Evolution of dosage compensation does not depend on genomic background

Organisms evolved various mechanisms to cope with the differences in the gene copy numbers between sexes caused by degeneration of Y and W sex chromosomes. Complete dosage compensation or at least expression balance between sexes was reported predominantly in XX/XY, but rarely in ZZ/ZW systems. However, this often-reported pattern is based on comparisons of lineages where sex chromosomes evolved from non-homologous genomic regions, potentially differing in sensitivity to differences in gene copy numbers. Here we document that two reptilian lineages (XX/XY iguanas and ZZ/ZW softshell turtles), which independently co-opted the same ancestral genomic region for the function of sex chromosomes, evolved different gene dose regulatory mechanisms. The independent co-option of the same genomic region for the role of sex chromosome as in the iguanas and the softshell turtles offers a great opportunity for testing evolutionary scenarios on the sex chromosome evolution under the explicit control for the genomic background and for gene identity. We showed that the parallel loss of functional genes from the Y chromosome of the green anole and the W chromosome of the Florida softshell turtle led to different dosage compensation mechanisms. Our approach controlling for genetic background thus does not support that the variability in the regulation of the gene dose differences is a consequence of ancestral autosomal gene content.

Comparative Anatomy of Axial Skeleton of Red-eared Turtle (Trachemys scripta elegans, Wied 1838) and Softshell Turtle (Amyda cartilaginea, Boddaert 1770)

Red-eared turtle and softshell turtles belong Cryptodira Suborder which has a different characteristic in neck length and head movement. The aim of this study was to determine of the axial skeleton anatomical structure including vertebrae, carapace and plastron of the red-eared turtle (Trachemys scripta elegans Wied, 1838) and softshell turtles (Amyda cartilaginea Boddaert, 1770) females. This research was carried out for five months starting from September 2013 to January 2014. The methods used in this study were th e X-Ray method, boiled bone and Alizarin Red S-Alcian blue staining. The result of research was analyzed descriptively comparatively by direct observation using a digital camera. Based on the results of the study the Red-eared turtle tortoise has a number of 7 cervical vertebrae, 9th vertebrae, sacral vertebrae 1 segment and vertebrae caudalis 27 segments. The anterior and posterior zygapophysis of the cervix elongate thus affecting the limited lateral movement. The thoracic center of the vertebrae adjusts the shape of the carapace. The sacralis vertebrae have 1 centrum segment extending on the lateral side attached to the carapace called the lateral pars, the caudal centrum is short and there is a shortened anterior zygapophysis structure. Whereas softshell turtles have slender and long centrums. The anterior and posterior zygapophysis are smaller and allow the softshell turtles to perform more lateral movements. Centrum vertebrae of the thorachalis have a flat shape adjusting the shape of the carapace. Sacralis vertebrae have 2 centrum and 2 lateral pars extending and meeting each other to form a hole sacralia pelvina, centrum vertebrae caudalis extends and there is a neural spinal structure. Carapace of the red-eared turtle consists of fused pieces. Whereas the carapace in the softshell turtles consists of pieces covered by cartilage. The constituent component of carapace and plastron of the red-eared turtle consists of true bones completely, while the constituent components of the carapace and plastron of softshell turtles consist of true bones and cartilage on the sides and connective between the carapace and plastron.

Rapid assessment method for population estimation of softshell turtle (Amyda cartilaginea Boddaert, 1770) and reticulated python (Python reticulatus Schneider, 1801)

Takandjandji M, Gunawan H, Sihombing VS. 2018. Rapid assessment method for population estimation of softshell turtle (Amyda cartilaginea Boddaert, 1770) and reticulated python (Python reticulatus Schneider, 1801). Biodiversitas 19: 265-271. The decreasing number of soft-shell turtle and reticulated python in the wild is due to high demand of the animal in local as well as international market. The condition made the Indonesian government set particular collecting and trading quota for the reptiles, but unfortunately, it does not automatically guarantee their preservation. Current collecting practices will lead to population decline and even extinction of the species since the reptiles’ population in the wild has not yet been accurately determined. The purpose of the research was to determine a rapid method of population estimation to establish a baseline for determining collecting quota for the reptiles, especially of softshell turtles and reticulated pythons. The study was conducted in East Kalimantan using the method of deep interviews of 20 respondents (exporters, fishers, traders, collectors) and 15 key respondents (government officials). The results of this survey showed that the collect reptiles were collected from the wild, since up to now, there has been no successful breeding program of reptiles. The collected reptiles were dominated by female adult softshell turtles collected from Kotabangun area which has collecting quota of 1,080/year (1/3 of the exporting quota for East Kalimantan). Softshell turtles collected from Kotabangun have bigger in stature than those found in West Java and Jakarta, and the reticulated pythons collected from Kotabangun are longer than those found in West Java and Jakarta. The number of reticulated pythons collected from Kotabangun reaches 4,800 individuals/year (1/4 of the quota set for East Kalimantan export).

An interview-based survey to determine the conservation status of Softshell Turtles (Reptilia: Trionychidae) in the Irrawaddy Dolphin Protected Area, Myanmar

We conducted an interview-based survey to investigate the conservation status of large (adult carapace length >400mm) Softshell Turtles (Amyda ornata, Chitra vandijki, and Nilssonia formosa) in the Irrawaddy Dolphin Protected Area (IDPA) of Myanmar during November 2015. Our objectives were to: (1) determine which species of Softshell Turtles occur in IDPA, (2) assess threats to these populations, (3) evaluate the protected area as a release site for captive-bred Softshell Turtles, and (4) make conservation recommendations. To this end, we interviewed 180 people (mostly males) in 30 villages and verified the occurrence of all three species of Softshell Turtles in IDPA. Softshell Turtle populations appear to have undergone precipitous declines during the last 10–15 years largely driven by commercial demand from the illegal trans-boundary wildlife trade with China. Turtle hunting is no longer considered economically worthwhile, but Softshell Turtles continue to be taken as fisheries by-catch. We recommend that existing regulations designed to protect dolphins be enforced, and most importantly electro-fishing be eliminated from IDPA. We also urge authorities to revisit earlier proposals to reduce or eliminate the use of monofilament gill netting in IDPA. Implementation of a community-based fisheries plan to address these issues is warranted. In lieu of effective action, Softshell Turtle populations in IDPA face almost certain extirpation in the near future. IDPA is currently considered unsuitable as a release site for captive-bred Softshell Turtles.