SummaryApproximately 1-2% of net primary production by land plants is re-emitted to the atmosphere as isoprene and monoterpenes. These emissions play major roles in atmospheric chemistry and air pollution-climate interactions. Phenomenological models have been developed to predict their emission rates, but limited understanding of the function and regulation of these emissions has led to large uncertainties in model projections of air quality and greenhouse gas concentrations. We synthesize recent advances in diverse fields, from cell physiology to atmospheric remote sensing, and use this information to propose a simple conceptual model of volatile isoprenoid emission based on regulation of metabolism in the chloroplast. This may provide a robust foundation for scaling up emissions from the cellular to the global scale.

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The tradeoff between offspring size and number is ubiquitous and manifestly similar in plants and animals despite fundamental differences between the evolutionary histories of these two major life forms. Fecundity (offspring number) primarily affects parental fitness, while offspring size underpins the fitness of parents and offspring. We provide an overview of theoretical models dealing with offspring size and fitness relationships. We follow that with a detailed examination of life-history constraints and environmental effects on offspring size and number, separately in plants and animals. The emphasis is on seed plants, but we endeavor to also summarize information from distinct animal groups-insects, fishes, reptiles, birds, and mammals. Furthermore, we analyse genetic controls on offspring size and number in two model organisms-Arabidopsis and Drosophila. Despite the deep evolutionary divergence between plants and animals, we find four trends in reproductive strategy that are common to both lineages: (i) offspring size is generally less variable than offspring number, (ii) offspring size increases with increasing parent body size, (iii) maternal genes restrict offspring size and increase offspring numbers, while zygotic genes act to increase offspring size; such parent-offspring conflicts are enhanced when there is sibling rivalry, and (iv) variation in offspring size increases under sub-optimal (harsh) environmental conditions. The most salient difference between plants and animals is that the latter tend to produce larger (fewer) offspring under sub-optimal conditions while seed plants invest in smaller (many) seeds, suggesting that maternal genetic control over offspring size increases in plants but decreases in animals with parental care. The time is ripe for greater experimental exploration of genetic controls on reproductive allocation and parent-offspring conflicts in plants and animals under sub-optimal (harsh) environments.

A combination of directed amplification of minisatellite DNA (DAMD) and random amplification of polymorphic DNA (RAPD) primes were used to assess the genetic variation within and between three isolated populations of Indian sandalwood (Santalum album). Eleven primers used in this study amplified 65.99 % polymorphic bands. Analysis of molecular variance revealed a high genetic variation among these populations (φ ST = 0.549). There are indications of clonality within the existing Indian sandalwood populations which can be attributed to habitat fragmentation, isolation and vegetative reproduction.