Fuselier L
University of Kansas, Department of Systematics and Ecology, Lawrence, KS 66045, USA.
Rev Biol Trop. 2001 Jun;49(2):647-55.
Five species of Cyprinodon in Laguna Chichancanab, Yucatan, Mexico comprise a young species flock whose ecology and evolution has not been thoroughly studied, but whose existence is threatened with extinction. Species flocks evolve in isolated areas where predators and competitors are absent. Since the description of the Chichancanab flock, Oreochromis mossambicus, a species introduced into the lake for which I examined habitat in the 1980's, has become common throughout the basin. I assessed relative abundance of flock species in the lake. examined habitat use and segregation among the three most common flock species and examined the affects of O. mossambicus upon flock species habitat use. Cyprinodon beltrani was the most abundant flock species in 1997, followed by C. maya and C. labiosus; C. verecundus and C. simus were rare. Cyprinodon beltrani was found in shallow water, nearshore, over thick beds of submerged Chara, and little emergent vegetation. Cyprinodon beltrani exhibited diurnal variation in nearshore habitat use. In the field, the habitat use of C. beltrani and O. mossambicus broadly overlapped. In aquarium experiments, three flock species exhibited habitat use segregation and C. beltrani and C. labiosus showed agonistic behaviors that strengthened segregation. Cyprinodon maya differed from C. beltrani and C. labiosus by its greater dispersion of individuals and use of areas higher in the water column. The presence of O. mossambicus caused a shift in habitat use by C. maya and C. labiosus that put these species into habitat occupied by C. beltrani. The presence of introduced species has caused a significant perturbation of the conditions that fomented speciation of the Chichancanab flock 8,000 years ago.
墨西哥尤卡坦半岛奇尚卡纳布湖中的五种鲤齿鳉构成了一个年轻的物种群，其生态和进化尚未得到充分研究，但其生存正面临灭绝威胁。物种群在没有捕食者和竞争者的孤立区域进化。自奇尚卡纳布物种群被描述以来，莫桑比克罗非鱼被引入该湖，我在20世纪80年代对其栖息地进行了研究，如今这种鱼在整个流域都很常见。我评估了湖中物种群物种的相对丰度，研究了三种最常见的物种群物种的栖息地利用情况和隔离情况，并研究了莫桑比克罗非鱼对物种群物种栖息地利用的影响。1997年，贝尔特拉尼鲤齿鳉是物种群中数量最多的物种，其次是玛雅鲤齿鳉和唇形鲤齿鳉；羞怯鲤齿鳉和辛氏鲤齿鳉很罕见。贝尔特拉尼鲤齿鳉出现在浅水区、近岸，生长着茂密的水下轮藻床且很少有挺水植物的地方。贝尔特拉尼鲤齿鳉在近岸栖息地利用上表现出昼夜变化。在野外，贝尔特拉尼鲤齿鳉和莫桑比克罗非鱼的栖息地利用有广泛重叠。在水族箱实验中，三种物种群物种表现出栖息地利用隔离，贝尔特拉尼鲤齿鳉和唇形鲤齿鳉表现出强化隔离的争斗行为。玛雅鲤齿鳉与贝尔特拉尼鲤齿鳉和唇形鲤齿鳉不同，其个体分布更分散，且利用水柱中较高的区域。莫桑比克罗非鱼的存在导致玛雅鲤齿鳉和唇形鲤齿鳉的栖息地利用发生变化，使这些物种进入了贝尔特拉尼鲤齿鳉占据的栖息地。外来物种的存在对8000年前促成奇尚卡纳布物种群物种形成的条件造成了重大干扰。
