Related Research Articles
Allopatric speciation – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.
Peripatric speciation is a mode of speciation in which a new species is formed from an isolated peripheral population. Since peripatric speciation resembles allopatric speciation, in that populations are isolated and prevented from exchanging genes, it can often be difficult to distinguish between them. Nevertheless, the primary characteristic of peripatric speciation proposes that one of the populations is much smaller than the other. The terms peripatric and peripatry are often used in biogeography, referring to organisms whose ranges are closely adjacent but do not overlap, being separated where these organisms do not occur—for example on an oceanic island compared to the mainland. Such organisms are usually closely related ; their distribution being the result of peripatric speciation.
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sharing a common range exemplifies sympatric speciation. Such speciation may be a product of reproductive isolation – which prevents hybrid offspring from being viable or able to reproduce, thereby reducing gene flow – that results in genetic divergence. Sympatric speciation may, but need not, arise through secondary contact, which refers to speciation or divergence in allopatry followed by range expansions leading to an area of sympatry. Sympatric species or taxa in secondary contact may or may not interbreed.
In evolutionary biology, disruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups. In this more individuals acquire peripheral character value at both ends of the distribution curve.
In parapatric speciation, two subpopulations of a species evolve reproductive isolation from one another while continuing to exchange genes. This mode of speciation has three distinguishing characteristics: 1) mating occurs non-randomly, 2) gene flow occurs unequally, and 3) populations exist in either continuous or discontinuous geographic ranges. This distribution pattern may be the result of unequal dispersal, incomplete geographical barriers, or divergent expressions of behavior, among other things. Parapatric speciation predicts that hybrid zones will often exist at the junction between the two populations.
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 gene flow between populations that are at some point on the continuum between diverging populations and separate species with reproductive isolation.
Sexual antagonistic co-evolution is the relationship between males and females where sexual morphology changes over time to counteract the opposite's sex traits to achieve the maximum reproductive success. This has been compared to an arms race between sexes. In many cases, male mating behavior is detrimental to the female's fitness. For example, when insects reproduce by means of traumatic insemination, it is very disadvantageous to the female's health. During mating, males will try to inseminate as many females as possible, however, the more times a female's abdomen is punctured, the less likely she is to survive. Females that possess traits to avoid multiple matings will be more likely to survive, resulting in a change in morphology. In males, genitalia is relatively simple and more likely to vary among generations compared to female genitalia. This results in a new trait that females have to avoid in order to survive.
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.
Reinforcement is a process of speciation where natural selection increases the reproductive isolation between two populations of species. This occurs as a result of selection acting against the production of hybrid individuals of low fitness. The idea was originally developed by Alfred Russel Wallace and is sometimes referred to as the Wallace effect. The modern concept of reinforcement originates from Theodosius Dobzhansky. He envisioned a species separated allopatrically, where during secondary contact the two populations mate, producing hybrids with lower fitness. Natural selection results from the hybrid's inability to produce viable offspring; thus members of one species who do not mate with members of the other have greater reproductive success. This favors the evolution of greater prezygotic isolation. Reinforcement is one of the few cases in which selection can favor an increase in prezygotic isolation, influencing the process of speciation directly. This aspect has been particularly appealing among evolutionary biologists.
The scientific study of speciation — how species evolve to become new species — began around the time of Charles Darwin in the middle of the 19th century. Many naturalists at the time recognized the relationship between biogeography and the evolution of species. The 20th century saw the growth of the field of speciation, with major contributors such as Ernst Mayr researching and documenting species' geographic patterns and relationships. The field grew in prominence with the modern evolutionary synthesis in the early part of that century. Since then, research on speciation has expanded immensely.
