Numerous marine molluscs, including both gastropods and bivalves, show phenotypicplasticity in their shell morphology in response to predation risk (Appleton & Palmer1988, Trussell & Smith 2000, Bourdeau selection stressor that produces particular prey phenotypes, such as thicker and heavier shells, round shell shape, and lower growth rate (Leonard et al. 1999,Trussell & Nicklin 2002, Hollander & Butlin 2010 their shell morphology in response to predation risk. Predation can act as a directional selection pressure, resulting in specific prey phenotypes, such as thicker and heavier shells, rounder shell shapes

%s -ss %s -to %s -b:a 128k %s" % % (( subprocess.call subprocess.call((ffmpegCmd, shell ffmpegCmd, shell==True True)) ffmpeg -i input_video.mp4 -vf ffmpeg -i input_video.mp4 -vf "delogo=x=474:y=6:w=162:h=90"

配置简单、，可配置主机恢复后是否切换回 master。不存在单点故障。  缺点： 当 mysql 服务挂掉或者不可用的情况下不能进行自动切换，需要通过 crm 模 式实现或者额外的脚本实现(比如 shell 脚本监测到 master 的 mysql 不可用就 将主上的 heartbeat 停掉，这样就会切换到 backup 中去)。 默认启动以及切换后的 backup 话 mysql 不会启动起来，因此这对于