ɐnˈʌðɚ tˈaɪp ʌv swˈiːp, ˈeɪ "sˈɔft swˈiːp fɹʌm stˈændɪŋ dʒɪnˈɛɾɪk vˌɛɹɪˈeɪʃən," əkˈɜːz wɛn ɐ pɹˈiːviəsli nˈuːtɹəl mjuːtˈeɪʃən ðæt wʌz pɹˈɛzənt ɪn ɐ pˌɑːpjʊlˈeɪʃən bɪkˌʌmz bˌɛnɪfˈɪʃəl bɪkˈʌz əvən ɛnvˌaɪɹənmˈɛntəl tʃˈeɪndʒ.
Another type of sweep, a "soft sweep from standing genetic variation," occurs when a previously neutral mutation that was present in a population becomes beneficial because of an environmental change.