Dispersal is a fundamental process in ecology influencing the genetic structure and the viability of populations. Understanding how variable factors influence the dispersal of the population is becoming an important question in animal ecology. To date, geographic distance and geographic barriers are often considered as main factors impacting dispersal, but their effects are variable depending o...

Relationships based on mtDNA and nDNA sequences were used to assess effects of two major geographic barriers (the >30 myo Atlantic ocean and the approximately 11 myo Amazon-Orinoco outflow) on speciation among Atlantic parrotfishes (Sparisoma and Nicholsina). Allopatric distributions of sister taxa implicate isolating actions of both barriers in all recent speciation in these fishes, with no cl...

Relationships based on mtDNA and nDNA sequences were used to assess eVects of two major geographic barriers (the >30 myo Atlantic ocean and the »11 myo Amazon–Orinoco outXow) on speciation among Atlantic parrotWshes (Sparisoma and Nicholsina). Allopatric distributions of sister taxa implicate isolating actions of both barriers in all recent speciation in these Wshes, with no clear indications t...

Open-ocean environments provide few obvious barriers to the dispersal of marine organisms. Major currents and/or environmental gradients potentially impede gene flow. One system hypothesized to form an open-ocean dispersal barrier is the Antarctic Polar Front, an area characterized by marked temperature change, deep water, and the high-flow Antarctic Circumpolar current. Despite these potential...

AVIAN SEED DISPERSAL ON VIRGINIA BARRIER ISLANDS: POTENTIAL INFLUENCE ON VEGETATION COMMUNITY STRUCTURE AND PATCH DYNAMICS. By Sheri A. Shiflett, Master of Science A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biology at Virginia Commonwealth University. Virginia Commonwealth University, 2008 Thesis Director, Dr. Donald R. Young, Department...

How do biogeographically different provinces arise in response to oceanic barriers to dispersal? Here, we analyse how traits related to the pelagic dispersal and adult biology of 985 tropical reef fish species correlate with their establishing populations on both sides of two Atlantic marine barriers: the Mid-Atlantic Barrier (MAB) and the Amazon-Orinoco Plume (AOP). Generalized linear mixed-ef...

This study examined the cladoceran assemblages in three oxbow lakes of the Taquari River floodplain, near the transition between the plateau and the plain. We sought to answer the following questions: does the Taquari River function as a geographical barrier or dispersal corridor for Cladocera? Can different degrees of connection induce different structures in the assemblages in each lake? Clad...