Abstract
The biogeographical distribution of invertebrates with different life history traits has frequently been linked with surrounding ecological factors selecting for these characteristics. This study documents the distribution of congeneric nudibranchs with lecithotrophic and planktotrophic larvae in the Gulf of Maine. Representative coastal study sites in the north‐east and south‐west regions of the Gulf of Maine were monitored for seasonal abundance of two Dendronotus species and their thecate hydroid prey, and mean water temperatures. The different dispersal potentials of the larvae from the two incipient species of nudibranch may correlate with differences in seasonal resource availability of the north‐east and south‐west coastal regions of the Gulf of Maine, while seasonal water temperature variability may be an indirect indicator of the trophic stability of the region. Seasonal resource stability (i.e. hydroid abundance) is the most likely selective agent for the distribution of these two species and their different life history strategies.
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Acknowledgements
Thanks to Larry Harris for his review and support of this research. One anonymous reviewer provided valuable suggestions for improving this manuscript. Thanks to dive partners: C. Biche, S. Chavanich, K. MacManus‐Frick, J. Thompson, R. Toppin, and J. Wanat, especially those that braved the cold weather. This research was supported by a Grant‐in‐Aid of Research from Sigma Xi, and research grants from the UNH Graduate School and Center for Marine Biology.
Notes
Cartesian coordinates presented as decimals.
Larvae were typed as either planktotrophic (P) or lecithotrophic (L) veligers based on their competence to metamorphose upon hatching. When larvae were not available, adults were identified by radula morphology and general external morphological features (Sisson 2002b).