Reproductive Isolation and the Integrity of Two Sympatric Species of Choristoneura (Lepidoptera: Tortricidae)

1953 ◽  
Vol 85 (4) ◽  
pp. 141-151 ◽  
Author(s):  
Stanley G. Smith
Keyword(s):  
Reproductive Isolation ◽  
Hybrid Sterility ◽  
Sympatric Species ◽  
Evolutionary Divergence ◽  
Gene Exchange ◽  
Hybrid Breakdown ◽  
Temporal Isolation ◽  
Isolating Mechanisms ◽  
Spatial Isolation ◽  
Mechanical Isolation

According to Dobzhansky (1951a, p. 262) “Species are … groups of populations the gene exchange between which is limited or prevented by one, or by a combination of several, reproductive isolating mechanisms”. This definition follows from his concept of a species not as a static unit but as a stage in the process of evolutionary divergence. Limitation or prevention of gene exchange is a property of geographic and reproductive isolation (Mayr, 1912), the various types of which Dobzhansky lists as follows:I. Geographic or Spatial IsolationII. Reproductive IsolationA. Ecological IsolationB. Seasonal or Temporal IsolationC. Sexual, Psychological or Ethnological IsolationD. Mechanical IsolationE. Gametic IsolationF. Hybrid InviabilityG. Hybrid SterilityH. Hybrid Breakdown

scholarly journals Patterns of regulatory divergence and gene expression in hybrids are associated with molecular evolution in species undergoing gene flow

2021 ◽  
Author(s):  
Fernando Diaz ◽  
Jason Wolf ◽  
Reinaldo de Brito
Keyword(s):  
Gene Expression ◽  
Gene Flow ◽  
Reproductive Isolation ◽  
Sequence Divergence ◽  
Evolutionary Divergence ◽  
Hybrid Breakdown ◽  
Allopatric Species ◽  
Examine Gene Expression ◽  
Molecular Divergence ◽  
Show Evidence

The extent to which hybridization disrupts a gene's pattern of expression likely governs its propensity for introgression, while its extent of molecular divergence can itself underlie such disruption. Together, these phenomena shape the landscape of sequence and transcriptional divergence across the genome as species diverge. To understand this process, we examine gene expression inheritance, regulatory and molecular divergences in the reproductive transcriptomes of species linked by gene flow. The fruit flies Anastrepha fraterculus and A. obliqua show evidence of gene flow despite clear evolutionary divergence and incomplete reproductive isolation. We find that their transcriptional patterns are a mosaic between those typically observed within and between allopatric species. Genes showing transgressive expression in hybrids or cis-regulatory divergence between species are associated with greater molecular divergence. This may reflect pleiotropic constraints that make them more resistant to gene flow or they may be more likely to experience divergent selection. However, while these highly divergent genes are likely to be important contributors to species differences, they are relatively rare. Instead, most differentially regulated genes, including those linked to reproduction, show high degrees of dominance in hybrids and trans-regulated divergence between species, suggesting widespread genetic compatibility that allowed for the identified introgression. These findings provide insights into how postzygotic isolating mechanisms might evolve in the presence of gene flow: regions showing cis-regulatory divergence or transgressive expression contribute to reproductive isolation, while regions with dominant expression and trans-regulatory divergence act as a buffer of hybrid breakdown, facilitating introgression, and leading to a genomic mosaic of expression and sequence divergence.

Reproductive isolating mechanisms between the peamouth, Mylocheilus caurinus, and the redside shiner, Richardsonius balteatus, at Stave Lake, British Columbia, Canada

1995 ◽  
Vol 73 (2) ◽  
pp. 330-338 ◽  
Author(s):  
Nevin Aspinwall ◽  
John D. McPhail
Keyword(s):  
British Columbia ◽  
Hybrid Sterility ◽  
Significant Proportion ◽  
Low Fertility ◽  
Gene Pools ◽  
Temporal Isolation ◽  
Lower Survival Rate ◽  
Isolating Mechanisms ◽  
Redside Shiner ◽  
Richardsonius Balteatus

Since at least 1952, the peamouth, Mylocheilus caurinus and the redside shiner, Richardsonius balteatus, have engaged in extensive hybridization (5.7–14.1% of the combined gene pools) in Stave Lake, British Columbia. A research project initiated in 1966 and continued to 1991 demonstrated that genetic swamping of the two species has not occurred. A study was conducted to determine the strength of premating and postmating isolating mechanisms between these two species. Temporal isolation is weak because both species had spawning periods in Devils Creek that overlapped by approximately 1.5 months. Also, both species spawned at night, and only on nights preceded by a sunny day. Both species were group spawners and both spawned on the first riffle of Devils Creek. Hybrid sterility is not well developed. While male F1 hybrids have low fertility, female F1 hybrids are as fertile as females of either species and would allow swamping if other postmating mechanisms were not operating. Hybrid inferiority was examined by laboratory experiments in which we measured survival of fingerling hybrids. While F1 hybrids displayed survival equal to that of M. caurinus, hybrid backcrosses to M. caurinus showed a 20% lower survival rate than M. caurinus. Also, hybrid backcrosses to M. caurinus included a significant proportion (8.4%) of deformed individuals.

