 | This article provides insufficient context for those unfamiliar with the subject.(March 2021) |
The Founder Takes All (FTA) hypothesis refers to the evolutionary advantages conferred to first-arriving lineages in an ecosystem. [1]
| This article provides insufficient context for those unfamiliar with the subject.(March 2021) |
The Founder Takes All (FTA) hypothesis refers to the evolutionary advantages conferred to first-arriving lineages in an ecosystem. [1]
Density-dependent processes such as gene surfing, high-density blocking, and competitive exclusion can play crucial roles in the spatial structuring of biodiversity. These interrelated demographic processes can generate striking geographic contrasts in the distributions of genes and species. [2] Density-dependent processes refer to biogeographical processes in which population density (relative to resources) constrains the ability of new arriving lineages to establish [3] [4]
It is proposed that well-studied evolutionary and ecological biogeographic patterns of postglacial recolonization, progressive island colonization, microbial sectoring, and even the "Out of Africa" pattern of human expansion are fundamentally similar. All these patterns are underpinned by the "founder takes all" density-dependent principle.[ citation needed ] For example, following a large-scale earthquake disturbance, two parallel recolonisation events and density-dependent blocking have been hypothesised to explain the occurrence of two distinct spatial sectors of population structure in Durvillaea antarctica on Turakirae Head in New Zealand. [5]
It is hypothesized that older historical constraints of density-independent processes are seen today, within the dramatic biogeographic shifts that occur in response to human-mediated extinction events. Due to these extinction events, surviving lineages can rapidly expand their ranges to replace extinct sister taxa. [2]
The FTA model is underpinned by demographic and ecological phenomena and processes such as the Allee effect, gene surfing, [6] high-density blocking, [7] and priority effects. [8] Early colonizing lineages can reach high densities and thus hinder the success of late-arriving colonizers. It has been suggested that this can strongly influence spatial biodiversity patterns.
Scientific evidence for FTA processes has emerged from a variety of evolutionary, biogeographic, and ecological research areas. Examples include: the sectoring patterns sometimes evident in microbial colonies; [9] phylogeographic sectoring of lineages, inferred to have rapidly expanded into new terrain-following deglaciation; [10] [11] the island progression rule; [12] and sudden biological replacement (lineage turnover) following extirpation. [13]
One possible scientific consequence of FTA dynamics is that gene flow measures based on the genetics of contemporary high-density populations may underestimate actual rates of dispersal and invasion potential. [14]
Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, isolation and habitat area. Phytogeography is the branch of biogeography that studies the distribution of plants. Zoogeography is the branch that studies distribution of animals. Mycogeography is the branch that studies distribution of fungi, such as mushrooms.
Phylogeography is the study of the historical processes that may be responsible for the past to present geographic distributions of genealogical lineages. This is accomplished by considering the geographic distribution of individuals in light of genetics, particularly population genetics.
Biological dispersal refers to both the movement of individuals from their birth site to their breeding site, as well as the movement from one breeding site to another . Dispersal is also used to describe the movement of propagules such as seeds and spores. Technically, dispersal is defined as any movement that has the potential to lead to gene flow. The act of dispersal involves three phases: departure, transfer, settlement and there are different fitness costs and benefits associated with each of these phases. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population genetics, and species distribution. Understanding dispersal and the consequences both for evolutionary strategies at a species level, and for processes at an ecosystem level, requires understanding on the type of dispersal, the dispersal range of a given species, and the dispersal mechanisms involved. Biological dispersal can be correlated to population density. The range of variations of a species' location determines expansion range.
Turakirae Head is a promontory on the southern coast of New Zealand's North Island. It is located at the western end of Palliser Bay, 20 kilometres southeast of Wellington, at the southern end of the Remutaka Range. The head hosts a series of uplifted Holocene marine terraces and beach ridges that record uplift from past earthquakes. After each earthquake, a new terrace and beach ridge formed below the previous one at sea level. The most recent earthquake to uplift Turakirae Head was the 1855 Wairarapa earthquake, which raised the shoreline up to 6.4 m. Turakirae Head is also home to a seal colony and southern bull kelp.
Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological processes that slowly alter the layout of the physical environment, and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species. More specifically, habitat fragmentation is a process by which large and contiguous habitats get divided into smaller, isolated patches of habitats.
Molecular ecology is a field of evolutionary biology that is concerned with applying molecular population genetics, molecular phylogenetics, and more recently genomics to traditional ecological questions. It is virtually synonymous with the field of "Ecological Genetics" as pioneered by Theodosius Dobzhansky, E. B. Ford, Godfrey M. Hewitt, and others. These fields are united in their attempt to study genetic-based questions "out in the field" as opposed to the laboratory. Molecular ecology is related to the field of conservation genetics.
Species richness, or biodiversity, increases from the poles to the tropics for a wide variety of terrestrial and marine organisms, often referred to as the latitudinal diversity gradient. The latitudinal diversity gradient is one of the most widely recognized patterns in ecology. It has been observed to varying degrees in Earth's past. A parallel trend has been found with elevation, though this is less well-studied.
A hybrid zone exists where the ranges of two interbreeding species or diverged intraspecific lineages meet and cross-fertilize. Hybrid zones can form in situ due to the evolution of a new lineage but generally they result from secondary contact of the parental forms after a period of geographic isolation, which allowed their differentiation. Hybrid zones are useful in studying the genetics of speciation as they can provide natural examples of differentiation and (sometimes) gene flow between populations that are at some point between representing a single species and representing multiple species in reproductive isolation.
