Loss of coral reef growth capacity to track future increases in sea level

Water-depths above coral reefs is predicted to increase due to global sea-level rise (SLR). As ecological degradation inhibits the vertical accretion of coral reefs, it is likely that coastal wave exposure will increase but there currently exists a lack of data in projections concerning local rates of reef growth and local SLR. In this study we have aggregated ecological data of more than 200 tropical western Atlantic and Indian Ocean reefs and calculated their vertical growth which we have then compared with recent and projected rates of SLR across different Representative Concentration Pathway (RCP) scenarios. While many reefs currently show vertical growth that would be sufficient to keep-up with recent historic SLR, future projections under scenario RCP4.5 reveal that without substantial ecological recovery many reefs will not have the capacity to track SLR. Under RCP8.5, we predict that mean water depth will increase by over half a metre by 2100 across the majority of reefs. We found that coral cover strongly predicted whether a reef could track SLR, but that the majority of reefs had coral cover significantly lower than that required to prevent reef submergence. To limit reef submergence, and thus the impacts of waves and storms on adjacent coasts, climate mitigation and local impacts that reduce coral cover (e.g., local pollution and physical damage through development land reclamation) will be necessary

The Evolution of Life Histories : Theory and Analysis

xii,535 hal,;ill,;21 c

The evolution of life histories: theory and analysis

xii+535hlm.;23c

Of flies, fitness and fluctuating environments

Environmental heterogeneity may be important in determining the amount of genetic variation within a population. Previous theoretical studies have analysed the importance of spatio-temporal variablity for ecological genetics within a very general framework. The present study attempts to analyse the consequences of environmental heterogeneity for a particular ecologically important character. The study is concerned with the evolution of body size in an 'r-selected' poikilotherm. Is body size. The measure of fitness, r, is determined by the fecundity of the organism and its development time. These two life history characters are correlated to body size and hence the latter may be used as a measure of changes in life history parameters, whether or not selection acts directly upon body size. A model is presented that relates the effect of spatial and temporal variation on body size. This effect may be due to direct effects on body size as with size selective predation or due to effects upon other characters such as development time. To demonstrate that the behaviour of the model does not result from implausible assumptions or parameter values the model is developed with reference to an organism for which these factors have been reasonably well studied. This group is the Drosophila and most particularly, Drosophila melanogaster. The conclusions drawn from the model are that spatial and temporal variability can determine both the optimum body size and the range in body size and that 'rare' events may have significantly more effect on the evolution of body size than the most frequently occurring conditions.Science, Faculty ofZoology, Department ofGraduat

Data from: The costs of being dark: the genetic basis of melanism and its association with fitness-related traits in the sand cricket

Melanism is an important component of insect cuticle and serves numerous functions that enhance fitness. Despite its importance, there is little information on its genetic basis or its phenotypic and genetic correlation with fitness-related traits. Here, we examine the heritability of melanism in the wing dimorphic sand cricket and determine its phenotypic and genetic correlation with wing morphology, gonad mass and size of the dorso-longitudinal muscles (the principle flight muscles). Previously demonstrated trade-offs among these traits are significant factors in the evolution of life history variation. Using path analysis, we show that melanization is causally related to gonad mass, but not flight muscle mass. Averaged over the sexes, the heritability of melanism was 0.61, the genetic correlation with gonad mass was −0.36 and with wing morph was 0.51. The path model correctly predicted the ranking of melanization score in lines selected for increased ovary mass, increased flight muscle mass, an index that increased both traits and an unselected control. Our results support the general hypothesis that melanization is costly for insects and negatively impacts investment in early reproduction

Data from: The guantitative genetics of sexually selected traits, preferred traits and preference: a review and analysis of the data

The maintenance of variation in sexually selected traits is a puzzle that has received increasing attention in the past several decades. Traits that are related to fitness, such as life-history or sexually selected traits, are expected to have low additive genetic variance (and hence, heritability) due to the rapid fixation of advantageous alleles. However, previous analyses have suggested that the heritabilities of sexually selected traits are on average higher than nonsexually selected traits. We show that the heritabilities of sexually selected traits are not significantly different from those of nonsexually selected traits overall or when separated into the three trait categories: behavioural, morphological and physiological. In contrast with previous findings, the heritability of preference is quite low (h2 = 0.25 ± 0.06) and is in the same range as life-history traits. We distinguish preferred traits as a category of sexually selected traits and find that the heritability of the former is not significantly different than sexually selected traits overall (0.48 ± 0.04 vs. 0.46 ± 0.03). We test the hypothesis that the heritability of sexually selected traits is negatively correlated with the strength of sexual selection. As predicted, there is a significant negative correlation between the heritabilities of sexually selected traits and the strength of selection. This suggests that heritabilities do indeed decrease as sexual selection increases but sexual selection is not strong enough to cause heritabilities of sexually selected traits to deviate from the same type of nonsexually selected traits