Complex sentence: In order to counteract the attacks made by "P. rejecta" the frog embryos hatch earlier, up to three times as early compared to embryos that are not likely to be attacked.
Split into simpler sentences: In order to counteract the attacks made by "P. rejecta" the from embryos hatch earlier. In fact they will hatch up to 3 times as early compared to embryos that are not likely to be attacked.