Graduate Thesis Defense

Name:Mike Johns
Title:Double brooding in Cassin's auklets: Demographic drivers and evidence of individual quality
Date:Wednesday, 31 January 2018
Location:Murie Life Science Bldg, Murie Auditorium.
Major Professor:Greg Breed, Mark Lindberg


Theory states that reproductive output and survival are balanced through a tradeoff between current success and future potential, in response to environmental conditions that vary on spatial and temporal scales. Demographic parameters at both the individual and population level influence this tradeoff. Long-term datasets that follow uniquely marked animals through time are excellent tools for isolating the individual effect, and describing how heritable or derived traits that influence reproduction and survival can be attributed to individual quality. A 32-year record of breeding histories from known-aged Cassin’s auklets from Southeast Farallon Island, a colony off the coast of central California, was used to examine this trade-off paradigm in long-lived species. The results of generalized linear mixed modeling and multistate mark-recapture modeling revealed that double brooding, a form of increased immediate breeding effort, was associated with both higher reproductive output and longer lifespans. Older individuals that initiated breeding early in the season were most likely to attempt a second brood, particularly when food availability was high. Surprisingly, individuals that double brooded many times throughout their lives were able to maximize reproductive success with no apparent long-term costs to survival or longevity. The findings from this work represent evidence of a positive relationship between greater investment in immediate reproductive success and survival that can only be attributed to some level of individual quality.

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