Matrix projection models are among the most widely used tools in plant ecology. However, the way in which plant ecologists use and interpret these models differs from the way in which they are presented in the broader academic literature. In contrast to calls from earlier reviews, most studies of plant populations are based on < 5 matrices and present simple metrics such as deterministic population growth rates. However, plant ecologists also cautioned against literal interpretation of model predictions. Although academic studies have emphasized testing quantitative model predictions, such forecasts are not the way in which plant ecologists find matrix models to be most useful. Improving forecasting ability would necessitate increased model complexity and longer studies. Therefore, in addition to longer term studies with better links to environmental drivers, priorities for research include critically evaluating relative ⁄ comparative uses of matrix models and asking how we can use many short-term studies to understand long-term population dynamics.

Abstract:Predicting the speed of biological invasions and native species migrations requires understanding the ecological and evolutionary dynamics of spreading populations. Theory predicts that evolution can accelerate species' spread velocity, but how landscape patchiness, an important control over traits under selection, influences this process is unknown. We manipulated the response to selection in populations of a model plant species spreading through replicated experimental landscapes of varying patchiness. After six generations of change, evolving populations spread 11% further than non-evolving populations in continuously favorable landscapes, and 200% further in the most fragmented landscapes. The greater effect of evolution on spread in patchier landscapes was consistent with the evolution of dispersal and competitive ability. Accounting for evolutionary change may be critical when predicting the velocity of range expansions.One Sentence Summary: Evolution on ecological timescales increases the velocity of experimental plant populations spreading through patchy habitats. Main text:In an era of global environmental change, biological invasions and the movement of species ranges with climate change present two of the greatest threats to natural and managed ecosystems (1, 2). At the core of each dynamic is the spread of populations across landscapes fragmented by natural and anthropogenic barriers to movement. That habitat fragmentation slows the velocity of spread has long been appreciated (3, 4), but its influence on the potential for evolution to increase population expansion is unknown (5). Theory shows that natural selection at the low-density front of populations expanding through continuously favorable landscapes coupled with the spatial sorting of offspring favors traits contributing to fecundity and dispersal, both of which accelerate the invasion velocity (6-10). Whether this eco-evolutionary process operates similarly in systems fragmented by unsuitable habitat is uncertain because spread in these systems depends on the build-up of high density populations capable of dispersing over gaps (5, 11). Any factor that alters selection on an expanding population can influence spread, but whether evolution through selection or genetic drift predictably affects spread velocity on the rapid time scale of ecological dynamics remains an open question. Answering such questions has Page 2 of 10! important implications for predicting the future spread of biological invasions and climate change migrants.Empirical progress toward understanding evolution in populations spreading through fragmented landscapes is limited, largely because the process occurs over many generations and at geographic spatial scales. Due to these constraints, nearly all empirical evidence for evolution affecting spread comes from a few retrospective, observational analyses (12-16). The spread velocity of cane toads, for example, increased 6-fold after introduction to Australia, consistent with evolved changes in dispersal (14,17,18). No...

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Understanding the movement of species' ranges is a classic ecological problem that takes on urgency in this era of global change. Historically treated as a purely ecological process, range expansion is now understood to involve eco-evolutionary feedbacks due to spatial genetic structure that emerges as populations spread. We synthesize empirical and theoretical work on the eco-evolutionary dynamics of range expansion, with emphasis on bridging directional, deterministic processes that favor evolved increases in dispersal and demographic traits with stochastic processes that lead to the random fixation of alleles and traits. We develop a framework for understanding the joint influence of these processes in changing the mean and variance of expansion speed and its underlying traits. Our synthesis of recent laboratory experiments supports the consistent role of evolution in accelerating expansion speed on average, and highlights unexpected diversity in how evolution can influence variability in speed: results not well predicted by current theory. We discuss and evaluate support for three classes of modifiers of eco-evolutionary range dynamics (landscape context, trait genetics, and biotic interactions), identify emerging themes, and suggest new directions for future work in a field that stands to increase in relevance as populations move in response to global change.