Liguus
Florida Liguus populations
03-12-2009 21:10
Tree snails in the
Florida Keys have been studied for about a century
now. They are a good subject to follow the fate of
the different populations on different ‘hammocks’.
Exactly what Fadely (2009) has done.
The study examined the past and present spatial distribution of the Florida tree snail, L. fasciatus solidus, in the Long Pine Key area of the Everglades National Park. Remote sensing and mobile GIS were used to create a GIS database of the field research results. Collection and survey-based data were used to create a current spatial distribution map of L. fasciatus solidus throughout the Long Pine Key area. The data collected during the 2006 survey were compared to a 1931 survey of the same study area conducted by Dr. William Clench of the Museum of Comparative Zoology (MCZ) of Harvard University. The data was used to determine the success of L. fasciatus solidus from 1931 to 2006, to evaluate a correlation between hammock size and the number of color forms, and to detect migration patterns of L. fasciatus solidus within the Long Pine Key area of Everglades National Park. Based on the average success rate for the seven color forms and the hammocks, the L. fasciatus solidus population in the Long Pine Key area
exemplifies one of a stable community. Each color form used for the analysis had a success rate between 67% and 100%. These percentages can only be the worst case scenario based on the fact that many Liguus were not observed, and any others that would have been observed, would only increase the success rate.
An interesting hypothesis is about the relation between the number of colour forms and the size of the hammock. The author supposed that there would be a linear relationship. However, as the figures show, this is clearly not the case. It is not evident from the data presented in his report to what extent re-introductions, migration and differences in data collection between the 1931 and 2006 surveys affect these results.
Reference:
Fadely, J.R., 2009. Population distribution of Liguus fasciatus solidus in Long Pine Key of Everglades National Park: i-xvi, 1-62. Thesis (M.Sc.), Florida Atlantic University, Boca Raton, Florida.
The study examined the past and present spatial distribution of the Florida tree snail, L. fasciatus solidus, in the Long Pine Key area of the Everglades National Park. Remote sensing and mobile GIS were used to create a GIS database of the field research results. Collection and survey-based data were used to create a current spatial distribution map of L. fasciatus solidus throughout the Long Pine Key area. The data collected during the 2006 survey were compared to a 1931 survey of the same study area conducted by Dr. William Clench of the Museum of Comparative Zoology (MCZ) of Harvard University. The data was used to determine the success of L. fasciatus solidus from 1931 to 2006, to evaluate a correlation between hammock size and the number of color forms, and to detect migration patterns of L. fasciatus solidus within the Long Pine Key area of Everglades National Park. Based on the average success rate for the seven color forms and the hammocks, the L. fasciatus solidus population in the Long Pine Key area
exemplifies one of a stable community. Each color form used for the analysis had a success rate between 67% and 100%. These percentages can only be the worst case scenario based on the fact that many Liguus were not observed, and any others that would have been observed, would only increase the success rate.
An interesting hypothesis is about the relation between the number of colour forms and the size of the hammock. The author supposed that there would be a linear relationship. However, as the figures show, this is clearly not the case. It is not evident from the data presented in his report to what extent re-introductions, migration and differences in data collection between the 1931 and 2006 surveys affect these results.
Reference:
Fadely, J.R., 2009. Population distribution of Liguus fasciatus solidus in Long Pine Key of Everglades National Park: i-xvi, 1-62. Thesis (M.Sc.), Florida Atlantic University, Boca Raton, Florida.
Florida Liguus
07-08-2009 21:26
Juan C. Aguero sent me links to his work on Florida
Liguus. The first is a
gallery,
picturing many of the colour forms present at
different hammocks in Florida and on different
tree species.
But Juan also has his own blog, on which he reports his trips in the field to make the nice photographs shown in the gallery. One thing is clear: besides snails you will readily find some mosquitoes. You win some and you lose some...
Thanks Juan, and keep up the good work!
But Juan also has his own blog, on which he reports his trips in the field to make the nice photographs shown in the gallery. One thing is clear: besides snails you will readily find some mosquitoes. You win some and you lose some...
Thanks Juan, and keep up the good work!
Florida Liguus
25-06-2009 22:04
Thomas Watters has published a very useful book on
Annulariidae a couple of years ago and when I looked
him up on the internet, I found out that the Ohio
State University Museum (OSUM) at Columbus has part
of their site dedicated to Florida
Liguus.
Liguus is a genus of arboreal snails that can be found in Florida on ‘hammocks’.
