenarios. The first being that plants with high WUE could have higher fitness because they are more water efficient in a water-limited environment. On the other hand, plants with low WUE may be taking advantage of water resources available early in the season and therefore have higher seed sets. Plant fitness was estimated using seed set, measured from one fruit per plant.  We found no general pattern for both taxa on how physiological rates may affect seed set. For both species, there was a difference in the mean seed set between the vegetative and reproductive stages. For C. xantiana, transpiration was positively correlated with seed set; plants with higher transpiration rates had higher seed set. For C. unguiculata, WUE was positively correlated with seed set. Future work in which we control for position at which the fruit was formed, may decrease ontogenetic noise and thus reveal patterns hidden in the present study."

       Adilene Martinez (REU 2010, CAMP 2010) Adilene started in our lab as an REU student and then stayed for another year.  She focused on two main projects during her time with us: one quantifying antioxidant levels from field collected leaves of four Clarkia taxa, two examining the relationship between seed weight and physiology.  Her first project "Biochemical basis and heritable component of physiological differences between sister taxa with contrasting life history, flowering phenology, and mating system"  tested the possible biochemical mechanisms that contribute to the physiological differences between sister taxa with distinct life histories, flowering phenology, and mating systems.  She helped to gather data to test two main hypotheses.  Hypothesis I: Anti-oxidant production will be lower in self-fertilizing taxa than in their outcrossing sister taxa. If selfing taxa benefit from their earlier flowering (relative to their outcrossing sister taxa) by having greater access to early-spring soil moisture, they should show evidence of reduced drought-stress. If the selfers are in fact avoiding drought stress, then they should exhibit lower anti-oxidant production than their later-flowering outcrossing counterparts. We focused on the measurement of glutathione reductase (GR) and ascorbate peroxidase (APX) activity in the two outcrossing taxa Clarkia xantiana ssp xantiana and C. unguiculata ; these anti-oxidant enzymes have been found to increase in response to drought or heat stress in a variety of species and to improve plant performance when elevated.  Hypothesis II: Anti-oxidant production will increase over the flowering season in both selfers and outcrossers, but the temporal increase will be stronger in outcrossers.  Adilene has since graduated and is living in San Francisco. 

Sandra (Sofi) Roman (CAMP 2009, SACNAS2010) Sofi worked in our lab for several quarters.  Her main project was linking plant physiology (photosynthesis, transpiration and instantaneous water use efficiency with fruit production and fruit set. The project in her own words "There are many types of mating systems, we focus on two: outcrossing and self-fertilization. There are two main hypotheses explaining self fertilization evolving from outcrossing. First, the reproductive assurance hypothesis, states that selfing evolved from poor pollinator services. Second, the drought avoidance hypothesis, states that selfing evolved as a byproduct of selection to avoid desiccation. We explore the drought avoidance hypothesis. Some drought avoidance traits are smaller transpirational area (such as petals), faster life-cycles (completed when water is plentiful), and/or physiological traits which help to prevent water loss (e.g. low transpiration rates). Clarkia, a California wild flower is known to have evolved selfing taxa from outcrossing taxa multiple times. We investigate drought avoidant traits in two outcrossing taxa, Clarkia xantiana ssp xantiana and Clarkia unguiculata in plants growing at the extremes of their ranges where they are found sympatrically with their self-fertilizing sister taxon. We predict that there would be a correlation between physiological traits, which may enable plants to avoid drought, and fitness.. In the field, we measured photosynthetic and transpiration rates by using an infared gas analyzer. Using the ratio between photosynthesis and transpiration, we estimated water use efficiency. Fitness was measured by fruit set, (bud/flower production). We saw no significant correlations for the outcrossing species Clarkia xantiana ssp xantiana, but we found trends supporting our hypotheses. Plants with higher photosynthetic and transpiration rates but lower water use efficiency had higher seed set, consistent with a faster life cycle (higher carbon gain for example). The non-significant correlations could be due to a small sample size (n=103) or other factors not included in the current models may help to explain some of the variation between physiological traits and fitness." Sofi has since graduated and is looking for work close to home.

