Naesiotus
Photo of the day (81): Naesiotus
11-01-2010 21:56
This is a photo of one
of the endemic species of the island of St. Lucia. It
is Naesiotus luciae (Pilsbry, 1897) and was taken
west of Desbarra.
This picture was taken by Ad Hovestadt during his recent trip to the island in November 2009. Thanks Ad!
This picture was taken by Ad Hovestadt during his recent trip to the island in November 2009. Thanks Ad!
Vanishing snails
05-01-2010 22:39
In another recent
publication, Christine Parent and Guy Coppois tell
the story of their fascination with Galápagos land
snails and their concerns about conservation issues
with these animals.
Coppois has a long experience with field work on these islands, visiting the archipelago for the first time in 1973 and continuing during 30 years. He succeeded to collect more than 80 taxa of bulimulids. One of his most remarkable finds was the discovery of living specimens of Naesiotus achatinellus (Forbes, 1850). This only one of the species with a very restricted distribution range and which probably has vanished into extinction. Several species are on the Red List of endangered species.
Habitat destruction and the negative impact of introduced predators and competition of alien pest species, like veronicellid slugs, may be considered the main causes of the decline of land snails on these islands.
The personal stories of both authors reveal their fascination with this group, which is a thankful subject for studies in evolutionary biology.
Reference:
Parent, C.E. & Coppois, G., 2009. On the snails’ trail: evolution and speciation among a vanishing tribe. In: De Roy, T. (ed.), Galápagos: preserving Darwin’s legacy: 74-81. Firefly Books, Richmond Hill, Ontario.
Coppois has a long experience with field work on these islands, visiting the archipelago for the first time in 1973 and continuing during 30 years. He succeeded to collect more than 80 taxa of bulimulids. One of his most remarkable finds was the discovery of living specimens of Naesiotus achatinellus (Forbes, 1850). This only one of the species with a very restricted distribution range and which probably has vanished into extinction. Several species are on the Red List of endangered species.
Habitat destruction and the negative impact of introduced predators and competition of alien pest species, like veronicellid slugs, may be considered the main causes of the decline of land snails on these islands.
The personal stories of both authors reveal their fascination with this group, which is a thankful subject for studies in evolutionary biology.
Reference:
Parent, C.E. & Coppois, G., 2009. On the snails’ trail: evolution and speciation among a vanishing tribe. In: De Roy, T. (ed.), Galápagos: preserving Darwin’s legacy: 74-81. Firefly Books, Richmond Hill, Ontario.
The ecology of adaptive radiation in bulimulids
04-01-2010 11:29
The land snails of the
Galápagos archipelago are amoung the best studied
Neotropical snails. Thanks to Christine Parent
and co-workers, much
progress has been made on our understanding of the
ecology and phylogenetic relationships of this
group (Parent & Crespi, 2006; Parent et al.,
2008).
Recently, a new paper was published with details on the ecology of these species (Parent & Crespi, 2009). Although Galápagos bulimulids are not host-plant specific, they are distributed in space according to different local microhabitats, with differences in substrates, plant species, vegetation types and resting places. The authors also notice an elevational variation in shell shape associated with moisture levels, with more slender shells at lower elevations and more conical shells at higher.
In this study a three-level zonation is followed (coastal, dry lowland, humid highland). Endemic plant species are used as a proxy for resource and habitat complexity. The effect of ecological opportunity and intraspecific phenotypic variation is also quantified by the number of congeners. The results show that the number of congeners inhabiting the same vegetation zone is negatively correlated with the degree of intraspecific variation in shell shape and resource heterogeneity was positively correlated. Ecological opportunity is greatest on younger islands, where relatively high resource heterogeneity combines with low interspecific competition.
The main conclusion of this study is that competition and resource heterogeneity are significant determinants of interspecific phenotypic variation in the context of adaptive radiation.
It should be noted (again) that the taxonomic treatment of this group in this paper is misleading. Galápagos bulimulids are not Bulimulus but should be placed - for now - in Naesiotus. Their proper relationships and taxonomic placement will be treated in one of my upcoming papers. Nevertheless, the authors have done an insightful study into the ecological relationships, which stimulates further research.
Reference:
Parent, C.E. Caccone, A. & Petren, K., 2008. Colonization and diversification of Galápagos terrestrial fauna: a phylogenetic and biographical synthesis. - Phliosopical Transactions of the Royal Society, B 363: 3347-3361.
Parent, C.E. & Crespi, B.J., 2006. Sequrntial colonization and diversification of Galápagos endemic land snail genus Bulimulus (Gastropoda, Stylommatophora). - Evolution 60: 2311-2328.
Parent, C.E. & Crespi, B.J., 2009. Ecological opportunity in adaptive radiation of Galápagos endemic land snails. - American Naturalist 174: 898-905.
Recently, a new paper was published with details on the ecology of these species (Parent & Crespi, 2009). Although Galápagos bulimulids are not host-plant specific, they are distributed in space according to different local microhabitats, with differences in substrates, plant species, vegetation types and resting places. The authors also notice an elevational variation in shell shape associated with moisture levels, with more slender shells at lower elevations and more conical shells at higher.
In this study a three-level zonation is followed (coastal, dry lowland, humid highland). Endemic plant species are used as a proxy for resource and habitat complexity. The effect of ecological opportunity and intraspecific phenotypic variation is also quantified by the number of congeners. The results show that the number of congeners inhabiting the same vegetation zone is negatively correlated with the degree of intraspecific variation in shell shape and resource heterogeneity was positively correlated. Ecological opportunity is greatest on younger islands, where relatively high resource heterogeneity combines with low interspecific competition.