The word “hammock” was first used by early inhabitants to mean a cool and shady place. Later, settlers of Florida used the word “hummock” to indicate areas that were slightly higher in elevation from the rest of the land. Today, the term hammock is used in Florida to describe forest habitats that are typically higher in elevation than surrounding areas and that are characterized by hardwood forests of broad-leaved evergreens. Tropical hardwood hammocks occur in south Florida and along the Florida coastlines where danger from frost is rare and tropical trees and shrubs common to the Caribbean islands (West Indian origin) are able to survive. (source: Karim & Mean, 2004)
On the OSUM there is a brief introduction to the Floridan Liguus. The many ‘varieties’ or ‘forms’ described in literature are nicely plotted on maps. What makes the museum collection important, is the availability of material collected in the beginning of the previous century when human “development” hadn’t spread out as far as it is today.
When you look at the maps, you can clearly see that the eastern colonies have been eradicated. Sometimes, museums act as the physical proof of lost biodiversity. Unfortunately, too many times...
Liguus is a genus of arboreal snails that can be found in Florida on ‘hammocks’.
The word “hammock” was first used by early inhabitants to mean a cool and shady place. Later, settlers of Florida used the word “hummock” to indicate areas that were slightly higher in elevation from the rest of the land. Today, the term hammock is used in Florida to describe forest habitats that are typically higher in elevation than surrounding areas and that are characterized by hardwood forests of broad-leaved evergreens. Tropical hardwood hammocks occur in south Florida and along the Florida coastlines where danger from frost is rare and tropical trees and shrubs common to the Caribbean islands (West Indian origin) are able to survive. (source: Karim & Mean, 2004)
On the OSUM there is a brief introduction to the Floridan Liguus. The many ‘varieties’ or ‘forms’ described in literature are nicely plotted on maps. What makes the museum collection important, is the availability of material collected in the beginning of the previous century when human “development” hadn’t spread out as far as it is today.
When you look at the maps, you can clearly see that the eastern colonies have been eradicated. Sometimes, museums act as the physical proof of lost biodiversity. Unfortunately, too many times...
Photo of the day (52): Liguus
03-06-2009 20:51
After my
post
on Cuban Rapid Assessments reports, Adrián González
kindly pointed out to me that the new record in one
of those reports for
Liguus
fasciatus
from the Cubitas area, wasn’t in fact any news but
had been mentioned before in literature [reference to
be added].
These pictures are Liguus fasciatus crenatus (Swainson, 1821) from this area. Besides being a devoted malacologist, Adrián is a very skillful photographer to whom I like to give full credits.
These pictures are Liguus fasciatus crenatus (Swainson, 1821) from this area. Besides being a devoted malacologist, Adrián is a very skillful photographer to whom I like to give full credits.
Rapid assessment in Cuba
15-05-2009 11:30
During a literature survey on
Liguus,
I came across a
report
(Diaz et al., 2006) that was published some years
ago. It is the result of a joint Cuban-American
assessment of the biodiversity in part of the
province Camagüey in east Cuba, the Sierra de
Cubitas.
Malacology is but a small part of the results, for which field observations were made during four days in September 2002. The only picture of snails is, however, from Liguus fasciatus.
It is a new record for the Sierra de Cubitas and together with another new record for Steatocoptis bioscati, the total number of molluscs for the area is 50.
When I glanced through the report, my eyes caught some interesting sentences related to Opisthosiphon (Annulariidae). Four species of this genus occur in the Sierra de Cubitos: O. banoense, O. evanidum, O. greenfieldi, and O. obturatum. “Individuals of the four species were seen copulating with one another and I was able to determine that females always have a pattern of dark stripes on their shells, while the males have pale or dark shells without those stripes.” The authors add that this observation should serve as a starting point for a taxonomic review of the genus.
It is precisely observations like this which can only be made in the field and which make these reports special. A little gem found, that I wanted to pass on to you.
More reports from the same series, covering also other Neotropical countires, can be found here. However, not all contain data on molluscs. Actually, only a few others related to Cuba...
Reference:
Díaz, L.M., Alverson, W.S., Barreto, A. & Wachter,T., 2006. Cuba: Camagüey, Sierra de Cubitas: 1-180. Rapid Biological Inventories Report 08. The Field Museum, Chicago.
Malacology is but a small part of the results, for which field observations were made during four days in September 2002. The only picture of snails is, however, from Liguus fasciatus.
It is a new record for the Sierra de Cubitas and together with another new record for Steatocoptis bioscati, the total number of molluscs for the area is 50.
When I glanced through the report, my eyes caught some interesting sentences related to Opisthosiphon (Annulariidae). Four species of this genus occur in the Sierra de Cubitos: O. banoense, O. evanidum, O. greenfieldi, and O. obturatum. “Individuals of the four species were seen copulating with one another and I was able to determine that females always have a pattern of dark stripes on their shells, while the males have pale or dark shells without those stripes.” The authors add that this observation should serve as a starting point for a taxonomic review of the genus.
