The Moors of Al-Andalus intermarried heavily with the native Spaniards (Mozarabs), not to mention their Slavic slaves. But there have been suggestions that the possible genetic imprint on southern Spain by the Muslim conquests was minor (as marginal as the Visigothic legacy). The following study from The Human Races Archive (which you should visit at least once a week if you have an interest in archaeogenetics and its affiliated fields) might seem to negate that position:
The highest frequency of haplotype 5 (68.9%) was previously observed in Berbers from Morocco, and it has been established that this haplotype is a characteristic Berber haplotype in North Africa. The relative frequencies of haplotype 5 distribution show a geographical gradient of decreasing frequency according to latitude in Iberia: 40.8% in Andalusia, 36.2% in Portugal, 12.1% in Catalonia, and 11.3% in the Basque Country; such a cline of decreasing frequency of haplotype 5 from the south to the north in Iberia clearly establishes a gene flow from North Africa towards Iberia.
Of course, another reasonable explaination is that southern Iberia and northern Africa have always been closely affiliated racially (just as there are swarthy Andalusians-there are red-haired Berbers). No wonder Antonio Banderas could play an Arab in The 13th Warrior.