The ecology of Lumbriculus variegatus (Müller) (Oligochaeta, Lumbriculidae) in Newfoundland

1971 ◽  
Vol 49 (3) ◽  
pp. 337-342 ◽  
Author(s):  
J. R. Pickavance
Keyword(s):  
Life History ◽  
Newfoundland And Labrador ◽  
Adaptive Significance ◽  
Lumbriculus Variegatus ◽  
Temporary Pool ◽  
Juvenile Mortality ◽  
History Of ◽  
Asexual Populations

Lumbriculus variegatus (Müller) is reported from Newfoundland and Labrador in asexual populations with occasional sexual individuals. The life history of a population inhabiting a temporary pool at Logy Bay is described. The season of maximum regeneration is shown to be the first 4 months of the year and the adaptive significance of this is discussed. The possibility that the regeneration season of the species may be only a period of reduced juvenile mortality is discussed.

scholarly journals Building a better frog trap: The benefits of mal-adaptive habitat choice for metapopulations with different life history strategies

2014 ◽  
Author(s):  
Rosemary Hartman ◽  
Noam Ross
Keyword(s):  
Life History ◽  
Life Histories ◽  
Maximum Growth ◽  
Habitat Choice ◽  
Ecological Trap ◽  
Life History Strategies ◽  
Bet Hedging ◽  
Juvenile Mortality ◽  
History Of ◽  
Varying Environments

By spatially distributing offspring among several habitat patches in varying environments, an organism can "hedge its bets" to protect against bad conditions in any single patch. This strategy can maintain populations even when some or even all locations are, on average, population sinks. However, species may not have evolved this bet-hedging mechanism, especially when sink environments are anthropogenic "traps" - locations where traditional habitat cues have been altered. Using a model based on the life history of the Cascades frog (*Rana cascadae*), we examine the conditions that maximize growth in an environment with ecological traps created by the introduction of predators. In a temporally stochastic environment, maximum growth rates occur when some juveniles disperse to the trap. We then examine how different life histories and predation regimes affect the ability of an organism gain an advantage by bet-hedging, and find that bet-hedging can be less useful when the ecological trap drives adult, rather than juvenile, mortality.

Laboratory Observations On the Life History of the Isopod Sphaeroma Quadridentatum Say, 1818

Crustaceana ◽  
1996 ◽  
Vol 69 (1) ◽  
pp. 94-100 ◽  
Author(s):  
Betty Borowsky
Keyword(s):  
Life History ◽  
Mortality Rate ◽  
Cost Effective ◽  
High Rate ◽  
Juvenile Mortality ◽  
History Of

AbstractAdult Sphaeroma quadridentatum were maintained in the laboratory for up to tcn months. It was found that males exhibit terminal molts, but females continue to molt until they die. Mature females alternate reproductive and resting intermolt periods, and these periods are characterized by distinct oostegite morphologies. Immature females have small rounded oostegites; brooding females have large, overlapping oostegites, and females in the resting stage have small oostegites with arrow-shaped, angled tips. Amplexus only precedes a reproductive molt, but is not a prerequisite for fertilization. Copulation occurs in the interval between the female's shedding the posterior and anterior parts of the exoskeleton. Brood sizes ranged from 14 to 67, x = 33.7±11.3. Offspring were cultured to maturity in the laboratory, but this took as long as five months, and there was a mortality rate of 48%. Given the relatively lengthy time to maturity, and the relatively high rate of juvenile mortality, culturing this species for use in bioassays is not cost-effective.

Experimental life history of Echinostoma cinetorchis

1990 ◽  
Vol 28 (1) ◽  
pp. 39 ◽  
Author(s):  
S H Lee ◽  
J Y Chai ◽  
S T Hong ◽  
W M Sohn
Keyword(s):  
Life History ◽  
History Of
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