It has long been recognized that the patterns of growth play an important role in the evolution of age trajectories of fertility and mortality (Williams, 1957). Life history studies would benefit from a better understanding of strategies and mechanisms of growth, but still no comparative research on individual growth strategies has been conducted.Growth patterns and methods have been shaped by evolution and a great variety of them are observed. Two distinct patterns -determinate and indeterminate growth -are of a special interest for these studies since they present qualitatively different outcomes of evolution. We attempt to draw together studies covering growth in plant and animal species across a wide range of phyla focusing primarily on the noted qualitative features. We also review mathematical descriptions of growth, namely empirical growth curves and growth models, and discuss the directions of future research.1 Email: karkach@demogr.mpg.de http://www.demographic-research.org 347Karkach: Trajectories and models of individual growth IntroductionThe ontogenetic growth of an individual is intuitively understood to be an increase in the size of the whole organism or parts of it with age. But the very "natural" notion of growth is, in fact, very difficult to define. Living organisms are complex systems, consisting of parts that often grow at different rates and displaying different patterns. Some parts of the body may grow faster than others, some may stop growing at a certain stage while others continue to grow, and organs may grow "on demand" during regeneration. The cells of an organ may divide continuously throughout an organism's life, replacing aging cells and producing cell turn-over in the tissues; still the body size may remain constant. Growth is coordinated by a program of ontogenetic development that allows for variability in the development rates and sizes in order to adapt to environmental conditions. Size and growth rates are subject to evolutionary optimization and constraints. On the one hand, larger size usually leads to greater mating success, greater fertility, lower vulnerability to environmental hazards, and thus lower mortality. On the other, growth needs resources, and trades-off with other traits.Studies on growth and maintenance shed light on the problem of senescence. Most organisms experience cell turn-over in most tissues. Some organisms (e.g. hydra) apparently escape senescence due to a quick turn-over of cells (Martínez, 1998).Growth and body size are strongly related to other traits and fitness. Research on extant species showed a strong statistical relationship between body mass and a remarkable variety of biological features (Smith, 1996). Measures of growthGrowth as an increment in size can be measured in many different ways, each having advantages and drawbacks. An increase in mass or volume often can be measured easily, but may be only indirectly related to growth as increase in biomass. Organisms may change in content of water or fat, in mass and volume, but this i...

(2010) Metformin extends life span of HER-2/neu transgenic mice and in combination with melatonin inhibits growth of transplantable tumors in vivo, Cell Cycle, 9:1,[188][189][190][191][192][193][194][195][196][197]

The general approach that uses multistage models of disease progression and accordingly stratified notification data can be applied in various settings for the routine estimation of incidence and CDR.

Understanding the factors that determine the allocation and utilization of organism resources may provide an insight into the mechanisms of adaptation, ageing and reproduction. Resource allocation, which is regarded as a method of adaptation, increases fitness and is genetically controlled. Experiments with variable diet feeding of female Mediterranean fruitflies (Ceratitis capitata) demonstrated that the feeding regime dramatically influences lifespan, mortality and the reproduction of flies. An analysis of experimental data and numerical experiments reveals that resource allocation could explain lifespan increase when females are switched from a sugar-only to a protein-containing diet. The heterogeneity of the initial female cohort in terms of the total amount of resources and its allocation to the processes of maintenance and reproduction plays a significant role in this.