scholarly journals Wolbachia and host intrinsic reproductive barriers contribute additively to post-mating isolation in spider mites

2020 ◽  
Author(s):  
Miguel Alfredo Cruz ◽  
Sara Magalhaes ◽  
Elio Sucena ◽  
Flore Zele
Keyword(s):  
Reproductive Isolation ◽  
Spider Mite ◽  
Cytoplasmic Incompatibility ◽  
Hybrid Sterility ◽  
Spider Mites ◽  
Reproductive Barriers ◽  
Hybrid Breakdown ◽  
F1 Hybrid ◽  
Hybrid Production ◽  
Relative Contribution

Wolbachia are widespread maternally-inherited bacteria suggested to play a role in arthropod host speciation through induction of cytoplasmic incompatibility, but this hypothesis remains controversial. Most studies addressing Wolbachia-induced incompatibilities concern closely-related populations, which are intrinsically compatible. Here, we used three populations of two genetically differentiated colour forms of the haplodiploid spider mite Tetranychus urticae to dissect the interaction between Wolbachia-induced and host-associated incompatibilities, and to assess their relative contribution to post-mating isolation. We found that these two sources of incompatibility act through different mechanisms in an additive fashion. Host-associated incompatibility contributes 1.5 times more than Wolbachia-induced incompatibility in reducing hybrid production, the former through an overproduction of haploid sons at the expense of diploid daugters (ca. 75% decrease) and the latter by increasing the embryonic mortality of daughters (by ca. 49%). Furthermore, regardless of cross direction, we observed near-complete F1 hybrid sterility and complete F2 hybrid breakdown between populations of the two forms, but that Wolbachia did not contribute to this outcome. This study identifies the mechanistic independence and additive nature of host-intrinsic and Wolbachia-induced sources of isolation. It suggests that Wolbachia could drive reproductive isolation in this system, thereby potentially affecting host differentiation and distribution in the field.

LINEATIN ENANTIOMER PREFERENCE, FLIGHT PERIODS, AND EFFECT OF PHEROMONE CONCENTRATION AND TRAP LENGTH ON THREE SYMPATRIC SPECIES OF TRYPODENDRON (COLEOPTERA: SCOLYTIDAE)

2000 ◽  
Vol 132 (6) ◽  
pp. 877-887 ◽  
Author(s):  
B.S. Lindgren ◽  
S.E.R. Hoover ◽  
A.M. MacIsaac ◽  
C.I. Keeling ◽  
K.N. Slessor
Keyword(s):  
Sex Ratio ◽  
Reproductive Isolation ◽  
Release Rate ◽  
Sympatric Species ◽  
Ambrosia Beetle ◽  
Flight Period ◽  
Trypodendron Lineatum ◽  
Temporal Separation ◽  
Baited Traps ◽  
Pheromone Concentration

AbstractThe effects of lineatin enantiomer ratios, lineatin release rate, and trap length on catches and the flight periods of three sympatric species of Trypodendron Stephens were investigated in field bioassays using multiple-funnel traps. The ambrosia beetle, Trypodendron betulae Swaine, was caught in similar numbers in baited traps and blank control traps, showing that this species does not respond to lineatin. Our results confirmed that Trypodendron lineatum (Olivier) is attracted only to (+)-lineatin. Trypodendron rufitarsus (Kirby) and Trypodendron retusum (LeConte) were shown to utilize lineatin and like T. lineatum were caught only when (+)-lineatin was present. These results indicate that lineatin does not govern reproductive isolation among these three species. There was no effect by (+)-lineatin release rate within the range tested. The flight of T. rufitarsus commenced earlier and ceased before the peak of the T. lineatum flight, suggesting that temporal separation may be an important component of reproductive isolation between these two species. The flight period of T. retusum was similar to that of T. lineatum. Host odours may aid in reproductive isolation of these two species. Enantiomer blend did not significantly affect sex ratio in any species; however, sex ratio differed among species, indicating that different species responded differently to the traps or that natural sex ratios differ. Catches of T. rufitarsus and T. retusum increased with trap length when pheromone release per trap was held constant and when release was held constant relative to trap length. Trap length and release rate did not affect sex ratio.

