Coat patterns

In this study 63 m useum skins o f A epyceros m elam pus (A ppendix I) w ere analysed to score coat patterns and to investigate if there w as correspondence betw een the patterns found and described subspecies.

M ales (n=40), females (n=20) and specim ens o f unknow n sex (n=3) w ere analysed together since no sexual dim orphism related to coat pattern has been reported for im palas. O f the study skins, 34 specim ens (53.9% ) had m useum label identification at subspecies level. O f the six described subspecies o f im pala, four w ere represented in our sam ple set (Table 4.16).

TABLE 4.16 - Subspecies o f A epyceros m elam pus and corresponding num ber of skins of males and females from the British N atural History M useum and Powell-Cotton Museum analysed in the present study.

Subspecies Num ber Skin identification num bers

A. nu rendilis 0

A. m. suara 7 F 19, F37, M49, M53, M59, M62, and M63

A. nu jo h n s to n i 7 M8, FIO, U26, F33, F45 and M50

A .nu petersi 14 M l8, M20, F21, M22, M23, F24, F27, F29, M30,

F31,M 32, F47, F48 and M60

A .nu m elam pus 6 F 15, M34, U35, M44, M54 and F55

Total 34

M=male; F=feraale; U=sex unknown

In order to visualise the distribution o f the skin sam ple along the sp ecies’ geographic range, each individual or group w as plotted on A frican map based on co ­ ordinates extracted from th eir geographic origin (Figure 4.24).

A total o f 28 localities covering 9 countries are represented. F or Tanzania ( M l2,51,56,57,58,61) and N am ibia ( F I 5 and M 44,52,54,55) both m useum s share the sam e specim en origins. Eleven localities w ere represented by m ales and females, 11

males from Angola and one specimens o f unknown sex from South Africa were also included in the analyses despite their museum label only mentioning country o f origin.

# # 32-60 18-20-27-47 8-45 22-29-31-48 25-36 34 12-51-56-57-58-61 1-2-7-11-13 Æ m. tm M s ■ Æ m. st/ars ■ A. a?, p ftn stm ^

A. m. e not labelled with subspecies

FIGURE 4.24 - Southern African map showing geographical distribution of A. melampus male and female skin samples. The specimens labelled at subspecies level are marked with different colours (see map legend). Boxes show specimen identification numbers. Each individual or group was plotted based on co-ordinates extracted from their geographic origin ? = Specimens with unknown sample locality.

A fter detailed observations o f each m useum skin, three characters w ere considered for analysis - coat colour, eye and face patterns.

The colour w as defined by m atching the left rum p area o f the antelope skin w ith the M unsell C olour Charts. As m entioned before, this system defines and codes colour by three different physical proprieties nam ed Hue, V alue and Chroma.

The H ue indicated that im palas’ skin colour w as related to red, 5 YR (“y” o f yellow and “r” o f red) being the chart used. The V alue, w hich indicates colour lightness, varied betw een code values 4, 5, 6 and 7. The C hrom a that defines saturation varied betw een code values 2, 3, 4, 6 and 8. These three features w ere com bined in order to form the colour designation.

The skin analysis showed that three colours define all the sam pled m aterial: reddish grey (H ue 5YR, V alue 5 and Chrom a 2); reddish brow n (H ue 5YR, V alue 4 or 5 and Chrom a 3 or 4); and reddish yellow (Hue 5YR, value 6 or 7 and Chrom a 6 or 8). The result for each specim en w as displayed on an A frican m ap (Figure 4.25) follow ing the same geographical position previously presented in Figure 4.24. These colours w ere coded as “G ” for reddish grey, “B ” for reddish brow n and “Y” for reddish yellow.

The presence or absence o f a black stripe, dow n the m iddle o f the face below the eyes, and another through the line o f each eye, w ere the second and third skin characters analysed. Three states o f each pattern w ere coded. A bsence o f black stripe in the m iddle o f the face or eyes w as coded as “0” . The presence o f a light black stripe in the m iddle o f the face or eyes w as coded as “ 1”, and a darker stripe as “2”. R esults for each specim en w ere displayed on an A frican m ap (Figure 4.26 and 4.27) follow ing the sam e geographical position previously presented in Figure 4.24.

Reddish grey Reddish brown Reddish yellow G B Y Y / B Y / Y Y / B / B / B Y / Y / Y / Y / B / B G / G B / B / G / B Y / Y B / G / G / B G / G / G / G / G B / Y Y / Y / Y / Y / Y B Y / B B B / B / B / B / B

■ /w. M A. m. suara ■ vf ot. /ofmstoni A. m.

I A. m. rn é a n ^ s • not labelled with subspecies

FIGURE 4.25 - Southern African map showing geographical distribution of A. melampus skin samples. The specimens labelled at subspecies level are marked with different colours (see map legend). Boxes show specimens’ coat colour based on Munsell Colour Charts and coded as follow: G= reddish grey, B= reddish brown and Y=reddish yellow.

I

A. m. m d a iï^S # not l<*elled with subspecies

F IG U R E 4 .2 6 - Southern African map showing geographical distribution of A m elam pus skin samples. The specimens labelled at subspecies level are marked with different colours (see map legend). Boxes show specimens’ eyes patterns coded as follow: B=no black line, 1= light black line, 2=dark black line.

. 1 / 0 2 I 2 I 2 I 2 2/2/212 2 l/l/l/O/ 1 / 1 l / O / O / l / O / O O/O/l/I/l Æ m. rsmMs I Æ m. st/ara ■ /?. m. phnstoni ^

/?. m. tæfatnpt/s # not labelled with subspecies

FIGURE 4.27 - Southern African map showing geographical distribution of A. melampus skin samples. The specimens labelled at subspecies level are marked with different colours (see map legend). Boxes show specimens face patterns coded as follow: 0=no black blaze, 1 Night black blaze, and 2=dark black blaze.

Generally, the im pala’s coat is described as short, glossy and having a reddish saddle over a light tan torso and w hite underside. H ow ever, and despite the ways that authors describe the colour, subspecies publications always describe South and E ast African impalas differently.

From the colour designation generated by our analyses, 40% specimens w ere reddish brow n, 38% reddish yellow and only 22% reddish grey. A clear correspondence betw een coat colour and geographical region or described subspecies w as not detected in this study, how ever reddish grey individuals did not occur in South Africa, Kenya or Tanzania.

The face and eye patterns described in ou r analysis generated four phenotypes; Tvpe 1 - no black stripe in the middle o f the face and no black line dow n eye (20,7% ); Tvpe 2 - light black stripe in the middle o f the face and light line dow n eye (19,1% ); Tvpe 3 - light black stripe in the middle o f the face and no line dow n eye (38% ); and Tvpe 4 - dark black stripe in the middle o f the face and dark line dow n eye (22,2% ).

There w as predom inance o f light black stripe (57.2% ) in the middle o f the face over the absence o f the black stripe (20.6% ), and the majority o f the specimens do not have a black line dow n eye (58.7% ). It w as observed that a black line dow n the eye is only present if there is also black stripe in the middle o f the face (Type 2).

The face and eye patterns are shown to be strongly diagnostic for specimens identified as A, m. petersi. N one o f th e other individuals presents a black stripe in th e middle o f the face so dark and well delimited as the ones from w estern A ngola and w estern Nam ibia (Type 4).