Rotifers by Atsushi Hagiwara & Tatsuki Yoshinaga

Author:Atsushi Hagiwara & Tatsuki Yoshinaga
Language: eng
Format: epub
Publisher: Springer Singapore, Singapore

7.2 Sources of Variation in Life History Traits

There are two main reasons why life history traits might differ between two individuals: phenotypic plasticity and genetic variation. The former refers to changes in the phenotype due to differences in the environment in which the individual has grown up. The latter refers to differences that are due to the genetic makeup of individuals. Such genetic differences might be fixed within a species, or they may show some degree of variation within or among populations. Of course, a combination of both sources of variation is possible, such that two genotypes might differ in their phenotypic response to environmental factors.

Aside these two sources of variability, individuals of the same clone might differ in their life history traits owing to factors that are not (or at least not directly) dependent on the environment. This includes maternal effects and transgenerational effects (which last for several generations). Finally there may be some inherent developmental stochasticity causing enhanced variability in certain life history traits (e.g., entry and exit of diapause). Such cases are often interpreted as diversified bet-hedging strategies, i.e., the production of variable offspring in anticipation of unpredictable environmental conditions (Schröder 2005).

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