Kate officially became Dr. McLean at the Winter Commencement on December 18th! Congrats again, Kate! Kate has begun a postdoc with Prof. Marisa Eisenberg in Epidemiology at UMich — we’re looking forward to their new work!
The 2022 field season ended last week. It was definitely the first time we had weather in the 70s on the last day of field season!
Here’s a gorgeous photo from this past field season, taken by Teresa Sauer.
And here’s a photo of the ridiculous amount of food that we had at the end of the week to celebrate the end of field season & a lab birthday. 🙂
Congratulations to Kate, who is now Dr. McLean! Kate’s dissertation included some chapters on the Daphnia-parasite system, plus a chapter on SARS-CoV-2 in Michigan. Kate defended their dissertation last week and is now in the process of doing final edits. Next up for Kate will be a postdoc studying the effects of global change on infectious disease dynamics. It’s a really exciting position: watch this space for more info after everything is official! And congrats, Kate!
Aniqa and Sun both had their last days in the lab in July — we’re sad about them leaving and also excited about their new adventures!
Aniqa worked as an undergrad researcher in the lab beginning in Fall 2019 (in the before times!), working particularly closely with Kristel. (Fun fact: Aniqa also worked on fixing captions on Intro Bio videos during the 2020-2021 school year!) Aniqa will be starting an MS program in Physiology here at Michigan this fall.
Sun began as a postdoc in the lab in 2021, and to say that he hit the ground running would be an understatement! Sun did lots of fieldwork (and took gorgeous photos of our lakes!) and also carried out a series of lab experiments. Sun is now moving back to Taiwan where he will begin a faculty position at National Taiwan University. Check out his website!
A beautiful sunrise at Whitmore Lake (photo credit: Syuan-Jyun Sun)
One of Kate McLean’s dissertation chapters just appeared in Evolutionary Ecology! The paper explored the roles of sexual recombination and temporal gene flow (via the egg bank) in maintaining host resistance and genetic diversity. Many studies (including some from our lab) have focused on how host resistance changes within a growing season. Others have looked at long term trends in resistance evolution across many years. Kate’s study looks at the neglected middle ground: how the resistance distribution that exists at the end of one growing season changes by the start of the next growing season as a result of sexual recombination and temporal gene flow from the egg bank.
To study this, Kate and colleagues tracked resistance to Metschnikowia and genetic diversity in Daphnia dentifera in two lakes. This involved collecting sexual females in the autumn, getting them to release their resting eggs, and hatching those resting eggs. Comparing the resistance phenotypes of the moms vs. the hatchlings let us uncover the effect of sexual recombination on resistance, and also to estimate the heritability of resistance. In addition, we sampled the populations early the following spring to characterize the populations shortly after they were reestablished from the egg bank. Since the hatchlings told us about what had gone in to the egg bank the prior year, comparing them with the spring population allowed us to determine the effect of temporal gene flow via the egg bank. Resistance was quantified using infection assays, and genetic diversity was quantified using microsatellites; the diversity component of this project was the foundation of the undergraduate Honors Thesis of Haniyeh Zamani, who is a coauthor on the study.
Because we know that resistance and fecundity trade off in the Daphnia dentifera–Metschnikowia system, we expected that populations would evolve toward higher susceptibility (due to its fecundity advantages) unless an epidemic had recently selected for resistance. Moreover, if an epidemic did occur, we expected resistance to increase temporarily but that sexual recombination and temporal gene flow would then shift the population back towards susceptibility. This is not what we found! Instead, susceptibility was the transient state, with recombination and gene flow restoring and/or maintaining high resistance.
For genetic diversity, we expected that fall offspring would show greater genotypic diversity than their parents due to the effects of sexual recombination; this was observed in one lake (Hackberry) but not in the other (Midland), where genotypic diversity of parents was already very high. We also predicted that the egg bank clones would have higher diversity than the fall offspring, since we anticipated hatching of individuals produced across multiple years; again, this was observed in Hackberry but not in Midland.
In short, sexual recombination and temporal gene flow are both important players in determining inter-annual variation in host resistance in this study system, but not always in the ways we predicted!
In addition to lead author Kate McLean, the authors on this paper are former Duffy Lab grad student Camden Gowler, lab postdoc Marcin Dziuba, former lab undergrad Haniyeh Zamani, long term collaborator Spencer Hall, and Meghan.
Congrats to Kate on their new publication!
We didn’t manage to get everyone, but we did get everyone who was there looking at the camera, so we’ll call it a win!
Every year, we make the (pretty short!) walk to the Arb to see the peonies. This year, we didn’t quite make it for peak peonies, but there were still lots in bloom!
Kate, Libby, and Teresa all traveled to Atlanta this week to present posters at EEID. They are the first lab folks to travel to a meeting since 2019!
Check out this gorgeous photo of Gosling Lake, taken by Sun!
This snapping turtle likes Gosling, too!
Our field season has begun! And it turns out the weather gets better every day of field season — this trend will continue through November, right?
Day 1: We started sampling on June 1st which was, unfortunately, a rainy day, but that didn’t stop the field crew!
in the rain.Day 2: The weather was somewhat nicer — no rain, but still cloudy.
Day 3:
Beautiful weather for Noah’s first day in the field!
We’re looking forward to field season, even if the weather isn’t always as nice as it was on day 3!
The Duffy Lab 