Energetics and Fitness Introduction to the Symposium

Author Institution: Environmental Biology Program, The Ohio State Universit

A trade-off invariant life-history rule for optimal offspring size

Optimization models have been widely and successfully used in evolutionary ecology to predict the attributes of organisms. Most such models maximize darwinian fitness (or a component of fitness) in the face of trade-offs and constraints; the numerical results usually depend on the exact form of the trade-offs/constraints. Here we report the first (to our knowledge) numerical optimum for life-history evolution which is independent of the details of the underlying trade-off, for a large array of trade-off forms. The rule is that at small litter sizes, the range in offspring size is inversely proportional to the size of the litter. Details of the offspring-survival/offspring-size trade-off set the value of the proportionality constant, but the -1 exponent, the inverse proportionality itself, is universal. Studies of life histories have yielded many empirical examples of universality for various scaling exponents (for example, adult lifespan scales as = 0.25 with adult body mass within many taxa); this is an example of the numerical value of an exponent (here -1) emerging from a life-history model as independent of all but a few general features of the underlying economic structure

Demography of Yellow-Bellied Marmont Populations

This is the publisher's version, also available electronically from http://www.jstor.org/stable/info/1935452Marmot (Marmota flaviventris) populations are colonial or satellite. The number of adults of colonial populations is relatively stable; fluctuations occur primarily because of changes in numbers of young and yearlings. Population trends among five colonial populations are dissimilar. Satellite populations are unstable and reproduce at a lower rate than do colonial populations. Satellite marmots are shorter resident than colonial marmots. Both colonial and satellite females usually are longer resident than males. All adult colonial males are 41% of adult colonial females are recruited from other places; all satellite adults are recruited from other places. Losses of colonial marmots are attributed primarily to mortality during hibernation and emigration. Predation appears to be a minor source of mortality of colonial marmots, but may be of greater significance to satellite populations. Demographic relationships of individual colonies appear to be density-independent. Dispersal of colonial animals occurs primarily among yearlings, which have a higher expectation of reaching sexual maturity than young have. The major cause of dispersal is social pressure, but social stress is not simply density-dependent. The colonial social organization is more adaptive than the more nearly solitary (=satellite)

A strategy of cost control for Mariner Venus/Mercury 1973

The spacecraft launched by NASA on November 3, 1973 to explore Venus and Mercury proved a notable success as a development project both in space and on the ground. This article on the development points our management approaches and techniques that kept schedules and controlled costs, the intent being to stimulate thought about how to do the same with future spacecraft and payloads. The Mariner Venus/Mercury '73 (MVM '73) project kept within its originally established goals for schedule, performance, and cost. Underlying this development success was the availability of the Mariner technology. But meeting the goals demanded management determination, planning, and discipline to make optimum use of state-of-the-art technology--on the part of people at NASA, JPL, and The Boeing Co. (the contractor)

How large should whales be?

The evolution and distribution of species body sizes for terrestrial mammals is well-explained by a macroevolutionary tradeoff between short-term selective advantages and long-term extinction risks from increased species body size, unfolding above the 2g minimum size induced by thermoregulation in air. Here, we consider whether this same tradeoff, formalized as a constrained convection-reaction-diffusion system, can also explain the sizes of fully aquatic mammals, which have not previously been considered. By replacing the terrestrial minimum with a pelagic one, at roughly 7000g, the terrestrial mammal tradeoff model accurately predicts, with no tunable parameters, the observed body masses of all extant cetacean species, including the 175,000,000g Blue Whale. This strong agreement between theory and data suggests that a universal macroevolutionary tradeoff governs body size evolution for all mammals, regardless of their habitat. The dramatic sizes of cetaceans can thus be attributed mainly to the increased convective heat loss is water, which shifts the species size distribution upward and pushes its right tail into ranges inaccessible to terrestrial mammals. Under this macroevolutionary tradeoff, the largest expected species occurs where the rate at which smaller-bodied species move up into large-bodied niches approximately equals the rate at which extinction removes them.Comment: 7 pages, 3 figures, 2 data table

Social variety in the yellow bellied marmot: a population behavioural system.

This is the publisher's version, which can also be found at: http://www.sciencedirect.com/science/article/pii/000334727790108

Cetaceans have complex brains for complex cognition

MEDLINE® is the source for the citation and abstract of this record.Peer reviewedPublisher PD

Testing the optimal defence hypothesis for two indirect defences: extrafloral nectar and volatile organic compounds

Many plants respond to herbivory with an increased production of extrafloral nectar (EFN) and/or volatile organic compounds (VOCs) to attract predatory arthropods as an indirect defensive strategy. In this study, we tested whether these two indirect defences fit the optimal defence hypothesis (ODH), which predicts the within-plant allocation of anti-herbivore defences according to trade-offs between growth and defence. Using jasmonic acid-induced plants of Phaseolus lunatus and Ricinus communis, we tested whether the within-plant distribution pattern of these two indirect defences reflects the fitness value of the respective plant parts. Furthermore, we quantified photosynthetic rates and followed the within-plant transport of assimilates with 13C labelling experiments. EFN secretion and VOC emission were highest in younger leaves. Moreover, the photosynthetic rate increased with leaf age, and pulse-labelling experiments suggested transport of carbon to younger leaves. Our results demonstrate that the ODH can explain the within-plant allocation pattern of both indirect defences studied

The classical case of character release: Darwin's finches ( Geospiza ) on Isla Daphne Major, GalÁpagos

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75575/1/j.1095-8312.1984.tb01679.x.pd

Female within-nest spawning-site preference in a paternal brooding blenny and its effect on the female mate choice

Female spawning-site preference within a nest and its effect on the female mate choice in a paternal brooding blenny Rhabdoblennius ellipes, were examined in rocky intertidal pools using artificial nests. The number of eggs deposited at the nest entrance site was lower than the number deposited at the center and at deep sites. Moreover, the within-nest difference in the egg developmental stage indicated that eggs at the nest entrance site were deposited after those at the center and deep sites. These results indicated that females prefer to spawn eggs in the center and deep sites rather than at the entrance site. Owing to the higher egg mortality rate at the entrance site, females may avoid spawning at such sites. An analysis of the nests in the study area suggested that the within-nest site preference affects female mate choice that is females avoided nests where only the entrance site was available for spawning and instead spawned in nests where the center and deep sites were available