Oscillating systems with cointegrated phase processes

Journal of Mathematical Biology - We present cointegration analysis as a method to infer the network structure of a linearly phase coupled oscillating system. By defining a class of oscillating...     

Thompsonia dofleini,a colonial akentrogonid rhizocephalan with dimorphic,ova- or sperm-producing,externae (Crustacea,Cirripedia)

Summary Specimens of the blue swimming crab,Portunus pelagicus, are often infected with many thousands of externae ofThompsonia dofleini, all of which are connected through a common root system within the host crab. The species is unique in that the production of sperm cells takes place within the visceral mass of a small minority of the population of the externae. Spermatogonia are probably introduced by male cyprids into these externae when they are young, and they multiply and develop at the expense of the oocytes which rapidly disintegrate and ultimately disappear. It is assumed that the sperm cells are transferred to the ovary of the ordinary, egg-producing externae through the root system. Shortly after the eggs have been fertilized within the ovary they are transferred to the mantle cavity where they develop into cyprid larvae. The larvae become liberated when the externae drop off and the mantle wall disintegrates.Abbreviations used in the figures a annulus - an antennule - bm basal membrane around ovary - ce compound eye - cg cerebral ganglion - cr connecting root - cy cyprid larva(e) - c1 cuticle 1 - c2 cuticle 2 - do degenerating oocytes - e eggs in early division - ec embryonic cells - em embryos - en endocuticle of host - ep epidermis of host - ex exocuticle of host - hc hemocoelic cavity - m mantle - mc mantle cavity - mcy male cyprid - o ovary - oo oocyte - r rupture in wall of visceral mass - rs root system - sc scar - se spawned eggs - so spent ovary - sp spermatogonia - ss sperm and spermatids - st stalk - tc thickened cuticle of mantle cavity - th thorax - vm visceral mass - y yolk granules     

Hibernation adaptation and eclosion synchrony in leaf-galling sawflies in subarctic Norway

The winter dormancy adaptation in gall-inducing sawflies is poorly known. Diapause termination and the following post-diapause quiescence enhance synchronous eclosion in spring. This is probably the most critical part in the life history in gall-inducing sawflies, as there is only a short phenological window of opportunity for mating and oviposition. In a 2?years’ study, diapause duration, termination, survival and eclosion synchrony were experimentally investigated for three gall-inducing sawfly species (Symphyta: Tenthredinidae: Pontania nivalis, P. glabrifrons and P. arcticornis). Field-collected galls, sampled from willows (Salix spp.) in early autumn, were kept under natural temperatures outdoors until next spring. Subsamples were successively transferred to the laboratory at 14-day intervals from October to April in a test of development time to eclosion and survival ratio. The time to eclosion decreased throughout the experiment, whereas the proportion successfully eclosed and eclosion synchronicity increased, all indicative of prepupae entering a diapause in early autumn. The diapause terminates midwinter, and the prepupae enter a post-diapause quiescence until the temperature in spring allows a direct development and contributes to a nearly synchronous eclosion. In all three species, males eclosed 1–2?days prior to females (protandry). We hypothesize that synchronous eclosion as well as protandry enhance mating and oviposition success. Our finding indicates that gall-inducing sawflies are well adapted to its harsh subarctic and arctic environment.