Variation in genetic traits of the Baltic clam Macoma balthica from a tidal gradient in the subarctic

Hummel, H.; Günther, Carmen-Pia; Bogaards, R.H.; Fedyakov, V. V.

doi:10.1007/s003000050256

Cited by 7 publications

(5 citation statements)

References 21 publications

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“…This agrees with our ®ndings of relatively higher AAT activities in low shore L. saxatilis from the White and the North Seas (see above). It is worth mentioning that a similar vertical cline in allele frequencies associated with the tidal height was found for IdhI locus coding the NADP-IDH in White Sea Macoma balthica (Hummel et al 1998). However, similarity in enzyme activities and E a of NADP-IDH in L. saxatilis from dierent latitudes and shore levels suggests that this may be not the case in this species.…”

Section: Discussionmentioning

confidence: 82%

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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Section: Discussionmentioning

confidence: 82%

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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“…Koehn et al, 1980;Johannesson et al, 1995). If, as suggested by Hummel et al (1995Hummel et al ( , 1998, selection on allozyme polymorphism also plays a role in M. balthica, it is possible that our allozyme survey either overestimates or underestimates population subdivision. However, the F ST estimated from the mitochondrial haplotype data, which are independent of the nuclear allozymes, is in the same order of the F ST s from the allozyme data (unlike in the survey of Karl & Avise, 1992).…”

Section: Specifics Of Molecular and Morphological Datamentioning

confidence: 87%

“…Koehn et al ., 1980; Johannesson et al ., 1995). If, as suggested by Hummel et al . (1995, 1998), selection on allozyme polymorphism also plays a role in M. balthica , it is possible that our allozyme survey either overestimates or underestimates population subdivision.…”

Section: Specifics Of Molecular and Morphological Datamentioning

confidence: 99%

Spatially structured genetic variation in a broadcast spawning bivalve: quantitative vs. molecular traits

Luttikhuizen

Drent

Delden

et al. 2003

Journal of Evolutionary Biology

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Understanding the origin, maintenance and significance of phenotypic variation is one of the central issues in evolutionary biology. An ongoing discussion focuses on the relative roles of isolation and selection as being at the heart of genetically based spatial variation. We address this issue in a representative of a taxon group in which isolation is unlikely: a marine broadcast spawning invertebrate. During the free-swimming larval phase, dispersal is potentially very large. For such taxa, small-scale population genetic structuring in neutral molecular markers tends to be limited, conform expectations. Small-scale differentiation of selective traits is expected to be hindered by the putatively high gene flow. We determined the geographical distribution of molecular markers and of variation in a shell shape measure, globosity, for the bivalve Macoma balthica (L.) in the western Dutch Wadden Sea and adjacent North Sea in three subsequent years, and found that shells of this clam are more globose in the Wadden Sea. By rearing clams in a common garden in the laboratory starting from the gamete phase, we show that the ecotypes are genetically different; heritability is estimated at 23%. The proportion of total genetic variation that is between sites is much larger for the morphological additive genetic variation (Q ST ¼ 0.416) than for allozyme (F ST ¼ 0.000-0.022) and mitochondrial DNA cytochrome-c-oxidase-1 sequence variation (U ST ¼ 0.017). Divergent selection must be involved and intraspecific spatial genetic differentiation in marine broadcast spawners is apparently not constrained by low levels of isolation.

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“…1995, 1997). There are indications that some of the studied allozyme variation may be under the influence of selection, most notably an Idh locus (Hummel et al . 1995, 1998), which is also the most strongly differentiated locus in Europe.…”

Section: Introductionmentioning

confidence: 99%

Disjunct distribution of highly diverged mitochondrial lineage clade and population subdivision in a marine bivalve with pelagic larval dispersal

2003

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Mitochondrial DNA sequence data for 295 individuals of the marine bivalve Macoma balthica (L.) were collected from 10 sites across the European distribution, and from Alaska. The data were used to infer population subdivision history and estimate current levels of gene flow. Inferred historical biogeography was expected to be congruent with colonization of the Atlantic Ocean from the Pacific Ocean after the opening of the Bering Strait 3.5 Ma. In addition, the last glacial maximum, about 18000 years ago, was expected to have been responsible for most of the present-day distribution of molecular variation within Europe, because the area must have been recolonized after confinement to France and the south of the British Isles during the last glacial maximum. Current gene flow was hypothesized to be high, because the larvae of M. balthica spend 2-5 weeks drifting in the water column. The geographical distribution of one highly diverged haplotype clade was found to be disjunct and was encountered exclusively in samples from the Baltic Sea and Alaska. A molecular clock calibration for marine bivalve cytochrome-c-oxidase I dates this clade as having split off from the other haplotypes 9.8-39 Ma. Multiple colonizations of the Atlantic Ocean from the Pacific by M. balthica may explain the strong differences found between Baltic Sea and other European populations of this species. The sympatric occurrence of the highly diverged mitochondrial lineages in western parts of the Baltic Sea points to secondary admixture. With the use of coalescent analysis, population divergence times for French vs. other non-Baltic European populations ('Atlantic population assemblage') were estimated at a minimum of about 110000 years ago, well before the last glacial maximum 18000 years ago. Signatures of population divergence of M. balthica that appear to have originated during the Pleistocene have thus survived the last glacial maximum. Some of the populations within the Atlantic assemblage are currently isolated, while others appear to be connected by gene flow. Apparently, populations of this species can remain highly subdivided in spite of the potential for high gene flow, implying that their population and evolutionary dynamics can be independent.

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Variation in genetic traits of the Baltic clam Macoma balthica from a tidal gradient in the subarctic

Cited by 7 publications

References 21 publications

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

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

Spatially structured genetic variation in a broadcast spawning bivalve: quantitative vs. molecular traits

Disjunct distribution of highly diverged mitochondrial lineage clade and population subdivision in a marine bivalve with pelagic larval dispersal

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