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Introduction
I am a Professor in the Department of Biology and Marine Biology at the University of North Carolina Wilmington.
Additional affiliations
July 2007 - July 2013
Publications
Publications (40)
North Carolina (NC) is in a biogeographic transition zone where climate change is altering the relative abundances (e.g., areal extent, percent cover, biomass) of Zostera marina and Halodule wrightii. Warmer water temperatures are driving losses in Z. marina, leading to increased meadow patchiness. Although water temperatures are rising in NC, heat...
Genetic diversity can modulate a population's response to a changing environment and plays a critical role in its ecological function. While multiple processes act to maintain genetic diversity, sexual reproduction remains the primary driving force. Eelgrass (Zostera marina) is an important habitat‐forming species found in temperate coastal ecosyst...
Genetic diversity can modulate a population’s response to a changing environment and plays a critical role in its ecological function. While multiple processes act to maintain genetic diversity, sexual recruitment remains the primary driving force. At its southern edge-of-range, warming sea surface temperatures have resulted in shifts to a mixed-an...
Predator–prey interactions structure ecological communities, and personality can significantly mediate these interactions. Personality expression is often contingent on social context, suggesting that group personality may be key in determining the outcomes of predator encounters. Here, we test the influence of individual personality and group comp...
Parasites can alter species interactions either by modifying infected host behaviour or by influencing behavioural responses in uninfected individuals. Salt marsh ecosystems are characterized by a predator–prey interaction between the keystone grazer, Littoraria irrorata, and its main predator, Callinectes sapidus, both integral players in mediatin...
Animal personality results from a complex interplay between consistent individual differences in behaviour and behavioural plasticity in response to environmental variation and can have significant impacts on intraspecific interactions. Littoraria irrorata, the marsh periwinkle, is an important consumer in salt marsh ecosystems and can directly inf...
The Gopher Frog (Rana capito) is a threatened species native to the southeastern longleaf pine ecosystem. Although once much more widespread across the southeastern United States, they now occur in North Carolina at only a handful of disjunct sites in the Coastal Plain and Sandhills regions of the state. The long-term persistence of these populatio...
Comparative population genetic studies of closely related taxa provide a powerful framework for evaluating if and to what degree a species of conservation concern has been negatively impacted by factors such as habitat fragmentation, decreased population connectivity, inbreeding and genetic drift. In this study, we take advantage of a paired sampli...
Evolutionary invasion analysis seeks to identify those phenotypes that cannot be invaded and replaced by alternative organismal strategies. This is achieved by first constructing a dynamical system that governs a rare mutant’s dynamics when introduced into an ecological setting at equilibrium with a resident strategy. From this, a mutant fitness fu...
Beach nourishment is a common coastal management practice used to protect and maintain infrastructure, tourist revenue, and sandy beach habitats. Coastal erosion and increased development along the coast of North Carolina, USA, have resulted in increased use of beach nourishment as an environmentally friendly alternative to hard structures, such as...
Seagrass meadows are some of the most productive marine plant ecosystems in the world, yet their loss continues on a global scale. Zostera marina , an ecologically important foundation species, reproduces both sexually and asexually, yielding different levels of genetic diversity throughout its range, which in turn can influence resistance to, and...
Larval dispersal, particularly for sessile or sedentary marine organisms, significantly influences the scale of population structure in many species and fundamentally depends on the degree to which larvae from different populations are mixed in the plankton. In general, larval dispersal is thought to lead to well-mixed populations; however, recent...
Much of evolutionary epidemiology theory is derived from a perspective in which all hosts, and all parasites, are epidemiologically equivalent. This stands in contrast to the well-documented existence of the numerous processes generating heterogeneity among hosts and parasites that can profoundly influence evolutionary/epidemiological dynamics. Age...
Genetic diversity and population structure reflect complex interactions among a diverse set of processes that may vary temporally, limiting their potential to predict ecological and evolutionary outcomes. Yet, the stability of these patterns is rarely tested. We resampled eelgrass (Zostera marina) meadows from published studies to determine variabi...
Much of the theory on offspring size variation within a brood relies on unequal maternal allocation of resources to each embryo. However, maternal allocation strategies are subject to an inherent conflict between mothers and offspring: individual offspring, being more closely related to themselves than to their siblings, should always prefer a larg...
The most recent climate change projections show a global increase in temperatures, along with major adjustments to precipitation, throughout the 21st century. Species exhibiting temperature-dependent sex determination are highly susceptible to such changes since the incubation environment influences critical offspring characteristics such as surviv...
In organisms with temperature-dependent sex determination, the incubation environment plays a key role in determining offspring sex ratios. Given that global temperatures have warmed approximately 0.6 °C in the last century, it is necessary to consider how organisms will adjust to climate change. To better understand the degree to which mothers inf...
The northern Gulf of California (NGC) is one of the most dynamic and productive marine ecosystems in the world, yet knowledge about population connectivity and dispersal patterns is lacking for many of its resident species. Using nuclear and mitochondrial markers, we investigated the effects of open water, geographical distance and suitable habitat...
Until recently, little attention has been paid to the existence of kin structure in the sea, despite the fact that many marine organisms are sessile or sedentary. This lack of attention to kin structure, and its impacts on social evolution, historically stems from the pervasive assumption that the dispersal of gametes and larvae is almost always su...
