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Echinacea pallida, a non-native Echinacea species that is compatible with E. angustifolia, was planted at a restoration at Hegg Lake WMA. One aspect of the potential that E. pallida has to interact with E. angustifolia individuals is the synchrony of their flowering timing, or phenology. To study this, we have kept track of the start and end dates of flowering for Echinacea pallida individuals in the Hegg restoration plot since 2011. In 2015, we identified 48 flowering plants with 139 heads. Flowering began on June 30th. Then, on July 15th, we chopped off all the Echinacea pallida heads. Before this date, 34 individuals flowered.
 Flowering schedule and map of Echinacea pallida at Hegg WMA. Note the abrupt end of flowering on July 15th. Click to enlarge! Read more about this experiment.
Start year: 2011
Site: Hegg Lake WMA restoration
Products: In Fall 2013, Aaron and Grace, externs from Carleton College, investigated hybridization potential by analyzing the phenology and seed set of Echinacea pallida and neighboring Echinacea angustifolia that Dayvis collected in summer 2013. They wrote a report of their study.
Overlaps with: Echinacea hybrids (exPt6, exPt7, exPt9), flowering phenology in remnants
Previous team members who have worked on this project include: Nicholas Goldsmith (2011), Shona Sanford-Long (2012), Dayvis Blasini (2013), and Cam Shorb (2014)
 Keke hard at work counting the q3 offspring Keke is a senior Environmental Studies major at Lake Forest College who has been working in the lab for the past semester. For her project, she focused on the maternal plants of qGen_3. In that experiment, we crossed individuals in p1 with pollen collected from plants at Staffanson and Landfill during the summer and planted the seeds from those crosses in the fall. When dissecting the heads, we only selected achenes that we knew had been crossed properly.
This left ray achenes and achenes that may have been contaminated with other pollen, plus any achenes that we missed! Although we didn’t want to plant inviable or contaminated achenes, knowing the fecundity of the maternal plants is an important part of estimating fitness, so we wanted to have accurate achene counts for each mom. This is where Keke comes in. She removed all of the “extra” achenes and counted them, along with the rest of the maternal achenes which had been scanned in the fall.
Keke also analyzed the effect of a new pollen management procedure that we followed for q3. This procedure involved collecting pollen in multiple vials and taking care to only remove a vial from the refrigerator for crossing once. This was in an effort to reduce exposure of pollen to repeated warming and cooling cycles, which we thought might have reduced its viability in q2. Keke assessed the percent of successful crosses in q2 versus q3 and found that the percent of successful crosses increased 5% with the new procedure. Cool!
You can read more about what Keke did this winter and spring in her report, which can be found here:
Keke’s Q3 Report
Thanks Keke and best of luck in all of your future endeavors!
In 2015, we continued an experiment that investigates hybridization between the native Echinacea angustifolia and the unintentionally planted non-native E. pallida. This year, out the the 758 plants planted in spring 2014, 521 were still alive which is a survival rate of 68.7%.
In the late summer of 2013, members of Team Echinacea collected heads from Echinacea angustifolia and Echinacea pallida from two nearby populations at Hegg Lake Wildlife Management Area. Unlike previous experiments, we performed no artificial crosses. This allows us to determine if hybridization is occurring naturally. In the winter of 2014, Lydia English germinated seeds from these heads. In the spring, Lydia and Stuart planted 758 seedlings at Hegg Lake WMA near experimental plot 7. We took fitness measurements, such as number of rosettes and leaf lengths, this year.
In addition to the experimental plot, we collected heads and tissue samples from 28 E. angustifolia that were near the restoration with E. pallida. We have not yet done any analysis on these plants but we are hoping to determine if hybridization in continuing.
Read more posts about this experiment here.
 Echinacea Pallida at Hegg Lake Start year: 2014
Location: Hegg Lake Wildlife Management Area – Experimental plot 9
 A hybrid at Hegg Lake In 2015, we continued an experiment that quantifies fitness of Echinacea angustifolia x pallida hybrids and pure-strain plants. Out of the the original 522 plants, 323 were still alive in 2015, which is a survival rate of 62%. The mean leaf length of these plants was roughly 11.7 cm. Stuart planted the 522 seedlings at Hegg Lake WMA in spring 2013. The seedlings result from hand reciprocal crosses conducted by Shona Sanford-Long during the summer of 2012.
Read more posts about this experiment here.
