Morphological Variations in the Skulls of Male and Female Persian Fallow Deer (Dama dama mesopotamica)

Document Type : Anatomy- Biochemistry

Authors

1 Department of Basic Sciences, Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran

2 Department of Fisheries, Faculty of Natural Resources, Azadshahr Branch, Islamic Azad University, Azadshahr, Iran

3 Veterinary School, Babol Branch, Islamic Azad Universities, Babol, Iran

4 Veterinary School, Babol Branch, Islamic Azad University, Babol, Iran

Abstract

BACKGROUND:
Persian fallow deer (PFD), Dama dama mesopotamica, is one of the rarest members of the Cervidae family currently listed as endangered by the International Union for Conservation of Nature.
OBJECTIVES:
Morphological variations in the skulls of male and female PFDs were evaluated in this investigation.
METHODS:
In cooperation with the Department of Environment, skulls and mandibles were obtained from five male and four female animals. After the usual practices of bone cleaning, the specimens were evaluated for morphological differences. Next, 29 parameters were measured on the skulls and mandibles by a digital Vernier caliper for morphometric studies. In addition, ten, six, and nine landmark points were defined on the left lateral photos of mandibles, dorsal, and left lateral photos of skulls, respectively. The points were digitized on two-dimensional images using the TpsDig2 software. The shape differ-ences between the two genders were analyzed using discriminate function analysis in the MorphoJ software.
RESULTS:
The interfrontal ridge was more prominent in male PFDs than in female animals. Moreover, there were some significant differences in the measured parameters, mostly in the mandible. The geometric morphometric evaluations showed no significant differences between the two genders.
CONCLUSIONS:
The findings of the present investigation revealed some morphological differences between the skulls of male and female PFDs

Keywords


Article Title [فارسی]

تفاوت های مورفولوژیک جمجمه گوزن زرد ایرانی نر و ماده (Dama dama mesopotamica)

Authors [فارسی]

  • بهرخ مرزبان عباس آبادی 1
  • فریبرز قجقی 2
  • صابر رحمتی 3
  • امید حاجیان 4
1 گروه علوم پایه، دانشکدۀ دامپزشکی، دانشگاه تخصصی فناوری‌های نوین آمل، آمل، ایران
2 گروه شیلات، دانشکدۀ منابع طبیعی، واحد آزادشهر، دانشگاه آزاد اسلامی، آزادشهر، ایران
3 دانشکدۀ دامپزشکی، واحد بابل، دانشگاه آزاد اسلامی، بابل، ایران
4 دانشکدۀ دامپزشکی، واحد بابل، دانشگاه آزاد اسلامی، بابل، ایران
Abstract [فارسی]

چکیده
زمینه مطالعه: گوزن زرد ایرانی (Dama dama mesopotamica) ، یکی از نادرترین اعضای خانواده Cervidae می باشد که در حال حاضر توسط اتحادیه جهانی حفاطت از طبیعت(IUCN) در لیست حیوانات در معرض انقراض قرار گرفته است.
هدف: در تحقیق حاضر تفاوت‌های مورفولوژیک جمجمه گوزن زرد ایرانی نر و ماده (Dama dama mesopotamica) مورد بررسی قرار گرفت.
روش کار: در ابتدا با همکاری اداره حفاظت از محیط زیست، پنج جمجمه نر و چهار جمجمه ماده این حیوان تهیه شد. پس از انجام روشهای معمول تمیز کردن استخوان ، نمونه ها از نظر اختلافات مورفولوژیک مورد بررسی قرار گرفتند. سپس 29 پارامتر در جمجمه و فک پایین توسط کولیس دیجیتال جهت مطالعات مورفومتریک اندازه گیری شد. علاوه بر این، بر روی تصاویر جانبی فک پایین از سمت چپ و تصاویر جانبی جمجمه از سمت چپ و تصاویر پشتی جمجمه به ترتیب ده ، شش و نه نقطه تعریف و به کمک نرم افزار TpsDig2 به صورت دو بعدی درآمدند و تفاوتهای شکلی بین دو جنس با استفاده نرم افزار MorphoJ مورد بررسی قرار گرفت.
نتایج: همانطور که مشاهدات مورفولوژیکی نشان داد ، سوچر بین دو استخوان پیشانی در جنس نر به طور معنی داری بیشتر از ماده بود. علاوه بر این، تفاوتهای معنی داری در برخی از پارامترهای اندازه گیری شده در جمجمه و فک پایین دو جنس مشاهده شد که بیشتر تفاوتها مربوط به پارامترهای اندازه گیری شده در فک پایین بود. نتایج بررسی های مورفوژئومتریک تفاوت معنی داری بین جنس ها نشان نداد.
نتیجه گیری نهایی: این پژوهش نشان داد که جمجمه گوزن زرد ایرانی نر و ماده در برخی ویژگی های مورفولوژیک تفاوت دارند.

