The study and implementation of no-take marine reserves have increased rapidly over the past decade, providing ample data on the biological effects of reserve protection for a wide range of geographic locations and organisms. The plethora of new studies affords the opportunity to reevaluate previous findings and address formerly unanswered questions with extensive data syntheses. Our results show, on average, positive effects of reserve protection on the biomass, numerical density, species richness, and size of organisms within their boundaries which are remarkably similar to those of past syntheses despite a near doubling of data. New analyses indicate that (1) these results do not appear to be an artifact of reserves being sited in better locations; (2) results do not appear to be driven by displaced fishing effort outside of reserves; (3) contrary to often-made assertions, reserves have similar if not greater positive effects in temperate settings, at least for reef ecosystems; (4) even small reserves can produce significant biological responses irrespective of latitude, although more data are needed to test whether reserve effects scale with reserve size; and (5) effects of reserves vary for different taxonomic groups and for taxa with various characteristics, and not all species increase in response to reserve protection. There is considerable variation in the responses documented across all the reserves in our data set -variability which cannot be entirely explained by which species were studied. We suggest that reserve characteristics and context, particularly the intensity of fishing outside the reserve and inside the reserve before implementation, play key roles in determining the direction and magnitude of the reserve response. However, despite considerable variability, positive responses are far more common than no differences or negative responses, validating the potential for well designed and enforced reserves to serve as globally important conservation and management tools.

There are a variety of proposed evolutionary and ecological explanations for why some species have more extensive geographical ranges than others. One of the most common explanations is variation in speciesÕ dispersal ability. However, the purported relationship between dispersal distance and range size has been subjected to few theoretical investigations, and empirical tests reach conflicting conclusions. We attempt to reconcile the equivocal results of previous studies by reviewing and synthesizing quantitative dispersal data, examining the relationship between average dispersal ability and range size for different spatial scales, regions and taxonomic groups. We use extensive data from marine taxa whose average dispersal varies by seven orders of magnitude. Our results suggest dispersal is not a general determinant of range size, but can play an important role in some circumstances. We also review the mechanistic theories proposed to explain a positive relationship between range size and dispersal and explore their underlying rationales and supporting or refuting evidence. Despite numerous studies assuming a priori that dispersal influences range size, this is the first comprehensive conceptual evaluation of these ideas. Overall, our results indicate that although dispersal can be an important process moderating speciesÕ distributions, increased attention should be paid to other processes responsible for range size variation.Keywords Biogeography, colonization, dispersal, geographical distribution, marine, pelagic larval duration, range size, selection, speciation. Why do some species have larger geographical ranges than others? This is a fundamental, yet largely unanswered, question in ecology and biogeography. Even closely related species can have dramatically different range sizes (Brown et al. 1996), and a variety of evolutionary and ecological explanations for range size variation have been suggested, including niche breadth or environmental tolerance, body size, population abundance, latitude, environmental variability, colonization and extinction dynamics, and dispersal ability (Stevens 1989;Brown et al. 1996;Gaston 1996Gaston , 2003. However, tests of many of these hypothetical causes are limited, and none has emerged as a universal driver of the extent of speciesÕ geographical distributions.An organism's ability to disperse is one of the more commonly cited potential determinants of a speciesÕ range (Hanski et al. 1993;Brown et al. 1996;Gaston 1996Gaston , 2003. Dispersal ability is invoked as an explanation for range size variation in both terrestrial and marine systems and for a wide range of taxa, including insects (Juliano 1983;Gutierrez & Menendez 1997;Malmqvist 2000;Brandle et al. 2002), plants (Oakwood et al. 1993Edwards & Westoby 1996;Thompson et al. 1999;Clarke et al. 2001;Lloyd et al. 2003;Lowry & Lester 2006), fish (Wellington & Victor 1989;Goodwin et al. 2005;Lester & Ruttenberg 2005;Mora & Robertson 2005) and mollusks (Hansen 1980;Perron & Kohn 1985;Jablonski 1986;Scheltema 1989;...

