this study was conducted to investigate direct and maternal effects on some economic traits in north iranian native fowls. traits considered were body weight at 1 day of age (bw1), body weight at 8 weeks of age (bw8), body weight at 12 weeks of age (bw12), egg number (en) during the first 12 weeks of laying period, egg weight at 1st day of laying (ew1), mean egg weight at 28th, 30th and 32nd we...

The Tanner-Whitehouse method to predict adult stature uses current stature, current skeletal age (SA), and chronological age (CA), and, if available, change (gain) in stature and SA over the previous year. Since assessment of SA requires invasive techniques, a method is proposed to predict adult stature noninvasively and to use percentage of adult stature as a maturity indicator. Age-specific m...

Objectives: Social development in children is influenced by several factors, including family, school friends, television, gender, race, socioeconomic status, and locomotor activity, and depending on the situation and how they react to it, social development and maturity might get accelerated or get undermined. Therefore, in this study, we aimed to investigate the relationship between fine moto...

Several hypotheses have been proposed to explain cyclic fluctuations in abundance of some small mammal populations. These hypotheses have been controversial, however, and there is no consensus among biologists as to why population cycles occur. In a demographically based model, we tested the potential influence of phase-specific changes in life history traits (age at maturity, fertility, juveni...

Theoretical and empirical studies suggest that the age of first reproduction (the age at which reproduction begins) can have a substantial influence on population dynamics and individual fitness. Using complete survival and reproductive histories of 428 female yellowbellied marmots (Marmota flaviventris) from a 40-year study (1962-2001), we investigated causes and fitness consequences of delaye...

The evolution of the long, slow human life history is a major challenge to evolutionary biologists. A compelling theory states that our late age at maturity allows us to acquire the many skills needed to survive in the economically intensive human foraging niche. Cultural transmission may be a crucial part of this process, by exposing learners to a wealth of information and skills that they wou...

Angiosperm diversification has been associated with plant-animal interactions such as seed dispersal and pollination and life-history characters such as rapid growth and fast reproduction. This paper relates a life-history character (age at maturity) to woody angiosperm diversification. Here I present a comparative analysis of data drawn from the literature, indicating that time to first reprod...