LIFE-HISTORY TRAITS OF ENDEMIC JAMAICAN SESARMID CRABS


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kanger [ at ] awi-bremerhaven.de

Abstract

In land-locked limnic and terrestrial habitats on the island of Jamaica, a guild of sesarmid crabs has undergone a conspicuous process of adaptive radiation, leading to rapid evolution of at least 10 endemic species. Reproductive and developmental traits have previously been studied in only one of these species, the terrestrial "bromeliad crab, Metopaulias depressus. Its larval development is abbreviated, consisting of two non-feeding (fully lecithotrophic) zoeal stages and a facultatively lecithotrophic megalopa (i.e. the latter eats and grows when food is available, but it can also successfully develop through metamorphosis in complete absence of food). New investigations showed similar developmental patterns in the recently described limnic species Sesarma windsor, S. fossarum, S. meridies, and S. dolphinum. Developmental changes in biomass and elemental composition (C, H, N) reveal that larval independence of food is based on an enhanced female energy allocation in the production of large yolky eggs. This allows for metabolic utilization of stored organic matter (preferentially lipids) during non-feeding zoeal development and in megalopae kept in continued absence of food. Fed megalopae gained greater amounts of dry mass (including inorganic matter) and N as compared to C and H. This indicates preferential investment of nutritional energy in protein synthesis required for the formation of new tissues and organs as well as an increasing mineralization of the cuticle, rather than a replenishment of previously depleted lipid reserves. Survival and moult-cycle duration of the megalopa stage were not affected by absence of food, but significant effects were found in body size and sometimes in survival of first-stage juvenile crabs. This shows a trade-off between nutritional flexibility in the megalopa and post-metamorphic fitness. Larval lecithotrophy is interpreted as an evolutionary adaptation to scarce or unpredictable production of planktonic food in land-locked aquatic habitats. It is suggested that this trait, in combination with an early expression of osmoregulatory functions, has played a key role in the adaptive radiation of Jamaican crabs, aiding to nutritional and physiological independence of early life-history stages from the ancestral environment, the sea.



Item Type
Conference (Talk)
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Not peer-reviewed
Publication Status
Published
Event Details
3rd Brazilian Crustacean Congress and 2004 TCS Summer Meeting, Florianopolis, Brazil..
Eprint ID
12930
Cite as
Anger, K. (2004): LIFE-HISTORY TRAITS OF ENDEMIC JAMAICAN SESARMID CRABS , 3rd Brazilian Crustacean Congress and 2004 TCS Summer Meeting, Florianopolis, Brazil. .


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