Willem Martijn Roosenburg

Ohio University · Ohio Center for Ecology and Evolutionary Studies

Turtles and tortoises (chelonians) have been integral components of global ecosystems for about 220 million years and have played important roles in human culture for at least 400,000 years. The chelonian shell is a remarkable evolutionary adaptation, facilitating success in terrestrial, freshwater and marine ecosystems. Today, more than half of th...

Fire can have diverse effects on ecosystems, including direct effects through injury and mortality and indirect effects through changes to available resources within the environment. Changes in vegetation structure such as a decrease in canopy cover or an increase in herbaceous cover from prescribed fire can increase availability of preferred micro...

Globally, populations of diverse taxa have altered phenology in response to climate change. However, most research has focused on a single population of a given taxon, which may be unrepresentative for comparative analyses, and few long‐term studies of phenology in ectothermic amniotes have been published. We test for climate‐altered phenology usin...

Diamondback terrapins (Malaclemys terrapin) were a popular food item in early twentieth century America, and were consumed in soup with sherry. Intense market demand for terrapin meat resulted in population declines, notably along the Atlantic seaboard. Efforts to supply terrapins to markets resulted in translocation events, as individuals were mov...

Likelihood scores for north Atlantic populations. Overlapping likelihood scores for the number of population in the north Atlantic (Fig 1E and 1F). (TIFF)

PCA analysis of terrapin genotypes. PCA analysis of sampling localities. Location number corresponds with Figs 4 and 6. (EPS)

Raw data. Dataset with all terrapin genotypes. (XLSX)

Population structure files. STRUCTURE/adegent input files. (STRU)

Contemporary gene flow. BAYESASS input file. (TXT)

Historical gene flow. MIGRATE input file. (TXT)

Bottleneck file. BOTTLENECK input file, sampling localities. (TXT)

There is widespread concern regarding the impacts of anthropogenic activities on connectivity among populations of plants and animals, and understanding how contemporary and historical processes shape metapopulation dynamics is crucial for setting appropriate conservation targets. We used genetic data to identify population clusters and quantify ge...

Reservoirs possess gradients in conditions and resources along their long (deep-shallow) axis, but the response of littoral vertebrates (fish and turtles) to these gradients is poorly understood. We have quantified the littoral vertebrate communities throughout a small reservoir in Southeastern Ohio during July and August using traps, and related c...

Reservoirs exhibit gradients in conditions and resources along the transition from lotic to lentic habitat that may be important to bluegill ecology. The lotic-lentic gradient can be partitioned into three functional zones: the riverine, transitional, and lacustrine zones. We measured catch frequency and length of bluegills (Lepomis macrochirus) ca...

Aquatic turtles worldwide are plagued with habitat loss due to development and shoreline alteration that destroys the terrestrial–aquatic linkage which they must cross to reproduce successfully. Furthermore, nesting habitat loss can concentrate nesting, increasing nest predator efficiency. We describe how the Paul S. Sarbanes Ecosystem Restoration...

While conducting an on-going project investigating the effects of prescribed fire on reptile communities, 31 Terrapene carolina carolina (Eastern Box Turtle) were captured in burned and unburned study sites; some with extensive injuries that were likely caused by a recent prescribed burn. In order to determine if the disturbance had any negative ef...

Bycatch in Blue Crab (Callinectes sapidus) pots threatens many populations of the Diamondback Terrapin (Malaclemys terrapin), a small turtle inhabiting estuaries from Massachusetts to Texas, USA and freshwater ponds in Bermuda. Bycatch reduction devices (BRD) dramatically reduce terrapin bycatch in crab pots with little or no effect on crab catch....

Effective and targeted conservation action requires detailed information about species, their distribution, systematics and ecology as well as the distribution of threat processes which affect them. Knowledge of reptilian diversity remains surprisingly disparate, and innovative means of gaining rapid insight into the status of reptiles are needed i...

Understanding phenotypic differentiation among populations of wide-ranging species remains at the core of life-history research, because adaptation to local environmental conditions is expected. For example, when energy resources influence offspring fitness (as in oviparous ectotherms), the egg and hatchling environments are expected to influence s...

We examined mitochondrial DNA sequence variation among populations of the Ouachita Map turtle (Graptemys ouachitensis ouachitensis), an aquatic species distributed throughout the Mississippi River drainage. We sequenced a 620 base-pair segment of the mitochondrial control region for 65 individuals collected throughout this turtle's range, identifyi...

Diamondback terrapin (Malaclemys terrapin) populations in the Chesapeake Bay region of the United States have declined from their historic abundance because of multiple factors, including commercial harvesting, habitat loss due to human development and erosion, drowning in crab and eel pots, and accessibility of nests to predators. In areas with hi...

