The Colonization of Land By Crustaceans

陆栖等足类或林虱构成了唯一在陆地上定居的主要甲壳类动物，现存的动物群显示出不同寻常的完整的进化辐射表现。至少有5个独立的谱系在陆地上定居，其中包括占据从潮间带到全陆地过渡栖息地的物种。这一点，再加上最近在等足类动物系统发育方面的进展，使得蛇尾纲特别适合于进化生理学的研究。研究将集中在四个主要系统的比较生理学上，所有这些系统在水陆过渡期间都将经历重大的适应性改变：水蒸气吸收；氮排泄的单一和替代途径；血淋巴渗透调节;以及胚胎的耐热性和渗透性。具体项目的例子包括研究多形虫鳃中的膜运输及其在水蒸气吸收、潮间带盐排泄和水生渗透调节中的作用之间可能的同源性。谱系内的比较生理学为理解诸如水蒸气吸收和氨挥发等陆地适应的预适应基础提供了一种手段。谱系之间的比较将探索不同的殖民路线——从间隙栖息地的高湿度和热稳定性到海洋沿岸地区的极端小气候——如何塑造和限制生理系统的进化。

Wright 9808144 The onsicidean isopods or woodlice constitute the only major group of crustaceans to have colonized land, and the extant fauna shows an unusually complete representation of evolutionary radiations. At least 5 independent lineages have colonized land, and include species occupying a number of transitional habitats from intertidal to fully terrestrial. This, combined with recent advances in isopod phylogeny, makes the Oniscidea particularly suited to studies of evolutionary physiology. Research will focus on comparative physiology of four main systems, all expected to undergo major adaptive modification during an aquatic-terrestrial transition: water vapour absorption; ammonotely and alternative avenues of nitrogenous excretion; haemolymph osmoregulation; and the thermal and osmotic tolerance of embryos. Examples of specific projects include studies of membrane transport in the pleopodal gills and possible homology between its role in water vapor absorption, intertidal salt excretion, and aquatic osmoregulation. Comparative physiology within lineages provides a means to understand the preadaptive basis of such terrestrial adaptations as water vapour absorption and ammonia volatilization. Comparisons between lineages will explore how different colonization routes - from the high humidity and thermal stability of interstitial habitats to the microclimatic extremes of the marine littoral zone have both shaped and constrained the evolution of physiological systems.