Transcription

Zebra

DNA (3' end) ...GATACCCATAAGCAGGGATGACTGTTG... (5' end)

    (5' end) ...CTATGGGTATTCGTCCCTACTGACAAC... (3' end)

(to RNA)

mRNA(5' end) ...CUAUGGGUAUUCGUCCCUACUGACAAC... (3' end)

Donkey

DNA (3' end) ...GGTACCCATCAGCAGAGAGTACTGTTC... (5' end)

    (5' end) ...CCATGGGTAGTCGTCTCTCATGACAAG... (3' end)
(to RNA)

mRNA(5' end) ...CCAUGGGUAGUCGUCUCUCAUGACAAG... (3' end)

Horse

DNA (3' end) ...CGTACCCATCATCAGAGAGTACTGTTC... (5' end)

    (5' end) ...GCATGGGTAGTAGTCTCTCATGACAAG... (3' end)
(to RNA)

mRNA(5' end) ...GCAUGGGUAGUAGUCUCUCAUGACAAG... (3' end)

Translation

Zebra

mRNA(5' end) ...CUAUGGGUAUUCGUCCCUACUGACAAC... (3' end)
                  (start)
              AUG GGU AUU CGU CCC UAC UGA CAAC
              M   G   I   R   P   Y   STOP

Donkey

mRNA(5' end) ...CCAUGGGUAGUCGUCUCUCAUGACAAG... (3' end)
                  (start)
              AUG GGU AGU CGU CUC UCA UGA CAAG
              M   G   S   R   L   S   STOP

Horse

mRNA(5' end) ...GCAUGGGUAGUAGUCUCUCAUGACAAG... (3' end)
                  (start)
              AUG GGU AGU AGU CUC UCA UGA CAAG
              M   G   S   S   L   S   STOP

PAM Score

Donkey vs. Zebra

MGSRLS
MGIRPY

M,M = +5 
G,G = +6
S,I = -2
R,R = +5
L,P = -3
S,Y = -2

PAM = +5 +6 -2 +5 -3 -2 = +9

Horse vs. Donkey

MGSSLS
MGSRLS

M,M = +5
G,G = +6
S,S = +4
S,R = -1
L,L = +4
S,S = +4

PAM = +5 +6 +4 -1 +4 +4 = +22

Horse vs. Zebra

MGSSLS
MGIRPY

M,M = +5
G,G = +6
S,I = -2
S,R = -1
L,P = -3
S,Y = -2

PAM = +5 +6 -2 -1 -3 -2 = +3

Conclusion

It seems that the evolutionary data suggests that horse and donkeys are the closest related species. It's more likely that $\text{Horse}\to \text{Donkey}$ or vice versa than going through an intermediary species like the Zebra. It's also more likely that the Zebra came from the Donkey compared to the Horse.