Earth's biodiversity: What do we know and where are we headed?

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Various contributors to the Special Issue

Earth's biodiversity—the number of microorganisms, plants, and animals, their genes, and their ecosystems (such as rainforests and grasslands)—is declining at an alarming rate, even faster than the last mass extinction 65 million years ago. In fact, two thirds of the terrestrial species that exist today are estimated to be extinct by the end of this century. Humans are an integral part of this extensive network of life. We depend on biodiversity for goods and services; we impact biodiversity via rapidly expanding human population growth, consumption of resources, and spread of disease; and we study biodiversity in order to understand, conserve, and protect it. To celebrate, analyze, and suggest future avenues of biodiversity research, three world-renowned scientists—Dr. Peter Raven, President Emeritus of the Missouri Botanical Garden, Dr. Jonathan Chase, from Washington University in St. Louis, MO, and Dr. J. Chris Pires, from the University of Missouri Columbia—have co-edited a Special Issue on Biodiversity, published in March by the American Journal of Botany (http://www.amjbot.org/cgi/reprint/ajb.1100055v1). Raven, Chase, and Pires overlap in their interest in biodiversity, yet their specialties complemented each other when it came to inviting "some of the best and brightest biodiversity scientists from each of [their] fields" to provide contributing papers to this issue.

Peter Raven is a long-time champion of biodiversity, drawing attention to the importance of conserving rare and endangered plant species all over the world. Jon Chase is interested in what drives patterns of species diversity in aquatic and terrestrial systems, and uses experiments as well as models and computer simulations to analyze ecological questions pertaining to biodiversity. Chris Pires's research focuses on plant evolutionary biology, from phylogenetic studies in plant diversity to genome-wide analyses of gene expression, from the molecular and gene level to the evolution and ecology of polyploidy in plants. The interests and talents of these three researchers led them to ask questions such as, "What is the Earth's current status regarding biodiversity?" and "What are our future prospects?" This unique collaboration resulted in 20 papers submitted by an international suite of biodiversity experts.

As Raven et al. are quick to point out in the Introduction to the Special Issue, a wide range of topics is presented, spanning from 150 million years ago to present (and future) day. For example, modern-day ecosystems are put into perspective by Alan Graham of the Missouri Botanical Garden, who demonstrates that today's ecosystems are a product of past events and, as such, their history can tell us something about present environmental conditions and where we might be heading. Several articles describe how many of the plant groups that we know of today arose, and their authors use modern molecular, genetic, and phylogenetic approaches to gain insights into evolutionary and developmental trends and suggest advancements in methodologies and data acquisition for future research. Other papers address the previous lack of knowledge on groups such as microorganisms and fungi and use modern molecular techniques to demonstrate the discovery of their incredible levels of biodiversity. The challenge of species identification using modern DNA techniques is also addressed—Pamela Steele and J. Chris Pires, both from the University of Missouri, propose a combination of genomes as a tool for species identification.

Other articles in the special issue focus on ecological, evolutionary, conservation, and restoration issues. Do some of the key fundamental evolutionary and ecological theories proposed a few decades ago to explain ecological relationships among species, such as Island Biogeography or the Species Area Curve, hold up now that we have acquired more data with which to test them? These issues are examined at local and global spatial scales and fine-tune, as well as provide interesting twists, on these fundamental theories. For example, Jana and Steven Vamosi from the University of Calgary, examined patterns of angiosperm diversity around the world and concluded that one of the key mechanisms to angiosperm diversification is the amount of area available—area can limit the carrying capacity per se of a species' lineage. Several articles review the literature or use mathematical models or meta-analyses to examine patterns of diversity at the local (alpha-diversity) or regional (beta-diversity) scale, from plant-pollinator interactions to networks of networks, to describe how habitat transformation or loss can not only impact the number of species, but can break down ecosystem functions and services, and point out areas of research for the future that will provide us with a deeper understanding of biodiversity, especially within the context of global climate change, habitat loss, and biological invasions.

This Special Issue on Biodiversity has articles that should be of interest to a wide audience, from the budding conservationist to professionals on the cutting edge of their field. These articles provide up-to-date analyses of many aspects of biodiversity and should stimulate the direction of up-and-coming research in their various fields.

Source: American Journal of Botany