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Topic: Allopatry


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In the News (Wed 20 Mar 19)

  
  Speciation
Ernst Mayr proposed a speciation mechanism called allopatry.
Allopatry begins when subpopulations of a species become isolated geographically, for example by habitat fragmentation or migration.
The isolated populations are then liable to diverge evolutionarily over many generations as a) they become subjected to dissimilar selective pressures and b) they independently undergo genetic drift; particularly when one of the subpopulations is small[?], a scenario that leads to the "founder's effect").
www.ebroadcast.com.au /lookup/encyclopedia/sy/Sympatry.html   (295 words)

  
 Speciation   (Site not responding. Last check: 2007-10-23)
The isolated populations are then liable to diverge evolutionarily over many generations as a) they become subjected to dissimilar selective pressures and b) they independently undergo genetic drift ; particularly when one of the subpopulations is small, a scenario that leads to the " founder effect ").
A further mechanism is parapatry, a middleground between the extremes of allopatry and sympatry.
There is only partial separation afforded by geography, so certain individuals of a particular species may cross the barrier from time to time.
www.serebella.com /encyclopedia/article-Speciation.html   (654 words)

  
 PAIR COMPOSITION AND REPRODUCTIVE SUCCESS ACROSS A HYBRID ZONE OF CARRION CROWS AND HOODED CROWS
Area of allopatry of Carrion Crow.--This was an area of 65 km 2 covering all the bottom of the Stura di Demonte River valley from 750 to 950 m above sea level and a few small lateral valleys of the Stura Val- ley.
Data on the reproductive biology of the crows in areas of allopatry were collected in 1988, 1989 and 1990, while data from the hybrid zone were obtained during 1989 and 1990.
This dual approach to the analysis of the variation in the breeding parameters is similar to that adopted by Johnson and Johnson (1985) in a study of hybridization between sapsuckers (Sphyrapicus ru- ber daggetti and S. nuchalis), and by Moore and Koenig (1986) in a study of a flicker (Colaptes auratus) hybrid zone.
elibrary.unm.edu /sora/Auk/v109n03/p0543-p0555.html   (10921 words)

  
 Lect_12.html
Allopatry simply means that two populations do not come into physical contact as a consequence of some physical barrier (e.g, a mountain range, an ocean).
Allopatry results in speciation because the lack of gene flow allows populations to evolve differences that cause incompatibilities if/when the populations come back into contact.
An interesting idea put forward by Dobzhansky is that speciation is not usually completed in allopatry, but rather is completed when two previously allopatric populations that are partially isolated come back into contact.
trc.ucdavis.edu /djbegun/Lect.13-15.04.html   (4006 words)

  
 UCD Geology: GEL 107 Midterm I Review
Allopatry: Requires geographic isolation in order for divergence in morphology to occur.
Parent population increases in size and geographic extent over time; peripheral isolates (subpopulations on the edges of the geographic range) interact less and less with the central parent population; eventually become fully isolated geographically and diverge morphologically over time as divergent selection pressures act on them.
Could see an increase in variance of one or more morphological features that eventually increases further, with loss of the intermediate state, resulting in a Y-shaped pattern in the stratigraphic record, that could potentially be tested by examining the geographic extent of the specimens involved.
www.geology.ucdavis.edu /~gel107/sp06_carlson/lectures/midtermkey1.html   (965 words)

  
 Re: Species is only Taxonomic level that is "real"
allopatry in birds is a different story than allopatry in herps).
Allopatry is, always has been, and always will be the toughest test of any species concept.
Many "old-school" folks would avoid the problem of allopatry by saying that if the two pops can interbreed and produce fertile offspring, then the two are the same species.
forum.kingsnake.com /tax/messages/85.html   (644 words)

  
 macroevol   (Site not responding. Last check: 2007-10-23)
Many biologists believe that allopatry is a matter of scale: for some organisms, very small distances might suffice.
Use it to discuss why "sympatry" and "allopatry" are end-points on a continuum.
Allopatry is defined in your textbook as physical isolation through geographic isolation.
www.uvm.edu /~lehiggin/teaching/bio1/macroevol.html   (377 words)

