In evolutionary biology, adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a multitude of new forms, particularly when a change in the environment makes new resources available, alters biotic interactions or opens new environmental niches. Starting with a single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different morphological and physiological traits. The prototypical example of adaptive radiation is finch speciation on the Galapagos, but examples are known from around the world.
Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within lineages. Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book On the Origin of Species. He also identified sexual selection as a likely mechanism, but found it problematic.
The Beak of the Finch: A Story of Evolution in Our Time (ISBN 0-679-40003-6) is a 1994 nonfiction book about evolutionary biology, written by Jonathan Weiner. It won the 1995 Pulitzer Prize for General Non-Fiction. In 2014, a substantially unchanged 20th-anniversary edition e-book was issued with a preface by the author.
The three-spined stickleback is a fish native to most inland and coastal waters north of 30°N. It has long been a subject of scientific study for many reasons. It shows great morphological variation throughout its range, ideal for questions about evolution and population genetics. Many populations are anadromous and very tolerant of changes in salinity, a subject of interest to physiologists. It displays elaborate breeding behavior and it can be social making it a popular subject of inquiry in fish ethology and behavioral ecology. Its antipredator adaptations, host-parasite interactions, sensory physiology, reproductive physiology, and endocrinology have also been much studied. Facilitating these studies is the fact that the three-spined stickleback is easy to find in nature and easy to keep in aquaria.
David Lambert Lack FRS was a British evolutionary biologist who made contributions to ornithology, ecology, and ethology. His 1947 book, Darwin's Finches, on the finches of the Galapagos Islands was a landmark work as were his other popular science books on Life of the Robin and Swifts in a Tower. He developed what is now known as Lack's Principle which explained the evolution of avian clutch sizes in terms of individual selection as opposed to the competing contemporary idea that they had evolved for the benefit of species. His pioneering life-history studies of the living bird helped in changing the nature of ornithology from what was then a collection-oriented field. He was a longtime director of the Edward Grey Institute of Field Ornithology at the University of Oxford.
Peter Raymond Grant and Barbara Rosemary Grant are a British married couple who are evolutionary biologists at Princeton University. Each currently holds the position of emeritus professor. They are known for their work with Darwin's finches on Daphne Major, one of the Galápagos Islands. Since 1973, the Grants have spent six months of every year capturing, tagging, and taking blood samples from finches on the island. They have worked to show that natural selection can be seen within a single lifetime, or even within a couple of years. Charles Darwin originally thought that natural selection was a long, drawn out process but the Grants have shown that these changes in populations can happen very quickly.
Character displacement is the phenomenon where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur, but are minimized or lost where the species' distributions do not overlap. This pattern results from evolutionary change driven by biological competition among species for a limited resource. The rationale for character displacement stems from the competitive exclusion principle, also called Gause's Law, which contends that to coexist in a stable environment two competing species must differ in their respective ecological niche; without differentiation, one species will eliminate or exclude the other through competition.
The Cocos finch or Cocos Island finch is the only one of the Darwin's finches not native to the Galápagos Islands, and the only member of the genus Pinaroloxias. Sometimes classified in the family Emberizidae, more recent studies have shown it to belongs in the tanager family, Thraupidae. It is endemic to Cocos Island, a Pacific island which is approximately 360 miles (580 km) south of Costa Rica.
Sallie Watson "Penny" Chisholm is an American biological oceanographer at the Massachusetts Institute of Technology. She is an expert in the ecology and evolution of ocean microbes. Her research focuses particularly on the most abundant marine phytoplankton, Prochlorococcus, that she discovered in the 1980s with Rob Olson and other collaborators. She has a TED talk about their discovery and importance called "The tiny creature that secretly powers the planet".
Ian Grote Stirling is a research scientist emeritus with Environment and Climate Change Canada and an adjunct professor in the University of Alberta Department of Biological Sciences. His research has focused mostly on Arctic and Antarctic zoology and ecology, and he is one of the world's top authorities on polar bears. Stirling has written five books and more than 150 articles published in peer-reviewed scientific journals. He has written and spoken extensively about the danger posed to polar bears by global warming.
