Biological Sciences
Sympatric Speciation
Sympatric speciation is a process in which new species evolve from a single ancestral species within the same geographic area. This type of speciation can occur through mechanisms such as disruptive selection, polyploidy, or habitat differentiation. It is characterized by the emergence of reproductive isolation and genetic divergence among populations without physical barriers to gene flow.
Written by Perlego with AI-assistance
Related key terms
1 of 5
12 Key excerpts on "Sympatric Speciation"
No longer available |Learn more- (Author)
- 2014(Publication Date)
- The English Press(Publisher)
Ecologists refer to parapatric and peripatric speciation in terms of ecological niches. A niche must be available in order for a new species to be successful. Observed instances • Ring species o The Larus gulls form a ring species around the North Pole. o The Ensatina salamanders, which form a ring round the Central Valley in California. o The Greenish Warbler ( Phylloscopus trochiloides ), around the Himalayas. • the grass Anthoxanthum has been known to undergo parapatric speciation in such cases as mine contamination of an area. Sympatric A speciation in which new species evolve from a single ancestral species while inhabiting the same geographic region. In evolutionary biology and biogeography, sympatric and sympatry are terms referring to organisms whose ranges overlap or are even identical, so that they occur together at least in some places. If these organisms are closely related (e.g. sister species), such a distribution may be the result of Sympatric Speciation . Etymologically, sympatry is derived from the Greek roots συν (together, with) and πατρίς (homeland or fatherland). The term was invented by Poulton in 1904, who explains the derivation. Sympatry is one of four theoretical models for the phenomenon of speciation. In contrast to allopatry, populations undergoing Sympatric Speciation are not geographically isolated by, for example, a mountain or a river. ________________________ WORLD TECHNOLOGIES ________________________ In multicellular eukaryotic organisms, Sympatric Speciation is thought to be an uncommon but plausible process by which genetic divergence (through reproductive isolation) of various populations from a single parent species and inhabiting the same geographic region leads to the creation of new species. In bacteria, however, the analogous process (defined as the origin of new bacterial species that occupy definable ecological niches) is more common and occurs through horizontal gene transfer.
eBook - PDFEvolution
The First Four Billion Years
- Michael Ruse, Joseph Travis, Michael Ruse, Joseph Travis(Authors)
- 2011(Publication Date)
- Belknap Press(Publisher)
This could result in genetic reorganizations that could incidentally yield reproductive isolation and result in rapid speciation. Sympatric Speciation occurs between populations that overlap in geographic distribution. It is the only model of speciation where reproductive isolation evolves between populations that are not geographically separated. It is usually associated with a host or habitat shift accompanied by assortative mating on the new host or in the new habitat. The Pattern and Process of Speciation 190 8 6 4 2 6 4 2 8 6 4 2 8 6 4 2 8 6 4 2 6 4 2 6 4 2 6 4 2 0.5s kHz Figure 5. An illustration of by-product reproductive isolation as a result of adaptive divergence in beak morphology occurs in Darwin’s finches. Beak morphology and representative sound spectrograms of songs from eight Darwin’s finch species on Santa Cruz Island (from top to bottom: Geospiza magnirostris, G. fortis, G. fuliginosa, G. scandens, Camarhynchus parvulus, C. psittacula, C. pallida, C. olivacea) are shown. Spectrogram frequency resolution, 98 Hz; scale bar, 0.5s. Interspecific variation is apparent in both morphology and song structure. Species with large beaks (e.g., G . magnirostris ) have lower rates of syllable repetition and narrower frequency ranges than those species with smaller beaks (e.g., C . olivacea ). (From Podos 2001.) (Schluter and Nagel 1995). The best examples of parallel speciation come from Sympatric Speciation events where independent colonizations of partic-ular environments have led to similar, repeated patterns of character diver-gence in adaptive traits associated with different niches and the parallel buildup of assortative mating by selective environment based upon differ-ences in those adaptive traits (Figure 6). The threespine stickleback (Gasterosteus aculeatus) has become a model system for the study of parallel speciation.
