OpenStax Biology 2e
Traditionally, ecologists have measured biodiversity, a general term for the number of species present in the biosphere, by taking into account both the number of species and their relative abundance to each other. Biodiversity can be estimated at a number of levels of organization of living organisms. These estimation indices, which came from information theory, are most useful as a first step in quantifying biodiversity between and within ecosystems; they are less useful when the main concern among conservation biologists is simply the loss of biodiversity. However, biologists recognize that measures of biodiversity, in terms of species diversity, may help focus efforts to preserve the biologically or technologically important elements of biodiversity.
The Lake Victoria cichlids provide an example with which we can begin to understand biodiversity. The biologists studying cichlids in the 1980s discovered hundreds of cichlid species representing a variety of specializations to specialized habitat types and specific feeding strategies: such as eating plankton floating in the water, scraping/eating algae from rocks, eating insect larvae from the lake bottom, and eating the eggs of other species of cichlid. The cichlids of Lake Victoria are the product of an complex adaptive radiation. An adaptive radiation is a rapid (less than three million years in the case of the Lake Victoria cichlids) branching through speciation of a phylogenetic clade into many closely related species. Typically, the species “radiate” into different habitats and niches. The Galápagos Island finches are an example of a modest adaptive radiation with 15 species. The cichlids of Lake Victoria are an example of a spectacular adaptive radiation that formerly included about 500 species.
At the time biologists were making this discovery, some species began to quickly disappear. A culprit in these declines was the Nile perch, a species of large predatory fish that was introduced to Lake Victoria by fisheries to feed the people living around the lake. The Nile perch was introduced in 1963, but its populations did not begin to surge until the 1980s. The perch population grew by consuming cichlids, driving species after species to the point of extinction (the disappearance of a species). In fact, there were several factors that played a role in the extinction of perhaps 200 cichlid species in Lake Victoria: the Nile perch, declining lake water quality due to agriculture and land clearing on the shores of Lake Victoria, and increased fishing pressure. Scientists had not even catalogued all of the species present—so many were lost that were never named. The diversity is now a shadow of what it once was.
The cichlids of Lake Victoria are a thumbnail sketch of contemporary rapid species loss that occurs all over Earth that is caused primarily by human activity. Extinction is a natural process of macroevolution that occurs at the rate of about one out of 1 million species becoming extinct per year. The fossil record reveals that there have been five periods of mass extinction in history with much higher rates of species loss, and the rate of species loss today is comparable to those periods of mass extinction. However, there is a major difference between the previous mass extinctions and the current extinction we are experiencing: human activity. Specifically, three human activities have a major impact: 1) destruction of habitat, 2) introduction of exotic species, and 3) over-harvesting. Predictions of species loss within the next century, a tiny amount of time on geological timescales, range from 10 percent to 50 percent. Extinctions on this scale have only happened five other times in the history of the planet, and these extinctions were caused by cataclysmic events that changed the course of the history of life in each instance.
