CONTENT - International Society of Zoological Sciences

S2 ICZ2008 - Abstracts
S3 - Animal genitalia in evolution-in honour of William G.Eberhard
Dragonflies (Aeshnidae, Corduliidae, Gomphidae and
Libellulidae), of the Llanos Orientales, Colombia: species, inter
and intraspecific variation of the genitalia
Catalina Amaya-Perilla 1 and Gonzalo Fajardo 2
1 Universidad Jorge Tadeo Lozano, Facultad de Ciencias Naturales,
Programa de Biología Ambiental, Bogotá, Colombia
2 Universidad Jorge Tadeo Lozano, Facultad de Ciencias Naturales,
Programa de Biología Marina, Bogotá, Colombia
The knowledge about the genitalia of Anisoptera (Insecta:Odonata)
is very little since these individuals are very difficult to capture and
mark. In Colombia there is no information about this subject,
therefore, the purpose of this study is to add information about the
variation of the genitalia for the suborder Anisoptera in the Llanos
Orientales Meta department of Colombia. We sampled the
specimens of the suborder Anisoptera (Odonata) on 11 sampling
areas (farms): 8 sampling areas of gallery forest and savannah, 2
sampling areas of Andean foothills and 1 sampling area of lower
mountain forest. We used entomological nets in two different
seasons from 2003 to 2007 and one season of 2008. All the
collected material was preserved through immersion in acetone for
12 hours, and was later determined to genera. We explored the
variation between the genitalia of the specimens collected with
Elliptic Fourier analysis and semilandmarks. We found in total 575
specimens and 24 genera distributed in 4 families: Aeshnidae,
Corduliidae, Gomphidae and Libellulidae. The genitalia studied for
the males showed inter and intra specific variation, showing a
significant variation between the genera studied. These differences
could be used as tools for the evolutionary relationships among the
genitalia of the group.
The secret sexual life of Pea Crabs – Reproductive Morphology
of European Pinnotheridae (Crustacea, Decapoda, Brachyura)
Carola Becker 1 , Dirk Brandis 2 , Volker Storch 3 and Michael Tuerkay 1
1
Research Institute Senckenberg, Senckenberganlage 25, 60325
Frankfurt/Main, Germany
2
Zoological Museum, University of Kiel, Hegewischstr. 3, 24105 Kiel,
Germany
3
Zoological Institute, University of Heidelberg, Im Neuenheimer Feld
230, 69120 Heidelberg, Germany
Pea Crabs are not larger than a thumbnail and live commensally
inside a variety of invertebrates. While juveniles of both sexes still
look very similar - being agile swimmers, partly free-living and just
occasionally found inside the host - a metamorphosis takes place in
the female after mating which results in a conspicuous sexual
dimorphism. From now on, the female focuses her life on feeding
and breeding hidden inside the host, while the male remains freeliving,
only occasionally found together with the female in the host.
Pea Crabs have a quite complicated life cycle and due to their cryptic
way of life it is hard to observe their sexual behaviour. Instead of that,
I examined the functional reproductive morphology in order to
understand basic adaptions and possible processes in copulation,
sperm storage and fertilisation. I used histological methods, Electron
Microscopy (SEM & TEM) and Confocal Laser Scanning Microscopy
(CLSM).
The pinnotherids’ female spermatheca shows a high degree of
complexity: While a holocrine glandular tissue is located in the
ventral “insemination area” where oviduct and vagina are connected
to the spermatheca, an apocrine glandular epithelium lines out the
dorsal “sperm-storage area” of the spermatheca, that is described
here for the first time for true crabs.
The significance of the morphology and function of the male and
female reproductive systems for understanding the evolutionary
pathways of the sexual biology is discussed in the context of other
true crab families.
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Sexual coevolution and the evolution of genital traits in
Lepidoptera
Carlos Cordero 1 , Víctor Sánchez 2 and Blanca Hernández 3
1 Departamento de Ecología Evolutiva, Instituto de Ecología,
Universidad Nacional Autónoma de México (UNAM), Mexico City.
2 Posgrado en Ciencias Biológicas, Instituto de Ecología, UNAM.
3 Departamento de Biología Evolutiva, Facultad de Ciencias, UNAM.
The convergence and divergence of male and female interests
during sexual reproduction generates reciprocal selection pressures
between the sexes. The continuous development and elaboration of
male and female traits resulting from these selection pressures is
known as sexual coevolution. We present sexual coevolution
hypotheses for the evolution of two genital traits widely distributed in
the Lepidoptera. (1) Signa are sclerotized structures located on the
inner wall of the corpus bursa of females, whose main function is
tearing open spermatophores. We propose that polyandry would
favor the evolution of thick spermatophore envelopes that take
longer to be broken, thus decreasing female remating rate, and that
this would select for signa that allow females to recover control of
their remating rate. We tested this hypothesis by a comparative
study and found: (a) the predicted association between mating
pattern and the presence of signa in a sample of 37 taxa, and (b) the
predicted association between thickness of the spermatophore
envelopes and the presence and characteristics of signa in a sample
of Heliconius and Eueides (Nymphalidae) species with different
mating system. (2) The cornuti are sclerotized structures of the
endophallus, which in some species break off and remain within the
corpus bursae of females. We describe the diversity of cornuti,
propose hypotheses on their function, and discuss ways of testing
these hypotheses. Our analyses suggest that sexual coevolution has
played a major role in the evolution of genitalia in the Lepidoptera.
Sexually antagonistic coevolution and rapid divergent evolution
of animal genitalia
William G. Eberhard
Smithsonian Tropical Research Institute, and Universidad de Costa
Rica
A recent summary by Hosken and Stockley concluded that current
evidence strongly favors sexual selection as the primary force driving
rapid divergent evolution of genitalia, but that it is not clear whether
sexually antagonistic coevolution (SAC) or cryptic female choice
(CFC) is responsible. I will explain in this talk why I believe the
current balance is more strongly tilted against SAC than they imply.
SAC has the virtue of generating relatively clear predictions. The
evidence against it includes large surveys of insects and spiders
(involving many thousands of species) that found: a lack of the
predicted correlation between rapid divergent evolution of male
genitalia and the behavioral contexts in which male-female interests
are more likely to be in conflict in different species; a general lack of
the predicted female defensive coevolution in groups with speciesspecific
male genitalia; only weak genital diversification in groups
with especially intense male-female conflicts; and a strong trend
toward allometric scaling patterns that are opposite of those
predicted by SAC. This evidence does not rule out SAC for particular
cases at particular moments in evolution; but the combination of very
large sample sizes and the lack of traces of trends predicted by SAC
implies that the effect of SAC on rapid divergent genital evolution
must be small. If SAC has acted, it has apparently been brief, weak,
or inconsistent; most of the modern diversity of genitalia is
apparently due to some other factor.