Animal Research International (2020) 17(2): 3747 – 3760 3747 INTERNAL AND EXTERNAL MORPHOMETRY OF THOMAS’S ROPE SQUIRREL ( FUNISCIURUS ANERYTHRUS ) AND GAMBIAN SUN SQUIRREL ( HELIOSCIURUS GAMBIANUS ) IN IBADAN, NIGERIA 1 COKER, Oluwakayode Michael , 2 JUBRIL, Afusat Jagun , 1 ISONG, Otobong Mfon and 1 OMONONA, Abosede Olay emi 1 Department of Wildlife and Ecotourism Management, University of Ibadan, Ibadan, Nigeria . 2 Department of Veterinary Pathology, University of Ibadan, Ibadan, Nigeria . Corresponding Author: Coker, O. M. Department of Wildlife and Ecotourism Management , University of Ibadan, Ibadan, Nigeria. Email: [email protected] Phone: +234 805 415 0061 Received May 15, 2020; Revised June 13, 2020; Accepted July 1 8 , 2020 ABSTRACT Currently, no information exists regarding internal and external morphometrics and their correlations in Funisciurus anerythrus and Heliosciurus gambianus . Therefore, this study examined the relationships among the internal and external morphometrics of the two species in University of I badan, Ibadan, Nigeria. Samples of adult F. anerythrus (n = 20) and H. gambianus (n = 13) were trapped from the wild at various locations within the campus. Live weights (LW), external measurements and weights of internal organs were taken. Comparisons wit hin and between both species were carried out using T - tests and Pearson’s correlation coefficient at p<0.05. H. gambianus was significantly bigger than F. anerythrus for all the measured parameters, except in ear and snout lengths. Male F. anerythrus was s ignificantly bigger than female in LW, body length (BL) and shoulder to tail length (STL) while, female H. gambianus was significantly bigger than male in trunk circumference (TC). In male F. anerythrus , BL significantly correlates with STL (r = 0.8 5 ). In female F. anerythrus , LW correlates significantly with hind limb length (r = 0.62) and both kidneys. In male H. gambianus , LW correlates significantly with head length (r = 0.79), tail length (r = 0.8 1 ), BL (r = 0.97), STL (r = 0.87), and the weights of lu ngs and kidneys. In female H. gambianus , LW correlates significantly with TC (r = 0.9 9 ) and right lung weight (r = 0.9 2 ). Both species show some levels of sexual dimorphism and substantial positive correlations among the external and internal measurements. Keywords: Correlation, Funisciurus anerythrus , Heliosciurus gambianus, Internal organs, Morphometrics, Sexual dimorphism INTRODUCTION Reyment, 2010; Parés - Casanova , 2017 ). Claude (2008) stated that morphometrics can be used Body forms (the direct products of genetic to monitor the impact of mutations on shape, make - up) and their measurements detect developmental changes in form, study (morphometrics) had contributed to the st udy of evolutionary relationships, as well as for forms, shapes and fitness in organisms (Tanna estimating quantitative - genetic parameters . et al ., 2011). According to Claude (2008), it is Variation among individuals is essential, useful in the field of biology, agriculture and as its presence in a species is a requirement for forensic science. Morphometrics is used in adaptive evolutionary change (Allentoft and analyzing variability in size and shape of organs O’Brien, 2010; Allendorf et al ., 2013). and organisms and how these parameters vary Morphological variability among different with other variables ( Slice, 2007; Claude, 2008; geographical populations could be attributed to ISSN: 1597 – 3115 ARI 2020 17(2): 3747 – 3760 www.zoo - unn.org Coker et al. 3748 different genetic structure of populations and to purposes are major threats for these species different environmental conditions prevailing in (IUCN , 2018). each geographic area (Mamuris et al ., 1998). According to Kingdon (1997), F. This variation is influenced and constrained by anerythrus weighs between 20 0 and 220 g, has the interaction of complex genetic and a head and body (HB) length ranging between environmental factors (A lberch, 1983) shown by 1 6 and 2 3 cm and a tail length of between 13 development al responses (Klingenberg, 2010). and 20 cm . H. gambianus weighs between 250 As such, assessment of variation within and and 350g at maturity , has a head and body among individuals in populations of a species is length of between 17 and 27 cm with a tail important at morphological and molecular levels length of between 18 and 26 cm (Kingdon, (Habel et al ., 2015). 