  
 Levels of Selection, and Speciation Mechanisms, Barry Sinervo
In this case, the two species were in allopatry in the remote past and brought into secondary contact and weak gene flow began once the sibling species were rejoined at the hybrid zone.
In areas of allopatry the songs of both species are of medium duration.
When the dispersal of birds occurs among islands, gene flow is minimized because of evolved differences in song type among males, and because females tend to choose males on the basis of song.
bio.research.ucsc.edu /~barrylab/classes/animal_behavior/SPECIATE.HTM   (6803 words)

  
 Habitat Shift of a Native Darter Etheostoma Olmstedi (Teleostei: Percidae) in Sympatry With a Non-Native Darter ...
Sympatry and allopatry with Etheostoma zonale.-Etheostoma olmstedi shifted its habitat in the presence of E. onale.
In the high flow data set, E. olmstedi populations in sympatry and allopatry with E. onale differed in depth (F = 42.48; 1, 100 df; P = 0.0001) and mean water velocity distribution (F = 12.46; 1, 100 df; P = 0.0006; Table 1; Fig.
The percent decrease in niche width from populations in sympatry to populations in allopatry with E. onale are given
www.redorbit.com /news/display?id=187732&source=r_science   (4319 words)

  
 SPECIATION IN SAPSUCKERS (SPHYRAPICUS): II. SYMPATRY, HYBRIDIZATION, AND MATE PREFERENCE IN S. RUBER DAGGETTI AND S. ...
This is demon- strated by the plotting of hybrid index scores of allopatric breeding specimens of 126 daggetti and 88 nuchalis in Fig.
Variation of parental forms in regions of allopatry was used to distinguish parental phenotypes from hybrids in the zone of overlap and hybridization.
The percentage representation of various categories of mating (conspecific, 75.8%; backcross, 16.6%; hybrid, 1.4%; and interspecific, 6.2%) shown by 145 nesting pairs in the zone of overlap was used to infer the relative fitness of F 1 and F 2 generation hybrids.
elibrary.unm.edu /sora/Auk/v102n01/p0001-p0015.html   (12327 words)

  
 BBS - Results - USGS Patuxent Wildlife Research Center   (Site not responding. Last check: 2007-10-23)
Assigning data in regions of allopatry was routine.
All BBS data for this species complex were obtained from regions of allopatry, and the retroactive assignment between these two species was routine.
The retroactive assignment of the 1966-1973 data was routine within areas of allopatry.
www.pwrc.usgs.gov /bbs/bbsnews/AOUsplt1.htm   (5377 words)

  
 Sympatry, Allopatry, etc.
Allopatry: Phylogenetically closely related taxa living in different areas are called allopatric.
---- David Marjanovic also made comments on how allopatry and sympatry would be synonymous to some degree, but they are in fact mutually exclusive: syn- + Greek patr, fatherland (from patr, patr-, father; see pter- in Appendix I) + -ic.
Both definitions are apt, but geography is, in fact, the issue in the discussion of sympatry and allopatry.
dml.cmnh.org /2002Dec/msg00712.html   (611 words)

  
 OIKOS 000: 000-000, 2003   (Site not responding. Last check: 2007-10-23)
At the population level, we compared performance of the two species in their natural sympatric state with that of Arctic charr in allopatry.
Arctic charr did not expand their niche in allopatry, indicating that the two species compete to a limited degree for the same resources and that interference may suppress the growth of charr in sympatric enclosures.
At the individual level, however, we found directional selection in sympatric enclosures against individual Arctic charr with large head and long fins and against individuals feeding on zoobenthos rather than zooplankton indicating competition for common resources (possibly exploitative) between trout and these charr individuals.
www.oikos.ekol.lu.se /oikos.101.3.abstracts/11257forseth.htm   (304 words)

