Estruturação genetica e morfologica em Collisella subrugosa (Patellogastropodo : Acmaeidae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

Intertidal molluscs are submitted to a great environmental heterogeneity what strongly influence their evolutionary biology. The limpets are one of the most common gastropods on rocky shores around the world, and Collisella subrugosa is the only species of this group in Brasilian continental shores. In the present manuscript we investigated two aspects of their evolutionary biology: 1) the genetic variability and structure in macro and microgeographic scales and 2) the shell shape and size variations and influence of environment on its shape. The samplings were divided in two groups. For the first, 14 beaches were sampled, in a coast range of 2.700 Km. For the second, 2 shores were sampled in a stratified way, on points along horizontal transects defined by 10g2. The last sampling group was repeated in three different seasons. The first and the second sampling groups were used for genetic analysis on isozyme loci and the second one was also used for geometric morphometrics. C. subrugosa showed high genetic variability and low structure in large-scale. Also, all of those large-scaled samples showed high levels of heterozygote deficiency for almost all loci. The "breeding groups" hypothesis was considered the most adequate to explain the high heterozygote deficiency and the aim of the microgeographic samples analysis was to test this hypothesis. In fine-scale samples all loci showed great variation in allelic frequencies in time and a little variation on the shore space. It was also observed that the high heterozygote deficiency disappear in fine-scaled samples. Those results suggest that could exist "breeding groups" on shores as hypothesized, but the pattern could be better explained by Wahlund effect. C. subrugosa also showed variation in shape and size, higher in space than in time. However, variations were not similar for the two studied shores, what can result of different environmental characteristics. Observed variations in shell shape suggest that strong waves and water turbulence have great influence on it

ASSUNTO(S)

evolução molusco conchas

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