. The ecology and life history of the common frog (Rana temporaria temporaria) . lO 20 30 MAY 9 19 29 JUNE 9 19 29 JULY 8 *"l 8 28 AUGUST Fig. 21. Mean Numbers o£Polystoma per Tadpole in Lower Parkfield Pond, 1947 In this pond, with a very large number of tadpoles surviving the first few weeks, the infestation was low at first. Metamorphosis was delayed, and a large influx of secondary larvae took place in August. On the other hand, when metamorphosis is late, the losses from the gill chamber are so large that in these ponds there would be few primary larvae left. The neotenic cycle then
. The ecology and life history of the common frog (Rana temporaria temporaria) . lO 20 30 MAY 9 19 29 JUNE 9 19 29 JULY 8 *"l 8 28 AUGUST Fig. 21. Mean Numbers o£Polystoma per Tadpole in Lower Parkfield Pond, 1947 In this pond, with a very large number of tadpoles surviving the first few weeks, the infestation was low at first. Metamorphosis was delayed, and a large influx of secondary larvae took place in August. On the other hand, when metamorphosis is late, the losses from the gill chamber are so large that in these ponds there would be few primary larvae left. The neotenic cycle then provides a means of injecting a supply of larvae into the tadpole population just as the original lot are disappearing. It now seems certain that the wide variations in dates of metamorphosis that I reported are so much part of the normal hfe of
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Keywords: ., bookcentury1900, bookcollectionbiodiv, booksubjectranatemporaria