  
 IngentaConnect Proximate sources of marine biodiversity   (Site not responding. Last check: 2007-10-23)
It is not suggested that sympatry is exclusive to centres of origin, nor that allopatry is confined to peripheral provinces.
Considering that numbers of widespread species produced by centres of origin may eventually become subdivided by barriers, and thus give rise to descendants by allopatry, it is difficult to say how much of our present species diversity has come from one source or the other.
Both speciation by sympatry from centres of origin and speciation by allopatry in peripheral provinces appear to be important sources of marine biodiversity.
www.ingentaconnect.com /content/bsc/jbiog/2006/00000033/00000001/art00001   (377 words)

  
 Species and Speciation [MT Dorak]
When divergences (eventually leading to speciation) between populations are not adaptive, they are attributed to genetic drift (some Hawaiian Drosophila species and the North American flowering plant Clark lingual).
The debate is whether adaptation or chance (genetic drift) plays a major role in divergence in allopatry (in small population it is more likely to be drift).
After subsequent sympatry (secondary contact), initially slight differences in mate recognition traits are exaggerated by selection in favor of pre-zygotic isolation -through assortative mating- (reinforcement theory).
www.dorak.info /evolution/species.html   (2241 words)

  
 Current Research: William Rice
My research on speciation began in the early 1980's and it focused initially on the question of whether the evolution of reproductive isolation required allopatry (the separation of populations in space or time, which causes gene flow to be absent).
I first used multilocus simulation modeling to show that the evolution of reproductive isolation without allopatry was more genetically plausible when reproductive isolation evolved indirectly as a correlated trait rather than directly due to selection for positive assortative mating (Rice 1984a).
The second set of experiments was carried out and, as predicted by theory, complete reproduction isolation was observed to evolve in response to divergent selection on habitat preference (Rice and Salt 1988a; 1990a).
www.lifesci.ucsb.edu /eemb/faculty/rice/research/research.html   (3421 words)

  
 Speciation - Wikinfo
In asexually reproducing organisms, there are other modes that become prominent including horizontal gene transfer by viruses and mutations.
A further mechanism is parapatry, a middleground between the extremes of allopatry and sympatry.
There is only partial separation afforded by geography, so certain individuals of a particular species may cross the barrier from time to time.
www.wikinfo.org /wiki.php?title=Speciation   (1579 words)

  
 Abstract of Turner & Burrows (1995)   (Site not responding. Last check: 2007-10-23)
Assuming a four-locus quantitative male trait and single-locus female preference rule and overlapping generations, we present a simulation model which indicates that reversal of female mate preference in a single individual can lead rapidly to full reproductive isolation in a small population.
Speciation may be produced by the proposed mechanism in allopatry, parapatry or full sympatry.
We suggest that differences in mating system and its genetic bases may account for some of the differences in speciation rates among lineages.
www.malawicichlids.com /_popup_abs_tub95.htm   (172 words)

  
 Kingsnake.com - Herpforum - RE: another try: Sibling species...
Allopatry is a poor determinant of species distinctness.
"Doesn't allopatry also mean not having gene flow, a reduced gene pool and therefore eventually the development of certain characters (due to environmental factors)?"
Allopatry means that two populations that are geographically isolated from each other will each develop their own unique alleles.
forums.kingsnake.com /view.php?id=841192,949423   (528 words)

  
 Article Summary–Speciation and Hybridization
There are two alternative models to explain speciation in island birds: allopatry or peripatry (or founder speciation).
The present publication highlights every step during the presumed speciation of Darwin's finches in allopatry and provides background mechanistic data, in order to really evaluate each step of the model.
The punch line is: "Differences that evolve in allopatry are reinforced by a regime of divergent selection on the taxa in sympatry arising from ecological pressures and not from reproductive (genetic) incompatibility....
wps.prenhall.com /esm_freeman_evol_3/0,8018,849873-,00.html   (384 words)

  
 ljacobsabs
This was TWRA's first attempt at brook trout restoration that did not involve removing or reducing a pre-existing rainbow trout population.
Upper Little Jacob Creek will be monitored to determine the efficacy of this method of re-introducing brook trout, which could be useful where establishment of a brook trout population is desirable (e.g., to create a fishery), but allopatry is not considered necessary or the removal of other salmonids is impractical.
To help brook trout become established in Little Jacob Creek, it was placed (along with Left Prong Hampton Creek) under the set of regulations that currently apply to Rocky Fork, Higgins Creek, and several others (only three of the seven-fish creel limit may be brook trout ³152 mm; artificial single-hook lures only).
www.homestead.com /twra4streams/ljacobsabs.html   (252 words)

