Species Specificity of Sperm Chemotaxis

Is sperm chemotaxis specific, i.e., are the chemoattractants specific for each species or are there chemoattractants common to several species There is no single answer to this question. With some exceptions, species specificity appears to be the rule in marine species [102, 103]. There, the gametes are released in to seawater, and gametes of different species may be in close proximity. Therefore, in these cases, chemotaxis may be needed as one of the means to avoid interspecies fertilization. Indeed, in some marine groups (e.g., sea urchins, hydromedusae and certain ophiuroids), the specificity of sperm chemotaxis is very high. In other groups (e.g., starfish), the specificity is at the family level and, within the family, there is no specificity. In contrast, in mollusks, there appears to be no specificity at all ([35,102,103] and references therein). 

In plants, a unique simple compound [for example, fucoserratene—a linear, unsaturated alkene (1,3-trans 5-cis-octatriene)] might be a chemoattractant for various species [92]. These differences in specificity between species may reflect the different physiological tasks that sperm chemotaxis fulfills in different species. 

What is the situation in mammals The need for species specificity in mammalian sperm chemotaxis is not obvious. On the one hand, specificity might be desired as a mean to avoid cross-species fertilization. 

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