Start year: 2013
Location: Hegg Lake Wildlife Management Area – Experimental plot 7
In 2015, we continued an experiment investigating fitness of Echinacea angustifolia x E. pallida hybrids. This year, out the the original 66 plants, 55 were still alive. That’s an impressive survival rate of 83% since they were planted in 2012. The mean leaf length of the plants was roughly 16 cm. In the summer of 2011, Nicholas Goldsmith and Gretel Kiefer performed reciprocal crosses between 5 plants of Echinacea pallida (non-native) found in a prairie restoration at the Hegg Lake Wildlife Management Area and 31 plants of the native Echinacea angustifolia from experimental plot 1 to determine the hybridization potential of these two species. In the summer of 2012, team members planted 66 seedlings.
Read more flog posts about this experiment here.
Echinacea Pallida on Hegg Lake Start year: 2012
Location: Experimental plot 6
I successfully created a generalized linear model to describe reproductive success at Staffanson Prairie Preserve for the 2015 season. I started out with a model containing distance to the 3rd nearest neighbor, flowering start date, flowering duration, section of head from with the achene came, and all interactions between these main effects. In addition, I included both linear and quadratic terms for distance, start date, and duration. The purpose of including a quadratic term is to test for evidence of curvature in the relationship to seed set.
Through a process called backwards elimination, I removed all terms from the model that did not have a significant impact on reproductive success. The final model I came up with contained both linear and quadratic terms distance and start date, as well as the section of head. No interactions were found to be significant. In the plots below, the raw data are shown as points, and the predicted valued from the model are shown as curves. There are three plots of seed set as a function of distance, with the three plots representing low (10 days or fewer), mid (11-13 days), or high (14 days or more) flowering duration. The colors correspond to section of head, with red being top, blue is middle, and green is bottom.
  
While this is an observational study, so attributing causation would be inappropriate, it is helpful to think about why these relationships may exist. The general trend with increasing distance and spatial isolation is that seed set and reproductive success decrease. This is probably because isolated plants have fewer available mates or may be visited by fewer pollinators. However, the relationship is curved and plants in very densely populated areas also have diminished seed set. This may be caused by overcrowding and competition between plants for pollinators in areas of high population density.
Seed set has a similar peak at mid-duration of flowering. One explanation for this phenomenon is that plants that flower for a very short period of time co-flower with fewer potential mates, so a longer flowering time would maximize the number of compatible mates flowering at the same time. However, it is also known that extended flowering can be a sign that the head has not been receiving sufficient pollen, explaining the negative relationship between duration and seed set seen at higher durations.
In the future, this model will be compared to similar models from previous years during which Staffanson underwent controlled burns. Any differences seen between the models may be indicative of how the mating scene changes during the year after a burn.
 Reina, Pamela, and Mike with the photosynthesis machine used in Kittelson et al. (2015) In 2015, we continued to study the effects of inbreeding on Echinacea angustifolia fitness. This experiment was planted in 2006 where each plant was produced from one of three cross types: between maternal half siblings; between plants originating from the same remnant, but not sharing a maternal parent; and between individuals from different remnants. We continued to measure fitness and flowering phenology in these plants.
This year, of the original 1443 plants in INB2, 561 were still alive. Of the plants that were alive this year, 8.3% were flowering and 76.3% have never flowered – we’re still waiting! Among the plants that were flowering, mean head count was 1.53 heads, with a maximum of five heads.
Read more posts about this experiment here.
Start year: 2006
Location: Experimental plot 1
Overlaps with: Phenology and fitness in P1
Products: Fitness measurements were collected during our annual assessment of fitness in P1.
The following paper was published in summer 2015 based on fieldwork conducted in 2013.
Kittelson, P., S. Wagenius, R. Nielsen, S. Qazi, M. Howe, G. Kiefer, and R. G. Shaw. 2015. Leaf functional traits, herbivory, and genetic diversity in Echinacea: Implications for fragmented populations. Ecology 96:1877–1886. PDF
With all of my data collected and visualized for the heads from Staffanson Prairie Preserve from 2015, it is now time to start with some initial data analysis. As I mentioned in my last post, I will be using R for all of my analyses, taking advantage of skills I learned in Stuart’s class at Northwestern this quarter. I will be creating statistical models based on the data to look for relationships between variables that may influence mate availability and reproductive success. The variables I am specifically looking at are:
- Distance to the kth nearest flowering neighbor. This is a measure of spatial isolation, with greater distance indicating greater isolation. Stuart has found a significant relationship between distance and reproductive success in Echinacea previously (that study can be found here: https://echinaceaproject.org/pub/wagenius2006.pdf)
- Start date and flowering duration. Flowering phenology, the timing and duration of flowering, is perhaps more important than spatial isolation in determining availability of compatible mates. If two plants are very close in space, but they do not flower at the same time, there is no possibility for mating. Previous data has shown that plants flowering earlier in the season have higher reproductive success (https://echinaceaproject.org/pub/isonAndWagenius2014.pdf)
- Section of head from which the achene originated. Because florets at the base Echinacea heads begin flowering first, and the ones at the top flower last, it is possible to examine how reproductive success, and thus the mating scene, differ for a single head across time. The bottom 30 achenes, the middle achenes, and the top 30 achenes are separated to represent the beginning, middle, and end of the timing of flowering.
