In the article called "Sexual dimorphism and male mating success in the tentacled blenny, Parablennius tentacularis (Teleostei: Blenniidae)"
The sexually selected trait or traits in question. Based on what you gathered from the Article, What is the trait determining which individuals get to reproduce that the authors are interested in?
Transcribed Image Text: Abstract Although external sexually dimorphic traits are
commonly found in males of combtooth blenny species,
little is known about the benefit they can convey to male
mating success. Indeed, while female preferences for
large males have been demonstrated in some species, the
possible role played by dimorphic ornaments has been
neglected. We now report on the tentacled blenny, Pa-
rablennius tentacularis, a species where males are char-
acterized by bulb glands on the anal fin and both sexes
exhibit a dark spot on the dorsal fin and orbital tenta-
cles. Males are territorial, make nests in empty bivalve
shells, and provide solitary parental care for the eggs.
Using morphometric analysis and field collected data on
male and female external features, nest characteristics
and number of eggs in the nests, we have assessed the
development of dimorphic traits in both sexes and male
mating success. The results reveal that orbital tentacles
of males are more developed and more variable in size
than those of females. Larger males exhibit longer
orbital tentacles and larger anal glands but do not nec-
essarily occupy larger nests. Male mating success is sig-
nificantly correlated with the inner nest surface area and
with orbital tentacle size but not with body size. These
results provide support for a primary role of male
ornaments in enhancing blenny male mating success and
are discussed in the context of mate choice for direct and
indirect benefits.
Introduction
When Darwin (1871), referring to some Blenniidae
species, penned: ".. a crest is developed on the head of
the male during the breeding-season, and the body at the
same time becomes more bright-coloured. There can be
little doubt that this crest serves as a temporary sexual
ornament, for the female does not exhibit a trace of it."
he was using an excellent model to indicate the possible
role of sexual selection in shaping fish external traits.
Combtooth blennies are one of the teleost families
exhibiting the most diverse array of sexually dimorphic
traits, including body size, colour pattern, enlarged
dorsal fins, cephalic ornaments such as crests or different
types of tentacles, and specialized glands on the median
fins (Breder and Rosen 1966; Zander 1975; Papaco-
stantinou 1979). Blenny dimorphic features can be either
temporary, such as male spawning colours, or perma-
nent (Thresher 1984). Among the latter, some are pres-
ent only in males, while others are present in both sexes
but more pronounced in males (Smith 1974; Zander
1975; Papacostantinou 1979; Thresher 1984).
A crest on the head, as well as nasal, orbital, and
nape tentacles, have been described in both sexes of
some Mediterranean blennies (Zander 1975). In Salaria
pavo, one of the most extensively studied species (Fi-
shelson 1963; Patzner et al. 1986; Ruchon et al. 1995;
Gonçalves et al. 1996; Oliveira et al. 1999), the crest's
height is known to be influenced by sexual selection,
with males adopting an opportunistic mating tactic
being poorly ornamented compared to dominant, terri-
torial males (Ruchon et al. 1995; Gonçalves et al. 1996).
Orbital tentacles have been described to be more devel-
oped in males of Aidablennius sphynx and some Para-
blennius species (Zander 1975); however, quantitative
information on their inter- and/or intra-sexual variabil-
ity has never been collected. Another set of dimorphic
traits in blennies that is permanent and found only in
males are the glands located on median fins: fleshy pads
on the leading edge of the anal fin or on the rays of the
Transcribed Image Text: anal and dorsal fins (Eggert 1931; Wickler 1957; Smith
1974; Zander 1975; Northcott and Bullock 1991). The
glands, developing on the two most anterior anal spines,
called bulb glands, are globular and rugose, while those
developing on the ends of soft anal and dorsal fin rays,
called club glands, are elliptical and smooth (Zander
1975). Their presence and morphology appear to vary
widely among species (Smith 1974; Zander 1986). In
addition, in some Mediterranean species the presence of
these glands appears to vary with male mating tactics,
being highly developed in territorial nesting males while
absent or rudimentary in parasitic males (Ruchon et al.
1995; Gonçalves et al. 1996; Oliveira et al. 2001a; Neat et
al. 2003). However, the role of these glands in repro-
duction and sexual selection is not well understood. In
summary, despite Darwin's indication that some blenny
external traits may serve to enhance male attractiveness,
detailed studies on the full set of dimorphic characters
displayed by a species in order to verify their intra- and/
or inter-sexual variability and their possible relation
with male mating success, still remain scanty.
Blenny reproductive patterns appear to be consistent
throughout the family (Breder and Rosen 1966;
Thresher 1984; Patzner et al. 1986; Côté and Hunte
1989a; Kraak 1994; Sunobe et al. 1995; Oliveira et al.
1999). Males defend a breeding territory in which fe-
males come to spawn in a cavity, such as holes, empty
shells, crevices, etc. Eggs are demersal, are laid in a
single layer on the inner surface of the nest, and are
guarded exclusively by the male until hatching (Breder
and Rosen 1966; Thresher 1984). In all species studied to
date, egg batches at different stages of development have
been found in the same nest, a robust indication of
polygyny, and females have been described to sequen-
tially lay eggs with different males (Patzner et al. 1986;
Côté and Hunte 1989a; Santos and Barreiros 1993;
Kraak 1994; Neat and Locatello 2002). Hence, the
mating system, often defined as a resource defence
polygyny, can be considered promiscuous. Male mating
success has consistently been shown to be positively
correlated with body size and/or nest size (Côté and
Hunte 1989a, b; Sunobe et al. 1995; Oliveira et al. 1999;
Oliveira et al. 2000; Gonçalves et al. 2002; Neat and
Locatello 2002). Other morphological and behavioural
male traits, such as age, body colour, intensity of
courtship and intensity of parental care, while playing a
major role in some species (Côté and Hunte 1993;
Oliveira et al. 2000), appeared unrelated to male success
in others (Kraak 1994). The variability of sexually
dimorphic traits, other than male size and coloration,
was investigated only in the peacock blenny where they
did not appear to be significantly related to male mating
success (Oliveira et al. 1999; Gonçalves et al. 2002).
In this study we examined the natural variation of
some external traits and male mating success in the
tentacled blenny, Parablennius tentacularis (Brünnich
1768), a shallow water species inhabiting rocky sub-
strates in the Mediterranean, Black Sea and the Atlantic
(Zander 1986). This medium-sized blenny spawns in
holes where males care for eggs; both sexes have a black
spot on the dorsal fin and orbital tentacles (Zander
1986). Males, in addition, exhibit bulb glands on the
spiny rays of the anal fin (Zander 1986). With the aim to
investigate the correlates of male mating success, nests
and nesting males were collected in the field and data on
male traits, nest inner surface area and egg clutches were
recorded.