PDF《Fluorescent sperm offer a method》

07 December

2015 accepted:

17 February

2016 Published:

04 March

2016 OPEN

2 of non-genetic paternal effects through sperm19C21 . Finally, because broadcast spawning is likely the ancestral animal reproductive strategy22,23 , the selective forces shaping this form of reproduction may yield insights into early evolutionary transitions, such as anisogamy to isogamy and external to internal fertilisation (for a recent theoretical model of this sexual cascade of events, see ref. 24). One key challenge facing researchers studying gamete-level sexual selection is to determine male reproduc- tive success at the moment of conception. Even in external fertilisers, where gamete interactions are not hid- den, there are considerable logistical challenges in identifying the outcome of sperm competition at fertilisation. Sperm competitiveness has typically been estimated through paternity analyses, which involves assigning off- spring parentage among two or more putative sires using genetic markers8 . Although paternity success is clearly an important component of a male'

s reproductive fitness, its use in understanding sperm competition poten- tially confounds variation in embryo viabi........