International Journal of Marine Science 2015, Vol.5, No.19, 1-10
1
Research Article Open Access
Sexual differentiation and variations sexual characteristics
Rapana venosa
(Valenciennes, 1846)
Igor P. Bondarev
Benthos Ecology Department, Institute of Biology of the Southern Seas (IBSS), Nakhimov av., 2, Sevastopol, 299011, Russian Federation
Corresponding author email
International Journal of Marine Science, 2015, Vol.5, No.19 doi: 10.5376/ijms.2015.05.0019
Received: 26 Feb., 2015
Accepted: 15 Mar., 2015
Published: 24 Mar., 2015
Copyright
©
2015
Bondarev, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Bondarev, 2015, Sexual differentiation and variations sexual characteristics
Rapana venosa
(Valenciennes, 1846), International Journal of Marine Science,
Vol.5, No.19 1
-
10 (doi
Abstract
For the first time provides photographic images, and discussed a wide range of normal and abnormal colors of gonads
Rapana venosa
from the Black Sea. It has been shown that some abnormal variants of gonads color are becoming the norm, at least
for some contemporary populations of Crimea. The dependence of the change in color gonads with age of the rapa-whelk is shown.
Attention is paid to the color variations of the digestive gland and their relationship to the color of gonads. It is assumed that
specified color changes are evidence of environmentally caused of the species’ form-generation in the evolution process. The species
intersexuality and absence of imposex females in the
R. venosa
Crimean populations is discussed.
Keywords
Anomaly; Ecology; Evolution; Gonad color; Sexual differences;
Rapana venosa
; Imposex females
Introduction
A large predatory gastropod
Rapana venosa
was
accidentally introduced from the native range (North
West Pacific seas) in the Black Sea in the early 1940s
(Chuhchin, 1961b, Bondarev, 2014). High ecological
plasticity of the species and a favorable complex of
environmental factors allowed
R. venosa
to colonize
the Black Sea coastal waters fast enough and continue
resettlement through the Mediterranean basin in the
various areas of the eastern and western Atlantic
(Chuhchin, 1984, Mann et al., 2004, 2006,
Lanfrankoni et al, 2009, Bondarev, 2010, Bondarev,
2014). The need for adaptation to different
environmental conditions, as well as significant
changes in the ecosystem of the Black Sea have
occurred since the time of invasion (Bondarev, 2014)
led to a diverse morphogenesis (Bondarev, 2010,
Bondarev, 2013). First of all morphogenesis appeared
in conchological changes, but as shown in the present
study, the internal organs of
R. venosa
also changing.
Most importantly these changes relate to the gonads
which are color-differentiation of the sexes.
Our present studies found wider spectrum of color
gonads of both males and females, than is available in
previously published material (Chuhchin, 1961 a,
1984, Mann et al., 2006, Micu et al., 2009,
Lanfrankoni et al., 2009, Saglam and Duzgunes, 2014).
Moreover it is shown that the diversity of these colors
is not (necessarily) associated with intersex status of
individuals. Absence or presence of imposex females
analyzed against environmental and physiological
information. For comparison, we studied samples from
several places that differ in their orography and location
relative to the port city of Sevastopol (Figure 1) which
is a source of seawater pollution. The results are
compared with existing data from other
R. venosa
habitats.
The main purpose of this paper is description and
image-fixing of normal and abnormal colors of
R.
venosa
gonads and some other soft parts existing
diversity and discuss possible reasons for extensions
and change their color spectrum. This baseline
information will allow to monitor the further evolution
of the species and to identify directions of further research.
1 Results
Rapana venosa
is dioecious mollusk with
well-defined external sexual characteristics. Its
reproductive system adapted to internal fertilization
and female laying leatherback cocoons. For the
fertilization male has big size penis is usually longer
than 2cm. Gonads of males and females differs in
color, occupy the upper part of the visceral bag lying
on the digestive gland (Figure 2).
