29 June 2018. A new experiment with Atlantic silversides (Menidia menidia) starts and as usual, it’s an all hand on deck operation. This time, we have Chris Tsang shadowing all of us and Emma professionally explaining the process.
14 June 2018. Members of the Baumann and Mason lab went on a trip to Mumford Cove, today, and Chris Tsang went along with his GoPro. Thanks to Charlie, the skipper, the ride was smooth and a pleasure, a swapping our pH, Temperature, oxygen, and salinity sensor was successfully swapped with a new one recording for the next weeks in 30 minute intervals. Wes Hoffman from the Mason lab, collected zooplankton with a Bongo-net. Sydney Stark, our NSF-REU student this summer, came along just for the fun.
Friday, 8 June 2018. Hannes and Maria traveled to Boston’s Harvard University to meet with Valentina di Santo from the Lauder Lab at the Museum for Comparative Zoology. Thanks to our collaborators there, we were able to use a 2D-digital X-ray machine there, which we needed to complete the next big step in our Menidia Gene project.
A few weeks ago, Maria had already measured each individual fish's length, weight, shape, routine metabolism, and maximum sustained swim speed. The next trait we're keen on mapping quantitatively to the silverside genome is the number of vertebrae, which we know increases in wild populations from south to north. What will our South/North hybrid F2 generation show?
Thanks to Valentina's excellent help, the work went without a hitch. At the end, we even had some spare time to enjoy the great atmosphere int the Lauder Lab during lunchtime, the tour through various lab installations, the experimental fish, and even the adjacent Harvard Zoological museum. Thank you all for the fun day at Harvard!
The 282 fish are now split in a DNA sample for extraction and a body sample for further trait measurements.
On 18 May 2018, the Baumann lab teemed with activity. Maria Akopyan from Cornell University was busy phenotyping juvenile silversides for our Menidia Gene project. Mia and Mackenzie were busy working up field samples of silversides. And Hannes prepared adult silverside samples for later analyses.
4 April 2018. Today, Adelle Molina and Teresa Schwemmer from the Nye Lab at Stony Brook University visited us with a bunch of respirometry equipment in tow. We were trying to find out how to measure critical swimming speeds and oxygen consumption on individual silverside juveniles. This information, along with other individual traits such as growth, lipid content, and vertebral number will later be used in our new NSF-project examining the genetic underpinnings of local adaptation in this species.
One crucial piece of equipment to do this work is a swimming chamber, also called swim flume. The one we will use is almost 20 years old and has already been used for silverside work more than a decade ago. After a long odyssey through several labs and institutions in the US, we finally got hold of it again, gave it some serious TLC and now hope to resurrect it. Thanks to our pro’s from Stony Brook, the first tests were promising today! Thank you Adelle and Teresa.
31 March 2018. We’re happy to announce that Marine Biology just published our latest study examining the starvation tolerance of silverside larvae and juveniles at contrasting CO2 conditions. We compiled observations from five separate experiments spanning different years, laboratories, temperatures, life stages, and CO2 levels. Contrary to expectation, we found that starvation rates were largely independent of the CO2 environment in this fish species.
One major set of data was produced by Elle Parks as part of her Research Experience for Undergraduates (NSF-REU) in summer 2017. Well done, everybody!
Baumann, H., Parks, E.M.*, and Murray, C.S.* (2018)
26 March 2018. Today we got our first glimpse of an incredible new way of imaging the inner calcified structures of a fish body, particularly the ear bones (otoliths), of which every teleost fish has six, three on each side inside the skull. Otoliths are long known to fish ecologists for their properties to record and store information about a fish’s age, growth and habitat. With an adult Atlantic silverside, Hannes visited John Shepherd, facilities scientist and member of the Goldhamer lab at UConn, Storrs (Biology Physics Building), who showed us the use of a new, state-of-the-art micro CT-scanner (IVIS). Turns out, the system effortlessly imaged all six otoliths inside of the fish’s head. Later in the year, we will use the technique to image silversides reared at contrasting CO2 conditions to see whether they differ in their otolith size, volume, and structure. Thank you, John, for this truly inspiring demonstration!
We are overjoyed to announce that NSF is funding a new and collaborative research project to look at the genomic underpinning of local adaptation in the Atlantic silverside! Check out below for a first glimpse of the project website.
NSF-OCE #1756751 The genomic underpinnings of local adaptation despite gene flow along a coastal environmental cline (2018-2021)
Oceans are large, open habitats, where it was previously believed that the lack of obvious barriers to dispersal would result in extensive mixing, thereby preventing organisms from adapting genetically to particular habitats. It has recently become clear, however, that many marine species are subdivided into multiple populations that have evolved to thrive best under contrasting local environmental conditions. Nevertheless, we still know very little about the genomic mechanisms that enable divergent adaptations in the face of ongoing intermixing.
This project focuses on the Atlantic silverside (Menidia menidia), a small estuarine fish that exhibits a remarkable degree of local adaptation in growth rates and a suite of other traits tightly associated with a climatic gradient across latitudes. Decades of prior lab and field studies have made M. menidia one of the marine species for which we have the best understanding of evolutionary tradeoffs among traits and drivers of selection causing adaptive divergence. Yet, the underlying genomic basis is so far completely unknown.We will integrate whole genome sequencing data from wild fish sampled across the distribution range with breeding experiments in the laboratory to decipher these genomic underpinnings. This will provide one of the most comprehensive assessments of the genomic basis for local adaptation in the oceans to date, thereby generating insights that are urgently needed for better predictions about how species can respond to rapid environmental change. The project will provide interdisciplinary training for a postdoc as well as two graduate and several undergraduate students from underrepresented minorities. The findings will also be leveraged to develop engaging teaching and outreach materials (e.g. a video documentary and popular science articles) to promote a better understanding of ecology, evolution, and local adaptation among science students and the general public.
The project is organized into four interconnected components
Part 1 examines fine-scale spatial patterns of genomic differentiation along the cline to a) characterize the connectivity landscape, b) identify genomic regions under divergent selection, and c) deduce potential drivers and targets of selection by examining how allele frequencies vary in relation to environmental factors and biogeographic features.
Part 3 integrates patterns of variation in the wild (part 1) and the mapping of traits under controlled conditions (part 2) to a) examine how genomic architectures underlying local adaptation vary across gene flow regimes and b) elucidating the potential role of chromosomal rearrangements and other tight linkage among adaptive alleles in facilitating adaptation.
Part 4 examines dispersal – selection dynamics over seasonal time scales to a) infer how selection against migrants and their offspring maintains local adaptation despite homogenizing connectivity and b) validate candidate loci for local adaptation.
This research feature makes the case for multistressor research to a broad general audience and introduces our NSF project and its participants. Download the feature by clicking on the pictures or the link below.