Wayne Paul Maddison, is a professor and Canada Research Chair in Biodiversity at the departments of zoology and botany at the University of British Columbia, and the Director of the Spencer Entomological Collection at the Beaty Biodiversity Museum.
Sarah Perin "Sally" Otto is a theoretical biologist, Canada Research Chair in Theoretical and Experimental Evolution, and is currently a Killam Professor at the University of British Columbia. From 2008-2016, she was the director of the Biodiversity Research Centre at the University of British Columbia. Otto was named a 2011 MacArthur Fellow. In 2015 the American Society of Naturalists gave her the Sewall Wright Award for fundamental contributions to the unification of biology. In 2021, she was awarded the Darwin–Wallace Medal for contributing major advances to the mathematical theory of evolution.
Ecological speciation is a form of speciation arising from reproductive isolation that occurs due to an ecological factor that reduces or eliminates gene flow between two populations of a species. Ecological factors can include changes in the environmental conditions in which a species experiences, such as behavioral changes involving predation, predator avoidance, pollinator attraction, and foraging; as well as changes in mate choice due to sexual selection or communication systems. Ecologically-driven reproductive isolation under divergent natural selection leads to the formation of new species. This has been documented in many cases in nature and has been a major focus of research on speciation for the past few decades.
Leticia Avilés is an Ecuadoran evolutionary biologist and ecologist who studies the evolution of social behavior and the evolution of life history traits in metapopulations. Her methods include a combination of theory and empirical work, the latter using social spiders as a model system. Her research on these organisms has addressed questions such as why some spiders live in groups, why do they exhibit highly female-biased sex ratios, and why have they evolved a system where individuals remain in the natal nest to mate from generation to generation.
Judith (Judy) H. Myers is a Canadian-American ecologist. In 2014, she was elected president of the Canadian Society for Ecology and Evolution, and served in that role until 2016. Professor Myers is well known for her decades-long research into plant-animal-microbe interactions, including insect pest outbreaks, viral pathogens of insects, and pioneering work on biological control of insects and plants, particularly invasive species. Throughout her career she has advocated strongly for both the public understanding of science and for increasing the number of women in the STEM subjects: Science, Technology, Engineering, and Mathematics.
Kathy Martin is a Canadian ornithologist who is an expert on arctic and alpine grouse and ptarmigan, and on tree cavity-nesting vertebrates. She is a professor in the Faculty of Forestry at the University of British Columbia and was a senior research scientist with Environment and Climate Change Canada.
Patricia M. Schulte is a Canadian zoologist who is a Professor of Zoology at the University of British Columbia. Her research considers physiology, genomics and population genetics. Schulte is a Fellow of the Royal Society of Canada and the former President of the Canadian Society of Zoologists.
Judith Elizabeth Mank is an American-British zoologist who is a Canada 150 Chair at the University of British Columbia. She studies how evolution produces variation in animals. She is interested in sexual dimorphism and the formation of sex chromosomes.
In biology, parallel speciation is a type of speciation where there is repeated evolution of reproductively isolating traits via the same mechanisms occurring between separate yet closely related species inhabiting different environments. This leads to a circumstance where independently evolved lineages have developed reproductive isolation from their ancestral lineage, but not from other independent lineages that inhabit similar environments. In order for parallel speciation to be confirmed, there is a set of three requirements that has been established that must be met: there must be phylogenetic independence between the separate populations inhabiting similar environments to ensure that the traits responsible for reproductive isolation evolved separately, there must be reproductive isolation not only between the ancestral population and the descendent population, but also between descendent populations that inhabit dissimilar environments, and descendent populations that inhabit similar environments must not be reproductively isolated from one another. To determine if natural selection specifically is the cause of parallel speciation, a fourth requirement has been established that includes identifying and testing an adaptive mechanism, which eliminates the possibility of a genetic factor such as polyploidy being the responsible agent.
Professor Amy Angert is a population ecologist and evolutionary ecologist, working in the Botany and Zoology departments and Biodiversity Research Centre at the University of British Columbia. Her research is known for pioneering experimental approaches to study species geographic distributions.