1997). Currently, no information exists According to Brown et al . (2014), t he regarding the comparisons between internal and squirrels are diverse group of small mammals external morphometrics of F . anerythrus and H . which vary in size and belong to a family of gambianus . Therefore, the relationships within rodents known as the Sciuridae . There are and between the internal and external approximately 280 species of squirrels belonging morphometrics of the two squirrel species ( F . to 60 genera broken into five subfamilies (IUCN, anerythrus and H . gambianus ) in University of 2018), which vary greatly in geographic range Ibadan, Ibadan, Ni geria were examined in this and habitat and are found on all the continents study. excluding Australia and Antarctica. Squirrels are predominantly herbivorous. However, insects, MATERIALS AND METHODS eggs and the occasional small vertebrate may be part of the diverse diet of th ese This study was carried out within the University animals (Jansa and Myers, 2000; Lurz, 2011; of Ibadan campus located in the city of Ibadan Brown et al ., 2014; IUCN, 2018). Squirrels are (7°23'47''N and 3°55'0''E), Southwestern economically important as sources of protein, Nigeria. Twenty (20) samples of adult Thomas’s pollination agents and agents of seed dispersal Rope Squirre l ( F. anerythrus ) and thirteen (13) ( Fitzgibbon et al ., 1995; Chakravarthy and samples of adult Gambian Sun Squirrel ( H. Thyagaraj, 2012; IUCN, 2 018 ) . They are useful gambianus ) were trapped from the wild at in medical and scientific research (Gurnell, various locations within the University of Ibadan 1987; Thorington and Ferrell, 2006) and serve campus. These were then transported in box as vectors of human and domestic animal cages to the Faculty of Veterinary Medicine, diseases as well as crop and household pests. University of Ibadan where morphometric data Both Thomas’s Rope Squirrel were collected. Animal capture occurred ( Funisciurus anerythrus Thomas , 1890 ) and between October 2018 and January 2019. Gambian Sun Squirrel ( Heliosciurus gambianus Captured species were identified and Ogilby , 1835 ) are listed as Least Concern (LC) authenticated by an animal taxonomist using by the International Union for the Conservation the field guides of Happold (1987) and Kingdon of Nature (IUCN), in view of its wide distribution (19 97). and presumed large population. They are Live weights (LW) of the animals were generally considered to be quite common taken using a weighing balance (Scout Pro species with a stable population. They are SPU402). The tail thickness (TT) (taken at the tolerant to a degree of habitat modification and part of the tail closest to the body) was are considered to be declining at rates not fast measured by means of a digital vernier calliper enough to qualify for listing in a more (ML Tools Digital Caliper 68202) for accurate threatened category. It is also possible that readings to the nearest millimetre (mm). Eleven these species occur in numerous protected other external measurements were taken to the areas ( Cassola, 2016; 201 7 ). Despite this, nearest 0.01 cm by means of a tape/meter rule. hunting and trading for food and medicinal These measurements include: head length (HL) - taken from the tip of snout to the base of the Animal Research International (2020) 17(2): 3747 – 3760 Internal and external morphometry of squirrels in Ibadan, Nigeria 3749 skull, trunk circumference (TC) - taken just comparison of data within and between both below the forelimbs, tail length (TL) - taken species were ca rried out by means of T - tests, from the base of the body to the tip of the tail , and relationships among parameters were left and right ear lengths (EL) - taken from the carried out using Pearson’s correlation tragus of the ear to the tip of the pinna , body coefficient at p<0.05. These were done with length (BL) - taken from th e tip of the snout to IBM SPSS 20 Statistical package. the base of the body just before the tail begins, snout length (SNL) - taken from the tip of the RESULTS snout to the inner eye corner , fore limb length (FLL) - taken from the joint of the forelimb to External and Internal Morphometry of the base of the longest digit , hind limb length Male and Female F. a nerythrus : The means (HLL) - taken from the joint of the knee to the and standard deviations of the measured joint just before the feet, hind foot length (HFL) parameters fo r both male and female F . - taken from the joint of the hind limb to the anerythrus are presented in Table 1. Most of the base of the longest digit , and shoulder to tail mean values of the measured parameters were length (STL) (Figure 1). higher in males except HL, REL, FLL, HFL and TT. Despite the obv ious higher values in male F. anerythrus only three ( LW, BL and STL) of the parameters were significantly higher (p<0 . 05) in female than males . The average LW, BL and STL were 135.91 ± 15.04g, 18.10 ± 0.85 cm and 29.67 ± 2.91 cm , respectively. A ll values o btained for the weights of the internal organs for F. anerythrus were higher in males than in females (Table 1). External and Internal Morphometry of Male and Female H. gambianus : In H. gambianus , the average LW, HL, TC, FLL, HLL and TT were 186.74 ± 19. 37g, 6.95 ± 0.81 cm , 10.9 ± 1.03 cm , 6.30 ± 0.34 cm , 5.82 ± 0.32 cm and 0.81 ± 0.15 cm , respectively (Table 2).