Ranavirus and Batrachochytrium dendrobatidis both cause lethal infections, but Ranavirus decimates local populations of amphibians, whereas Batrachochytrium dendrobatidis is wiping out amphibians on a continental scale in North and South America
What difference between those pathogens might account for the difference in the scale of their effects?
The origin of Ranavirus in the Americas is unknown, but it has probably been present long enough for amphibians in this region to develop some resistance to its effects. In contrast, Batrachochytrium dendrobatidis probably reached the Americas within the last century. Amphibians in this region have not had time to evolve resistance, and the wave of infection is moving too rapidly to allow resistance to evolve.
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Fill in the blank(s) with the appropriate word(s).
Nerves that innervate the muscles and skin of the leg arise from the ________.
A. brachial plexus B. sacral plexus C. lumbar plexus D. Both the sacral and lumbar plexuses are correct.
The ________ uses iodine in a synthesis reaction.
A. liver B. thyroid gland C. spleen D. thymus
The onset of puberty is triggered by an increase in:
A. sensitivity of the gonads to pituitary gonadotropins. B. sensitivity of the pituitary to GnRH. C. GnRH secretion. D. sensitivity of the hypothalamus to negative feedback by sex steroids. E. sensitivity of the pituitary to negative feedback by sex steroids.