Life History Variation in Dioecious Plant Populations: A Case Study of Chamaelirium luteum

Author(s):  
Thomas R. Meagher ◽  
Janis J. Antonovics
The Auk ◽  
2021 ◽  
Vol 138 (1) ◽  
Author(s):  
Jared D Wolfe ◽  
Ryan S Terrill ◽  
Erik I Johnson ◽  
Luke L Powell ◽  
T Brandt Ryder

Abstract The slow-paced life history of many Neotropical birds (e.g., high survival and low fecundity) is hypothesized to increase lifetime fitness through investments in self-maintenance over reproduction relative to their temperate counterparts. Molt is a key investment in self-maintenance and is readily shaped by environmental conditions. As such, variation in molt strategies may be a key mechanism underlying life-history trade-offs and adaptation to new environments. Here, we review molt strategies from a diversity of lowland Neotropical landbirds and examine how variation in molt strategies, characterized by differences in molt insertions, timing, extent, and duration contribute to life-history variation and adaptation to diverse ecological conditions. In addition to our synthesis, we present a case study to examine the relationship between home range size and duration of the definitive prebasic molt of a well-studied subset of Amazonian landbirds. Our results suggest a connection between prolonged molt duration and larger home range size of small-to-medium-sized Amazonian landbirds. Our aims were to identify key gaps in our knowledge of Neotropical bird molt, to stimulate further comparative studies into the evolution of molt strategies, and to highlight how variation in molt strategies may be a key mechanism underlying life-history variation across latitudes.


2019 ◽  
Vol 77 (2) ◽  
pp. 645-654
Author(s):  
Qi Lee ◽  
Alice Lee ◽  
Zunlei Liu ◽  
Cody S Szuwalski

Abstract Many intensely exploited fish stocks have experienced changes in trophic structure and environmental conditions, resulting in non-stationary population processes. We evaluate the ability of assessment methods to estimate quantities used in management (like target biomasses and fishing mortalities) when life history processes are non-stationary and comprehensive data are not available. We use the small yellow croaker (Larimichthys polyactis) fishery in the East China and Yellow Seas as a case study. We simulate age-structured populations with time-varying fishery and life history characteristics similar to that of the small yellow croaker in China based on historical studies that demonstrate changes in life history. We then fit surplus production and statistical catch-at-age models to simulated catch and index data from these populations. Given our assumptions, both estimation models yielded biased quantities important to management. The production model estimated reference points associated with target biomass with less bias than the age-structured model, while the latter outperformed the former when estimating reference points associated with target fishing mortality. The age-structured model also better captured relative population trends and provided flexibility to consider impacts of life history changes over time. We suggest that assessments of similar stocks consider the potential of life history variation impact management quantities.


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