Reinforcement is a process within speciation where natural selection increases the reproductive isolation between two populations of species by reducing the production of hybrids. Evidence for speciation by reinforcement has been gathered since the 1990s, and along with data from comparative studies and laboratory experiments, has overcome many of the objections to the theory. Differences in behavior or biology that inhibit formation of hybrid zygotes are termed prezygotic isolation. Reinforcement can be shown to be occurring by measuring the strength of prezygotic isolation in a sympatric population in comparison to an allopatric population of the same species. Comparative studies of this allow for determining large-scale patterns in nature across various taxa. Mating patterns in hybrid zones can also be used to detect reinforcement. Reproductive character displacement is seen as a result of reinforcement, so many of the cases in nature express this pattern in sympatry. Reinforcement's prevalence is unknown, but the patterns of reproductive character displacement are found across numerous taxa, and is considered to be a common occurrence in nature. Studies of reinforcement in nature often prove difficult, as alternative explanations for the detected patterns can be asserted. Nevertheless, empirical evidence exists for reinforcement occurring across various taxa and its role in precipitating speciation is conclusive.
Laboratory experiments of speciation have been conducted for all four modes of speciation: allopatric, peripatric, parapatric, and sympatric; and various other processes involving speciation: hybridization, reinforcement, founder effects, among others. Most of the experiments have been done on flies, in particular Drosophila fruit flies. However, more recent studies have tested yeasts, fungi, and even viruses.
In evolutionary biology, developmental bias refers to the production against or towards certain ontogenetic trajectories which ultimately influence the direction and outcome of evolutionary change by affecting the rates, magnitudes, directions and limits of trait evolution. Historically, the term was synonymous with developmental constraint, however, the latter has been more recently interpreted as referring solely to the negative role of development in evolution.
Amy Reed McCune is an American ecologist and evolutionary biologist. She is a professor of ecology and evolutionary biology at Cornell University. McCune specializes in the history of life through the study of fishes. Her lab focuses on evolution with methodologies including paleobiology, phylogenetics, genetics and morphology.
Drosophila silvestris is a large species of fly in the family Drosophilidae that are primarily black with yellow spots. As a rare species of fruit fly endemic to Hawaii, the fly often experiences reproductive isolation. Despite barriers in nature, D. silvestris is able to breed with D. heteroneura to create hybrid flies in the laboratory.
Eukaryote hybrid genomes result from interspecific hybridization, where closely related species mate and produce offspring with admixed genomes. The advent of large-scale genomic sequencing has shown that hybridization is common, and that it may represent an important source of novel variation. Although most interspecific hybrids are sterile or less fit than their parents, some may survive and reproduce, enabling the transfer of adaptive variants across the species boundary, and even result in the formation of novel evolutionary lineages. There are two main variants of hybrid species genomes: allopolyploid, which have one full chromosome set from each parent species, and homoploid, which are a mosaic of the parent species genomes with no increase in chromosome number.
Etheostomatinae is a species-rich subfamily of freshwater ray-finned fish, the members of which are commonly known as the darters. The subfamily is part of the family Percidae which also includes the perches, ruffes and pikeperches. The family is endemic to North America. It consists of three to five different genera and well over 200 species. A common name for these fish in southern Indiana is pollywog.
Allochronic speciation is a form of speciation arising from reproductive isolation that occurs due to a change in breeding time that reduces or eliminates gene flow between two populations of a species. The term allochrony is used to describe the general ecological phenomenon of the differences in phenology that arise between two or more species—speciation caused by allochrony is effectively allochronic speciation.
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.
Douglas Schemske is an evolutionary ecologist who made major contributions to research on pollination, the latitudinal gradient in species diversity, the evolution of polyploidy, and plant mating systems.
References
- ↑ "Servedio, Maria R." UNC DEPARTMENT OF BIOLOGY. Retrieved 2019-05-17.
- ↑ "Current Executive Council of the ASN". www.amnat.org. Retrieved 2019-05-17.
- ↑ "Results of the 2021 Election". www.amnat.org. Retrieved 2021-04-23.
- ↑ "Maria Servedio CV" (PDF).