eBook - PDFPhylogenies in Ecology
A Guide to Concepts and Methods
- Marc W. Cadotte, T. Jonathan Davies(Authors)
- 2016(Publication Date)
- Princeton University Press(Publisher)
Hypothesis (2), the evolutionary explanation, assumes the divergence of ecological phe-notypes driven by mutually negative interaction as a response to selection acting to reduce competition; the result would be evolutionary character displacement (Brown and Wilson 1956, Taper and Case 1992). If we consider two populations of a single species (rather than two competing species), it is possible that competition for resources might be sufficient to drive speciation in sympatry (Diekmann and Doebeli 1999, Day and Young 2004), with divergent selection driving rates of character change (Schluter 2000, Coyne and Orr 2004). GEOGRAPHY OF SPECIATION • 123 Sympatric Speciation remains a controversial topic and biogeographical evidence supports the predominance of a geographical (allopatric) mode of speciation (Mayr 1963, Lynch 1989). However, recent theoretical and empirical work has generated renewed interest in the subject (Turelli et al. 2001, Via 2001, Bolnick 2004, Coyne and Orr 2004). Alternatively, speciation may be allopatric; range shifts result in secondary sympatry and subsequent character displacement. The two cases may be represented as follows: a. Sympatry (incipient species) → ecological divergence → speciation (sympatric) b. Speciation (allopatric) → sympatry → ecological divergence Time flows from left to right; the arrows indicate direction of causality. Hypothesis (3), the ecological explanation, assumes speciation and ecological diver-gence occurs in allopatry; sympatry is the product of subsequent independent range shifts or dispersal over time. This case may be represented as follows: c. Speciation (allopatric) → ecological divergence → sympatry This last hypothesis is the closest match to assumptions underlying most analyses of phylogenetic community structure (e.g., chapter 3); but see Cadotte and Jin (2014). The mode of speciation can differentiate between case (a) and case (b) or (c).
eBook - ePubA New Approach to Conservation
The Importance of the Individual through Wildlife Rehabilitation
- Gill Aitken(Author)
- 2018(Publication Date)
- Routledge(Publisher)
Finally, there are also significant differences in the time required for the formation of new species. At one end of the spectrum is allopatric speciation while at the other end is Sympatric Speciation. The former kind of speciation may take a very long time (many generations) whereas polyploid speciation 'is virtually instantaneous in its effect, potentially isolating a group of individuals from its ancestors in one generation' (p. 63).Wilson captures the significance of these differences in the speciation process in his characterisation of species that can evolve rapidly, in large numbers, and with little genetic variation, as cheap species (p. 67). He writes that if such species fill a new niche:they probably do so with relative inefficiency. They have not yet been fine-tuned by the vast number of mutations and episodes of natural selection needed to insert them solidly into the community of organisms into which they were born ... Great biological diversity takes long stretches of geological time and the accumulation of large reservoirs of unique genes. The richest ecosystems build slowly, over millions of years ... A panda or a sequoia represents a magnitude of evolution that comes along only rarely. It takes a stroke of luck and a long period of probing, experimentation, and failure (p. 68).Once we take into consideration the speciation process, we see that the term 'species' encompasses more variety than might be supposed. The different processes are suggestive of a qualitative difference that may easily be missed by conservationists putting too much emphasis on the 'product'. If what we are seeking to do in conserving nature in something like its current form is conserving the levels of variety we currently have, then the process of speciation – the way species have evolved – is of central importance to this aim.Emphasis of the species concept not only masks differences in the speciation process, it also masks the process itself. The species concept is merely a way of expressing biological diversity. If conservationists fail to appreciate this then they are in danger of failing to value, sufficiently, the means by which diversity comes about and is maintained. And it is the means of maintaining future diversity that the conservationist needs to be concerned about. 'Speciation', and not 'species' is the important player in the perpetuation of diversity.
eBook - PDFEvolution's Wedge
Competition and the Origins of Diversity
- David Pfennig, Karin Pfennig(Authors)
- 2012(Publication Date)
- University of California Press(Publisher)
As it turns out, numerous definitions of species have been proposed (Coyne and Orr 8 SPECIATION 180 • C H A P T E R E I G H T 2004; Wilkins 2009). The definition that we adopt here — the biological species con-cept — states that “species are groups of interbreeding natural populations that are repro-ductively isolated from other such groups” (Mayr 2001, p. 166). Put simply, under the biological species concept, populations are considered to be separate species if they do not interbreed regularly when sympatric in nature, or, if they do interbreed, they fail to produce fertile offspring. FIGURE 8.1. Two routes by which character displacement potentially promotes speciation. Both routes begin when separate populations that have been evolving in allopatry (Time 1) contact each other (Time 2) and then undergo character displacement (Time 3). White and black birds are from different populations; character displacement is indicated by divergence in tail length, which signifies here a trait involved in reproduction. In the first route (indicated by the arrow labeled “a” and shown at Time 4), character displacement finalizes specia-tion when competitively mediated selection promotes differences between populations in traits associated with resource use or reproduction, such that individuals from separate populations no longer interbreed. In the second route (indicated by the arrows labeled “b” and also shown at Time 4), as an indirect consequence of character displacement between newly formed species (as occurs in sympatry during the first route and indicated by the arrow labeled “a”), sympatric and allopatric populations of each species also diverge. This divergence then favors the evolution of reproductive isolation between these populations.
