Abstract: Understanding the relationship between life-history patterns and population growth is central to demographic studies. Here we derive a new method for calculating the timing of reproductive output, from which the generation time and its variance can also be calculated. The method is based on the explicit computation of the net reproductive rate (R0) using a new graphical approach. Usin...

The peanut (Arachis hypogaea L.) plant is indeterminate in growth habit and day-neutral with respect to flower initiation. The Spanish-type cultivar used in this study begins flowering 3 to 4 weeks from planting under optimum environmental conditions. In this study, irradiance and photoperiod were used to alter the development of the peanut plant. Plants grown at low irradiance (300 microeinste...

thrips species injurious to grapes are known as pests in vineyards all over the world and belong to the main pests of grapes in west azarbaijan, iran. in this study, thrips species occurring in west azarbaijan vineyards were identified and the predominant species documented according to their relative abundance at different growth stages. the seasonal abundance of predominant species was invest...

While dietary restriction usually increases lifespan, an intermittent feeding regime, where periods of deprivation alternate with times when food is available, has been found to reduce lifespan in some studies but prolong it in others. We suggest that these disparities arise because in some situations lifespan is reduced by the costs of catch-up growth (following the deprivation) and reproducti...

Key-words: red swamp crayfish, Procambarus clarkii, reproduction, population structure and population dynamics, invasive species Understanding population dynamics and regulation is fundamental for predicting establishment and spread of invasive alien species. In addition, the population biology of invasive alien species offers an opportunity to study basic ecological processes. In this context,...

(Growth and reproduction of the understory palm Geonoma schottiana Mart. in the gallery forest in Central Brazil). To understand the growth and reproduction of the palm Geonoma schottiana in the gallery forest of Central Brazil, two hypotheses were raised: (i) production of leaves and reproductive structures are concentrated in the period of the year with high light availability; (ii) leaf prod...

The ideal free distribution (IFD) requires that individuals can accurately perceive density-dependent habitat quality, while failure to discern quality differences below a given perception threshold results in distributions approaching spatial uniformity. Here, we investigate the role of population growth in restoring a nonideal population to the IFD. We place a simple model of discrete patch c...

We used parentage analysis to estimate seedling recruitment distances and genetic composition of seedling patches centred around reproductive trees of the animal-dispersed Neotropical canopy palm Iriartea deltoidea in two 0.5 ha plots within second-growth forest and one 0.5 ha plot in adjacent old-growth forest at La Selva Biological Field Station in north-eastern Costa Rica. Seedlings were sig...

Habroconus semenlini is a micro-terrestrial gastropod native to South America. There are no previous studies on its biology. We studied its pattern of growth, fertility and lifespan under laboratory conditions. For this purpose, 80 snails were either grouped or kept isolated (40 animals in each condition) during their lifetime. Growth is indeterminate and the species is capable of self-fertiliz...

By the use of Perron-Frobenius theory, simple proofs are given of the Fundamental Theorem of Demography and of a theorem of Cushing and Yicang on the net reproductive rate occurring in matrix models of population dynamics. The latter result is further refined with some additional nonnegative matrix theory. When the fertility matrix is scaled by the net reproductive rate, the growth rate of the ...