Karyological studies of four Cladophora (Cladophorales, Chlorophyta) species from coastal North Carolina

Abstract

Chromosome numbers for four species of Cladophora from coastal North Carolina are presented. The basic chromosome number is six, with three median and three submedian chromosomes. Cladophora species represent a polyploid series, with numbers of 12, 18, 24, 30, and 36 found in the present study. Three chromosome size classes (large, medium, and small) are represented by individual species. Correlations between each species' karyotype and its morphology and distribution are discussed. Karyotype morphology and probable evolutionary trends in the form sections Glomeratae and Rupestres are presented. Mechanisms responsible for reduction in chromosome size in both form sections are discussed in relation to similar reduction patterns in flowering plants with significant heterochromatin content.

Key Words:

• Algal karyotypes
• Cladophora
• chromosomes