Keywords [فارسی]

  • گوزن زرد ایرانی
  • دوشکلی جنسی
  • سر
  • جمجمه
  • فک پایین

 

Introduction

 

Persian fallow deer (PFD) with the scientific name Dama dama mesopotamica, as one of the rarest deer species in the world, was previously abundant throughout western Asia. Nowadays, they are inhabiting only a small habitat in Khuzestan, Southern Iran, two rather small protected areas in Mazandaran Province (Northern Iran), and some other small areas in the Near and Middle East. This member of the subfamily Cervinae belonging to the family Cervidae is currently listed as endangered by the International Union for Conservation of Nature (Jantschke, 1990; Rabiei and Saltz, 2011; Berger-Tal et al., 2012; Ekrami et al., 2016; Vigne et al., 2016).

Due to the importance of skull anatomy in diverse fields of science, including clinical and surgical practices, wildlife and evolutionary sciences, and sexual dimorphism. Therefore, many studies have been carried out on distinct animals, such as various species of dogs, equines, felines, porcine, sheep, talpas, and rodents (Kieser and Groeneveld, 1992; Evans and McGreevy, 2006; Carreira and Ferreira, 2016; Pitakarnnop et al., 2017; Kyllar et al., 2016; Choudhary and Singh, 2016; de la Barra et al., 2020; Selçuk et al., 2019; Selçuk et al., 2018). Marzban Abbasabadi et al. (2018) evaluated the morphometric differences of the skull between male and female Zell sheep. They found significant in sexual dimorphism between males and females. Parés‐Casanova (2015) analyzed the skulls of adult White Rasquera goat breed to explore sexual dimorph-ism based on geometric morphometric in this local goat breed. Their results demonstrated that the differences in the skull of the two genders may be attributed to the extensive management styles of the animals as under a low anthropogenic influence they tend to reinforce their natural sexual size dimorphism.

In this regard, some studies have evaluated skull anatomy in various species of the Cervidae family. Markov (2014) analyzed the extent of sexual dimorphism in the skull features of red deer (Cervus elaphus L.) in Bulgaria and reviewed the population morphometric variations in the skull of red deer from mountainous and lowland habitats. In addition, there are many studies on skull anatomy in European roe deer (And and Reig, 1993; Sabalinkiene et al., 2017). However, information about PFD skull anatomy is limited. Therefore, the current study aimed to evaluate morphological differences in the skulls of male and female PFDs.

 

Materials and Methods

Samples Preparation

In cooperation with the Department of Environment of Mazandaran province, Iran, a total of nine PFD skulls or heads (five adult male and four adult female) were obtained from the museum of the Department of Environment and the dead deer of Dasht-e Naz Wildlife Refuge, Sari, Iran protected area during the past two years. Only the skulls of adult PFDs with completely formed dentition were used (Selçuk et al., 2018). The heads and skulls were examined for any skeletal damages or deformities and then the heads were prepared by boiling method. Next, the mandibles were disarticulated from the temporomandibular joint. The samples were numbered and photographed (Canon EOS 4000D, Tokyo, Japan) from dorsal, lateral, ventral, and caudal views. During photography, the camera and the samples were fixed in place to keep the distance and angles of the shots constant.

Morphological Observations

At the first step, the male and female PFD skulls and mandibles were assessed to find remarkable morphological differences. As the horns or cornual process are different between sexes, the other components of the skull and mandible were searched. Afterwards, the accuracy of the found hallmarks was examined.

Morphometric Geometric Studies

As demonstrated in Figures 1 and 2, ten, six, and nine landmark points were defined on the left lateral photos of mandibles and the dorsal and left lateral photos of skulls, respectively. These points were digitized on two-dimensional (2D) images using the TpsDig2 software version 2.16 (Rohlf, 2010).

The adequacy of tangent shape for statistical analysis was investigated utilizing the TpsSmall (Rohlf, 2003). The non-shape inform-ation was removed from landmark configurations applying General Procrustes Ana-lysis The covariance matrices were generated and the shape differences between the two sexes were analyzed by the discriminant function analysis (DFA) in the MorphoJ version 1.02j (Klingenberg, 2011). The patterns of skull and mandible shape differences were illustrated in the wireframe relative to each other for quantification and visualization purposes.