- ↑ "Birds choose mates with ornamental traits". ScienceDaily. Retrieved 2019-05-17.
- ↑ "Current Executive Council of the ASN". www.amnat.org. Retrieved 2019-05-17.
- ↑ "Evolution". onlinelibrary.wiley.com. Retrieved 2019-05-17.
- ↑ "Servedio Lab - People". sites.google.com. Retrieved 2019-05-17.
- ↑ Servedio, Maria R.; Noor, Mohamed A.F. (2003-11-01). "The Role of Reinforcement in Speciation: Theory and Data". Annual Review of Ecology, Evolution, and Systematics. 34 (1): 339–364. doi:10.1146/annurev.ecolsys.34.011802.132412. ISSN 1543-592X.
- ↑ Nosil, Patrik; Frame, Alicia M.; Kopp, Michael; Doorn, G. Sander Van; Servedio, Maria R. (2011-08-01). "Magic traits in speciation: 'magic' but not rare?". Trends in Ecology & Evolution. 26 (8): 389–397. doi:10.1016/j.tree.2011.04.005. ISSN 0169-5347. PMID 21592615. S2CID 10412384.
- ↑ Wiens John J.; Servedio Maria R. (2000-04-07). "Species delimitation in systematics: inferring diagnostic differences between species". Proceedings of the Royal Society B: Biological Sciences. 267 (1444): 631–636. doi:10.1098/rspb.2000.1049. PMC 1690594 . PMID 10821606.
- ↑ Svensson, Erik I.; Boughman, Jenny W.; Kozak, Genevieve M.; Servedio, Maria R.; Cate, Carel ten; Verzijden, Machteld N. (2012-09-01). "The impact of learning on sexual selection and speciation". Trends in Ecology & Evolution. 27 (9): 511–519. doi:10.1016/j.tree.2012.05.007. ISSN 0169-5347. PMID 22705159.
- ↑ Saether, S. A.; Saetre, G.-P.; Borge, T.; Wiley, C.; Svedin, N.; Andersson, G.; Veen, T.; Haavie, J.; Servedio, M. R. (2007-10-05). "Sex Chromosome-Linked Species Recognition and Evolution of Reproductive Isolation in Flycatchers". Science. 318 (5847): 95–97. Bibcode:2007Sci...318...95S. doi:10.1126/science.1141506. ISSN 0036-8075. PMID 17916732. S2CID 17355474.
- ↑ Servedio, Maria R.; Kirkpatrick, Mark (1997). "The Effects of Gene Flow on Reinforcement". Evolution. 51 (6): 1764–1772. doi:10.1111/j.1558-5646.1997.tb05100.x. ISSN 1558-5646. PMID 28565111. S2CID 12269299.
- ↑ Servedio, Maria R. (2000). "Reinforcement and the Genetics of Nonrandom Mating". Evolution. 54 (1): 21–29. doi: 10.1111/j.0014-3820.2000.tb00003.x . ISSN 1558-5646. PMID 10937179. S2CID 12563023.
- ↑ Lachlan, R. F.; Servedio, M. R. (2004). "Song Learning Accelerates Allopatric Speciation". Evolution. 58 (9): 2049–2063. doi: 10.1111/j.0014-3820.2004.tb00489.x . ISSN 1558-5646. PMID 15521461.
- ↑ Servedio, Maria R. (2001). "Beyond Reinforcement: The Evolution of Premating Isolation by Direct Selection on Preferences and Postmating, Prezygotic Incompatibilities". Evolution. 55 (10): 1909–1920. doi: 10.1111/j.0014-3820.2001.tb01309.x . ISSN 1558-5646. PMID 11761053.
- ↑ Servedio, Maria R.; Lande, Russell (2006). "Population Genetic Models of Male and Mutual Mate Choice". Evolution. 60 (4): 674–685. doi: 10.1111/j.0014-3820.2006.tb01147.x . ISSN 1558-5646. PMID 16739450.
