Challenges for Diadromous Fishes in a Dynamic Global Environment

2009 ◽  
Keyword(s):  
Life Cycle ◽  
Life Histories ◽  
Life Cycles ◽  
Partial Migration ◽  
Environmental Stochasticity ◽  
Species Dynamics ◽  
Life Cycle Pattern ◽  
Aquatic Sciences ◽  
Diversity Of Life

<em>Abstract</em>.-In the study of species life histories and the structure of diadromous populations, an emerging trend is the prevalence of life cycle diversity-that is, individuals within populations that do not conform to a single life cycle pattern. A rapid rise in publications documenting within-population variability in life cycles has resulted in the use of numerous terms and phrases. We argue that myriad terms specific to taxa, ecosystem types, and applications are in fact describing the same phenomenon-life cycle diversity. This phenomenon has been obscured by the use of multiple terms across applications, but also by the overuse of typologies (i.e., anadromy, catadromy) that fail to convey the extent of life cycle variations that underlay population, metapopulation, and species dynamics. To illustrate this, we review migration and habitat-use terms that have been used to describe life cycles and life cycle variation. Using a citation index (Cambridge Scientific Abstracts © Aquatic Sciences and Fisheries Abstracts), terms were tallied across taxonomic family, ecosystem, type of application, analytical approach, and country of study. Studies on life cycle diversity have increased threefold during the past 15 years, with a total of 336 papers identified in this review. Most of the 40 terms we identified described either sedentary or migratory lifetime behaviors. The sedentary-migratory dichotomy fits well with the phenomenon of partial migration, which has been commonly reported for birds and Salmonidae and is postulated to be the result of early life thresholds (switch-points). On the other hand, the lexicon supports alternate modes of migration, beyond the simple sedentary-migratory dichotomy. Here more elaborate causal mechanisms such as the entrainment hypothesis may have application. Diversity of life cycles in fish populations, whether due to partial migration, entrainment, or other mechanisms, is increasingly recognized as having the effect of offsetting environmental stochasticity and contributing to long-term persistence.

scholarly journals Household Debt and Delinquency over the Life Cycle

2020 ◽  
Vol 37 (1) ◽  
pp. 61-92
Author(s):  
Sommarat Chantarat ◽  
Atchana Lamsam ◽  
Krislert Samphantharak ◽  
Bhumjai Tangsawasdirat
Keyword(s):  
Life Cycle ◽  
Financial Stability ◽  
Age Groups ◽  
Policy Implications ◽  
Retirement Age ◽  
Household Debt ◽  
Extensive And Intensive Margins ◽  
Level Data ◽  
Per Capita ◽  
Life Cycle Pattern

This paper uses loan-level data from Thailand's National Credit Bureau to study household debt over the life cycle of borrowers. We decompose two aggregate and commonly used measures of debt—debt per capita and delinquency rate—into components that unveil the extensive and intensive margins of household indebtedness. We find a striking inverted-U life-cycle pattern of indebtedness as predicted by economic theories. However, peaks are reached at different ages for different loan products and different lenders. We also find that debt has expanded over time for all age groups. Younger cohorts seem to originate debt earlier in their lives than older generations. Meanwhile, older borrowers remain indebted well past their retirement age. Finally, we find a downward pattern of delinquency over the life cycle. Our findings have important policy implications on financial access and distress of households as well as on economic development and financial stability of the economy.

The life‐cycle pattern of east‐west countertrade

1997 ◽  
Vol 14 (4) ◽  
pp. 248-265
Author(s):  
Charles W. Neale ◽  
Yesim T. Akis ◽  
Christopher L. Pass
Keyword(s):  
Life Cycle ◽  
Life Cycle Pattern ◽  
East West

Egalitarianism, Inequality, and Age: The Rural North in 1860

1981 ◽  
Vol 41 (1) ◽  
pp. 85-93 ◽  
Author(s):  
Jeremy Atack ◽  
Fred Bateman
Keyword(s):  
Life Cycle ◽  
Civil War ◽  
Age Structure ◽  
Wealth Distribution ◽  
Distribution Of Wealth ◽  
Egalitarian Society ◽  
Heads Of Household ◽  
Life Cycle Pattern

Little is known about the distribution of wealth in the allegedly egalitarian society of the rural North on the eve of the Civil War. This paper investigates the role of the age structure of the heads of household and a life-cycle pattern of accumulation in determining the wealth distribution within that society and among the various groups that comprised it. The results suggest a need for caution in making cross-group or inter-temporal comparisons in wealth distributions without taking account of such factors.

scholarly journals Relative growth and population dynamics of Macrobrachium iheringi (Decapoda, Palaemonidae)

2019 ◽  
Vol 59 ◽  
pp. e20195908 ◽  
Author(s):  
Caio Dos Santos Nogueira ◽  
Júlia Fernandes Perroca ◽  
Emerson Luiz Piantkoski ◽  
Rogerio Caetano da Costa ◽  
Fabiano Gazzi Taddei ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Life Cycle ◽  
Sex Ratio ◽  
Larval Development ◽  
Sexual Maturity ◽  
Abiotic Factors ◽  
Relative Growth ◽  
Males And Females ◽  
Life Cycle Pattern ◽  
Precipitation And Temperature

During the ontogenetic development of crustaceans, the relative growth of some structures may change, especially during the transition from juvenile to adult. This study describes the relative growth of body structures of Macrobrachium iheringi, and provides information on its population dynamics, such as structure, fecundity, and morphological sexual maturity. The sampling of M. iheringi was carried out in “Ribeirão da Hortelã”, in Botucatu (SP, Brazil). The length of the carapace (CL), abdomen (AL), and ischium (IL), merus (ML), carpus (CrL), propodus (PpL), and dactyl (DcL) of the second right pereopod were measured. In addition, the width of the second abdominal pleura (PW) and propodus height (PpH) were included in analyses. The relationships that best demonstrated the changes in the allometric coefficient were CL vs PpL in males and females. The CL, in which males and females reach morphological sexual maturity, was estimated as 13.3 mm and 11.1 mm, respectively. The sex-ratio differed from the expected 1:1 and was skewed towards females. Precipitation and temperature influenced the abundance of different demographic classes. Macrobrachium iheringi has few but large eggs, which is expected since this species has an abbreviated larval development. Based on these results, we conclude that the propodus are good indicators of the size at onset of morphological sexual maturity. In addition, important information was obtained on the biology of M. iheringi, including its life cycle pattern, reproduction and influence of abiotic factors.

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