GENETIC DIFFERENTIATION DURING THE SPECIATION PROCESS IN
            <i>DROSOPHILA</i>

Ayala, Francisco J.; Tracey, Martin L.; Hedgecock, Dennis; Richmond, Rollin C.

doi:10.1111/j.1558-5646.1974.tb00791.x

Cited by 276 publications

(159 citation statements)

References 48 publications

(32 reference statements)

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“…Between Lineus longissimus and Spanish specimens of the new morphotype, and between Lineus viridis and Welsh examples of the new form, the value of Nei's (1972) genetic identity falls below 0.35 (Table 2). This indicates that not only are these likely to be separate species, but that they show genetic identity values lower than those usually found in congeneric comparisons (Ayala, 1975(Ayala, , 1983Thorpe, 1982Thorpe, , 1983. However, similarly low values of genetic identity have been found between other species of nemerteans which, on morphological grounds, are considered congeneric (Williams etal., 1983;Sundberg & Janson, 1988).…”

Section: Electrophoretic Results and Discussionmentioning

confidence: 92%

Enzyme electrophoresis, genetic identity and description of a new genus and species of heteronemertean (Nemertea, Anopla) from northwestern Spain and North Wales

et al. 1993

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The anoplan order Heteronemertea, particularly the genera Cerebratulus, Lineus and A4icrura, contains a very large number of nominate species, many of which are inadequately described. As a consequence, systematic difficulties are encountered with the identification of many taxa in this group, especially those originally established primarily on the basis of their external features. The present paper concerns heteronemerteans collected from two locations, the Foz Estuary (north-western Spain) and Llandudno (North Wales). The Spanish collection included specimens identified as Lineus longissimus (Gunnerus), whilst samples from Llandudno contained large numbers of Lineus viridis (Mtiller); samples of a third similar but apparently undescribed species were found at both locations. Starch gel electrophoresis showed that samples of the apparent third species were genetically almost identical from each of the two locations, but were clearly different from the two described Lineus species. Histological studies of the unknown specimens revealed anatomical characters, including the unique feature of a proboscis epithelium ciliated throughout its length, which exclude it from any known heteronemertean taxon; it is accordingly placed in a new genus and species, for which the name Riseriellus occultus is proposed.

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Section: Electrophoretic Results and Discussionmentioning

confidence: 92%

Enzyme electrophoresis, genetic identity and description of a new genus and species of heteronemertean (Nemertea, Anopla) from northwestern Spain and North Wales

et al. 1993

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“…Exactly the opposite situation can prevail, e.g. in sibling species of the Drosophila willistoni group (Ayala et al 1974) and is indeed the case in Tropheus in Lake Tanganyika (Sturmbauer & Meyer 1992).…”

Section: Rates Of Evolutionmentioning

confidence: 99%

Endemism, speciation and adaptive radiation in great lakes

Fryer

1996

Environ Biol Fish

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SynopsisEvolution in great lakes has often been both quantitative (many endemic species of distantly related taxa often being present) and qualitative (outstanding levels of adaptive radiation having sometimes been achieved). These situations pose many questions, such as why there are so many endemics and so many superspecialists (and at the same time often many sibling species), as well as presenting problems relating to such matters as convergent evolution in different lakes, the possible role of key innovations, the nature of isolating mechanisms, competition and co-existence in complex communities, the roles of diverse mutualistic associations, and many others. These rich faunas also provide particularly favourable opportunities for studying patterns of speciation, while attempts to elucidate phylogenies in groups such as African cichlid fishes, that have radiated .in several lakes, can be pursued on both a broad scale and at the intralacustrine level using both recently devemped techniques and time-honoured methods. Rates of evolution, which differ widely between ecologically equivalent taxa in different lakes, have sometimes been extremely rapid, as attested by both molecular data and evidence from field studies. Notwithstanding their evolutionary exuberance, these rich faunas are fragile as demonstrated dramatically by the appalling tragedy that has befallen the haplochromine cichlid flock elf Lake Victoria.

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“…Ayala, 1975): (a) appearance of karyological differences due to chromosome aberrations (centric fusion) causing sterility in the hybrids; (b) possible reinforcement of isolation by premating isolating mechanisms; (c) gradual disappearance of hybrid areas; (d) an increase in genetic distance.…”

Section: Evolutionary Aspectsmentioning

confidence: 99%

Comparative karyotype studies between Spanish and French populations of Eliomys quercinus L.

Nombela¹,

Murcia²,

Delibes

et al. 1982

Genetica

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The cytogenetic study of two populations ofEliomys quercinus L. (R odentia, Gliridae), whose geographic ranges are relatively near, showed that numerical and morphological differences exist between their karyotypes. The French dormouse has a diploid number 2n = 50, while the Spanish one had 2n = 48. The sex chromosomes and the number of autosomal arms are identical in both populations. The morphological differences are limited to the autosomal metacentric pair 12 of the Spanish dormouse, which does not appear in the French dormouse. However, the latter possesses two pairs of acrocentric chromosomes (20, 24) which are absent in the Spanish dormouse. The bands that correspond to the q and p arms of pair 12 in the Spanish dormouse are identical to pairs 20 and 24 in the French one, respectively. Consequently, we consider the Spanish Eliomys quercinus and the French Eliornys quercinus as having a common ancestor. The Spanish form has originated by means of a Robertsonian translocation, Rb (20, 24), between pairs 20 and 24 of the common ancestor.

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GENETIC DIFFERENTIATION DURING THE SPECIATION PROCESS IN DROSOPHILA

Cited by 276 publications

References 48 publications

Enzyme electrophoresis, genetic identity and description of a new genus and species of heteronemertean (Nemertea, Anopla) from northwestern Spain and North Wales

Enzyme electrophoresis, genetic identity and description of a new genus and species of heteronemertean (Nemertea, Anopla) from northwestern Spain and North Wales

Endemism, speciation and adaptive radiation in great lakes

Comparative karyotype studies between Spanish and French populations of Eliomys quercinus L.

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