INVESTIGADORES
CIGLIANO Maria Marta
congresos y reuniones científicas
Título:
A biogeographic study of South American Melanoplinae: pattern of diversification along the Andes Mountain Chain
Autor/es:
DINGHI, P.A.; CONFALONIERI, V.A.; CIGLIANO, M. M.
Lugar:
Kunming
Reunión:
Congreso; 11th International Congress of Orthopterology; 2013
Institución organizadora:
The Orthopterists´Society
Resumen:
89
A biogeographic study of South American Melanoplinae: pattern of diversification along the
Andes Mountain Chain
Dinghi, PA1; Confalonieri VA1 and Cigliano, MM2
1Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales,
Universidad de Buenos Aires, Buenos Aires, Argentina;
2División Entomología, Museo de La Plata, La Plata, Argentina
Melanoplinae is one of the largest subfamilies and, one of the main components of the Acrididae
fauna in the American Continent (except in the rain forest biomes). The systematics of this group is
controversial, with different authors recognizing different numbers of tribes, and an evolutionary history
that remains unclear. Three scenarios have been proposed to explain the early biogeographic history
of the Melanoplinae. The first posed a Eurasian origin of the group followed by migrations to North
America, and then South America (Amédégnato, 1977). The second proposed an ancient Laurentian
origin with the Nearctic region as centre, from which migrations began towards the Palaearctic and the
Neotropic regions (Vickery, 1987). The third one, which is based on molecular studies (Amédégnato et
al., 2003), suggests a South American origin followed by a substantial number of northward, eastward
and/or westward migrations.
The Andes, the world?s longest mountain chain, seems to be the main basis for speciation and
diversification events for this group, harboring a great taxonomic and ecological diversity. Despite their
young age, it is highly diverse due to recent geological uplift. Doan (2003) proposed a South-to-North
Speciation Hypothesis (SNSH) for speciation of high Andean taxa, following a South-to-North pattern
generally coinciding with the progression of final uplift of the Andes. According to this scenario, a
phylogenetic hypothesis of relationships of a taxonomic group occurring in the high Andes would show
a branching pattern in which the southernmost species diverged first, followed by the more northern
species, and so on in a northerly pattern. Early studies based on the morphological diversification
of Ponderacris (Melanoplinae), posited a North-to-South progression of speciation (Ronderos &
Carbonell, 1971) but recently, Pocco et al. (2012) postulated just the opposite direction for this same
genus: i.e. a South-to-North speciation pattern, in accordance with the progressive Andean uplift.
Considering these issues, a molecular phylogenetic approach was carried out in order to test the
different scenarios proposed for the Melanoplinae diversification in South America, especially for those
distributed along the Andes Mountain chain, and also to solve some taxonomic controversies within the
group. To these purposes, COI and NADH2 mitochondrial genes from several Melanoplinae species
collected from Argentina to Venezuela along the Andes, were sequenced and analyzed. The following
genera were included (sorted by tribe and bio-region): Jivarus Giglio-Tos, Urubamba Brunerand
Nahuelia Liebermann (Jivarini), which are distributed in the Venezuela and Ecuador ?Páramos?, and
in Argentinean Patagonic Andes; Maeacris Ronderos (Jivarini) from the Peruvian ?Puna?; Coyacris
Ronderos, Chlorus Giglio-Tos, Ponderacris Ronderos & Cigliano, BoliviacrisRonderos & Cigliano,
Baeacris Rowell & Carbonell (Dichroplini), all from the ?Yungas? of Argentina, Perú and Bolivia;
Orotettix Ronderos & Carbonell (Dichroplini), distributed in the Peruvian ?Puna?; Chibchacris Hebard,
Timotes Roberts (Dichroplini) from the Venezuelan ?Páramos?; and finally, the insertae sedis genera
90
Pediella Roberts, Huaylasacris Cigliano, Pocco & Lange, Tiyuantiyana (Cigliano, unpublished), all from
Peruvian ?Puna?; and Meridacris Roberts, from the Venezuelan ?Páramos?. Locusta migratoria (L.) and
several Melanoplus Stål(Melanoplini) species from North America were used as outgroup. The latter
corresponding sequences were downloaded from the GeneBank.
Bayesian and Maximum Parsimony (MP) searches were performed. The evolutionary model
selected for the Bayesian search was GTR. Both searching criteria yielded similar topologies. Six
distinct monophyletic clades were recovered. Maeacris (Jivarini) and the insertae sedis genus
Tiyuantiyana resolves as the most basal sister group. Then, a cluster formed by the two insertae sedis
genera Pediella and Huaylasacris emerge basally to the rest groups. These basal clades belong both
to the Peruvian ?Puna?, supporting a South American origin for the Melanoplini, and to this region as
the primary centre. The rest tribes resolve as follows: (Dichroplini, (Jivarini, Melanoplini)). Again, a
South to North pattern of diversification was observed within both ?Jivarini? and Dichroplini groups.
Within the former, the most basal species is distributed in Patagonia (Argentina), and the most derivate
in the Venezuelan ?Páramos?. Within Dichroplini, the most basal species belongs to the Yungas of
Argentina, Bolivia and Perú, and the most derivate to the Venezuelan ?Páramos?. Finally, the position
of North American Melanoplini also supports the South American origin and posterior dispersion
to the north. On the other hand, the taxonomic status of the Jivarini tribe is again questioned. This
preliminary study suggests the need of a reformulation and/or creation of new taxonomic entities in
order to maintain the natural groups within this subfamily. Summarizing, the biogeographical history
of each main evolutionary group show similar direction of diversification, congruently supporting the
SNSH. However, further analyses will be necessary in order to determine if this process was in concert
with the Andes geological uplift.