eBook - ePub- Michael Heads(Author)
- 2016(Publication Date)
- CRC Press(Publisher)
Biological groups, especially close relatives, are often allopatric; that is, they occupy different areas. Allopatric groups may be separated by a gap (they are “disjunct”), but their distributions often meet without any obvious physical barrier between them. In other groups, the distributions overlap—they show varying degrees of sympatry. Biogeography needs to explain both allopatry and sympatry, but allopatry is a distinctive, fundamental phenomenon seen in most groups, and many authors have accepted its primary significance in evolution. Among the New Zealand gentians, for example, “allopatry is much more frequent than sympatry” (Glenny, 2004).Species ConceptsThe concept of species is controversial, and the particular concept that is used in a biological analysis is often regarded as critical. This book uses the species concept outlined by Darwin (1859: 32): “I look at the term species, as one arbitrarily given for the sake of convenience to a set of individuals closely resembling each other, and that it does not essentially differ from the term variety.” This is very different from the neodarwinian concept, in which species have a fundamental importance. In Darwin’s model, species are not regarded as special compared with groups at other ranks, above or below the species level (Heads, 2014). As Dennett (1996: 95) wrote, discussing the definition of species: “Where should we draw the line? Darwin shows that we don’t need to draw the line in an essentialist way to get on with our science… I am inclined to interpret the persisting debates [about species definitions] as more a matter of Aristotelan tidiness than a useful disciplinary trait.” Dobzhansky (1937: 312) argued in a similar vein: “Species is a stage in a process, not a static unit.” (In contrast, the neodarwinian view stressed that “a species is not a stage of a process, but the result of a process” [Mayr, 1942: 119].)
- Dietrich Stauffer, Suzana Maria Moss de Oliveira, Paulo Murilo Castro de Oliveira, Jorge Simoes de Sá Martins(Authors)
- 2006(Publication Date)
- Elsevier Science(Publisher)
If sexual selection is not in-cluded, competition will induce only a polymorphism (Sections 4.1.2 and 4.1.3 ) and the speciation process remains incomplete. The most important aspects of these computational models are that they offer the possibility of verifying whether speciation is likely to occur depending on different contingencies (which means that the outcome of two different simulations with identical parameters may de-pend strongly on the random number seed used in each one), and to measure the speciation velocity ( Figure 4.9 ) which, as already emphasised in Section 2.6 , is related to some critical exponent. The importance of fluctuations, absent in mean-field approaches, will appear again in the next section. 4.2. Parapatric speciation 129 4.2. Parapatric speciation As mentioned in the introduction of this chapter, allopatric speciation occurs when a physical barrier divides an original population into two geographically sepa-rated ones; in this case genetic drift and adaptation to the environment are the main ingredients for speciation. In case of Sympatric Speciation the two popula-tions inhabit the same region, and its most important ingredients are competition for resources and assortative mating. Parapatric speciation is an intermediate case where there is no physical barrier but there is a gradient of temperatures or altitudes, for example, across the same region (for a review see Gavrilets (2004) as well as Coyne and Orr (2004) ). The idea of traits being differentially adapted in different spatial locations is not new ( Endler, 1973; Lande, 1982; Sanderson, 1989; Kirkpatrick and Barton, 1997 ), although still under investiga-tion. The interesting question is how much does gene flow actually retard the development of geographic differentiation within a species.
eBook - ePub- Stanley Rice(Author)
- 2020(Publication Date)
- Facts On File(Publisher)
(gene flow) between the populations. After the populations have begun to diverge, natural selection may favor isolating mechanisms and specific mate recognition systems that complete the process of speciation.- Different and random genetic changes may occur in each group. Even if natural selection favors the same characteristics in both populations, they will probably diverge because they will not have the same genes upon which natural selection can act.
