Sympatry between threespine Gasterosteus aculeatus and ninespine Pungitius pungitius sticklebacks in English lowland streams

摘要

The comparative biology of stream-dwelling threespine Gasterosteus aculeatus L. and ninespine Pungitius pungitius L. sticklebacks was examined in streams of eastern England. Threespine occurred throughout, but ninespine occurred < 50 km from stream source, varying from regular distribution to contagion. The species co-occurred more often than expected in macro and microhabitats, and dietary overlap occurred overall and within Callitriche beds. Threespine occurred infrequently and ninespine frequently in Apium beds, contrasting silt/detritus habitats. Threespine and ninespine microhabitat preferences differed in distance from bank, substratum composition, and amount of ligneous debris, and seems uninfluenced by bullhead Cottus gobio, which used faster flowing areas. Greater use of vegetation by ninespine is facilitated by a more stream-lined and small body, which imposes corporal space constraints on gonad size. To compensate, ninespine maintain a lower proportion of mature eggs, produce smaller batches more frequently than threespine and thus incur a lower annual investment to reproduction. [References: 45]