GENETICALLY CONTROLLED CHROMOSOME BREAKAGE AS AN ISOLATION BARRIER IN THE ORIGIN AND MAINTENANCE OF SECALE ANCESTRALE

1976 ◽  
Vol 18 (1) ◽  
pp. 105-109 ◽  
Author(s):  
Howard C. Stutz
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Endemic Species ◽  
Related Species ◽  
Chromosome Breakage ◽  
Closely Related Species ◽  
Left Behind ◽  
Selection For

Meiosis in hybrids derived from crosses of Secale ancestrale Zhuk. with related species is highly irregular: chiasmata fail to terminalize; numerous AI and AII bridges form but are usually unaccompanied by fragments; acentric fragments without true bridges are left behind at AI and AII; numerous micronuclei are produced at TII. These anomalies appear to be the result of genetically induced subchromatid exchanges. This appears to be a mechanism established by natural selection for reproductive isolation, thereby permitting this narrowly endemic species to successfully continue in sympatric association with closely related species.

Reproductive isolation between two closely related species of the Queensland fruit fly Dracus tryoni (Frogg) and D. neohumeralis Hardy (Diptera : Tephritidae) I. Variation in humeral callus pattern and the occurrence of intermediate colour forms in the wild

1967 ◽  
Vol 15 (3) ◽  
pp. 501 ◽  
Author(s):  
H Wolda
Keyword(s):  
Reproductive Isolation ◽  
Related Species ◽  
Fruit Fly ◽  
Abundant Species ◽  
Colour Pattern ◽  
Wild Populations ◽  
Closely Related Species ◽  
Similar Variation ◽  
In The Wild

A number of samples from wild populations of the Queensland fruit fly, Dacus tryoni and D. neohumeralis, were studied. There is a considerable variation in the colour pattern on the humeral callus. This variation is continuous so that any criterion for distinguishing between "intermediates" and "good species" is purely arbitrary. It was found in areas where D. neohumeralis does not occur as well as in localities where it is very abundant. By whatever criterion one defines intermediates, there appears to be no relation between the frequency of such forms and the presence or absence of D. neohumeralis or with the relative proportions of the two species in the population. However, flies with only a very small yellow area on an otherwise brown humeral callus were found only in Cairns where D. neohumeralis is usually the most abundant species. A similar variation in humeral callus pattern was found in other related species, such as D. kraussi and D. halfordiae. It is concluded that the intermediate colour forms may not be hybrids between D. tryoni and D. neohumeralis but variants of D. tryoni and, possibly the darker forms from Cairns, of D. neohumeralis.

scholarly journals Miconia gigantea, a long-forgotten endemic and endangered species of Melastomataceae in the Brazilian Atlantic Forest

2016 ◽  
Vol 88 (3 suppl) ◽  
pp. 1809-1818
Author(s):  
LILIAN P.G. DA ROSA ◽  
JOSÉ F.A. BAUMGRATZ ◽  
SEBASTIÃO J. DA SILVA NETO
Keyword(s):  
Endangered Species ◽  
Atlantic Forest ◽  
Endemic Species ◽  
Related Species ◽  
Conservation Status ◽  
Type Specimen ◽  
Brazilian Atlantic Forest ◽  
Closely Related Species ◽  
Floristic Studies ◽  
Occurrence Records

ABSTRACT Taxonomic and floristic studies in the state of Rio de Janeiro allowed the rediscovery of Miconia gigantea, an endemic species to the Atlantic Forest, until recently known only from the type specimen, collected over 100 years by A.F.M. Glaziou. We present an amended and detailed description of M. gigantea, providing characteristics of the flowers, fruits and seeds, in addition to illustrations, comments about taxonomic affinities with closely related species, the presently known distribution together with new occurrence records, and the conservation status.

scholarly journals Contact-Chemosensory Evolution Underlying Reproductive Isolation in Drosophila Species

2020 ◽  
Vol 14 ◽  
Author(s):  
Kosei Sato ◽  
Daisuke Yamamoto
Keyword(s):  
Decision Making ◽  
Mate Choice ◽  
Reproductive Isolation ◽  
Sibling Species ◽  
Related Species ◽  
Main Theme ◽  
Biological Factors ◽  
Premating Isolation ◽  
Closely Related Species ◽  
Neural Activities

The main theme of the review is how changes in pheromone biochemistry and the sensory circuits underlying pheromone detection contribute to mate choice and reproductive isolation. The review focuses primarily on gustatory and non-volatile signals in Drosophila. Premating isolation is prevalent among closely related species. In Drosophila, preference for conspecifics against other species in mate choice underlies premating isolation, and such preference relies on contact chemosensory communications between a female and male along with other biological factors. For example, although D. simulans and D. melanogaster are sibling species that yield hybrids, their premating isolation is maintained primarily by the contrasting effects of 7,11-heptacosadiene (7,11-HD), a predominant female pheromone in D. melanogaster, on males of the two species: it attracts D. melanogaster males and repels D. simulans males. The contrasting preference for 7,11-HD in males of these two species is mainly ascribed to opposite effects of 7,11-HD on neural activities in the courtship decision-making neurons in the male brain: 7,11-HD provokes both excitatory and inhibitory inputs in these neurons and differences in the balance between the two counteracting inputs result in the contrasting preference for 7,11-HD, i.e., attraction in D. melanogaster and repulsion in D. simulans. Introduction of two double bonds is a key step in 7,11-HD biosynthesis and is mediated by the desaturase desatF, which is active in D. melanogaster females but transcriptionally inactivated in D. simulans females. Thus, 7,11-HD biosynthesis diversified in females and 7,11-HD perception diversified in males, yet it remains elusive how concordance of the changes in the two sexes was attained in evolution.

