[All-postdocs] Bioseminar this Thursday: Silke Van Daalen, WHOI Postdoc

[Margot McKlveen]

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*Biology Department Virtual Seminar*

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Thursday, January 7 at Noon

Zoom link: 
https://whoi-edu.zoom.us/j/98783604265?pwd=dS9TclAwekRyMHp1OWdUSU4zaVNQQT09


Silke Van Daalen, WHOI Postdoctoral Scholar


A demographic and evolutionary analysis of maternal age effects in 
rotifers at the individual and population level

Maternal age (the age of the mother at the birth of her offspring) can 
influence, positively or negatively, the quality of offspring, affecting 
any of the vital rates. Maternal age is therefore a form of 
heterogeneity among individuals within a population and affects 
population-level dynamics and evolutionary processes. In order to 
explore the effects of maternal age, we develop matrix models that 
classify individuals by both age and maternal age. We fit these models 
to data from individual-based culture experiments on the aquatic 
invertebrate, Brachionus manjavacas (Rotifera). We manipulated 
laboratory survival and fertility estimates to produce stationary or 
nearly stationary populations, and to alter the magnitude of maternal 
age effects.

At the population-level, we show that individuals born to older mothers 
see a fitness expressed primarily as a decrease in fertility. We use the 
models representing the laboratory, low-fertility and low-survival 
environments, with or without maternal age, to estimate selection 
gradients on survival and fertility, which measure the strength of 
selection. In all cases, selection gradients decrease with both age and 
maternal age, suggesting evolution can lead to such a maternal age 
effect as an example of maternal effect senescence.

When we shift perspective to the individual level, we investigate the 
effect of heterogeneity in vital rates due to maternal age on mean and 
variance in lifetime reproductive output. By turning the matrix model 
into Markov chains, we quantify the contribution of heterogeneity and 
individual stochasticity, i.e. luck experienced while moving through the 
life cycle, to variance in LRO. We conclude that heterogeneity, even 
with large effects on vital rates, may not make an important 
contribution to variance in LRO.  The contribution of heterogeneity 
depends on the environmental conditions that determine the vital rates.


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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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