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The inland water fishes of Africa

 | 
Didier Paugy
, 
Christian Levêque
, 
Olga Otero

Life-history strategies

Didier Paugy, Christian Levêque et Fabrice Duponchelle

Résumé

The biological and demographic profile of a population is defined by a set of biological traits such as age or size at first reproduction, fecundity rate, lifespan, mortality rate of each age group, etc. This demographic profile represents a certain adaptation of a population to its environment. The theory of adaptive strategies is based on the assumption that demographic, ecological, ethological and physiological features of a population are co-adapted and modelled by natural selection.
Since environmental changes are continuous, each state of adaptation is only provisional, and the sustainability of a species depends on its aptitude for adapting its demographic strategy to new environmental conditions in order to maintain large populations.
Over the last forty years, several studies have tried to explain the origin of variability of characters among organisms. The various methods of reproduction and their degrees of success in various environments thus formed a basis for theoretical and empirical research referred to as “life history”.
Life history studies attempt to explain the trade-off between reproductive and demographic parameters (Stearns, 1983a; Reznick, 1985; Pease & Bull, 1988) in relation to various environmental conditions (Whittaker & Goodman, 1979; Winnemiller & Rose, 1992).

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Extrait du texte

Resource allocation: constraints and compromises

One of the principal ideas of the concept of demographic strategy is that various biological features are interdependent. A fundamental point is the comprehension of how and to what point an organism is willing to invest into each bio-demographic option in order to optimize the use of the resources and their distribution among its various fundamental needs. In other words, each organism has limited time and energy to survive and reproduce. What is thus the ideal resource partition in regards to time and energy for growth, maintenance and reproduction? This allocation of energy among these requirements must be equitable in order to enable the species to optimize the success of its reproduction.

The current theories consider that the evolution of biological features generally involve compromise. An increase in the time (or energy) devoted to an activity will be done at other activities’ expense. Thus, for a similar availability of resourc...

Auteurs

Research director at IRD. He has published numerous works on the systematics, distribution, and ecology of West African fresh water fishes, and expanded the collections of the MNHN in Paris.

Research director at IRD. He has published numerous works on the systematics, distribution, and ecology of West African fresh water fishes, and expanded the collections of the MNHN in Paris.

© IRD Éditions, 2017

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