  
 Allopatric speciation Summary
Allopatric speciation, also known as geographic speciation, occurs when populations physically isolated by an extrinsic barrier evolve intrinsic (genetic) reproductive isolation such that if the barrier between the populations breaks down, individuals of the two populations can no longer interbreed.
Although there is some debate about the frequency of other types of speciation (such as sympatric speciation and parapatric speciation), all evolutionary biologists agree that allopatry is a common way that new species arise.
The evolution of reproductive isolation is generally thought to be an incidental by-product of genetic divergence of other traits, particularly adaptive changes that evolve through natural selection in response to different environmental conditions in separate geographic areas.
www.bookrags.com /Allopatric_speciation   (924 words)

  
 Contiguous allopatry of the masked shrew and southeastern shrew in the Southern Appalachians: segregation along an ...
Contiguous allopatry of the masked shrew and southeastern shrew in the Southern Appalachians: segregation along an elevational and habitat gradient
Upper elevation limits of southeastern shrew and lower elevational limits of masked shrew show an inverse relation with latitude relative to shrew collections from farther north along the Appalachians.
Southeastern shrews and masked shrews are allopatric in the Southern Appalachians except in the Blue Ridge, where the species exhibits contiguous allopatry, based on elevation and habitat associations.
www.srs.fs.usda.gov /pubs/viewpub.jsp?index=3192   (370 words)

  
 Abstract of Seehausen & van Alphen (1999)   (Site not responding. Last check: 2007-10-23)
Plotting numbers of pairs of closely related species against the amount of distributional overlap between the species reveals a bimodal distribution with modes on allopatric and sympatric.
The proportion of sister species pairs that are heteromorphic for the traits under disruptive selection is higher in sympatry than in allopatry.
These data support the hypothesis that disruptive sexual selection on colour polymorphisms has caused sympatric speciation and help to explain the rapid radiation of haplochromine species flocks.
www.malawicichlids.com /_popup_abs_sva99.htm   (178 words)

  
 Models of Speciation
In this case speciation was not completed in allopatry and fate of the two populations depends on the outcome of the interaction upon secondary contact.
Patterns of discontinuities between differentiated forms/populations may be due to secondary contact after a period in allopatry, or the discontinuity could be due to primary differentiation in situ.
This is not true since the hybrid zone may be the result of secondary contact after allopatry, rather than primary differentiation at the hybrid zone interface.
biomed.brown.edu /Courses/BIO48/21.Models.HTML   (1986 words)

  
 [No title]   (Site not responding. Last check: 2007-10-23)
Two closely related species that in zones of allopatry have similar morphologies, but in areas of sympatry their morphologies diverge
- allopatry - area in a species range where it does not overlap with the its potential competitor
- in zones of allopatry both species of finches have the same depth to their beaks
cneuro.zool.ohiou.edu /~roosen/ecology/Lec11.html   (1153 words)

  
 Conspecific sperm and pollen precedence and speciation
I predict that if reproductive isolation is in part the product of male mate choice, males of each species should preferentially mate with conspecifics, produce more sperm when in the presence of a conspecific female than when in the presence of a heterospecific female, and expend more sperm when mating with conspecific females.
This prediction is based on the hypothesis of reproductive character displacement, which states that there is stronger selection on males in sympatry than on males in allopatry to mate with conspecific females as a result of reduced fitness consequences of heterospecific matings.
If one species prefers conspecific females between allopatry and sympatry, then reproductive isolating mechanisms are stronger in one species than in the other.
www.bio.txstate.edu /~gabor/eeb/CMEProposal120306aa2.doc   (2649 words)

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