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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 83 (1990), S. 267-276 
    ISSN: 1432-1939
    Keywords: Amphipods ; Ampithoe ; Epiphytes ; Herbivory ; Sargassum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Herbivorous marine amphipods have been implicated as important grazers on filamentous and ephemeral algae, and thus as beneficial to macrophytes in reducing overgrowth by epiphytic competitors. In North Carolina, USA, amphipods comprise 97% of all macroscopic animals inhabiting the abundant brown seaweed Sargassum filipendula, and peak in abundance between late winter and early summer. I used outdoor tank experiments to test the species-specific impact of common phytal amphipods on the growth of Sargassum and its epiphytes. The results show that seaweed-associated amphipods are a trophically diverse group that could either increase or decrease host fitness depending on their feeding preferences. The amphipods Ampithoe marcuzii, Caprella penantis, and Jassa falcata each significantly reduced growth of epiphytes on Sargassum plants relative to amphipod-free controls, while Ericthonius brasiliensis had no significant effect on Sargassum or its epiphytes. However, amphipod grazing was not necessarily beneficial to Sargassum. A. marcuzii consumed Sargassum in one outdoor tank experiment, reducing its mass by 11%, while Sargassum plants without amphipods grew by 81%. Epiphytes (mostly diatoms and the filamentous brown alga Ectocarpus siliculosus) and detritus remained abundant on these plants suggesting that A. marcuzii preferred the host to its epiphytes. Similarly, when given simultaneous access to Sargassum and to several common foliose and filamentous epiphytes in the lab, A. marcuzii ate Sargassum almost exclusively. The other three amphipods ate no macroalgae. In contrast to A. marcuzii, C. penantis consistently reduced epiphytes with no negative effect on Sargassum. Thus the species composition of the amphipod fauna can determine whether these animals increase or decrease seaweed fitness.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Human evolution 8 (1993), S. 281-289 
    ISSN: 1824-310X
    Keywords: Hominids ; Recognition Concept of Species ; Specific Mate Recognition System ; Postcrania
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Recognition Concept of Species is examined for its potential usefulness in discriminating speciation events in the hominid fossil record. Controversies over species-specific characteristics amongHomo erectus and archaicHomo sapiens have centred on traits of the skull, largely because this element is most commonly preserved. Modern humans have an intuitive knowledge of their own Specific Mate Recognition System (SMRS), and therefore have the opportunity to compare their own SMRS to that of fossil hominids and the extent pongids. Such comparison suggests that our own skeletal SMRS may depend less on features of the skull than on the morphology of the postcranial anatomy. We propose that these components be further examined in this regard. We tentatively conclude that examination of the Recognition Concept of Species indicates that from lateHomo erectus onwards, the same SMRS has been shared in common by all hominids, including modernHomo sapiens. This suggests that, following the SMRS criterion, none of these forms can be categorized as separate species.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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