192 J. Bonnald et al.
FIG. 3 Scatter plot of the two first axes of the multiple correspondence analysis (with the per cent of variance accounted for by each axis) performed on the six morphological criteria and their states (Table 1), and the three populations (savannah and forest elephants and the Sebitoli elephant population).
conducted two analyses, one with two groups and one with three groups, to be able to detect a possible group of inter- mediate phenotypes. The two approaches were carried out on the dataset comprising the 705 Sebitoli elephants, with missing data. We then tested the sex and the age bias using a Pearson’s χ2 test.
Results
Validation of the reliability of the morphological criteria The combination of the six morphological criteria facilitated a good description of the species,with 100%beingwell assigned (K-neighbour= 1) when using observations without missing data and 91.67% being well assigned (K-neighbour = 1)when missing data were replaced with themost frequent class of the variable.
Sebitoli elephant morphology
The multiple correspondence analysis of the six morpho- logical variables revealed that the twomost important princi- pal components encompassed 54.17% of the total variance (Fig. 3). Reference savannah elephants showed the lowest variability, reference forest elephants showed medium variability and elephants surveyed in Sebitoli showed high variability. Clustering occurred between the two species, with a marked gap along the first axis, which is explained
mostly by the variables Space, TuskProfile and Forehead (Supplementary Fig. 3). The second axis is mostly explained by the variables Space and TuskProfile. The surveyed Sebitoli elephants do not seem to be a cohesive group: they overlap completely with the forest elephant variability and slightly overlap with savannah elephant variability. Thus, there are three groups (Supplementary Fig. 2): (1) savannah elephants from the reference sample and part of the Sebitoli sample, mostly explained by the states of the variables Ear_S, Space_S, TuskProfile_S, TuskFront_S, ForeHead_I and Back_I; (2) forest elephants from the reference sample and part of the Sebitoli sample,mostly explained by the states of the variables Ear_F, Space_F, TuskProfile_F, TuskFront_F, Forehead_F and Back_F; and (3) the rest of the Sebitoli sample. The use of the species assignment key enabled the iden-
tification of three types of phenotypes: forest (12.1%), savan- nah (36.8%) and an intermediate group (51.1%). We then compared the results obtained from this method with re- sults from the K-means analysis (Supplementary Table 2). All of the specimens assigned to the forest species using the species assignment key were assigned to Group 3,in which no savannah elephants but 50% of the intermediate- phenotype individuals were included. Group 2 comprised 78.5% of the individuals assigned to the savannah elephant phenotype, 15.5% of the individuals assigned to the inter- mediate phenotype and no forest elephant phenotypes. Group 1 includes 34.5% of the individuals assigned to the intermediate phenotype and 21.5% of individuals assigned
Oryx, 2023, 57(2), 188–195 © The Author(s), 2022. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605321001605
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