ðiːz tˈuː spˈiːsiːz ʌv sˈʌlfɚ bˈʌɾɚflˌaɪz hæv ɹᵻtˈeɪnd ɐ lˈɑːɹdʒ dᵻɡɹˈiː ʌv dʒɪnˈɛɾɪk kəmpˌæɾəbˈɪlᵻɾi ðæt ɐlˈaʊz ðˌɛm ðə pɹˈɑːduːs vˈaɪəbəl ænd fˈɜːɾəl ˈɔfspɹɪŋ.
These two species of sulphur butterflies have retained a large degree of genetic compatibility that allows them the produce viable and fertile offspring.