L. I. Mazon

Distribution of Cepaea nemoralis according to climatic regions in Spain

121 Populations of Cepaea nemoralis were sampled in Spain. In an area which extends from the coast of the Bay of Biscay to 182 km inland, following the meridian 3° west of Greenwich, and which has a width of approximately 40 km. In this study, we analysed the relationships between the populations and some selective agents, such as predation by Turdus ericetorum and climatic factors. These latter are represented by indirect parameters, such as altitude and distance from the sea, and direct parameters such as rainfall or temperatures. Visual selection is unimportant in the sampled populations. It was observed that our area of study is subdivided into 3 zones: Zone 1. Transitional and Zone 2, which have very different phenotype frequencies. What is more, these Zones correspond to very different climatic regions. Zone 1 is located in the climatic region known as “Green Iberia”. The most frequent phenotypes of Cepaea nemoralis are the pale ones. Zone 2 is located in “Brown Iberia”, and the most frequent phenotypes are the dark ones. Therefore we believe that in the populations sampled, one or more climatic factors are operating, and presumably causing the subdivision of these populations into Zones 1 and 2.

Polymorphism of Delta-Aminolevulinic Acid Dehydratase in Basque Populations

Human red cell delta-aminolevulinic acid dehydratase (ALADH; EC 4.2.1.24) polymorphism was studied in three population samples of the Basque Country. The frequency of the ALADH2 was around 0.08 and similar to that in other European countries.

Acid Phosphatase, Adenosine Deaminase and Esterase D Polymorphisms in the Spanish Basque Population

The 3 red-cell polymorphic systems acid phosphatase (ACP), adenosine deaminase (ADA) and esterase D (ESD) have been studied in a random sample of 1,112 individuals from the Basque country: The allelic frequencies obtained were ACP*A = 0.275, ACP*B = 0.718 and ACP*C = 0.007; ADA*2 = 0.021, and, ESD*2 = 0.066. The allelic frequencies have been compared with those of other Basque and other European populations. In comparison with Basques, significant differences were detected only for ACP, whereas as regards other Europeans significant differences were obtained with practically all the populations compared for the 3 genetic systems studied. The low values of the less frequent alleles, especially that for the ACP*C allele which is the lowest reported in Europe, are noteworthy.

A cline in the acid phosphatase1 distribution in the Iberian Peninsula

Blood samples from autochthonous and unrelated persons were examined for acid phosphatase (ACP1) phenotypes. The subjects were 143 Spanish Basques, 118 people from León and 295 from Castile. The samples were typed using starch gels, with one surface coloured with phenolphthalein diphosphate (Na5 salt) and the other surface revealed with 4-methylumbelliferyl-dihydrogenphosphate. The gene frequencies observed are compared with those obtained by other authors.

Some red cell enzymes and haptoglobin gene frequencies in two Basque regions and León

A study was conducted to determine the distribution of phenotypes and gene frequencies of haptoglobin, phosphoglucomutase 1, esterase D, 6-phosphogluconate dehydrogenase and three monomorphic systems SOD, sMDH and NADH DIA I. Results obtained from two Basque regions and León were compared with those from other Spanish populations. Gene frequencies observed in the León sample were similar to those obtained from the other Spanish samples. The Basque samples differed from the other Spanish populations in the gene frequencies of esterase D.

North/South differentiation in the distribution of Cepaea nemoralis in Spain

Sixteen enzymatic loci of Cepaea nemoralis were studied in an area of 180 km long by 40 km wide in northern Spain. Two new polymorphic loci DIA and GLO, and two monomorphics, ARYL and β-GAL are described.The analysis of principal components groups the populations in two geographical areas, in the north and south of the sampling area. There is also an intermediate area between them. Heterozygosity in the northern area is significantly higher than in the southern one. Heterozygosity seems to diminish in unfavourable conditions (greater dryness or greater altitude), which is in accordance with the niche width variation hypothesis. There seems to exist an association between alleles of GLO and PGM and altitude.The geographical areas created by the biochemical polymorphism coincide with those of the visible polymorphism, which in turn correspond to climatic zones. The northern area, according to visible and biochemical polymorphism is located in the so-called “Green Iberia”, and the southern area in “Brown Iberia”. The intermediate area corresponds to the area of climatic transition between them. These areas could correspond to “geographical races” of Cepaea nemoralis.Climatic selection may be acting upon some loci such as PGM and GLO while in others random drift could be the cause of heterogeneity.

Allozyme variation in populations of Cepaea nemoralis from Northern Spain

Allozyme frequencies at eleven gene loci have been tested electrophoretically in 46 populations of the land snail Cepaea nemoralis from the North of Spain. There is some geographic differentiation for molecular polymorphism which coincides to some small extent with the two main climatic regions in the Iberian peninsula, “green” and “brown” Iberia. However, there are no significant correlations between gene frequencies and climatic parameters. At least, part of this geographic change may have emerged through genetic drift, with a counterbalanced action of drift and climatic selection associated with a restricted gene flow, to promote a different genetic structure of C. nemoralis populations in each climatic region.

Polymorphism in Cepaea Hortensis in marginal populations in Spain

Cepaea hortensis (Mull) is found in Spain only in the western part of the Iberian mountain range. This is the southernmost limit of its range. The most frequent colour is yellow, brown being very rare. The most frequent band patterns are 12345, fused banded and unbanded. There are associations between maximum and minimum temperatures and pink and effectively unbanded yellow phenotypes. The populations may be grouped into two zones, one located in the north and the other in the south of the sampled area. Visual predation was not observed. The marginal populations studied by us were compared with others from Northern Europe, and it was observed that pink snails are more frequent at the southern limit, and unbanded ones at the northern limit. This was interpreted as a climatic selection.

Some genetic markers in Castillian populations

Haptoglobin, phosphoglucomutase 1 and 6-phosphogluconate dehydrogenase gene frequencies have been found for some Castillian provinces. The NADH diaphorase I, superoxide dismutase, lactate dehydrogenase, soluble oxaloacetate transaminase, soluble malate dehydrogenase, carbonic anhydrase I and carbonic anhydrase II are non-polymorphic red cell enzymes in Caucasoids and we have verified this in Castillian samples.

Red cell glyoxalase I polymorphism in Basque and Castilian populations

SummaryIn samples of Arratia and Gernika populations, who are indigenous Basque ethnic groups, the frequency of the GLO Ilallele was respectively 0.457±0.042 and 0.459±0.041. Four samples belonging to Castilian populations were also studied. The results of this work suggested homogeneity between the Spanish and other populations.