- Seed set, or proportion of achenes that contain a seed, will be used to quantify reproductive success. This will be the that the model I create will try to predict using the variables I listed above.
In order to create a model, I will be using a technique known as backwards elimination as described in Statistics: An Introduction Using R (Crawley 2015). I will start by creating a statistical model containing my response variable (seed set), and all of my explanatory or predictive variables (isolation, phenology, section of head), along with all interactive effects between the explanatory variables. I will then eliminate a single predictor or interaction at a time and perform an analysis of deviance to determine whether or not that predictor was important to the predictive value of the model. If it is important, I will leave it in, but if it’s not, I will take it out. This process continues until all predictors and interactions left in the model have a significant effect on the response. This model, known as the minimal adequate model, is the simplest model that still includes all important variables.
Beginning in 1996, Team Echinacea has monitored the flowering phenology of Echinacea angustifolia in remnant populations around Solem Township. The number of populations and plants we visit has varied over the years; a summary of which populations were monitored in each year can be found at this link. In 2015, we monitored phenology of 1763 heads on 1384 plants at 27 remnant populations. Whew! That is about 400 more flowering individuals than in 2014 although we monitored the same populations. Populations with big increases in numbers of flowering individuals from last year include Aanenson, East Riley, Landfill, and On 27. At each population, we identify all flowering individuals and track their development over the course of the season, gathering data on start and end dates of flowering for every individual. Flowering began at Loeffler’s Corner on June 23rd and ended at Aanenson on August 19th. We will use this data to describe temporal flowering patterns within and among remnants and relate this to potential for successful mating in populations.
 Blue line segments indicate the period of time that at least one individual was flowering at each population. The numbers to the left of the lines indicate the number of individuals that flowered from each population in 2015. Click to enlarge! Look here to read previous flog posts about this experiment.
Start year: 1996
Locations: roadsides, railroad rights of way, and nature preserves in and near Solem Township, MN
Overlaps with: mating compatibility in remnants, demography in remnants, phenology in experimental plots
Team members who have worked specifically on this project include: Amber Zahler (2011), Kelly Kapsar (2012), and Sarah Baker (2013), although gathering phenology data was a whole team effort in 2014 and 2015. Flog posts authored by Kelly, Amber, and other team members may provide additional details about day-to-day activities associated with our flowering phenology monitoring project.
Every year we keep track of flowering phenology in our main experimental plots, exPt1 and exPt2. Summer 2015 was a big year of flowering in both plots, especially in exPt2, where 1233 heads flowered between July 4th and August 26th. ExPt2 was designed especially to study phenology—you can read more about the team’s monitoring of phenology in the 2015 heritability of phenology project status update.
In exPt1, we kept track of 1212 heads on 649 plants (we left out the qGen_a ‘big batch’ cohort). The first head began shedding pollen on July 2nd and the latest bloomer shed pollen on September 2nd. Peak date in exPt 1 was on July 27th when there were 1034 heads flowering. At the end of the season we harvested the heads and brought them back to the lab, where we will count fruits (achenes) and assess seed set.
Read previous posts about this experiment.
 A plot of the 2015 flowering schedule in experimental plot 1 made with the brand new R package mateable–available now on CRAN! Each horizontal gray line segment on this plot represents the flowering time of one head. From bottom to top they are sorted by start day. Black dots show the number of heads in flower on each day. The vertical lines show the peak day (solid) and the days when half of the plants have started flowering and half have ended (dashed).
Start year: 2005
Location: Experimental plots 1 and 2
Overlaps with: Heritability of flowering time, common garden experiment, phenology in the remnants
Products:
These papers report on investigations of flowering phenology of individuals in experimental plot 1 in 2005, 2006, and 2007:
- Ison, J.L., and S. Wagenius. 2014. Both flowering time and spatial isolation affect reproduction in Echinacea angustifolia. Journal of Ecology 102: 920–929. PDF
- Ison, J.L., S. Wagenius, D. Reitz., M.V. Ashley. 2014. Mating between Echinacea angustifolia (Asteraceae) individuals increases with their flowering synchrony and spatial proximity. American Journal of Botany 101: 180-189. PDF
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