Sierra Nevada Aquatic Research Laboratory

01 May, 07 AM - 31 Jul, 04 AM

For my disseration research, I am studying plasticity in reproductive behavior in populations of Song Sparrow (Melospiza melodia) breeding along Convict Creek, on the SNARL reserve, and along nearby McGee Creek. The overarching objectives of my research are to: (1) Determine the extent to which individuals adjust reproductive effort to cope with variation in the selective environment. (2) Explore whether individuals respond differently to adult and nest predation risk due to differential balance of the tradeoff between survival and reproduction. (3) Elucidate how the adrenocortical stress response proximately mediates baseline levels of reproductive effort, and behavioral responses to predators. I have completed two field seasons of research (2010 and 2011). Based on outcomes of research completed thus far, I have concluded that mate quality may be an important factor influencing adaptive balance of the survival-reproduction tradeoff. Hence, during my third and final field season I hope to determine whether reproductive investment by female sparrows is best characterized by the differential allocation or reproductive compensation hypothesis (see research proposal for definitions). To this end I strive to: (1) Determine whether stress-induced CORT levels and parental components of reproductive investment in females correlate to metrics of male quality (repertoire size, baseline corticosterone). (2) Determine how parental investment by males varies with metrics of male quality, since validating the reproductive compensation hypothesis in females depends on demonstrating that lower quality males provide less parental support. This work will help elucidate the complexities inherent to systems in which social interactions influence adaptive investment decision-making rules. To attain my research goals I am monitoring color-banded pairs of M. melodia nesting in the riparian corridors of Convict and McGee Creeks and measuring reproductive effort via video-recordings at nests. As metrics of reproductive effort I am using female incubation attentiveness, male singing rates, and nestling provisioning rates. In addition, an added component of my 2012 study will be to better quantify male contributions to reproduction during the incubation stage by measuring nest guarding behavior and nest-defense. Further, to determine how individuals adjust reproductive effort in response to threats to the reproductive attempt and adult survival, respectively, I am presenting models of nest and adult predators at nests. Finally, I am measuring the adrenocortical stress response by mist-netting birds and obtaining serial blood samples. The magnitude of the stress response will serve both a possible correlate of reproductive effort in both males and females, and as a metric of male quality (see research proposal for rational). Findings from this research will forward understanding of how organisms adjust reproductive effort given shifting conditions, and the extend to which organisms may be able to cope with drastic changes in the selective environment induced by anthropogenic disturbance or global warming.

Visit #27104 @Sierra Nevada Aquatic Research Laboratory

Approved

Under Project # 21464 | Research

Coping with environmental perturbation: Adaptive plasticity in reproductive effort and mediation by the adrenocortical stress response

graduate_student - University of California, Riverside

Reservation Members(s)

Group of 2 Graduate Student May 1 - Jul 31, 2012 (92 days)
Melissa Grunst May 1 - Jul 31, 2012 (92 days)

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