Distribution, hybridization and variation in the Israeli landsnail Levantina (Pulmonata: Helicidae)

Heller, Joseph

doi:10.1111/j.1096-3642.1979.tb01109.x

Cited by 19 publications

(14 citation statements)

References 19 publications

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“…All examples of tropical snails and the European species Discus rotundatus show a negative correlation between relative height and rainfall, whereas the examples from Israel show the opposite pattern. As discussed above, drier Heller, 1979Buliminus spp. In most cases, published data are not sufficient to determine to what degree geographic variation in relative height is a function of variation in whorl number.…”

Section: Shell Shapementioning

confidence: 77%

Variation in Land-Snail Shell Form and Size and its Causes: A Review

Goodfriend¹

1986

Systematic Zoology

189

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JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Abstract.-Variation in land-snail shell form has been extensively documented, but its causes are poorly understood. For no character are there general rules relating shell form to environmental characteristics, although certain correlations are common. Size variation generally has a large genetic component. Larger snails are often associated with moister conditions; the effect may be inductive (direct) or selective, but the mechanism is not documented. Snails may attain smaller adult sizes at higher population densities, apparently through the effects of pheromones on growth rate. Relative aperture area tends to be smaller under drier conditions, probably because of selection for smaller whorl cross-sectional area to reduce water loss. Larger snails tend to have higher whorl expansion rates. This pattern is variously interpreted as relating to the maintenance of constant attachment area/weight, whether of foot surface area when the snail is active or when attached to a substrate or of aperture perimeter when attached. Apertural denticles are generally thought to represent adaptations to reduce predation. Relative shell height of snail species relates to the angle of the substrate on which activity occurs; this could be related to the mechanics of shell balance. For unknown reasons, helicid species in the Mediterranean area frequently have forms with keeled and with rounded shell peripheries. Snails living on calcareous substrates sometimes have thicker shells; the effect is not necessarily direct.Surprisingly, only a weak relationship exists between shell thickness and moisture conditions. Shell coiling sometimes occurs in the opposite direction between sympatric species, probably as a result of selection for reproductive isolation. A recurring problem in the explanation of shell form is the interpretation of covarying shell characters. Identification of nonadaptive variation which results from developmental dependence on another character is dependent on the study of the selective and direct-environmental causes of variation in land snail shell form.

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Section: Shell Shapementioning

confidence: 77%

Variation in Land-Snail Shell Form and Size and its Causes: A Review

Goodfriend¹

1986

Systematic Zoology

189

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“…Shell variability resides in the lack or presence of an umbilical opening in the adults (Glaubrecht 1993a(Glaubrecht , 1993b(Glaubrecht , 1995. In the Levant the two species differentiated by their shell form are distributed parapatrically (the non-umbilicate L. caesareana in the north and the umbilicate L. hierosolyma in the south) (Heller 1979). Heller (1979) identified a narrow hybrid zone between the two species.…”

Section: Introductionmentioning

confidence: 99%

“…In the Levant the two species differentiated by their shell form are distributed parapatrically (the non-umbilicate L. caesareana in the north and the umbilicate L. hierosolyma in the south) (Heller 1979). Heller (1979) identified a narrow hybrid zone between the two species. A similar pattern of parapatric distribution (but with no areas of hybridization identified thus far) is observed over a much-reduced geographic scale along the Turkish coasts.…”

Section: Introductionmentioning

confidence: 99%

The legacy of the Crusaders: Complex history of colonization and anthropochory in the land snails Levantina (Gastropoda, Pulmonata) in the Eastern Mediterranean

Ketmaier¹,

Glaubrecht

2015

ZSE

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The Eastern Mediterranean land snails Levantina display a disjunct distribution spanning the Middle East (Levant), Cyprus, few locations along the Aegean Turkish coast between Bodrum and Datça and on the islands of Rhodes, Karpathos and a few surrounding islets (Dodecanese). These land snails are strictly bound to limestone; shell variability is noticeable with a pair of umbilicate and non-umbilicate forms parapatrically distributed in the Levant and along the Aegean Turkish coast; they overlap on the Dodecanese islands. We sequenced fragments of two mitochondrial genes (Cytochrome Oxidase I and 16S rRNA) from the historical Levantina materials available at the Museums of Hamburg and Berlin. The aim of the study is to explain the current distribution of Levantina in the Eastern Mediterranean in light of an earlier hypothesis suggesting anthropochory due to the movements of Crusaders across the area. The deeper nodes in our phylogeny indicate that Levantina reached the Dodecanese from continental Turkey during the Pliocene exploiting continuity of landmasses. In five circumstances the same haplotype co-occurs on two different islands; one haplotype is shared between one island (Rhodes) and the Levant. We suggest that the movements of Crusaders likely explain the current distribution of haplotypes. In particular, the Knights Hospitaller of St. John occupied Cyprus, the Dodecanese and the facing Turkish coasts for more than two centuries (1306-1522) after they withdrew from Jerusalem in 1187 and from the Levant in 1291. Snails could have been introduced as an item of food or transported with other material including limestone used for building.

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“…desertorum increases with increasing humidity. A relationship between shell size and precipitation has also been found in other land snail species in other dry regions where humidity is a limiting factor (Sacchi ; Heller ; Magaritz & Heller ; Gould ; Goodfriend ). These results are in conflict with the expectations based on the hypothesis that large snails are superior in dry habitats, because they lose relatively less water because of their lower surface to volume ratio (Nevo et al .…”

Section: Discussionmentioning

confidence: 57%

Morphological and genetic differentiation of Eremina desertorum (Gastropoda, Pulmonata, Helicidae) in Egypt

et al. 2015

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2016). Morphological and genetic differentiation of Eremina desertorum (Gastropoda, Pulmonata, Helicidae) in Egypt. -Zoologica Scripta, 45, 48-61.To understand the processes that result in morphological and genetic diversity, we studied the differentiation of the land snails Eremina d. desertorum and Eremina desertorum irregularis in the deserts of northern Egypt. These two taxa are differentiated with regard to shell size and shape and are separated by a narrow hybrid zone west of Alexandria. The lack of differences in the genitalia and the lack of reciprocal monophyly of the mitochondrial haplotypes of E. d. desertorum and E. desertorum irregularis support their classification as subspecies rather than distinct species. Low genetic distances indicate that the differentiation is probably less than half a million years old. The genetic data indicate a population expansion in agreement with other evidence that the Nile region in northern Egypt was more humid well into historical times than today. Shell size and shape are correlated with a climatic gradient from cooler and more humid conditions along the Mediterranean coast to arid and hot conditions in the interior. The decrease of body size with decreasing precipitation and increasing temperature might be explained by limited time for food intake in the more arid regions. The shape differences between the taxa are partly an indirect consequence of selection for body size, but are also directly affected by selection for reduction of aperture size.

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Distribution, hybridization and variation in the Israeli landsnail Levantina (Pulmonata: Helicidae)

Cited by 19 publications

References 19 publications

Variation in Land-Snail Shell Form and Size and its Causes: A Review

Variation in Land-Snail Shell Form and Size and its Causes: A Review

The legacy of the Crusaders: Complex history of colonization and anthropochory in the land snails Levantina (Gastropoda, Pulmonata) in the Eastern Mediterranean

Morphological and genetic differentiation of Eremina desertorum (Gastropoda, Pulmonata, Helicidae) in Egypt

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