Durvillaea is a genus of large brown algae in the monotypic family Durvillaeaceae. All members of the genus are found in the southern hemisphere, including Australia, New Zealand, South America, and various subantarctic islands. Durvillaea, commonly known as southern bull kelps, occur on rocky, wave-exposed shorelines and provide a habitat for numerous intertidal organisms. Many species exhibit a honeycomb-like structure in their fronds that provides buoyancy, which allows individuals detached from substrates to raft alive at sea, permitting dispersal for hundreds of days over thousands of kilometres. Durvillaea species have been used for clothing, tools and as a food source by many indigenous cultures throughout the South Pacific, and they continue to play a prominent role in Chilean cuisine.
Durvillaea antarctica, also known as cochayuyo and rimurapa, is a large, robust species of southern bull kelp found on the coasts of Chile, southern New Zealand, and Macquarie Island. D. antarctica, an alga, does not have air bladders, but floats due to a unique honeycomb structure within the alga's blades, which also helps the kelp avoid being damaged by the strong waves.
A genetic isolate is a population of organisms with little genetic mixing with other organisms within the same species due to geographic isolation or other factors that prevent reproduction. Genetic isolates form new species through an evolutionary process known as speciation. All modern species diversity is a product of genetic isolates and evolution.
The 1855 Wairarapa earthquake occurred on 23 January at about 9.17 p.m., affecting much of the Cook Strait area of New Zealand, including Marlborough in the South Island and Wellington and the Wairarapa in the North Island. In Wellington, close to the epicentre, shaking lasted for at least 50 seconds. The moment magnitude of the earthquake has been estimated as 8.2, the most powerful recorded in New Zealand since systematic European colonisation began in 1840. This earthquake was associated with the largest directly observed movement on a strike-slip fault, maximum 18 metres (59 ft). This was later revised upward to about 20 m (66 ft) slip, with a local peak of 8 m (26 ft) vertical displacement on lidar studies. It has been suggested that the surface rupture formed by this event helped influence Charles Lyell to link earthquakes with rapid movement on faults.
Isolation by distance (IBD) is a term used to refer to the accrual of local genetic variation under geographically limited dispersal. The IBD model is useful for determining the distribution of gene frequencies over a geographic region. Both dispersal variance and migration probabilities are variables in this model and both contribute to local genetic differentiation. Isolation by distance is usually the simplest model for the cause of genetic isolation between populations. Evolutionary biologists and population geneticists have been exploring varying theories and models for explaining population structure. Yoichi Ishida compares two important theories of isolation by distance and clarifies the relationship between the two. According to Ishida, Sewall Wright's isolation by distance theory is termed ecological isolation by distance while Gustave Malécot's theory is called genetic isolation by distance. Isolation by distance is distantly related to speciation. Multiple types of isolating barriers, namely prezygotic isolating barriers, including isolation by distance, are considered the key factor in keeping populations apart, limiting gene flow.
Host–parasite coevolution is a special case of coevolution, where a host and a parasite continually adapt to each other. This can create an evolutionary arms race between them. A more benign possibility is of an evolutionary trade-off between transmission and virulence in the parasite, as if it kills its host too quickly, the parasite will not be able to reproduce either. Another theory, the Red Queen hypothesis, proposes that since both host and parasite have to keep on evolving to keep up with each other, and since sexual reproduction continually creates new combinations of genes, parasitism favours sexual reproduction in the host.
Microbial biogeography is a subset of biogeography, a field that concerns the distribution of organisms across space and time. Although biogeography traditionally focused on plants and larger animals, recent studies have broadened this field to include distribution patterns of microorganisms. This extension of biogeography to smaller scales—known as "microbial biogeography"—is enabled by ongoing advances in genetic technologies.
Rosemary Gillespie is an evolutionary biologist and professor of Environmental Science, Policy & Management, Division of Insect Biology at the University of California, Berkeley. She was the President of the American Genetics Association in 2018 and was previously President of the International Biogeography Society 2013–2015. From 2011 to 2013 she had served at the president of the American Arachnological Society. As of 2020 she is the faculty director of the Essig Museum of Entomology and a Professor and Schlinger Chair in systematic entomology at the University of California, Berkeley. Gillespie is known for her work on the evolution of communities on hotspot archipelagoes.
Evolutionary rescue is a process by which a population—that would have gone extinct in the absence of evolution—persists due to natural selection acting on heritable variation. Coined by Gomulkiewicz & Holt in 1995, evolutionary rescue was described as a continuously changing environment predicted to appear as a stable lag of the mean trait value behind a moving environmental optimum, where the rate of evolution and change in the environment are equal. Evolutionary rescue is often confused with two other commonplace forms of rescue: genetic rescue and demographic rescue-in nature due to overlapping similarities. Figure 1 highlights the different pathways that result in their respective rescue.
Landscape genetics is the scientific discipline that combines population genetics and landscape ecology. It broadly encompasses any study that analyses plant or animal population genetic data in conjunction with data on the landscape features and matrix quality where the sampled population lives. This allows for the analysis of microevolutionary processes affecting the species in light of landscape spatial patterns, providing a more realistic view of how populations interact with their environments. Landscape genetics attempts to determine which landscape features are barriers to dispersal and gene flow, how human-induced landscape changes affect the evolution of populations, the source-sink dynamics of a given population, and how diseases or invasive species spread across landscapes.
Ceridwen Fraser is a biogeographer, currently serving as a Professor in the Department of Marine Science at the University of Otago in Dunedin, New Zealand. She focuses her studies on ecology, evolution, climate change, and how they are all significant to the southern hemisphere, specifically at higher latitudes such as Antarctica.
Durvillaea poha is a large, robust species of southern bull kelp found in New Zealand.
