在與有毒的獵物粗皮蠑螈進行的“軍備競賽”中，西部襪帶蛇成為了最后的贏家（如圖）。
據美國《科學》雜志在線報道，隨著時間的推移,，蠑螈逐漸進化出了毒性—— 一只蠑螈足以毒死幾個成年人，而蛇對這種毒性的抵抗能力則也變得越來越強,。將近1/3的美國西部襪帶蛇能夠承受蠑螈的毒性,。這種保護功能主要依賴于一個與離子通道有關的基因產生的突變，從而防止該通道因毒素的作用而關閉,，并且由此產生了一個蠑螈難以企及的強大的免疫系統,。研究人員在最近的《科學公共圖書館·生物學》（PLoS Biology）網絡版上報告了這一研究成果。（來源：科學時報 群芳）
生物谷推薦原始出處：
（PLoS Biology）,，doi:10.1371/journal.pbio.0060060,，Charles T. Hanifin, Edmund D. Brodie Jr., Edmund D. Brodie III
Phenotypic Mismatches Reveal Escape from Arms-Race Coevolution
Charles T. Hanifin1¤*, Edmund D. Brodie Jr.1, Edmund D. Brodie III2
1 Department of Biology, Utah State University, Logan, Utah, United States of America, 2 Department of Biology, University of Virginia, Charlottesville, Virginia, United States of America
Because coevolution takes place across a broad scale of time and space, it is virtually impossible to understand its dynamics and trajectories by studying a single pair of interacting populations at one time. Comparing populations across a range of an interaction, especially for long-lived species, can provide insight into these features of coevolution by sampling across a diverse set of conditions and histories. We used measures of prey traits (tetrodotoxin toxicity in newts) and predator traits (tetrodotoxin resistance of snakes) to assess the degree of phenotypic mismatch across the range of their coevolutionary interaction. Geographic patterns of phenotypic exaggeration were similar in prey and predators, with most phenotypically elevated localities occurring along the central Oregon coast and central California. Contrary to expectations, however, these areas of elevated traits did not coincide with the most intense coevolutionary selection. Measures of functional trait mismatch revealed that over one-third of sampled localities were so mismatched that reciprocal selection could not occur given current trait distributions. Estimates of current locality-specific interaction selection gradients confirmed this interpretation. In every case of mismatch, predators were “ahead” of prey in the arms race; the converse escape of prey was never observed. The emergent pattern suggests a dynamic in which interacting species experience reciprocal selection that drives arms-race escalation of both prey and predator phenotypes at a subset of localities across the interaction. This coadaptation proceeds until the evolution of extreme phenotypes by predators, through genes of large effect, allows snakes to, at least temporarily, escape the arms race.
