EurekaMag.com logo
+ Translate

Rivuline studies taxonomic studies of rivuline cyprinodonts from tropical atlantic africa rivulinae cyprinodontidae atheriniformes pisces


, : Rivuline studies taxonomic studies of rivuline cyprinodonts from tropical atlantic africa rivulinae cyprinodontidae atheriniformes pisces. Koninklijk Museum voor Midden Afrika Tervuren Belgie Annalen Zoologische Wetenschappen (211): 1-150

The geographical distribution of the major rivuline phenotypes in tropical Atlantic Africa and the biology of selected representatives of Aphyosemion are discussed. An attempt is made to reconcile the old systematics based on phenotypes with the new systematics based on reproductive isolation of populations. The study of the zoogeorgraphy of cyprinodonts in tropical Atlantic Africa brought forth a rather simple pattern with 5 major faunal groups in the forest and 1 similar group in the savannahs. In some areas derived subgroups have developed in the adjacent savannahs. Zoogeography based on phenotypy appears to reflect the natural conditions for cyprinodonts in this part of Africa. There are no reasons to believe that in most cyprinodont taxa species discrimination may be based on phenotypy alone. Karyotypes and corresponding genotypes have stabilized or exhibit little variation. This is true for the procatopodine forms and for most phenotypes of the genus Aplocheilus with Aplocheilus fasciolatus as the only known exception. The condition among the major phenotypes of the genus Aphyosemion is different. Karotype and genotype variations (results of crossings) occur with little or no change of corresponding phenotype. This may be due to exchange of genes between different populations being limited, particularly across large rivers, and being insufficient to counteract karyotype and genotype changes which occur as a response to local ecological conditions. Superficially the karyotypic dynamics in Aphyosemion resemble the evolution of a young group of animals during an explosion. The picture is rather that of group which insufficiently fitted to ecological conditions and tryping to adjust karyotype and genotype in order to become better fitted. There are no indications that all this karyotypic change and confusion has created anything new. Probably, the different major phenotypes of this taxon and the closely related genus Nothobranchius differentiated a long time ago, when the karyotype was not very specialized and had .apprx. 20 haploid elements and many chromosomal arms. Subsequent parallel evolution of the karyotype, characterized by 3 features took place in several distinct lines of descent. The number of chromosome arms increased associated with similar increase in cell diameter. This produced gene linkages followed by an increasing uniformity of subsequent generations (specialization), which seems to represent an irreversible condition. This pattern may encourage polyploidy because of the enlarged cells, the reduced number of chromosomes and the absence of sex chromosomes. This pattern is not unique for Aphyosemion and Nothobranchius and is also evident in the South American Pterolebias. The zoogeographic importance of this cryptic speciation in Aphyosemion should not be overestimated. The zoogeographic patterns of the sympatric Aphyosemion bivittatum and Aphyosemion calliurum are different when based on karyotype, genotype and reproductive isolation. Development of sibling species in Aphyosemion was probably accidental in spite of the possible influence of large rivers and different soil types.

(PDF 0-2 workdays service)

Accession: 006345923

Submit PDF Full Text: Here


Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:
Close
Close

Related references

Scheel, JJ., 1974: Rivuline studies. Taxonomic studies of rivuline cyprinodonts from tropical Atlantic Africa. (Rivulinae, Cyprinodontidae, Ateriniformes, Pisces). Annales Mus r Afr cent (Ser 8 Sci zool): 211: 1-150

Scheel, JJ., 1972: Rivuline karyotypes and their evolution (Rivulinae, Cyprinodontidae, Pisces). Zeitschrift Zool Syst EvolForsch, 10(3): 180-209

Seegers L., 1984: A new rivuline fish from peru pterolebias rubrocaudatus pisces atheriniformes cyprinodontidae. P. rubrocaudatus, a new species of the genus Pterolebias Garman, 1895, is described from southeastern Peru from near Puerto Maldonado. This species is distinguished from all other species of the genus by its small size and the special form of its...

Seegers, L., 1984: Ein neuer Rivuline aus Peru: Pterolebias rubrocaudatus (Pisces: Atheriniformes: Cyprinodontidae). P. rubrocaudatus, a new species of the genus Pterolebias Garman, 1895, is described from southeastern Peru from near Puerto Maldonado. This species is distinguished from all other species of the genus by its small size and the special form of its...

Radda A., 1973: Studies on some recently described species and subspecies of rivulinae osteichthyes cyprinodontidae from tropical west africa. Annalen des Naturhistorischen Museums in Wien 77: 365-380

Grimm H., 1972: Cytological studies on west african cyprinodonts of the genera aphyosemion and roloffia pisces cyprinodontidae. Mitteilungen aus dem Hamburgischen Zoologischen Museum und Institut (68): 195-205

Radda, AC., 1977: Die Rivulinae (Cyprinodontidae, Atheriniformes, Osteichthyes) von Gabun. Oesterreichische Akademie der Wissenschaften Mathematisch-Naturwissenschaftliche Klasse Sitzungsberichte Abteilung I: 1866-10: 247-267

Chung, KS., 1997: Thermic tolerance of the tropical fish Cyprinodon dearborni Atheriniformes Cyprinodontidae under several heating and salinity rates Tolerancia termica del pez tropical Cyprinodon dearborni Atheriniformes Cyprinodontidae a diversas tasas de calentamiento y salinidades. Tropical salt marsh fish, Cyprinodon dearborni, collected from Laguna Los Patos were acclimated for four weeks at three salinities (10, 15 and 20permill) and a temperature of 25degreeC. Fish (average standard length 25.5+-3.6 mm) were then exposed...

Seegers, L., 1983: Rivulus deltaphilus n. sp. aus Venezuela. (Pisces: Atheriniformes: Rivulinae). Senckenbergiana Biologica1983]; 63(1-2): 39-44

Seegers, L., 1983: Rivulus deltaphilus n. sp. from Venezuela (Pisces: Atheriniformes: Rivulinae). Senckenbergiana biologica3(1-2): 39-44