Figure 2.

Life history traits are the consequences of reciprocal interaction and coordination of external and internal environments. The environment can be divided in broad outline into two components: (1) abiotic such as climatic parameters and physical structure of the habitat and (2) biotic that include inter- and intraspecific relationships. Animals have to collect the information to take adequate decision. In pluricellular organisms, these are the nervous and endocrine systems, which integrate the information. Phenotype is in large part regulated by hormones of the hypothalamus–pituitary–gonadal axis.