Adaptive characteristics of the endemic species Satureja horvatii Šilić (Lamiaceae) in mountain-mediterranean and mediterranean habitats

TODOROVIĆ, T. & STEVANOVIĆ, B., 1994. Adaptive characteristics of the endemic species Satureja horvatii Šilić (Lamiaceae) in mountain-mediterranean and mediterranean habitats. Morphoanatomical analysis in two popoulations of Satureja horvatii from habitats of different altitudes in the Orjen-Lovćen mountain massif (Montenegro, Yugoslavia) disclosed important adaptive differences and ecological plasticity of this local endemic species. The Satureja horvatii population growing on Mt. Orjen (1540m) comprises mesoxerophytes, while the population from the foothills of Mt. Lovćen (280 m) is of a typical xerophytic type, as demonstrated by the ecoanatomical study of their leaves.     

Genetic diversity and multilocus structure in sexual Otiorhynchus alpicola populations (Goleoptera: Gurculionidae)

Otiorhynchus alpicola Boh. (Coleoptera: Curculionidae) is distributed on high mountains of central, southern and south-eastern Europe. On the Balkan peninsula, this species is patchily distributed on mountain peaks at heights over 1800 m. To examine the organization of isoenzyme variation of the ten sexual (diploid) populations, starch gel electrophoresis of enzymes was used. The average heterozygosity over 14 gene loci was 0.11. For diploid O. alpicola, F-statistics were used to assess population heterogeneity and substructuring. The data indicate that, compared with other insects, this high-altitude weevil species is genetically very differentiated (the average F _ST= 0.35). In addition, gene-flow among populations was extremely low (the estimates of N_em from Wright's F _ST and Slatkin private-allele methods were 0.47 and 0.83, respectively). Pairwise linkage disequilibrium (LD) parameters were estimated from zygotic frequencies using Burrows' method. The average rate of significant LD in analysed populations of O. alpicola was about 27%. The pattern of LD over the diploid populations indicates that stochastic factors might be a primary cause of the observed multilocus associations.     

Homosexual behaviour and its longevity cost in females and males of the seed beetle Acanthoscelides obtectus

The level of homosexual behaviour is evaluated in one laboratory population of seed beetle and derived lines selected to reproduce early (E) or late in life (L), where inadvertent selection for either low or high heterosexual activity has been detected. The magnitudes of homosexual interaction, measured as chasing and mounting individuals of the same sex, are estimated over different age classes. These magnitudes are correlated with previously observed levels and patterns of age‐specific variation of heterosexual activity of both sexes in the E and L experimental lines. The results obtained support the perception error hypothesis proposing that a low degree of sexual discrimination is genetically correlated with high sexual activity. The fitness costs of the same‐sex interactions are tested by assessing their effects on longevity. In both sexes, the longevities of homosexual pairs are reduced relative to individually‐housed virgin beetles in both the E and L lines, although homosexual interactions have a more pronounced effect on male survival than on female survival. Although the results obtained suggest that the longevity cost of homosexual interactions can be substantial, this cost is much smaller than the cost of heterosexual interactions.