Gregory A Backus

University of California, Davis | UCD · Department of Environmental Science and Policy

Since the work of Alfred Russel Wallace, biologists have sought to divide the world into biogeographic regions that reflect the history of continents and evolution. These divisions not only guide conservation efforts, but are also the fundamental reference point for understanding the distribution of life. However, the biogeography of human-associat...

Invasive rodents are usually eradicated from islands through the application of chemical toxicants that can harm surrounding ecosystems. A recently proposed alternative involves engineering a house mouse (Mus musculus) to carry a genetic construct that would cause a majority of its offspring to be male, many of which would be sterile. Releasing the...

Island ecosystems are highly threatened by invasive rats and mice. Currently, the only effective technology for eradicating rodents from islands is toxicants. Though effective, they are expensive and have high failure rates. They are not species-specific and are potentially dangerous to humans. Gene drive technology is one alternative to toxicants...

Gene drive technology could allow the intentional spread of a desired gene throughout an entire wild population in relatively few generations. However, there are major concerns that gene drives could either fail to spread or spread without restraint beyond the targeted population. One potential solution is to use more localized threshold-dependent...

Assisted migration is the translocation of species beyond their historical range to more suitable locations given future climate change. This conservation approach poses risks of establishment failure because of uncertainty in decision making, climate, and interactions with the recipient ecological community. To quantify the risks and benefits of a...

The importance of dispersal rates and distances has long been appreciated by ecologists and evolutionary biologists. An emerging field of research is revealing how temporal variation in dispersal can substantially influence ecological and evolutionary outcomes. We review how dispersal rates can temporally vary substantially in many ecosystems, a pa...

Many plant species are likely to face population decline or even extinction in the coming century, especially those with a limited distribution and inadequate dispersal relative to the projected rates of climate change. The obligate seeding California endemic, Ceanothus perplexans is especially at risk, and depending on how climate change interacts...

Climate refugia are areas where species can persist through climate change with little to no movement. Among the factors associated with climate refugia are high spatial heterogeneity, such that there is only a short distance between current and future optimal climates, as well as biotic or abiotic environmental factors which buffer against variabi...

Many species are shifting their ranges to keep pace with climate change, but habitat fragmentation and limited dispersal could impede these range shifts. In the case of climate-vulnerable foundation species such as tropical reef corals and temperate forest trees, such limitations might put entire communities at risk of extinction. Restoring connect...

Many tree species might be threatened with extinction because they cannot disperse or adapt quickly enough to keep pace with climate change. One potential, and potentially risky, strategy to mitigate this threat is assisted migration, the intentional movement of species to facilitate population range shifts to more climatically suitable locations u...

Many species are shifting their ranges to keep pace with climate change, but habitat fragmentation and limited dispersal could impede these range shifts. In the case of climate-vulnerable foundation species such as tropical reef corals and temperate forest trees, such limitations might put entire communities at risk of extinction. Restoring connect...

Assisted migration is the translocation of species beyond their historical range to locations that are expected to be more suitable under future climate change. However, a relocated population might fail to establish within its donor community if there is high uncertainty in decision making, climate, and interactions with the recipient ecological c...

Invasive rodents have caused considerable damage to island ecosystems, contributing to the extinction of several rare endemic species. To protect these unique ecosystems, rodents have been eradicated from hundreds of islands throughout the world. Unfortunately, eradication usually involves the heavy application of chemical toxicants that can harm a...

Animal acoustic communication often takes the form of complex sequences, made up of multiple distinct acoustic units. Apart from the well-known example of birdsong, other animals such as insects, amphibians, and mammals (including bats, rodents, primates, and cetaceans) also generate complex acoustic sequences. Occasionally, such as with birdsong,...

Although crows cast pellets, there is little quantitative information on pellets from Corvus brachyrhynchos (American Crow), and none from C. ossifragus (Fish Crow). During a study of crow roost dispersal in Lancaster, PA, we collected samples of pellets from several locations. By mass, pellets consisted mostly of grit and other fi ne inorganic mat...

By reducing habitat connectivity and availability, landscape fragmentation can have a strong effect on biological communities. Since empirical studies in community ecology can require long-term surveys and include large numbers of variables, it is often more efficient to study these systems with predictive mathematical models. Using a dataset from...