Phylogeny of dwarf geckos of the genus Lygodactylus (Gekkonidae) in the Western Indian Ocean
Author
Röll, Beate
Institute of Zoology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany;
Author
Sanchez, Mickaël
Nature Océan Indien, 46 rue des Mascarins, 97429 Petite Ile, La Réunion, France; & Laboratoire PVBMT, Université de La Réunion, 97410 Saint-Pierre, La Réunion, France;
Author
Gippner, Sven
0000-0003-2621-1001
Zoological Institute, Technical University of Braunschweig, Mendelssohnstr. 4, 38106 Braunschweig, Germany; s. gippner @ tu-braunschweig. de; https: // orcid. org / 0000 - 0003 - 2621 - 1001
s.gippner@tu-braunschweig.de
Author
Bauer, Aaron M.
Department of Biology and Center for Biodiversity and Ecosystem Stewardship, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085, USA;
Author
Travers, Scott L.
0000-0003-4656-4613
Department of Biological Sciences, Rutgers University-Newark, 195 University Avenue, Newark, NJ 07102, USA; scott. travers @ rutgers. edu; https: // orcid. org / 0000 - 0003 - 4656 - 4613
scott.travers@rutgers.edu
Author
Glaw, Frank
Zoologische Staatssammlung München (ZSM-SNSB), Münchhausenstrasse 21, 81247 München, Germany;
Author
Hawlitschek, Oliver
Leibniz Institute for the Analysis of Biodiversity Change (LIB), Museum of Nature, Martin-Luther-King-Platz 3, 20146 Hamburg, Germany;
Author
Vences, Miguel
0000-0003-2621-1001
Zoological Institute, Technical University of Braunschweig, Mendelssohnstr. 4, 38106 Braunschweig, Germany; s. gippner @ tu-braunschweig. de; https: // orcid. org / 0000 - 0003 - 2621 - 1001
s.gippner@tu-braunschweig.de
text
Zootaxa
2023
2023-06-29
5311
2
232
250
http://dx.doi.org/10.11646/zootaxa.5311.2.4
journal article
10.11646/zootaxa.5311.2.4
1175-5326
8094276
0EDA9A54-81F2-4397-8F36-0FAC9A0CF356
4.3.
Lygodactylus verticillatus
Lygodactylus verticillatus
from
Madagascar
and from Europa Island do not differ in scalation (
Boettger 1913
;
Pasteur 1965
). The slight difference in the number of precloacal pores mentioned by
Pasteur (1965)
was not supported by this study. Both populations show a very similar variation in coloration and in patterning. Thus,
L. verticillatus
from
Madagascar
and Europa cannot be distinguished by their external appearance or by the number of precloacal pores.
The most basal node within
L. verticillatus
separates specimens from the southern Malagasy localities Sakaraha and Isalo from all other samples. Sakaraha lies approximately
135 km
from
Toliara
on the main road to the Isalo National Park. The remaining sister subgroup consists of specimens exclusively from the coastal regions of
Madagascar
, approximately from Morondava southwards to
Toliara
, and the insular population. We cannot exclude an inland origin of the
L. verticillatus
from Europa Island. However, based on our morphological and genetic dataset, it seems more likely that the nearest relatives of the insular
L. verticillatus
are conspecifics from populations in the coastal regions of south-western
Madagascar
.
We found no relevant morphological differences, and only weak genetic differences between the Malagasy and the insular population, and only weak genetic variation within the monophyletic lineage of Europa Island. This agrees with the hypothesis of a relatively recent colonization as suggested by
Pasteur (1965)
.
Europa Island is
355 km
west-northwest from Toliara or
300 km
southwest from Cap
Saint-Vincent
close to Morombe,
529 km
east-northeast from
Inhambane
(
Mozambique
) and approximately
600 km
south of Juan de Nova (
Caceres 2003
;
Fricke
et al.
2013
). It is nearly circular (6 ×
7 km
) with a total area of
30 km
2
(
Caceres 2003
) and represents the largest island of the Îles Éparses. Europa Island belongs to the group of ‘modern’ isolated seamounts in the Channel, possibly developed during Oligocene to Miocene times (
Courgeon
et al
. 2016
).
Lygodactylus verticillatus
could have reached Europa Island recently by natural transoceanic dispersal or by human-mediated dispersal. While a natural dispersal would be supported by flows westward from
Madagascar
to mainland Africa (
Ali & Huber 2010
), a much simpler and thus more parsimonious alternative explanation is ship-borne dispersal.
Lygodactylus verticillatus
could have arrived at Europa Island e.g., with ships of Malagasy fishermen seasonally searching for nesting chelonians, or with ships of European (French) settlers who started their settlement from
Toliara
and lived on the island from approximately 1860 to the 1920s (
Fricke
et al.
2013
). The amount of genetic variation found within Europa (three haplotypes differing by up to two mutations in 16S) would be in agreement with either (i) ship-borne dispersal or (ii) natural dispersal of multiple individuals, or (iii) natural dispersal of a single individual at a somewhat deeper point in time, with subsequent in-situ genetic diversification. Support for either of these hypotheses could come from a denser sampling of Malagasy populations: the presence of haplotypes identical to those on Europa in Malagasy populations would allow to reject the third hypothesis, and given that simultaneous or repeated natural dispersal to such a small islet is rather unlikely, ship-borne introduction would in this case remain as the most probable hypothesis. Only if the presence of the Europa haplotypes in
Madagascar
could be reasonably excluded, the third hypothesis would be supported.
Lygodactylus verticillatus
is adapted to dry climatic conditions. In south-western
Madagascar
, the species inhabits shrubs and trees in semi-arid areas as well as fences and walls in human settlements (
Puente
et al.
2009
). On Europa Island, it is widely distributed and occurs in most natural habitats on rocks, shrubs, trees and in a dry euphorbia forest as well as in human settlements (
Brygoo 1966
;
Sanchez
et al.
2015
, 2019). The conditions for
L. verticillatus
in the coastal regions of south-western
Madagascar
and on Europa are very similar, facilitating the survival on the island.