Thus, sympatry was not intermediate between the alternative allopatric sites.
Amanda J. Chunco, Todd Jobe, Karin S. Pfennig 2012, 'Why Do Species Co-Occur? A Test of Alternative Hypotheses Describing Abiotic Differencesin Sympatry versus Allopatry Using Spadefoot Toads', PLoS ONE10.1371/journal.pone.0032748. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
However, in some cases, allopatric host-parasite systems demonstrate similar or greater compatibility than in sympatry.
Anaïs Portet, Silvain Pinaud, Cristian Chaparro, Richard Galinier, Nolwenn M Dheilly,Julien Portela, Guillaume M Charriere, Jean-François Allienne, David Duval, BenjaminGourbal 2019, 'Sympatric versus allopatric evolutionary contexts shape differential immune responsein Biomphalaria / Schistosoma interaction.', PLoS Pathogenshttp://europepmc.org/articles/PMC6443186?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Instead, sympatry occurred at one extreme of the conditions occupied by both species.
Amanda J Chunco, Todd Jobe, Karin S Pfennig 2012, 'Why do species co-occur? A test of alternative hypotheses describing abiotic differencesin sympatry versus allopatry using spadefoot toads.', PLoS ONEhttp://europepmc.org/articles/PMC3316550?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
In some lakes both species live in sympatry.
WESTMAN K., SAVOLAINEN R. 2001, 'LONG TERM STUDY OF COMPETITION BETWEEN TWO CO-OCCURRING CRAYFISH SPECIES, THE NATIVEASTACUS ASTACUS L. AND THE INTRODUCED PACIFASTACUS LENIUSCULUS DANA, IN A FINNISHLAKE.', Knowledge and Management of Aquatic Ecosystemshttp://dx.doi.org/10.1051/kmae:2001008. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Character displacement between both species has been argued to explain bill sizes in sympatry.
Juan Carlos Rando, Josep Antoni Alcover, Juan Carlos Illera 2010, 'Disentangling ancient interactions: a new extinct passerine provides insights on characterdisplacement among extinct and extant island finches.', PLoS ONEhttp://europepmc.org/articles/PMC2944890?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Further, this research documented the sympatry of feral sorghum and johnsongrass in the roadside habitat.
Sara Ohadi, Matthew Littlejohn, Mohsen Mesgaran, William Rooney, Muthukumar Bagavathiannan 2018, 'Surveying the spatial distribution of feral sorghum (Sorghum bicolor L.) and its sympatrywith johnsongrass (S. halepense) in South Texas.', PLoS ONEhttp://europepmc.org/articles/PMC5919511?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
However, the two species appear to have partitioned their resources when living in sympatry.
Brooke Erin Crowley, Yurena Yanes, Stella Grace Mosher, Juan Carlos Rando 2019, 'Revisiting the Foraging Ecology and Extinction History of Two Endemic Vertebratesfrom Tenerife, Canary Islands', Quaternaryhttps://www.mdpi.com/2571-550X/2/1/10. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)