Evolutionary biologists distinguish species on the basis of either a biological or a phylogenetic species concept. The biological species concept recognizes the potential to interbreed under natural conditions as the definition of species membership. Even though this concept has some difficulties (hybridization between recognized species occurs frequently, and investigators cannot know the interbreeding potential of geographically isolated populations or fossil species), it is the concept that most closely reflects the evolutionary process itself. The phylogenetic species concept recognizes that species are different if they have evolved along distinct evolutionary lines.Natural or sexual selection may occur rapidly after reproductive isolation, as the incipient species adjusts by directional selection to the new environmental conditions or the new set of species with which it is in contact. This may be followed by a long period of stabilizing selection. This has occurred frequently enough, according to many paleontologists, to produce a pattern of punctuated equilibria in the fossil record, in which long periods of equilibrium are punctuated by brief spurts of speciation.Patterns of Speciation
Speciation can occur in different patterns, as described in the following sections.Allopatric speciation. Allopatric speciation occurs when populations are geographically or ecologically isolated. This has occurred frequently on islands, where dispersal of plants and animals from the mainland is rarely successful, and once it occurs, the island population is unlikely to disperse back to the mainland. This is the process that has produced the vast number of unique endemic
eBook - ePub- Andrew P. Hendry(Author)
- 2016(Publication Date)
- Princeton University Press(Publisher)
Ecological speciation is fragile, at least in its early stages, primarily because reproductive isolation is often ecologically dependent, and therefore sensitive to changing conditions. Thus, although divergent ecological environments can sometimes cause rapid progress toward ecological speciation (the previous question), the resulting reproductive isolation can remain dependent on current environmental conditions. Escape from this ecological-dependency through the evolution of absolute and irreversible reproductive isolation seems to take considerably longer, and might often depend on nonecological mechanisms (Coyne and Orr 2004, Price 2008). Even so, the nonecological “completion” of speciation could find its beginnings in ecological divergence. First, ecological differences might reduce gene flow to the point that complete and permanent barriers can evolve. Second, ecological speciation begins whenever populations colonize/use different environments, thereby increasing the number of chances for the (likely) rare events that permanently sunder evolutionary lineages. Third, divergent selection might directly cause the evolution of permanent ecologically independent reproductive barriers, such as genetic incompatibilities (Agrawal et al. 2011).QUESTION 5: HOW IMPORTANT IS COMPETITION TO ECOLOGICAL SPECIATION IN SYMPATRY?Sympatric Speciation is most likely when strong disruptive selection is coupled to a mechanism for assortative mating (Kirkpatrick and Ravigné 2002, Bolnick and Fitzpatrick 2007); but what drives the disruptive selection? One possibility is the existence of discrete, or at least reasonably discrete (i.e., multimodal), habitats or resources, such as different host plants on which phytophagous insects can specialize (Drès and Mallet 2002, Funk et al. 2002). The other potential source of disruptive selection arises when the most common phenotypes experience the strongest competition and thereby have the lowest fitness (Rueffler et al. 2006). Under some conditions, this competition-based disruptive selection can lead to speciation even in the absence of initially multimodal resource distributions (Dieckmann and Doebeli 1999, Doebeli and Dieckmann 2003, Bolnick 2004, Rueffler et al. 2006, Doebeli et al. 2007, Rettelbach et al. 2013). The question I consider here is which of these two potential sources of disruptive selection (multimodal resources or competition) is most likely to drive Sympatric Speciation?
eBook - PDFSpecialization, Speciation, and Radiation
The Evolutionary Biology of Herbivorous Insects
- Kelley Tilmon(Author)
- 2008(Publication Date)
- University of California Press(Publisher)
Ecological Adaptation, Host-Specific Mating, and Reproductive Isolation When thinking about functional approaches to biodiversity, it must be remembered that speciation in sexually reproduc- ing organisms is predicated on the evolution of reproduc- tive barriers to gene flow between populations. These barri- ers can take the form of inherent differences reducing the propensity of individuals from different populations to mate, to form zygotes following coupling, or to produce zygotes that develop into viable and fertile progeny (Dobzhansky 1937, 1951). Understanding speciation there- fore requires discerning the nature and origins (the histori- cal and biogeographic context) of traits that reproductively isolate populations during the formative stages of diver- gence (Coyne and Orr 2004). Apple- and hawthorn-infesting populations of the tephritid fly R. pomonella are a model for sympatric host- race formation and speciation in real time (Bush 1992; Berlocher and Feder 2002). As early as the mid-1800s, Walsh (1864) hypothesized that certain host-specific phy- tophagous insects speciate in the absence of geographic iso- lation in the process of shifting and adapting to new host plants. In particular, Walsh (1867) cited the shift of R. pomonella from its native host hawthorn (Crataegus spp.) to introduced, domesticated apple (Malus pumila) in the mid 1800s as a potential example of sympatric divergence in action. Bush (1966, 1969a, 1969b) subsequently argued that the entire complex of six or more taxa comprising the R. pomonella sibling species complex, to which the apple and hawthorn host races belong, possesses attributes con- sistent with the complex having radiated sympatrically via host-plant shifts. Sympatric Speciation via host shifting is a form of eco- logical divergence that occurs without geographic isola- tion, and in the face of gene flow (Via 2001; Schluter 2001).
