Differences in allele frequencies of <i>Aat</i> between high- and mid-rocky shore populations of <i>Littorina saxatilis</i> (Olivi) suggest selection in this enzyme locus

Johannesson, Kerstin; Johannesson, Bo

doi:10.1017/s0016672300028317

Cited by 46 publications

(32 citation statements)

References 17 publications

(23 reference statements)

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“…This reflects local environmental conditions at the 2 study sites, with much stronger and more extreme contrasts between high-and low-shore conditions at the White Sea as compared to the generally milder (micro-) climatic situation at the North Sea site. These data suggest that extreme and unpredictable conditions of the high-shore level may impose strong selection pressure on high-shore inhabitants, leading to considerable physiological (Sokolova et al 2000a, this study) and genetic differentiation (Johannesson & Johannesson 1989, Johannesson et al 1995a even within a single species, and agree with the notion that performance limits evolve especially rapidly when populations are exposed to short, extreme, selective bouts rather than chronic, sublethal stress (Parsons 1987, Trussell 1997, Mongold et al 1999.…”

Section: Discussionsupporting

confidence: 84%

Physiological adaptations to high intertidal life involve improved water conservation abilities and metabolic rate depression in Littorina saxatilis

Sokolova¹,

Pörtner²

2001

Mar. Ecol. Prog. Ser.

104

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Section: Discussionsupporting

confidence: 84%

Physiological adaptations to high intertidal life involve improved water conservation abilities and metabolic rate depression in Littorina saxatilis

Sokolova¹,

Pörtner²

2001

Mar. Ecol. Prog. Ser.

104

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“…4). Similarly exceptional associations of allelic frequencies with habitat have been found in two other littorines, Littorina saxatilis and L. mariae, in which most allozyme loci vary independently of habitat, but one locus shows strong, consistent associations with habitat (Johannesson & Johannesson, 1989;Tatarenkov & Johannesson, 1994). In each case, the repeatability of the associations in different places is difficult to explain other than in terms of habitat-related selection.…”

Section: Discussionmentioning

confidence: 68%

Increased genetic divergence and reduced genetic variation in populations of the snail Bembicium vittatum in isolated tidal ponds

Johnson

1998

Heredity

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Populations of the littorine gastropod Bembicium vittatum in 47 isolated tidal ponds were used to test effects of isolation and habitat on genetic divergence. The mean G ST at 13 polymorphic allozyme loci between pond populations and their adjacent shore sites, separated by surface barriers of 1-100 m, was 0.122, which is equivalent to subdivision over distances of 4-5 km among shore sites. At distances up to 15 km, subdivision among pond populations (mean G ST = 0.181) was substantially greater than among shore sites (mean G ST = 0.115); beyond 45 km mean G ST was 0.342 among ponds, compared with 0.279 among shore sites. Genetic divergence of pond populations from their adjacent shore counterparts was less in those ponds with greater interchange with the ocean. Greater divergence was associated with decreased allozyme variation within the pond populations, which was also lower in smaller ponds with smaller populations. With one exception, allelic frequencies did not differ consistently between ponds and shores or in association with differences in habitat among the ponds. The exception was the consistently higher frequency of Lap1 112 in pond populations. A mark-recapture experiment failed to detect differential survival or growth of Lap1 genotypes, either within or among ponds and shore sites, leaving open the mechanisms of this apparently adaptive divergence. Overall, the results confirm a substantial increase in genetic divergence associated with the tidal ponds, and favour the interpretation that degree of isolation and population size, rather than localized selection, are the major determinants of the allozyme divergence.

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“…In the common mussel Mytilus edulis, intertidal specimens displayed higher thermal stability of AAT than subtidal ones (Read 1963). It is interesting that an analysis of allozyme polymorphism of L. saxatilis demonstrated a consistent cline of allele frequencies at the Aat locus associated with the vertical shore gradient of the intertidal in the North and White Seas, with the slow allele Aat100 allele dominating in mid-and low shore and a faster one (Aat120) predominantly found at high shore levels (Johannesson and Johannesson 1989;M. Panova, unpublished results).…”

Section: Discussionmentioning

confidence: 97%

Temperature effects on key metabolic enzymes in Littorina saxatilis and L. obtusata from different latitudes and shore levels

Sokolova

Pörtner

2001

Marine Biology

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Eects of temperature on activities of key metabolic enzymes, citrate synthase (CS), NADPdependent isocitrate dehydrogenase (NADP-IDH), aspartate aminotransferase (AAT), pyruvate kinase (PK) and phosphoenolpyruvate carboxykinase (PEPCK), were studied in high and low shore Littorina saxatilis and in low shore L. obtusata from the temperate North Sea and the sub-arctic White Sea. It was found that adaptation of L. saxatilis and L. obtusata to life at dierent latitudes and/or shore levels involves constitutive changes in enzymatic activities, so that animals naturally adapted to (micro-) environments with lower mean temperatures (i.e. in the White Sea or at low shore levels) tend to have higher enzyme activities as compared to their counterparts from warmer habitats (e.g. the North Sea or high shore levels, respectively).This suggests metabolic temperature compensation in dierent populations/subpopulational groups of this eurythermal species. Activities of all ®ve studied enzymes were modulated by adaptations to high shore life in L. saxatilis, whereas only NADP-IDH, PK and PEPCK had dierent activities in animals from dierent latitudes. Adaptation to high shore life also involved an enhanced potential for anaerobic energy production via the succinate pathway in Littorina spp. (measured as the ratio of PEPCK and PK activities), which increased in the order: low shore L. obtusata £ low shore L. saxatilis< high shore L. saxatilis. Possibly, an increased anaerobic capacity is advantageous for snails at high shore levels, where they may experience limited oxygen access during prolonged air exposure. In contrast, the activation energies of the respective enzymes did not reveal a consistent pattern of variation and were similar in animals from dierent latitudes and shore levels. Arrhenius breakpoint temperatures (ABT) of the studied enzymes characterising a change in the thermal properties of the protein were found well within the average highs of ambient temperatures (20±35°C). Denaturation temperatures (T d ), indicating heat inactivation of the protein, were close to the environmental extremes experienced by L. saxatilis during summer low tide. These ®ndings suggest that the metabolic machinery of this eurythermal species may function close to its physiological limits during summer low tide, especially at high shore levels.

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Differences in allele frequencies of Aat between high- and mid-rocky shore populations of Littorina saxatilis (Olivi) suggest selection in this enzyme locus

Cited by 46 publications

References 17 publications

Physiological adaptations to high intertidal life involve improved water conservation abilities and metabolic rate depression in Littorina saxatilis

Physiological adaptations to high intertidal life involve improved water conservation abilities and metabolic rate depression in Littorina saxatilis

Increased genetic divergence and reduced genetic variation in populations of the snail Bembicium vittatum in isolated tidal ponds

Temperature effects on key metabolic enzymes in Littorina saxatilis and L. obtusata from different latitudes and shore levels

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