The evolutionary theory of senescence predicts that increased rates of extrinsic mortality select for faster declines in fertility and survival with age. One predicted mechanism is that increased mortality favours alleles that enhance fitness early in life at the expense of survival or reproduction later in life (antagonistic pleiotropy). We tested these predictions in natural populations of Daphnia ambigua from lakes that vary in the severity and duration of fish predation. Daphnia are found in lakes with (i) anadromous alewife (Alosa pseudoharengus) that migrate between marine and freshwater, (ii) permanent landlocked alewife and (iii) no alewife. Daphnia are rare year-round in 'landlocked lakes' and are seasonally eliminated from the water column in 'anadromous lakes' due to the very strong predatory impact of anadromous alewife on populations of zooplankton. Previous work has also shown that intense seasonal bouts of predation by anadromous alewife has selected for increased allocation towards growth and reproduction in Daphnia found in lakes with anadromous alewife. Such variation in the risk of mortality and the expression of life-history traits early in life provides the raw materials to test the evolutionary theory of ageing. We reared replicate populations of Daphnia from all three lake types and quantified lifetime rates of offspring production and intrinsic survival. We found no differences in age-related declines in fertility or survival. Daphnia from anadromous lakes produced significantly more offspring throughout their lifetime despite no differences in life span or in the number of reproductive bouts compared with Daphnia from lakes with landlocked and no alewife. The lack of divergence in ageing contradicts the prediction that elevated mortality rates drive evolutionary shifts in ageing. We reconcile these results by considering the predictions of theoretical frameworks that incorporate feedbacks associated with increased mortality such as density- and condition-dependent processes. Our results, which are better explained by a consideration of these processes, thus call for a greater consideration of models that more explicitly consider the ecology of focal organisms.
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http://dx.doi.org/10.1111/1365-2656.12247 | DOI Listing |
J Fish Biol
November 2024
Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
Migratory animals play a crucial role in connecting distinct habitats by transferring matter and energy across ecosystem boundaries. In the North Atlantic, anadromous species exemplify this through their movement between freshwater and marine environments. Alosids, including species such as alewife (Alosa pseudoharengus), blueback herring (Alosa aestivalis), and American shad (Alosa sapidissima), exhibit this migratory behavior to maximize growth and fecundity and are, therefore, vital components of Atlantic coastal ecosystems.
View Article and Find Full Text PDFViruses
May 2024
U.S. Geological Survey, Eastern Ecological Science Center, Leetown Research Laboratory, 11649 Leetown Road, Kearneysville, WV 25430, USA.
The alewife ( is an anadromous herring that inhabits waters of northeastern North America. This prey species is a critical forage for piscivorous birds, mammals, and fishes in estuarine and oceanic ecosystems. During a discovery project tailored to identify potentially emerging pathogens of this species, we obtained the full genome of a novel hepadnavirus (ApHBV) from clinically normal alewives collected from the Maurice River, Great Egg Harbor River, and Delaware River in New Jersey, USA during 2015-2018.
View Article and Find Full Text PDFJ Expo Sci Environ Epidemiol
November 2024
EPA, Region 1, Boston, MA, USA.
Background: Restoration efforts have led to the return of anadromous fish, potential source of food for the Penobscot Indian Nation, to the previously dammed Penobscot River, Maine.
Objective: U.S.
PLoS One
May 2023
Smithsonian Environmental Research Center, Edgewater, Maryland, United States of America.
Historical loss of river and stream habitats due to impassable dams has contributed to the severe decline of many fish species. Anadromous fishes that migrate from the sea to freshwater streams to spawn have been especially impacted as dams restrict these fish from accessing ancestral spawning grounds. In 2018, Bloede Dam was removed from the Patapsco River near Baltimore, Maryland, restoring approximately 100 km of potential habitat for migratory fish.
View Article and Find Full Text PDFEcotoxicol Environ Saf
January 2022
Department of Physiology, University of Toronto, Medical Sciences Building, Rm 3259, Canada M5S 1A8; Department of Surgery, University of Toronto, Canada M5S 1A8; Oceanographic Environmental Research Society, 12 Burton Avenue, Barrie, Ontario, Canada L4N 2R2. Electronic address:
Rivers along the eastern seaboard of the United States and Canada are becoming increasingly contaminated with heavy metals. This includes the Tusket River (Nova Scotia, Canada) which empties into the Gulf of Maine, near the Bay of Fundy. Whether anadromous fish such as alewife (Alosa pseudoharengus), exposed both to marine and freshwater contaminants, are accumulating these heavy metals and experiencing any changes in their morphology was explored in this study.
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