Microhabitat choice and polymorphism in the land snail Theba pisana (Müller)

Hazel, Wade N.; Johnson, M. S.

doi:10.1038/hdy.1990.116

Cited by 35 publications

(35 citation statements)

References 11 publications

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“…Apex colour has its direct, strongest effect on the small juvenile snails, which are present in late autumn and winter, and the direct effects of selection on apex colour vary with those seasonal conditions. Although the mechanism of selection favouring EUB shells is almost certainly resistance to thermal stress (Heller, 1981;Hazel and Johnson, 1990;Johnson, 2011a), it is not as clear what favours pale apices in the banded population in sunnier, drier winters (or dark apices in cloudier, wetter winters). Heat stress is very unlikely, and the direction of the association argues against it.…”

Section: Intensity Of Natural Selectionmentioning

confidence: 99%

“…As in previous studies of the Bold Park population (Johnson, 1980(Johnson, , 1981(Johnson, , 2011aHazel and Johnson, 1990), shells were classified simply as either EUB (in which bands are absent from the upper half of each whorl) or fully banded (FB, with some banding on the dorsal portion of the shell). The last 901 of the outermost whorl were ignored, because pigment is sometimes present in the newly formed shell, even of genetically unbanded snails (Cain, 1984).…”

Section: Shell Polymorphismmentioning

confidence: 99%

“…The land snail Theba pisana is genetically polymorphic for shell banding, and variation of morph frequencies indicates adaptation to local climate: snails with paler, unbanded shells are favoured in exposed habitats (Johnson, 1980(Johnson, , 2011aHeller, 1981) and in hot, sunny summers (Johnson, 2011a), and they select more exposed aestivation sites in summer than their banded counterparts (Johnson, 1981;Hazel and Johnson, 1990). The banding polymorphism is complex, and effectively unbanded (EUB) shells may be either genetically unbanded or banded with genetic suppression of bands on the upper portion of the shell (Cain, 1984;Cowie, 1984).…”

Section: Introductionmentioning

confidence: 99%

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Epistasis, phenotypic disequilibrium and contrasting associations with climate in the land snail Theba pisana

Johnson

2011

Heredity

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Hotter conditions favour effectively unbanded (EUB) shells in the snail Theba pisana. T. pisana is also polymorphic for colour of the shell's apex, determined by a pair of alleles at a locus linked to the banding locus. Apex colour is epistatic to shell banding, such that banded snails with a dark apex have darker bands. Annual censuses over 22 years across an ecotone between a sheltered Acacia thicket and open dune vegetation showed a persistent association of both EUB shells and pale apex with the Open habitat. The parallel variation was due partly to strong phenotypic disequilibrium, as the combination of EUB with dark apex was rare. Nevertheless, in fully banded shells the frequency of pale apex was also higher in the Open habitat, confirming independent, parallel associations of the two contributors to paleness. Within the Acacia habitat, temporal variation of the frequencies of banding morphs was much greater than for apex colour, and EUB shells were associated with hotter summers. Consistent with its primary effect only on the very small snails, apex colour did not vary with summer conditions, but instead, higher frequencies of pale apices were associated with sunnier winters. The intensity of selection was lower on apex colour than shell banding, due partly to the constraint of phenotypic disequilibrium. The shell traits in T. pisana are an example of complex responses to climatic variation, in which phenotypic disequilibrium constrains evolution of apex colour, but separate mechanisms of selection are evident.

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Section: Intensity Of Natural Selectionmentioning

confidence: 99%

Section: Shell Polymorphismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Epistasis, phenotypic disequilibrium and contrasting associations with climate in the land snail Theba pisana

Johnson

2011

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“…T. pisana was, analogous to X. derbentina, observed to climb vertical objects, thereby preventing overheating (McQuaid et al 1979). Quite frequently, the shell pigmentation of snails has been linked to higher shell temperatures, higher internal temperatures, and a quicker heating of dark banded morphs caused by solar radiation (Hazel and Johnson 1990;Heath 1975). Especially in habitats with high temperatures this should be a great disadvantage for darker individuals.…”