eBook - PDFExperimental Evolution
Concepts, Methods, and Applications of Selection Experiments
- Theodore Garland, Michael R. Rose, Theodore Garland, Michael R. Rose(Authors)
- 2009(Publication Date)
- University of California Press(Publisher)
While the results were not as striking as those of Hurd and Eisenberg (1975), the evolution of reproductive isolation in one of the two parapatric replicates in only ten generations suggests that lower but still substantial levels of gene flow (e.g., 5–10 percent) might not have impeded the evolution of reproductive isolation. More experiments of this type, with diverse organ-isms and traits, would help clarify the extent to which complete geographic separation is a prerequisite for the initial evolution of reproductive isolation. How feasible are models of Sympatric Speciation via divergence in host or habitat choice? Specialization on different habitats or hosts can lead to premating reproductive isolation by causing populations to be physically separated at the time of mating. This has caused Bush (1975, 1994) and others (e.g., Via 2001) to champion the idea that host shifts can precipitate Sympatric Speciation in phytophagous insect species in which mating takes place on the host. Although there is evidence suggesting that host shifts have contributed to sympatric divergence in some groups (Via 2001) or at least help maintain divergence (Rundle and Nosil 2005), Sympatric Speciation is notoriously difficult to document in nature. Labora-tory experiments can help clarify the feasibility of Sympatric Speciation via host or habitat shifts and identify the conditions under which it is most likely to occur. Rice and Salt (1988, 1990) conducted an elegant test of one model of sympatric spe-ciation via divergence in host or habitat preference, using D. melanogaster . The investiga-tors built an elaborate maze that forced newly emerged flies to make three successive binary choices (light/dark, up/down, and odor 1/odor 2) before being able to find food and mate. This generated eight different artificial “hosts,” each characterized by a unique set of stimuli.
eBook - ePub- David A. Baum, Douglas J. Futuyma, Hopi E. Hoekstra, Richard E. Lenski, Allen J. Moore, Catherine L. Peichel, Dolph Schluter, Michael C. Whitlock, David A. Baum, Douglas J. Futuyma, Hopi E. Hoekstra, Richard E. Lenski, Allen J. Moore, Catherine L. Peichel, Dolph Schluter, Michael C. Whitlock(Authors)
- 2013(Publication Date)
- Princeton University Press(Publisher)
When diverging populations experience migration, successful differentiation is dependent on the strength of selection and the rate of gene flow between those populations. Migration between populations resulting in gene flow allows recombination to homogenize differences. It is therefore unlikely that uniform directional selection could result in the evolution of reproductive isolation between populations that exchange genetic material, because any universally adaptive mutation arising in one population would quickly be spread through all populations that exchange migrants. In contrast, divergent directional selection across habitats can result in reproductive isolation between populations even in the face of considerable migration. If selection is strong enough, regions of the genome that are involved in adaptations to different habitats will remain divergent. Conversely, alleles at neutral loci and alleles beneficial in both habitats will move between populations through migration, thus resulting in the homogenization of those regions of the genome.Sympatric populations and those that exchange large numbers of migrants are more likely to require disruptive selection to evolve reproductive isolation. Theoreticians have explored this scenario extensively in an effort to understand how speciation might occur in sympatry, despite gene flow. However, efforts to find examples of Sympatric Speciation in nature have yielded only a few compelling examples (see chapter VI.3 ).2. TYPES OF REPRODUCTIVE BARRIERS AND THE EFFECT OF SELECTION ON THEIR EVOLUTIONConsidering that there are many agents of selection in nature, it is not surprising that natural selection can contribute to the process of speciation in multiple ways simultaneously. As pointed out by Dobzhansky and Clausen, speciation most often involves multiple reproductive isolating barriers driven by a combination of evolutionary forces. Types of barriers are listed in chapter VI.1 . The contribution of natural selection to the evolution of those barriers is explained here.Habitat IsolationHabitat isolation is a barrier that reduces gene flow owing to adaptations of populations to divergent habitats. When populations become adapted to different habitats, individuals have a greater chance of surviving and mating in their native habitats compared with foreign ones. The reduced viability of immigrant individuals in the foreign habitat leads to a reduced rate of mating between native and foreign individuals. A classic example of habitat isolation occurs in Timena cristinae walking-stick insects. In California, populations of walkingsticks have become locally adapted to living on either Adenostoma fasciculatum plants or Ceanothus spinosus
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
