Ke. Wynne-edwards, Evolutionary biology of plant defenses against herbivory and their predictive implications for endocrine disruptor susceptibility in vertebrates, ENVIR H PER, 109(5), 2001, pp. 443-448
Hormone disruption is a major, underappreciated component of the plant chem
ical arsenal, and the historical coevolution between hormone-disrupting pla
nes and herbivores will have both increased the susceptibility of carnivore
s and diversified the sensitivities of herbivores to manmade endocrine disr
upters. Here I review diverse evidence of the influence of plant secondary
compounds on vertebrate reproduction, including human reproduction. Three o
f the testable hypotheses about the evolutionary responses of vertebrate he
rbivores to hormone-disrupting challenges from their diet are developed. Sp
ecifically, the hypotheses are that a) vertebrate herbivores will express s
teroid hormone receptors in the buccal cavity and/or the vomeronasal organ;
b) absolute sex steroid concentrations will be lower in carnivores than in
herbivores; and c) herbivore steroid receptors should be more diverse in t
heir binding affinities than carnivore lineages. The argument developed in
this review, if empirically validated by support for the specific hypothese
s, suggests that a) carnivores will be more susceptible than herbivores to
endocrine-disrupting compounds of anthropogenic origin entering their bodie
s, and b) diverse herbivore lineages will be variably susceptible to any gi
ven natural or synthetic contaminant. As screening methods for hormone-disr
upting potential are compared and adopted, comparative endocrine physiology
research is urgently needed to develop models that predict the broad appli
cability of those screening results in diverse vertebrate species.