We reply to a critique on our paper on paternity/parental care in a marine snail.Issues identified in the critique had already been addressed in the original paper.We address concerns about the reliability and validity of our parentage analysis.
Abstract In multispecies assemblages, phylogenetic relatedness often predicts total community biomass. In assemblages dominated by a single species, increasing the number of genotypes increases total production, but the role of genetic relatedness is unknown. We used data from three published experiments and a field survey of eelgrass (Zostera mari...
Whether a sea turtle embryo develops into a male or a female depends, as with many other reptiles, on the temperature during incubation of the eggs. With sea turtles, warm temperatures produce 100% females and, thus, increasing global temperatures have the potential to significantly alter offspring sex ratios. Nest-site selection provides a potenti...
We investigated nest-site characteristics and clutch success of hawksbill sea turtles (Eretmochelys imbricata) nesting on Shidvar Island, Hormozgan Province, in the Islamic Republic of Iran. We found that hawksbills tended to cluster their nests at a specific elevation above sea level, and that emergence success was highest in nests nearest to this...
Background/Question/Methods There is growing evidence that genetic variation within and among populations of key species plays an important role in ecosystem processes. Several experiments provide compelling evidence that the number of genotypes in an assemblage (genotypic richness) can influence critical ecosystem functions including productivity,...
Males exhibit striking variation in the degree to which they invest in offspring, from merely provisioning females with sperm, to providing exclusive post-zygotic care. Paternity assurance is often invoked to explain this variation: the greater a male's confidence of paternity, the more he should be willing to provide care. Here, we report a striki...
The genetic composition of groups of individuals can significantly influence the productivity, resilience, and functioning of communities and ecosystems. For example, the re latedness of individuals within a group often dictates whether their interactions are competitive or cooperative. It is therefore necessary to characterize the genetic structur...
Background/Question/Methods
Intra-specific trait variation in habitat-forming species can have important ecological consequences at the population, community, and ecosystem level. However, the contribution of genetic variation among individuals to these effects is seldom documented, leaving it an open question whether overall trait variation resu...
All organisms face two fundamental trade-offs in the allocation of energetic resources: one between many small versus a few
large offspring, and the second between present and future reproduction. Nowhere are these trade-offs more apparent than in
the vast range of variation in the sizes of eggs and offspring exhibited among species of marine inver...
In sexually reproducing organisms, conflicts of interest among family members are inevitable. The intensity of these conflicts depends upon the opportunities for parents and offspring to interact and the level of promiscuity. Despite the acknowledged role of family conflict in the evolutionary ecology of terrestrial organisms, its influence in the...
Hawksbills have been the focus of conservation efforts over several decades and their status in the Caribbean is continuously being evaluated. Surprisingly, it appears that the island of Guadeloupe hosts one of the largest Hawksbill populations in this region, highlighting the importance of making the most recent data available for the purposes of...
In laboratory experiments, we determined pivotal temperature (29.6°C), i.e. the constant temperature yielding 50% of each sex, and pivotal incubation duration (57.3 d) for hawksbill turtles Eretmochelys imbricata (Agassiz, 1857) nesting on Mona Island, Puerto Rico. Based on the laboratory curves for sex ratio, predictions were made about sex ratio...
Whether a prey population goes extinct or adapts in response to an invading predator may depend on the number of contiguous populations that experience increased predation. We created invaded snail populations by building shelters for predatory shore crabs on a rocky intertidal bench. The crabs preyed selectively on thin-shelled snails tethered nex...
Within a single population of hawksbill sea turtles (Eretmochelys imbricata), we found a behavioral polymorphism for maternal nest site choice with respect to beach microhabitat characteristics. Some females preferred to nest in littoral forest and in places with overstory vegetation cover, and others preferred to nest in more open, deforested area...
Phenotypic sex in sea turtles is determined by nest incubation temperatures, with warmer temperatures producing females and cooler temperatures producing males. The common finding of highly skewed female-biased hatchling sex ratios in sea turtle populations could have serious repercussions for the long-term survival of these species and prompted us...
We investigated individual nest site choice behaviour and its fitness consequences in female hawksbills nesting at Trois Ilets, Guadeloupe. We found a significant repeatability of nest site choice, suggesting that this behaviour is heritable and may show the potential for further evolution. By looking at possible consequences of nest site choice, w...
We determined individual nest placement patterns for female leatherbacks nesting at Awa:la-Ya:lima:po, French Guiana, by measuring distance from the nest to several landscape features, such as the highest spring tide line (HSTL) and the vegetation line. Distance from the nest to the HSTL differed significantly between females, indicating the existe...
Pivotal temperature (the constant temperature giving 50% of each sex) for two clutches of loggerhead sea turtles (Caretta caretta) from Kyparissia Bay, Greece, was 29.3°C. Pivotal incubation duration (the time from laying to hatching giving 50% of each sex) was 52.6 days. These values are close to those obtained for this species in Brazil and the U...
The pile perch, Rhacochilus vacca (Embiotocidae), is abundant on the Pacific Coast of North America and is known to crush hard-shelled prey with its heavy pharyngeal teeth. We investigated whether pile perch predation has the potential to limit or regulate populations of Littorina sitkana, a direct-developing gastropod found on wave-sheltered shore...