Coastal species encounter numerous physiological stressors ranging from daily fluctuations in salinity and temperature to anthropogenic contaminants, yet the effects of such stressor combinations on aquatic organisms remain largely unknown. Exposure to environmental contaminants, such as polychlorinated biphenyls (PCBs), can disrupt physiological p...

Aquatic organisms encounter a number of contaminants in their environments. Here, we report polycyclic aromatic hydrocarbon (PAH) concentrations detected in diamondback terrapin eggs collected from the Patuxent River, Maryland, one year after an oil spill. Data suggested a geographic difference in egg hydrocarbon concentrations. However, at one yea...

The effect of commercial fisheries on nontarget species is a burgeoning issue for both fishery managers and estuarine biologists. We documented diamondback terrapin (Malaclemys terrapin) bycatch in cloth-funnel eel pots used in a Maryland (United States) commercial American eel (Anguilla rostrata) fishery. Between 1992 and 2001, we obtained 40 male...

The relationship between egg size and composition (relative amounts of lipid, protein, and water) can play an important role in determining neonate size, quality, or the amount of post-hatching care observed in many reptiles. We evaluated the relationship among egg wet mass, non-polar lipid mass, water content, shell dry mass, and lean dry mass wit...

On October 30 and 31, 1999, 165 herpetologists and other interested people attended a conference on turtle ecology at the Patuxent Wildlife Refuge in Laurel, Maryland. The purpose of this conference was to bring scientists and conservationists together to discuss the population status and ecology of turtles of the mid-Atlantic region (from Virginia...

The eastern fence lizard, Sceloporus undulatus, is a broadly distributed polytypic species. We surveyed allozyme variation with the goal of generating an intraspecific phylogeny to evaluate the current classification of the species. We electrophoretically assayed 24 loci from 12 populations of S. undulatus, which comprised 6 of the 11 recognized su...

Progress in science is presumed to occur through the hypothetico-deductive method. Balanced experimental design and rigorous statistical hypothesis testing control for extraneous factors and focus attention only on the effect of interest (Connor & Simberloff 1986). This pow-erful approach and inferences derived from results of rigorous statistical...

Bycatch in fisheries is receiving attention because of its impact on ecological diversity and resource sustainability. Male and juvenile female diamondback terrapins, Malaclemys terrapin, frequently drown as bycatch in crab pots, removing individuals with high reproductive value from the population and possibly skewing sex ratios. We tested a wire...

The entrapment of diamondback terrapins (Malaclemys terrapin) in crab pots frequently results in drowning and death of the trapped turtles. We determined the rate of capture, size, sex, and age of terrapins captured, and the potential impact crab pot mortality has on local terrapin populations. We estimated terrapin capture rates of 0.17 terrapins/...

A fundamental component of an organism's life history is the allocation of energy available for reproduction into units that will simultaneously produce successful offspring and maximize the lifetime reproductive success of the female. We present five years of data on egg- and clutch-size variation for a single population of the diamondback terrapi...

We conducted an incubation and rearing experiment to test the effects of incubation temperature and egg size on hatchling size and growth of the emydid turtle, Malaclemys terrapin, Eggs from four clutches were assigned randomly to two incubation temperatures, 26 C and 32 C, Half of the hatchings were sacrificed and sexed after five months and the r...

SYNOPSIS. Egg size and nest site selection are two potential effects that can have a persistent influence on the phenotype of offspring. In this paper, I develop the maternal condition-dependent choice hypothesis for the maintenance of environmental sex determination. The hypothesis stipulates three conditions: 1) there must be variation in the mat...

SYNOPSIS. Egg size and nest site selection are two potential effects that can have a persistent influence on the phenotype of offspring. In this paper, I develop the maternal condition-dependent choice hypothesis for the maintenance of environmental sex determination. The hypothesis stipulates three conditions: 1) there must be variation in the mat...

Sex determination in the diamondback terrapin, Malaclemys terrapin, is temperature-dependent. Eggs incubated at 31°C, and above, hatch in approximately 45 days as females. Eggs incubated below 27°C hatch in about 60 days as males. Sex is not reversible after hatching. Nest temperatures in the wild can be as low as 20°C and as high as 37°C with as m...

Geographic variation in life history phenotypes between populations of a single species is often assumed to reflect genetic divergence caused by natural selection. The relative contribution of genetic and environmental sources of phenotypic variation is rarely determined, especially for vertebrates. However, distinguishing between phenotypic plasti...

In the Atlantic and Gulf states, the crab pot fishery overlaps with much of the habitat of the diamondback terrapin, Malaclemys terrapin. The exclusively estuarine terrapin can be found throughout the coastal bays and creeks of the eastern and Gulf coasts of the United States. Terrapin populations can incur considerable mortality of males and juven...