Section: Introductionmentioning

confidence: 99%

Hsp70 and lipid peroxide levels following heat stress in Xeropicta derbentina (Krynicki 1836) (Gastropoda, Pulmonata) with regard to different colour morphs

Dieterich

Troschinski

Schwarz

et al. 2015

Cell Stress and Chaperones

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Terrestrial snails which live under dry and hot conditions need efficient mechanisms of adaptation to counteract the problems of desiccation and over-heating. A profoundly heat tolerant snail species is the Mediterranean Xeropicta derbentina, exhibiting different shell colour morphs ranging from pale white to darkly banded. Considering that dark-pigmented snails are believed to have a disadvantage due to faster heating, we investigated possible differences in the stress markers Hsp70 and lipid peroxideation between four pre-defined colour morphs which were exposed to different temperatures for eight hours. The highest Hsp70 levels were observed in response to 38-40°C. Levels decreased when this temperature was exceeded. Snails of a pre-defined colour category 3 (with a large black band at the umbilicus side of the shell) showed the most prominent Hsp70 response. Lipid peroxideation levels also showed a maximum at 38°C but displayed a second peak at rather high temperatures at which the Hsp70 level already had decreased (45-48°C). Particularly pure white snails (category 1) and the most pigmented ones (category 4) were found to have different levels of lipid peroxidation at 38°C and 45°C compared to the other morphs. A hypothesis involving a combined two-phase defence mechanism, to which both, the Hsp70 protection system and the antioxidant defence system, may contribute, is discussed.

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“…Habitat selection has been described for some intertidal neritids (Bovbjerg 1984) and other freshwater gastropods, such as the Mediterranean land snail Theba pisaría Müller (Hazel & Johnson 1990). However, microhabitat preferences, as well as environmental features that influence the abundance and microdistribution of freshwater gastropod populations on Pacific islands are not well known.…”

Section: Introductionmentioning

confidence: 99%

Abundance and microdistribution of freshwater gastropods in three streams of Moorea, French Polynesia

Liu

Resh

1997

Ann. Limnol. - Int. J. Lim.

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The microdistribution and abundance of freshwater gastropods were studied in lower reaches of three streams on Moorea, French Polynesia, during austral spring (AS) and austral fall (AF) 1994-1996. Seven species were examined: Neritina canalis Lamarck, Neritina turrita Gmelin, Clithon spinosa Budgin, Septana porcellana Linnaeus, Neritina auriculata Lamarck, Melanoides tuberculata Miiller, and Thiara granifera Lamarck ; the first five species are in the Neritidae, the latter two in the Thiaridae. Most gastropod species had higher densities during AF 1996 than AS 1995 (p = 0.0001) with higher densities being found in riffle than in pool habitats (p = 0.0001). No relationship between substrate type and either species presence-abundance or shell size was observed. A stepwise multiple regression indicated that velocity, depth, and substrate roughness were determinants of gastropod abundance for some species within these streams. A distinct microhabitat preference for the bottoms of rocks was observed for C. spinosa and N. canalis.. The limited range of N. auriculata's occurrence within streams results from its salinity tolerance and response to hydraulic stress. Microdistribution et abondance de gastéropodes d'eau douce dans trois rivières de Moorea, Polynésie françaiseMots clés : Gastéropode, benthos, mollusques, Clithon, Melanoides, Neritina, Septana, Océanie, salinité. La microdistribution et l'abondance de gastéropodes d'eau douce ont été étudiées dans les cours inférieurs de trois rivières de

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Microhabitat choice and polymorphism in the land snail Theba pisana (Müller)

Cited by 35 publications

References 11 publications

Epistasis, phenotypic disequilibrium and contrasting associations with climate in the land snail Theba pisana

Epistasis, phenotypic disequilibrium and contrasting associations with climate in the land snail Theba pisana

Hsp70 and lipid peroxide levels following heat stress in Xeropicta derbentina (Krynicki 1836) (Gastropoda, Pulmonata) with regard to different colour morphs

Abundance and microdistribution of freshwater gastropods in three streams of Moorea, French Polynesia

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