It is precisely observations like this which can only be made in the field and which make these reports special. A little gem found, that I wanted to pass on to you.
More reports from the same series, covering also other Neotropical countires, can be found here. However, not all contain data on molluscs. Actually, only a few others related to Cuba...
Reference:
Díaz, L.M., Alverson, W.S., Barreto, A. & Wachter,T., 2006. Cuba: Camagüey, Sierra de Cubitas: 1-180. Rapid Biological Inventories Report 08. The Field Museum, Chicago.
Colours, Cuba, Liguus
13-05-2009 21:48
Species of
Liguus
are very abundant on Cuba, and usually very
colourful. Or rather should I say: ‘varieties’,
colour forms’ or ‘subspecies’, as Hillis et al.
(1991) showed the various morphs can be grouped
genetically into a limited number of species.
Last year a beautiful book was published on Cuban land-snails (González Guillén, 2008); it was mentioned briefly in this and this post. Upon my request, the author sent me several pictures of Liguus, illustrating the bewildering variation as far as the colour pattern goes. Each colour form is restricted to a small area of limestone hill(s); in Cuba called ‘mogote’. Many of these morphs are already extinct or highly endangered, due to the destruction of the mogotes for tourism (or economic ‘development’). Still, there is none of them listed on the IUCN Red List 2008. I have expressed my doubts about the listing procedure earlier here.
Much has already been written about Liguus, most often in popular articles. Yet, the genetical mechanism is incompletely known and the phylogeography is still poorly understood. In my humble opinion, Liguus needs urgently more attention.
Many thanks to Andrián González for sending me these stunning pictures. From left to right, top to bottom: Liguus fasciatus achatinus Clench, 1934; L. f. goodrichi Clench, 1934; L. f. torrei Clench, 1934; L. flammellus bermudezi Clench, 1934.
References:
González Guillén, A., 2008. Cuba, the landshells paradise: 1-306. - Greta Editores, Lleida.
Hillis, D.M., Dixon, M.T. & Jones, A.L., 1991. Minimal genetic variation in a morphologically diverse species (Florida tree snail, Liguus fasciatus). - Journal of Heredity 82: 282-286.
Last year a beautiful book was published on Cuban land-snails (González Guillén, 2008); it was mentioned briefly in this and this post. Upon my request, the author sent me several pictures of Liguus, illustrating the bewildering variation as far as the colour pattern goes. Each colour form is restricted to a small area of limestone hill(s); in Cuba called ‘mogote’. Many of these morphs are already extinct or highly endangered, due to the destruction of the mogotes for tourism (or economic ‘development’). Still, there is none of them listed on the IUCN Red List 2008. I have expressed my doubts about the listing procedure earlier here.
Much has already been written about Liguus, most often in popular articles. Yet, the genetical mechanism is incompletely known and the phylogeography is still poorly understood. In my humble opinion, Liguus needs urgently more attention.
Many thanks to Andrián González for sending me these stunning pictures. From left to right, top to bottom: Liguus fasciatus achatinus Clench, 1934; L. f. goodrichi Clench, 1934; L. f. torrei Clench, 1934; L. flammellus bermudezi Clench, 1934.
References:
González Guillén, A., 2008. Cuba, the landshells paradise: 1-306. - Greta Editores, Lleida.
Hillis, D.M., Dixon, M.T. & Jones, A.L., 1991. Minimal genetic variation in a morphologically diverse species (Florida tree snail, Liguus fasciatus). - Journal of Heredity 82: 282-286.
Chirality
18-12-2008 09:19
Chirality is the phenomenon that an assymetric
structure can come in two, non-identical,
mirror-image forms. This phenomenon can be found in
many groups of animals and plants. Land snails are
just one example, leading to sinistral specimens
besides the normal dextral ones in a population
(intra-specific chirality) or sinistral species among
other, dextral species in a group (inter-specific
chirality).
In the Neotropics there are also a few examples of chirality. In Orthalicidae there are three genera: Drymaeus, Liguus and Corona. In the Subulinidae there is an example in Rhodea. And I have seen a report on a sinistral Megalobulimus, but that may be just an aberration, just like the specimens of Rabdotus, Thaumastus and Euglandina that can be found here.
Let’s explore a bit more of it. The first example is Rhodea wallisiana Dohrn, 1875 from Colombia. This is a rare species of which only a few specimens are known, which are all sinistral.