Variation in the chemical composition of fish otoliths has been used in recent years to address a range of ecological questions, including levels of stock mixing, variation in habitat use, and rates of larval exchange. While some of these questions have been answered with varying success, the degree to which discrete populations are connected via larval exchange remains unknown. To identify larval sources using natural variation in otolith chemistry, we must distinguish and measure the chemical composition of the otolith core, the portion of the otolith formed at the spawning site. Using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS), we found that the core regions of otoliths from 6 different species of fishes were highly enriched in manganese (Mn), and elevated in magnesium (Mg) and barium (Ba), relative to adjacent regions of the otolith. These patterns were consistent for species drawn from different taxonomic groups, which inhabit temperate and tropical regions, are found in marine and freshwater, and utilize a variety of spawning modes. Variation among species in Mn concentration in the core also corresponds to maternal investment, measured by egg size. These data suggest that core enrichment may be a general characteristic of otoliths, and that the chemical composition of the otolith core is fundamentally different from other regions of the otolith. The localized elemental enrichment of the core underscores the importance of methods that analyze the core region in small, discrete samples if otolith chemistry is used to address questions of larval exchange among populations.

We address the conflict in earlier results regarding the relationship between dispersal potential and range size. We examine all published pelagic larval duration data for tropical reef fishes. Larval duration is a convenient surrogate for dispersal potential in marine species that are sedentary as adults and that therefore only experience significant dispersal during their larval phase. Such extensive quantitative dispersal data are only available for fishes and thus we use a unique dataset to examine the relationship between dispersal potential and range size. We find that dispersal potential and range size are positively correlated only in the largest ocean basin, the Indo-Pacific, and that this pattern is driven primarily by the spatial distribution of habitat and dispersal barriers. Furthermore, the relationship strengthens at higher taxonomic levels, suggesting an evolutionary mechanism. We document a negative correlation between species richness and larval duration at the family level in the Indo-Pacific, implying that speciation rate may be negatively related to dispersal potential. If increased speciation rate within a taxonomic group results in smaller range sizes within that group, speciation rate could regulate the association between range size and dispersal potential.

Resale or republication not permitted without written consent of the publisherBlue parrotfish Scarus coeruleus cropping algae on a reef.

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The recent loss of key consumers to exploitation and habitat degradation has significantly altered community dynamics and ecosystem function across many ecosystems worldwide. Predicting the impacts of consumer losses requires knowing the level of functional diversity that exists within a consumer assemblage. In this study, we document functional diversity among nine species of parrotfishes on Caribbean coral reefs. Parrotfishes are key herbivores that facilitate the maintenance and recovery of coral-dominated reefs by controlling algae and provisioning space for the recruitment of corals. We observed large functional differences among two genera of parrotfishes that were driven by differences in diet. Fishes in the genus Scarus targeted filamentous algal turf assemblages, crustose coralline algae, and endolithic algae and avoided macroalgae, while fishes in the genus Sparisoma preferentially targeted macroalgae. However, species with similar diets were dissimilar in other attributes, including the habitats they frequented, the types of substrate they fed from, and the spatial scale at which they foraged. These differences indicate that species that appear to be functionally redundant when looking at diet alone exhibit high levels of complementarity when we consider multiple functional traits. By identifying key functional differences among parrotfishes, we provide critical information needed to manage parrotfishes to enhance the resilience of coral-dominated reefs and reverse phase shifts on algal-dominated reefs throughout the wider Caribbean. Further, our study provides a framework for predicting the impacts of consumer losses in other species rich ecosystems.

Many species vary in their ecology across their geographic ranges in response to gradients in environmental conditions. Such variation, which can influence life history traits and subsequent demography of populations, usually occurs over large spatial scales. However, describing and understanding the causes of such variation is difficult precisely because it occurs over such large spatial scales. In this study, we document spatial variation in the ecology of a common reef fish, Stegastes beebei, in the Galápagos Islands and test a number of potential causal mechanisms. The pattern resembles that seen in latitudinal variation: individuals are larger, occur in higher densities, and live longer in the coldest region of the islands than those in the warmest region. However, in this system, demography varies among regional populations separated by <150 km. Preferred nutritious algae are more available in the cold region and comprise a greater proportion of the diet of fish in this region. Per gram reproductive effort appears to be strongly related to temperature, despite differences in the gross magnitude and timing of reproduction in different regions. A model of reproductive output suggests that fish in the warmest region are allocating a greater proportion of available energy to reproduction, resulting in apparent regional life history tradeoffs. Our data suggest that regional demographic differences in S. beebei may be driven by a combination of variation in food availability and an environmentally mediated life history tradeoff.