I was lucky enough to be selected as a mentor for several programs at UC Santa Barbara. These programs included:  Internships in Nanosystems Science, Engineering and Technology (INSET); Society for Advancement of Chicanos and Native Americans in Science (SACNAS), Leadership Excellence Through Advanced Degrees (UC LEADS), and the California Alliance for Minority Participation in Science, Engineering and Mathematics (CAMP).  Students who have traipsed through the lab at UCSB (some even after they graduated!) and into my hands:  Amber Adam, Riley Allen, Joshua Arriola, Kyaw Aung, Bridget Bedsaul, Alex Bello, Sam Breyfogle, Maggie Chen, Andrew Cheng, Sam Chuang, Kyle Coleman, Jon Conway, Dani Coquia, Kim Crispin, Daren Elkrief, Randy Escalante, Anna Espinoza-Frangos, Meer Fakhry, Nicholas Flores, Zawisza Grabinski, Allison Gracer, Bryan Gurwitz, Josh Haddox, Lindsay Halford, Caitlin Horn, Jing Huang, Matthew Humphrey, Whitney Jones, Hannah Kaye, Stephanie Khairalla, Kevin Kihira, Richard Kim, Kristen Klinefelter, Phi Lai, Albert Lee, Jacqui Lee, Anthony Linarez, Mythreyi Mahalingam, Adilene Martinez, Stacey Matsuda, Micah McKechnie, Arrash Moghaddasi, Johnny Molina, Chelsea Moran, Kevin Morse, Dzuyen Nguyen, Lindsay Nord, Anai Novoa, Reina Okuda, Salinla Ounsakulseree, Laura Ramirez, Franklin Rauh, Bryce Rauterkus, Joseph Reveles, Santo Ricci, Sam Robinson, Sandra Roman, Dana Rutherford, Celeste Sage, Katherine Sander, Japneet Singh, Kelly Singsank, Danica Taber, Brittany Tadwilliams, Charles Tu, Sonya Vargas-Lima, Brett Vassar, Cristina Vigano, Erzsebet Vincent, Julia Walker, Brandon Wallace, Anna Xu, Suzy Yah, Jason Yang, Joseph Yoon, Nicole Yukawa, Brian Yurkas, and Jesus Zaragoza.

We have also attained several smaller NSF grants in support of our work on mating system evolution in Clarkia through the Research Experiences for Undergraduates (REU).  

I have enjoyed working closely with undergraduates who have had the opportunity to focus on research.  Most of the students in these programs have gone on to present their work at local, regional and national conferences.  For example:

Kristen Klinefelter. “Mating system evolution in Clarkia: Potential consequences of climate change for the evolution of self-fertilization in a California wildflower” November 2009, Southern California Conference for Undergraduate Research (SCCUR), Cal State Dominguez Hills—Oral presentation

Kristen Klinefelter. “The evolution of self-fertilization in a California wildflower, Clarkia” May 2011, UCSB Undergraduate Research Colloquium, UC Santa Barbara—Poster

Anthony Linarez. “Correlations between seed set and physiological rates in Clarkia” March 2011, UC LEADS Symposium, UC Berkeley—Poster

Anthony Linarez. “Mating system evolution: correlations between seed set and physiological rates” May 2010, UC LEADS symposium. UC Irvine—Oral presentation

Anthony Linarez. “Effects of physiological rates on fitness in Clarkia” November 2009, Southern California Conference for Undergraduate Research (SCCUR) conference, CSU Dominguez Hills—Oral presentation

Anthony Linarez. “Mating system evolution: correlations between seed set and physiological rates” October 2009, SACNAS national conference, Dallas, Texas—Poster

Anthony Linarez. “Mating system evolution: correlations between seed set and physiological rates” 9 February, 2010. SACNAS campus research poster session, Elings Hall, UCSB—Poster

Anthony Linarez. “Mating system evolution: correlations between seed set and physiological rates” August 2009, UC LEADS end of program colloquium and final talks, UCSB—Oral presentation

Anthony Linarez. “Mating system evolution: correlations between seed set and physiological rates” August 2009, UC LEADS end of program colloquium and final talks, UCSB—Poster

Adilene Martinez. “Fitness consequences of variation in photosynthetic rate in the California wildflower Clarkia”February 2011, California Alliance for Minority Participation Statewide Symposium, UC Irvine—Poster (Special Recognition in the Life Sciences session of this symposium)

Sandra Roman. “Mating system evolution: correlating physiology with fitness” October 2009, Society for Advancement of Chicanos and Native Americans in Science national conference, Dallas, TX—Poster (Special Merit Award)

Alberto Carreño. "Understanding the relationship between physiology and fruit set in Clarkia unguiculata and C. exilis"Society for the Advancement of Chicano and Native American Students National Meeting. Fall 2010, Anaheim, CA—Poster