Abstract
Regional surveys of the small cladoceran Bosmina longirostris reveal a complex morphological pattern. Body size and shape vary greatly, with the most pronounced differences found in the posterior mucrones and anterior antennules. Some lakes have short—featured clones, most have intermediates, while a few have very long—featured clones. Neighboring lakes of similar morphometry can have short— or long—featured clones. Possible explanations for the geographic patterns include: (1) initial colonization events, (2) competitive release following colonization, (3) hybridization between formerly isolated breeding stocks, and (4) natural selection from resident predators, particularly omnivorous copepods. Field translocation experiments demonstrated the importance of Epischura predation in determining the success of long—featured clones. Prey risk was both size— and shape—dependent, with fitness determined largely through the differential survivorship of early instars. Increased fitness associated with longer features was evident at several levels: (1) during clonal recruitment from resting eggs, (2) in the success of translocated stocks, and (3) as developmental responses within exposed prey populations. In long—term exposures to Epischura, feature lengths of short—featured stocks increased by several standard deviations. Mucro length showed the greatest response, although antennule lengths and egg lengths also showed significant increases. During the Epischura lacustris—Bosmina longirostris interaction, responses were clearly the joint effect of two separate phenomena: selective responses (due to differential mortality) and chemical induction (developmental plasticity). Mucro and antennule responses were accompanied by significant declies in coefficients of variation.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.