Thiel, Martin and Schubart, Christoph D. and Urtubia, Ulyces (2024) Sexual dimorphism and reproductive strategy of the kelp-dwelling isopod Amphoroidea typa (Isopoda, Sphaeromatidae). CRUSTACEANA, 97 (5-9). pp. 1075-1094. ISSN 0011-216X, 1568-5403
Full text not available from this repository. (Request a copy)Abstract
Sexual dimorphism and the reproductive strategy of the isopod Amphoroidea typa were examined and compared with other species from the isopod family Sphaeromatidae. We analyzed populations of A. typa occurring on the kelps Lessonia spp. and Macrocystis pyrifera at six locations on the coast of northern-central Chile. Males could be clearly distinguished from females starting at total body lengths (TL) >= 14 mm, taking as criteria the presence of reproductive appendages and the development of gonopods in males. Females reached substantially larger sizes (up to 22.20 mm) than males (up to 18.25 mm), confirming the existence of sexual size dimorphism in A. typa. Although females had developed oostegites at lengths >= 14 mm TL, only the largest females (>= 17 mm TL) were ovigerous. This suggests that female A. typa reproduce once before dying. At most study sites there were more adult females than males occurring on Lessonia spp., while males dominated on M. pyrifera. Some A. typa individuals had white stripes present on the dorsal part of the pereon, a colour polymorphism apparently independent of the sex of the isopods but becoming more frequent in large individuals, suggesting high predation pressure and that individuals with these stripes have higher survival rates. The results of this study confirm sexual size dimorphism in A. typa, which appears to be a semelparous species. A comparison with other sphaeromatid species indicates that the evolution of semelparity is unrelated to body size, but might be more common in species from habitats with high predation pressure.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | DYNAMENE-BIDENTATA CRUSTACEA; FRESH-WATER ISOPOD; LIFE-HISTORY; PARACERCEIS-SCULPTA; COLOR POLYMORPHISM; MARINE ISOPOD; SPATIAL-DISTRIBUTION; POPULATION-DYNAMICS; BORING ISOPOD; MATERNAL-CARE; Peracarida; population demographics; reproduction; semelparity; iteroparity; cryptic coloration; cryptic coloration |
| Subjects: | 500 Science > 590 Zoological sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Zoologie > Zoologie/Evolutionsbiologie (Prof. Dr. Jürgen Heinze) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 02 Dec 2025 06:47 |
| Last Modified: | 02 Dec 2025 06:47 |
| URI: | https://pred.uni-regensburg.de/id/eprint/64998 |
Actions (login required)
 |
View Item |
