In the Light of Evolution Volume II: Biodiversity and Extinction (2008) / Chapter Skim
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3 Patterns of Biodiversity and Endemism on Indo-West Pacific Coral Reefs--MARJORIE L. REAKA, PAULA J. RODGERS, and ALEXEI U. KUDLA
3 Patterns of Biodiversity and Endemism on Indo-West Pacific Coral Reefs--MARJORIE L. REAKA, PAULA J. RODGERS, and ALEXEI U. KUDLA
Pages 45-62
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From page 45... ...
Because it constrains reproductive traits and dispersal, body size is a reliable indicator of speciation and extinction potential in reef stomatopods and probably most marine organisms. Assemblages are dominated by small-sized species in the IAA and IOC.
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From page 46... ...
Coral reefs provide aesthetic beauty (and the bioeroded sand on beaches) for tourism -- an increasingly important economic resource for developing tropical countries.
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From page 47... ...
(iv) We will then examine information on body size, life history characteristics, geographic ranges, and speciation/extinction dynamics of reef stomatopods and other organisms to suggest mechanisms that, in combination with environmental factors, can explain the observed patterns of IWP coral reef diversity and endemism.
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From page 48... ...
Rodgers, and Alexei U Kudla FIGURE 3.1 Dorsal view of typically sized reef stomatopods (large Gonodactylaceus falcatus, small Gonodactylellus incipiens; scale bar for both is 10.0 mm)
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From page 49... ...
Arrows indicate major currents. All species of Alainosquillidae, Gonodactylidae, Odontodactylidae, Protosquillidae, and Takuidae are included; Pseudosquillidae occur on reefs but are excluded from analysis because their reproductive, larval, and life history patterns differ from those of other reef-dwelling families (Reaka, 1979, 1980; Reaka and Manning, 1987a)
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From page 50... ...
off the Arabian Peninsula and west coast of India/Sri Lanka, around the Malay Peninsula/Indonesia, and around New Guinea/northern Australia. Pigment concentrations decline to 0.15 mg/m3 in a relatively narrow band oceanward from the above areas; immediately offshore from the continental margin of western Australia, eastern Africa, Madagascar; and in an equatorial band extending westward from the central East Pacific.
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From page 51... ...
Life History Speciation/Extinction Hypothesis We will suggest that the biotic and environmental processes that govern body size and life history traits drive rates of speciation/extinction and thus patterns of diversity in IWP stomatopods and other reef organisms. ENDEMISM AND HOTSPOTS Endemism has been of particular interest as an indicator of extinction.
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From page 52... ...
is significantly concentrated in the IAA and drops in the adjacent oceanic regions but then rises toward the FIGURE 3.5 "Restricted regional endemic" species of reef stomatopods. Of the 24 subregions considered, those that exceed 10% are shown.
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From page 53... ...
. Hypothesizing that productivity influences body sizes and life histories of reef stomatopods, we further categorized the species in the six regions according to whether they inhabited productive or unproductive
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From page 54... ...
. However, a previous study of reef stomatopods showed that body size of individual populations within each of four species complexes of reef stomatopods declines significantly from the IAA toward the CP and that populations on high islands reach significantly larger body sizes than those inhabiting atolls in these regions (Reaka-Kudla, 2000)
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From page 55... ...
. LIFE HISTORY PATTERNS OF REEF STOMATOPODS We propose that the ecological and environmental factors that govern body size and life history traits drive patterns of diversity and endemism in reef organisms.
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From page 56... ...
The latter indicates that most reef stomatopods risk extinction if faced with rapid global environmental changes. Life history patterns of stomatopods are consistent with those found in other living and fossil groups for reproductive and life history traits, patterns of abundance, and frequency distributions of body size and geographic range.
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From page 57... ...
FIGURE 3.12 Size frequency distributions of maximum body sizes for total species, regional endemics, and nonendemic species of reef stomatopods. Endemics zpq9990837580010.g.eps are significantly smaller than nonendemics (t = 6.40, df = 146, P < 0.001; twosample t test assuming unequal variance)
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From page 58... ...
. Commonalities in patterns of body size, life history, and distribution between reef stomatopods and other taxa suggest that the relationship between life history mechanisms and patterns of diversity and endemism we find in benthic reef organisms also may operate in other systems.
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From page 59... ...
. Although adult body size is not significantly associated with such gaps, small body size correlates significantly with reduced larval dispersal and small geographic ranges and can be used as an indicator of extinction risk (Reaka, 1980; Reaka and Manning, 1987a)
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From page 60... ...
The dispersal and colonizing capability of large-sized species in these areas allows them to disproportionally colonize adjacent oceanic regions, where extensive larval immigration lowers extinction and retards speciation, yielding moderately diverse, somewhat larger-sized assemblages with low endemism. In the center of the IO and in the broader expanse of the Pacific, however, larval immigrants have been filtered by starvation, predation, and distance.
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From page 61... ...
, and species diversity itself (through ecological interactions) alter body size and thus influence life history and dispersal.
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