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Author(s): Joshua S. Madin (corresponding author) [1, 2]; Sean R. Connolly [1] A recent tsunami [1, 2] and an apparent increase in the frequency of severe tropical storms [3, 4, [...]

In aquatic invertebrates that form exoskeletons, the partitioning of energy between skeletal and tissue growth is an important tradeoff, especially under resource limitation or physiological stress. Here, we provide the first comparative analysis of energy investment into tissue and skeleton in corals. We develop a mathematical growth model based on colony geometry, tissue mass and quality (enthalpy), and predicted cost of calcification. For hemispherical colonies, the model predicts greater investment in tissue at small sizes, but a shift to skeletal-dominated growth at colony sizes greater than 5-14 cm radius, depending on tissue mass and quality. A similar transition occurs in branches, but is a function of radius and length. An experimental study to assess the impact of resource (light) limitation and physiological stress (sediment load) on energy partitioning in small hemispherical colonies (Goniastrea retiformis Lamarck) and branches (Porites cylindrica Dana) showed that tissue mass and quality varies greatly over small increments in colony or branch size. In particular, allocations to tissue growth varied tenfold (from positive to negative) more across sediment treatments than did allocations to skeletal growth. A model of energy acquisition versus loss (scope for growth) indicated that tissue growth is more responsive to resource variation and physiological stress than skeletal growth. These results suggest that (1) skeletal and tissue growth rates are weakly correlated across environmental conditions, and that (2) variation in tissue properties is a better proxy for coral health or stress than skeletal growth.

Abstract Background The observation that females mate multiply when males provide nothing but sperm - which sexual selection theory suggests is unlikely to be limiting - continues to puzzle evolutionary biologists. Here we test the hypothesis that multiple mating is prevalent under such circumstances because it enhances female fitness. We do this by allowing female Trinidadian guppies to mate with either a single male or with multiple males, and then tracking the consequences of these matings across two generations. Results Overall, multiply mated females produced 67% more F2 grand-offspring than singly mated females. These offspring, however, did not grow or mature faster, nor were they larger at birth, than F2 grand-offspring of singly mated females. Our results, however, show that multiple mating yields benefits to females in the form of an increase in the production of F1. The higher fecundity among multiply mated mothers was driven by greater production of sons but not daughters. However, contrary to expectation, individually, the offspring of multiply mated females do not grow at different rates than offspring of singly mated females, nor do any indirect fitness benefits or costs accrue to second-generation offspring. Conclusions The study provides strong evidence that multiple mating is advantageous to females, even when males contribute only sperm. This benefit is achieved through an increase in fecundity in the first generation, rather than through other fitness correlates such as size at birth, growth rate, time to sexual maturation and survival. Considered alongside previous work that female guppies can choose to mate with multiple partners, our results provide compelling evidence that direct fitness benefits underpin these mating decisions.

Abstract: Competition is an important determinant of assemblage structure and population regulation, often resulting in decreased growth, fecundity or survival. In corals, most studies testing for an effect of competition on demographic traits, such as growth, have been experimental and often impose very high levels of competition upon colonies. To more realistically assess the role of competition on coral traits, multispecies studies in the wild are required. Here, we use 5 yr of data that includes 11 coral species on the reef crest at Lizard Island on the Great Barrier Reef to quantify the effect of competition on growth. Additionally, we test whether species differ in their susceptibility to direct‐contact (overgrowth and digestion) and overtopping competition, and whether species from some morphological groups are more likely to compete with one another than with species from other morphological groups. We also investigate the relationships between competitive ability and three key traits: growth rate, mechanical stability and fecundity. In contrast to most previous work using field manipulations of competition, we found a negligible effect of competition on growth. Acropora species consistently won overtopping encounters but lost in direct‐contact encounters, and these results were consistent among the four Acropora morphological groups. In contrast, the massive Goniastrea spp. were poor at overtopping but generally won direct‐contact encounters. Only tabular colonies were disproportionally more likely to compete against one another than with other morphologies. This propensity increases intraspecific relative to interspecific competition, a phenomenon that can promote coexistence when it is present among dominant competitors. Good competitors grew more quickly and had higher fecundity but were less mechanically stable, implying a tradeoff between performance during disturbance vs. performance in the absence of disturbance. We conclude that competition among adults is less likely to influence community dynamics than previously thought. If competition does have an effect, it is more likely to occur at life‐stages other than adults. [ABSTRACT FROM AUTHOR]

Contemporary science educators must equip their students with the knowledge and practical know-how to connect multiple disciplines like mathematics, computing and the natural sciences to gain a richer and deeper understanding of a scientific problem. However, many biology and earth science students are prejudiced against mathematics due to negative emotions like high mathematical anxiety and low mathematical confidence. Here, we present a theoretical framework that investigates linkages between student engagement, mathematical anxiety, mathematical confidence, student achievement and subject mastery. We implement this framework in a large, first-year interdisciplinary science subject and monitor its impact over several years from 2010 to 2015. The implementation of the framework coincided with an easing of anxiety and enhanced confidence, as well as higher student satisfaction, retention and achievement. The framework offers interdisciplinary science educators greater flexibility and confidence in their approach to designing and delivering subjects that rely on mathematical concepts and practices. [ABSTRACT FROM PUBLISHER]

Predicting demographic rates is a critical part of forecasting the future of ecosystems under global change. Here, we test if growth rates can be predicted from morphological traits for a highly diverse group of colonial symbiotic organisms: scleractinian corals. We ask whether growth is isometric or allometric among corals, and whether most variation in coral growth rates occurs at the level of the species or morphological group. We estimate growth as change in planar area for 11 species, across five morphological groups and over 5 years. We show that coral growth rates are best predicted from colony size and morphology rather than species. Coral size follows a power scaling law with a constant exponent of 0.91. Despite being colonial organisms, corals have consistent allometric scaling in growth. This consistency simplifies the task of projecting community responses to disturbance and climate change. [ABSTRACT FROM AUTHOR]

Aim Species abundance distributions (SADs) are a synthetic measure of biodiversity and community structure. Although typically described by unimodal logseries or lognormal distributions, empirical SADs can also exhibit multiple modes. However, we do not know how prevalent multimodality is, nor do we have an understanding of the factors leading to this pattern. Here we quantify the prevalence of multimodality in SADs across a wide range of taxa, habitats and spatial extents. Location Global. Methods We used the second-order Akaike information criterion for small sample sizes (AICc) and likelihood ratio tests (LRTs) to test whether models with more than one mode accurately describe the empirical abundance frequency distributions of the underlying communities. We analysed 117 empirical datasets from intensely sampled communities, including taxa ranging from birds, plants, fish and invertebrates, from terrestrial, marine and freshwater habitats. Results We find evidence for multimodality in 14.5% of the SADs when using AICc and LRT. This is a conservative estimate, as AICc alone estimates a prevalence of multimodality of 22%. We additionally show that the pattern is more common in data encompassing broader spatial scales and greater taxonomic breadth, suggesting that multimodality increases with ecological heterogeneity. Main conclusions We suggest that higher levels of ecological heterogeneity, underpinned by larger spatial extent and higher taxonomic breadth, can yield multimodal SADs. Our analysis shows that multimodality occurs with a prevalence that warrants its systematic consideration when assessing SAD shape and emphasizes the need for macroecological theories to include multimodality in the range of SADs they predict. [ABSTRACT FROM AUTHOR]