Clark, M., Douglas, M., Choi, J. Biology 2e. Houston, Texas: OpenStax. Access for free at: https://openstax.org/details/books/biology-2e
Date Published: July 5, 2018 Publisher: Public Library of Science Author(s): Laura Tydecks, Jonathan M. Jeschke, Max Wolf, Gabriel Singer, Klement Tockner, Vipin Chandra Kalia. http://doi.org/10.1371/journal.pone.0199327 Abstract: The rapid erosion of biodiversity is among the biggest challenges human society is facing. Concurrently, major efforts are in place to quantify changes in biodiversity, to understand the … Continue reading
Date Published: August 1, 2011 Publisher: Public Library of Science Author(s): David P. Mindell, Brian L. Fisher, Peter Roopnarine, Jonathan Eisen, Georgina M. Mace, Roderic D. M. Page, Richard L. Pyle, Sean A. Rands. http://doi.org/10.1371/journal.pone.0019491 Abstract: Partial Text: Scientists are amassing details about the scope and status of life’s variation at an accelerating rate. This aids … Continue reading
Date Published: August 2, 2010 Publisher: Public Library of Science Author(s): Katsunori Fujikura, Dhugal Lindsay, Hiroshi Kitazato, Shuhei Nishida, Yoshihisa Shirayama, Joel M. Schnur. http://doi.org/10.1371/journal.pone.0011836 Abstract: To understand marine biodiversity in Japanese waters, we have compiled information on the marine biota in Japanese waters, including the number of described species (species richness), the history of marine … Continue reading
Date Published: March 18, 2019 Publisher: Public Library of Science Author(s): Christian König, Patrick Weigelt, Julian Schrader, Amanda Taylor, Jens Kattge, Holger Kreft, Georgina M. Mace Abstract: Recent years have seen an explosion in the availability of biodiversity data describing the distribution, function, and evolutionary history of life on earth. Integrating these heterogeneous data remains … Continue reading
Research Article: Assessing the Primary Data Hosted by the Spanish Node of the Global Biodiversity Information Facility (GBIF)
Date Published: January 25, 2013 Publisher: Public Library of Science Author(s): Javier Otegui, Arturo H. Ariño, María A. Encinas, Francisco Pando, Gajendra P. S. Raghava. http://doi.org/10.1371/journal.pone.0055144 Abstract: In order to effectively understand and cope with the current ‘biodiversity crisis’, having large-enough sets of qualified data is necessary. Information facilitators such as the Global Biodiversity Information Facility … Continue reading
Research Article: A simple survey protocol for assessing terrestrial biodiversity in a broad range of ecosystems
Date Published: December 12, 2018 Publisher: Public Library of Science Author(s): Asko Lõhmus, Piret Lõhmus, Kadri Runnel, Maura (Gee) Geraldine Chapman. http://doi.org/10.1371/journal.pone.0208535 Abstract: Finding standard cost-effective methods for monitoring biodiversity is challenging due to trade-offs between survey costs (including expertise), specificity, and range of applicability. These trade-offs cause a lack of comparability among datasets collected … Continue reading
Date Published: November 2, 2016 Publisher: Public Library of Science Author(s): Michael J. Benton Abstract: Biodiversity today is huge, and it has a long history. Identifying rules for the heterogeneity of modern biodiversity—the high to low species richness of different clades—has been hard. There are measurable biodiversity differences between land and sea and between the … Continue reading
Research Article: The Soul-Sucking Wasp by Popular Acclaim – Museum Visitor Participation in Biodiversity Discovery and Taxonomy
Date Published: April 22, 2014 Publisher: Public Library of Science Author(s): Michael Ohl, Volker Lohrmann, Laura Breitkreuz, Lukas Kirschey, Stefanie Krause, Ben J. Mans. http://doi.org/10.1371/journal.pone.0095068 Abstract: Taxonomy, the science of describing and naming of the living world, is recognized as an important and relevant field in modern biological science. While there is wide agreement on … Continue reading
Research Article: More Than Just Records: Analysing Natural History Collections for Biodiversity Planning
Date Published: November 21, 2012 Publisher: Public Library of Science Author(s): Darren F. Ward, M. Alex Smith. http://doi.org/10.1371/journal.pone.0050346 Abstract: Natural History Collections (NHCs) play a central role as sources of data for biodiversity and conservation. Yet, few NHCs have examined whether the data they contain is adequately representative of local biodiversity. I examined over 15,000 databased … Continue reading
Research Article: The GBIF Integrated Publishing Toolkit: Facilitating the Efficient Publishing of Biodiversity Data on the Internet
Date Published: August 6, 2014 Publisher: Public Library of Science Author(s): Tim Robertson, Markus Döring, Robert Guralnick, David Bloom, John Wieczorek, Kyle Braak, Javier Otegui, Laura Russell, Peter Desmet, Damon P. Little. http://doi.org/10.1371/journal.pone.0102623 Abstract: The planet is experiencing an ongoing global biodiversity crisis. Measuring the magnitude and rate of change more effectively requires access to … Continue reading