The main conclusion of this study is that competition and resource heterogeneity are significant determinants of interspecific phenotypic variation in the context of adaptive radiation.
It should be noted (again) that the taxonomic treatment of this group in this paper is misleading. Galápagos bulimulids are not Bulimulus but should be placed - for now - in Naesiotus. Their proper relationships and taxonomic placement will be treated in one of my upcoming papers. Nevertheless, the authors have done an insightful study into the ecological relationships, which stimulates further research.
Reference:
Parent, C.E. Caccone, A. & Petren, K., 2008. Colonization and diversification of Galápagos terrestrial fauna: a phylogenetic and biographical synthesis. - Phliosopical Transactions of the Royal Society, B 363: 3347-3361.
Parent, C.E. & Crespi, B.J., 2006. Sequrntial colonization and diversification of Galápagos endemic land snail genus Bulimulus (Gastropoda, Stylommatophora). - Evolution 60: 2311-2328.
Parent, C.E. & Crespi, B.J., 2009. Ecological opportunity in adaptive radiation of Galápagos endemic land snails. - American Naturalist 174: 898-905.
Photo of the day (35): Naesiotus
17-01-2009 12:30
Some species are very rare and may live in oblivion
for over a century. This is e.g. the case with
“Bulimulus
stenogyroides”
that was described by Guppy in 1868 from the island
of Dominica. In my 1974 revision I was unable to
recognize the species, despite the wealth of material
that I had at hand. Guppy’s type material - an
incomplete specimen with only the lower spire
preserved - was lost when the institute that housed
his collection burned down.
Independently, it was recently found by both Ad Hovestadt and David Robinson during brief surveys on the island. Not sure it was just a matter of luck or good collecting (perhaps both), but they even found living specimens.
Photo by courtesy of David Robinson.
The title of this post already unveiled the secret of this taxon: it is not a Bulimulus but a Naesiotus!
Independently, it was recently found by both Ad Hovestadt and David Robinson during brief surveys on the island. Not sure it was just a matter of luck or good collecting (perhaps both), but they even found living specimens.
Photo by courtesy of David Robinson.
The title of this post already unveiled the secret of this taxon: it is not a Bulimulus but a Naesiotus!
Galápagos bulimulids
04-01-2007 22:03
Yesterday I was at
Naturalis and had a very busy and interesting day.
First of all I dissected the myterious Simpulopsis from Hispaniola. Although I'm not 100% sure yet, it most probably isn't a Simpulopsis at all. To be continued...
I briefly met the new scientific director, Menno Schilthuizen, who was Secretary of the NMV in the 1980s when I was President. He returned from Malaysia last year after having successfully worked in Kota Kinabalu and set up a molecular genetics laboratory. I'm sure we will have a more lengthy discussion soon.
Speaking about molecular genetics... Just before Christmas I got notice from Bernhard Hausdorf that he sequenced a number of bulimulids that I had sent to him. Only specimens of two recently collected species produced good results. Most unfortunate for the specimens that I collected during the 1970s and apparently have been preserved too long in alcohol70 to be of any use in this respect. Aargghh, quite frustrating...
However I quickly scanned the collection for other recently collected material and found some species that I prepared for DNA research. Let's hope that they will produce good results. I also have asked several contacts if they possibly can provide me with some freshly collected specimens. It already turns out that - unlike 30 years ago - there are quite some administrative and bureaucratic hurdles to overcome.
But now about Galápagos bulimulids...
In the library I searched for literature referenced by Yesson & Culham. During my habitual check of the latest journals I found a very recent paper by Christine Parent*) on Galápagos bulimulids. She has a very conservative viewpoint regarding the taxonomy as she speaks of Bulimulus (Naesiotus). But content-wise her paper is most interesting, proving that the Galápagos bulimulids are monophyletic and discussion their diversification as they colonized the islands of the archipelago.
Her research will be of interest during the study of Plekocheilus on the Guayana Highlands, which has an islandlike distribution.
*) Parent, C.E. & B.J. Crespi (2006). Evolution 60: 2311-2328.
First of all I dissected the myterious Simpulopsis from Hispaniola. Although I'm not 100% sure yet, it most probably isn't a Simpulopsis at all. To be continued...
I briefly met the new scientific director, Menno Schilthuizen, who was Secretary of the NMV in the 1980s when I was President. He returned from Malaysia last year after having successfully worked in Kota Kinabalu and set up a molecular genetics laboratory. I'm sure we will have a more lengthy discussion soon.
Speaking about molecular genetics... Just before Christmas I got notice from Bernhard Hausdorf that he sequenced a number of bulimulids that I had sent to him. Only specimens of two recently collected species produced good results. Most unfortunate for the specimens that I collected during the 1970s and apparently have been preserved too long in alcohol70 to be of any use in this respect. Aargghh, quite frustrating...
However I quickly scanned the collection for other recently collected material and found some species that I prepared for DNA research. Let's hope that they will produce good results. I also have asked several contacts if they possibly can provide me with some freshly collected specimens. It already turns out that - unlike 30 years ago - there are quite some administrative and bureaucratic hurdles to overcome.
But now about Galápagos bulimulids...
In the library I searched for literature referenced by Yesson & Culham. During my habitual check of the latest journals I found a very recent paper by Christine Parent*) on Galápagos bulimulids. She has a very conservative viewpoint regarding the taxonomy as she speaks of Bulimulus (Naesiotus). But content-wise her paper is most interesting, proving that the Galápagos bulimulids are monophyletic and discussion their diversification as they colonized the islands of the archipelago.
Her research will be of interest during the study of Plekocheilus on the Guayana Highlands, which has an islandlike distribution.
*) Parent, C.E. & B.J. Crespi (2006). Evolution 60: 2311-2328.