[All-postdocs] Biology seminar next Thursday: Darren Johnson, California State University, Long Beach

[Margot McKlveen]

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*Biology Department Virtual Seminar*

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Thursday, March 11 at Noon

Zoom link: https://us02web.zoom.us/j/86254328359 
<https://us02web.zoom.us/j/86254328359>


Darren Johnson, Associate Professor

California State University, Long Beach


How ocean acidification may alter natural selection: A case study of 
California Grunion.

Climate change and ocean acidification can have strong effects on marine 
species. However, changes in seawater chemistry are expected to occur 
over decades, and it is possible that as ocean pH changes, populations 
will evolve to become more tolerant of lower pH levels. In order to 
anticipate the long-term effects of ocean acidification, we need to know 
1) the particulars of how selection will operate as seawater chemistry 
changes; 2) the degree to which populations have the genetic capacity to 
adapt to such changes; and 3) whether evolutionary changes will be quick 
enough to affect the dynamics of populations over relevant timeframes 
(e.g., 10-100 years). We studied the evolutionary potential of larvae of 
a coastal marine fish, the California Grunion (Leuresthes tenuis). In 
this species, and likely many others, offspring size is closely related 
to tolerance of OA conditions. To evaluate genetic variation in 
offspring size, we conducted breeding experiments and measured 
covariation in offspring size among close relatives. To measure how 
selection on offspring size may change in response to ocean 
acidification, we reared larvae in both ambient and high-CO2 conditions 
and examined relationships between offspring size and survival. 
Selection on offspring was stabilizing, but changes in seawater 
chemistry will result in a shift in optimal phenotype and will thus 
generate selection for larger offspring size. Our breeding experiments 
suggest a moderate amount of genetic variation in larval size (h2 = 
0.23). Projections of evolutionary responses suggest that grunion 
populations can evolve to become more tolerant of ocean acidification 
conditions, but they will not completely keep pace with environmental 
change. It is likely that evolutionary responses will slow, but not stop 
the long-term decline in population sizes expected under future climate 
change.


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Meeting ID: 862 5432 8359

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-- 
Margot McKlveen | she/her
Senior Administrative Assistant
Woods Hole Oceanographic Institution
Redfield Building Room 305 | MS 32
266 Woods Hole Rd.
Woods Hole, MA 02543
508-289-2334
mmcklveen at whoi.edu

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