Does Evolutionary History Correlate with Contemporary Extinction Risk by Influencing Range Size Dynamics?

Rules of Plant Species Ranges: Applications for Conservation Strategies

Earth is changing rapidly and so are many plant species’ ranges. Here, we synthesize eco-evolutionary patterns found in plant range studies and how knowledge of species ranges can inform our understanding of species conservation in the face of global change. We discuss whether general biogeographic “rules” are reliable and how they can be used to develop adaptive conservation strategies of native plant species across their ranges. Rules considered include (1) factors that set species range limits and promote range shifts; (2) the impact of biotic interactions on species range limits; (3) patterns of abundance and adaptive properties across species ranges; (4) patterns of gene flow and their implications for genetic rescue, and (5) the relationship between range size and conservation risk. We conclude by summarizing and evaluating potential species range rules to inform future conservation and management decisions. We also outline areas of research to better understand the adaptive capacity of plants under environmental change and the properties that govern species ranges. We advise conservationists to extend their work to specifically consider peripheral and novel populations, with a particular emphasis on small ranges. Finally, we call for a global effort to identify, synthesize, and analyze prevailing patterns or rules in ecology to help speed conservation efforts.

Evolutionary legacies in contemporary tetrapod imperilment

The Tree of Life will be irrevocably reshaped as anthropogenic extinctions continue to unfold. Theory suggests that lineage evolutionary dynamics, such as age since origination, historical extinction filters and speciation rates, have influenced ancient extinction patterns - but whether these factors also contribute to modern extinction risk is largely unknown. We examine evolutionary legacies in contemporary extinction risk for over 4000 genera, representing ~30,000 species, from the major tetrapod groups: amphibians, birds, turtles and crocodiles, squamate reptiles and mammals. We find consistent support for the hypothesis that extinction risk is elevated in lineages with higher recent speciation rates. We subsequently test, and find modest support for, a primary mechanism driving this pattern: that rapidly diversifying clades predominantly comprise range-restricted, and extinction-prone, species. These evolutionary patterns in current imperilment may have important consequences for how we manage the erosion of biological diversity across the Tree of Life.

The rise of octocoral forests on Caribbean reefs

Coral reefs throughout the tropics have experienced large declines in the abundance of scleractinian corals over the last few decades, and some reefs are becoming functionally dominated by animal taxa other than scleractinians. This phenomenon is striking on many shallow reefs in the tropical western Atlantic, where arborescent octocorals now are numerically and functionally dominant. Octocorals are one of several taxa that have been overlooked for decades in analyses of coral reef community dynamics, and our understanding of why octocorals are favoured (whereas scleractinians are not) on some modern reefs, and how they will affect the function of future reef communities, is not commensurate with the task of scientifically responding to the coral reef crisis. We summarize the biological and ecological features predisposing octocorals for success under contemporary conditions, and focus on those features that could have generated resistance and resilience of octocoral populations to environmental change on modern reefs. There is a rich set of opportunities for rapid advancement in understanding the factors driving the success of octocorals on modern reefs, but we underscore three lines of inquiry: (1) the functional implications of strongly mixotrophic, polytrophic, and plastic nutrition, (2) the capacity to recruit at high densities and maintain rapid initial rates of vertical growth, and (3) the emergent properties associated with dense animal forests at high colony densities.