scholarly journals NATURAL SELECTION FOR REPRODUCTIVE ISOLATION INPHLOX

Evolution ◽  
1967 ◽  
Vol 21 (4) ◽  
pp. 679-687 ◽  
Author(s):  
Donald A. Levin ◽  
Harold W. Kerster
Keyword(s):  
Natural Selection ◽  
Reproductive Isolation ◽  
Selection For

scholarly journals Chemical signals act as the main reproductive barrier between sister and mimeticHeliconiusbutterflies

2019 ◽  
Author(s):  
M.F. González-Rojas ◽  
K. Darragh ◽  
J Robles ◽  
M. Linares ◽  
S Schulz ◽  
...  
Keyword(s):  
Reproductive Isolation ◽  
Related Species ◽  
Mate Recognition ◽  
Geographic Region ◽  
Reproductive Barrier ◽  
Colour Pattern ◽  
Chemical Profile ◽  
Closely Related Species ◽  
Wing Colour ◽  
Behavioural Experiments

ABSTRACTColour pattern has been long recognised as the trait that drives mate recognition betweenHeliconiusspecies that are phylogenetically close. However, when this cue is compromised such as in cases of mimetic, sympatric and closely related species, alternative mating signals must evolve to ensure reproductive isolation and species integrity. The closely related speciesHeliconius melpomene malletiandH. timareta florencia, occur in the same geographic region and despite being co-mimics they display strong reproductive isolation. In order to test which cues differ between species, and therefore potentially contribute to reproductive isolation, we quantified differences in wing phenotype and male chemical profile. As expected, wing colour pattern was indistinguishable between the two species while the chemical profile of their male sex pheromones showed marked differences. We then conducted behavioural experiments to study the importance of these signals in mate recognition by females. In agreement with our previous results, we found that pheromones and not wing colour pattern drive the preference of females by conspecific males. In addition, experiments with hybrid males and females suggested an important genetic component for both pheromone production and preference. Altogether, these results suggest that pheromones are the major reproductive barrier opposing gene flow between these two sister and co-mimic species.

scholarly journals Lack of underdominance in a naturally occurring pericentric inversion in Drosophila melanogaster and its implications for chromosome evolution.

Genetics ◽  
1991 ◽  
Vol 129 (3) ◽  
pp. 791-802
Author(s):  
J A Coyne ◽  
S Aulard ◽  
A Berry
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Selection ◽  
Genetic Drift ◽  
Related Species ◽  
Pericentric Inversion ◽  
Chromosome Evolution ◽  
Natural Populations ◽  
Crossing Over ◽  
Closely Related Species ◽  
Naturally Occurring

Abstract In(2LR)PL is a large pericentric inversion polymorphic in populations of Drosophila melanogaster on two Indian Ocean islands. This polymorphism is puzzling: because crossing over in female heterokaryotypes produces inviable zygotes, such inversions are thought to be underdominant and should be quickly eliminated from populations. The observed fixation for such inversions among related species has led to the idea that genetic drift can cause chromosome evolution in opposition to natural selection. We found, however, that In(2LR)PL is not underdominant for fertility, as heterokaryotypic females produce perfectly viable eggs. Genetic analysis shows that the lack of underdominance results from the nearly complete absence of crossing over in the inverted region. This phenomenon is probably caused by mechanical and not genetic factors, because crossing over is not suppressed in In(2LR)PL homokaryotypes. Our observations do not support the idea that the fixation of pericentric inversions among closely related species implies the action of genetic drift overcoming strong natural selection in very small populations. If chromosome arrangements vary in their underdominance, it is those with the least disadvantage as heterozygotes, like In(2LR)PL, that will be polymorphic or fixed in natural populations.

Centaurea peltieri (Asteraceae), a new endemic species from the Oriental High Atlas of Morocco

Phytotaxa ◽  
2021 ◽  
Vol 523 (2) ◽  
pp. 192-198
Author(s):  
Abdelmonaim HOMRANI BAKALI ◽  
A. SUSANNA
Keyword(s):  
Endemic Species ◽  
Related Species ◽  
Closely Related Species ◽  
High Atlas

Centaurea peltieri (C. sect. Melanoloma) is described and illustrated as a new endemic species from the Oriental High Atlas of Morocco. The morphology of involucral bracts is the discriminant feature separating it from other closely related species of the section.

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