Drymaeus provides another example of a sinistral species, D. tropicalis (Morelet, 1849) from Mexico. Also Corona perversa (Swainson, 1820) - occurring in northern Brazil and the Guianas - and C. regalis (Hupé, 1857) - the latter also westward into lowland Peru and Ecuador - are normally sinistral. There is one taxon, described as Corona incisa forma machadoensis Strebel, 1909 from “Rio Machado” [in Brazil, it might be either Edo. Rodônia, Río Ji-Paraná or Río Machado in Edo. Tocantins, Minas Gerais or Matto Grosso], which is sinistral too.
Finally there are several examples of Liguus species, normally dextral, that show chirality. The excellent website of Emilio Power [unfortunately not longer updated] provides photos of sinistral Liguus vittatus (Swainson, 1822) and L. virgineus (L., 1758).
The phenomenon of chirality presents some interesting biological questions, e.g.:
- what is the genetic basis for each of the two chiral morphs?
- what maintains the chiral dimorphism in some species (intra-specific chirality)?
- what is the role of chirality in speciation?
References:
Grego, J., Steffek, J. & Infante, A.P., 2007. Review of the genus Rhodea (Gastropoda, Pulmonata, Subulinidae), with description of two new species from Colombia. - Basteria 71: 13-28.
In the Neotropics there are also a few examples of chirality. In Orthalicidae there are three genera: Drymaeus, Liguus and Corona. In the Subulinidae there is an example in Rhodea. And I have seen a report on a sinistral Megalobulimus, but that may be just an aberration, just like the specimens of Rabdotus, Thaumastus and Euglandina that can be found here.
Let’s explore a bit more of it. The first example is Rhodea wallisiana Dohrn, 1875 from Colombia. This is a rare species of which only a few specimens are known, which are all sinistral.
Drymaeus provides another example of a sinistral species, D. tropicalis (Morelet, 1849) from Mexico. Also Corona perversa (Swainson, 1820) - occurring in northern Brazil and the Guianas - and C. regalis (Hupé, 1857) - the latter also westward into lowland Peru and Ecuador - are normally sinistral. There is one taxon, described as Corona incisa forma machadoensis Strebel, 1909 from “Rio Machado” [in Brazil, it might be either Edo. Rodônia, Río Ji-Paraná or Río Machado in Edo. Tocantins, Minas Gerais or Matto Grosso], which is sinistral too.
Finally there are several examples of Liguus species, normally dextral, that show chirality. The excellent website of Emilio Power [unfortunately not longer updated] provides photos of sinistral Liguus vittatus (Swainson, 1822) and L. virgineus (L., 1758).
The phenomenon of chirality presents some interesting biological questions, e.g.:
- what is the genetic basis for each of the two chiral morphs?
- what maintains the chiral dimorphism in some species (intra-specific chirality)?
- what is the role of chirality in speciation?
References:
Grego, J., Steffek, J. & Infante, A.P., 2007. Review of the genus Rhodea (Gastropoda, Pulmonata, Subulinidae), with description of two new species from Colombia. - Basteria 71: 13-28.
Photo of the day (20): Liguus
12-10-2008 18:10
While browsing through Flickr’s nearly infinite
database I saw a lot of snails. They seem to
stimulate people’s creativeness, judging from the
weird ‘species’ you may encounter. Besides that, the
number of helices is overwhelming. That said, I still
found some gems and this is one of them: Liguus
virgineus (L.)
A new book on Cuban land snails
08-10-2008 17:03
Cuba is known for its diversity in land snails, but
until now no comprehensive book was available. This
seems to have changed recently, since I received
notice of the new publication by Alejandro G.
Guillén, Cuba - the landshells paradise, 305 pp., 25
colour plates. It is published by
Conchbooks.
Just a few pictures of Liguus from the brochure that was sent out today.
More on it later, when I’ve seen the actual book.
Just a few pictures of Liguus from the brochure that was sent out today.
More on it later, when I’ve seen the actual book.
Photo of the day
09-02-2008 17:32
Perhaps this will become a new thread, not sure
yet... After all, there are not so much new pictures
on Orthalicidae, at least not a daily basis :-)
This I found on a web site dedicated to Liguus in Florida. In human sexology it would be called interracial, in malacology intergenerical??
Liguus fasciatus (Müller, 1774) and Orthalicus floridensus Pilsbry, 1899 mating (photo: Phil Poland)
This I found on a web site dedicated to Liguus in Florida. In human sexology it would be called interracial, in malacology intergenerical??
Liguus fasciatus (Müller, 1774) and Orthalicus floridensus Pilsbry, 1899 mating (photo: Phil Poland)