Quantitative Trait Loci Affecting Differences in Floral Morphology Between Two Species of Monkeyflower (Mimulus)

Genetics ◽  
1998 ◽  
Vol 149 (1) ◽  
pp. 367-382 ◽  
Author(s):  
H D Bradshaw ◽  
Kevin G Otto ◽  
Barbara E Frewen ◽  
John K McKay ◽  
Douglas W Schemske
Keyword(s):  
Quantitative Trait Loci ◽  
Reproductive Isolation ◽  
Quantitative Trait ◽  
Floral Morphology ◽  
Cumulative Effect ◽  
Sympatric Species ◽  
Accurate Estimate ◽  
Phenotypic Variance ◽  
Trait Loci ◽  
Morphological Differences

Abstract Conspicuous differences in floral morphology are partly responsible for reproductive isolation between two sympatric species of monkeyflower because of their effect on visitation of the flowers by different pollinators. Mimulus lewisii flowers are visited primarily by bumblebees, whereas M. cardinalis flowers are visited mostly by hummingbirds. The genetic control of 12 morphological differences between the flowers of M. lewisii and M. cardinalis was explored in a large linkage mapping population of F2 plants (n = 465) to provide an accurate estimate of the number and magnitude of effect of quantitative trait loci (QTLs) governing each character. Between one and six QTLs were identified for each trait. Most (9/12) traits appear to be controlled in part by at least one major QTL explaining ≥25% of the total phenotypic variance. This implies that either single genes of individually large effect or linked clusters of genes with a large cumulative effect can play a role in the evolution of reproductive isolation and speciation.

Comparative morphology of two sympatric Pareledone species from South Georgia

1994 ◽  
Vol 6 (2) ◽  
pp. 163-169 ◽  
Author(s):  
Heather I. Daly ◽  
Paul G. Rodhouse
Keyword(s):  
Reproductive Isolation ◽  
Body Mass ◽  
Comparative Morphology ◽  
Sympatric Species ◽  
Morphometric Data ◽  
South Georgia ◽  
Buccal Mass ◽  
Significant Difference ◽  
Sharp Point ◽  
Trophic Niches

Morphometric data were collected for 410 specimens of Pareledone turqueti and P. polymorpha caught around South Georgia. The two species differ in beak morphology and in the male hectocotylus. The species have similar appearances although there is a small but significant difference in the mantle length/body mass relationship for females, with P. polymorpha having a relatively longer mantle. There is no significant difference in the arm length/body mass relationship between species or sexes (p>0.05), except in the case of arm IV of females. There is an interspecific significant difference between sucker number on arms I and II of males, arms I–IV of females, and between hood length and mass of the buccal mass (p<0.05), with P. turqueti having relatively lower sucker numbers, a longer hood length and greater buccal mass mass. The beak of P. turqueti is similar to that of Eledone spp. but P. polymorpha has a small, fine beak with the rostral tip ending in an elongated, sharp point. Differences in beak and buccal mass suggest that these sympatric species occupy distinct trophic niches and that the differing morphology of the male hectocotylus is a factor in reproductive isolation.

scholarly journals Rape and the Prevalence of Hybrids in Broadly Sympatric Species: a Case Study using Albatrosses

2014 ◽  
Author(s):  
Sievert Rohwer ◽  
Rebecca B. Harris ◽  
Hollie E. Walsh
Keyword(s):  
Species Differences ◽  
Field Studies ◽  
Sympatric Species ◽  
Male Reproductive Success ◽  
Gene Exchange ◽  
Nuclear Markers ◽  
Mitochondrial Markers ◽  
Extensive Field

Conspecific rape often increases male reproductive success. However, the haste and aggression of forced copulations suggests that males may sometimes rape heterospecific females, thus making rape a likely, but undocumented, source of hybrids between broadly sympatric species. We present evidence that heterospecific rape may be the source of hybrids between Black-footed and Laysan Albatrosses (Phoebastria nigripes, and P. immutabilis, respectively). Extensive field studies have shown that paired (but not unpaired) males of both of these albatross species use rape as a supplemental reproductive strategy. Between species differences in size, timing of laying, and aggressiveness suggest that Black-footed Albatrosses should be more successful than Laysan Albatrosses in heteropspecific rape attempts, and male Black-footed Albatrosses have been observed attempting to force copulations on female Laysan Albatrosses. Nuclear markers showed that the six hybrids we studied were F1s and mitochondrial markers showed that male Black-footed Albatrosses sired all six hybrids. The siring asymmetry found in our hybrids may have long persisted because an IM analysis suggests that long-term gene exchange between these species has been from Black-footed Albatrosses into Laysan Albatrosses. If hybrids are sired in heterospecific rapes, they presumably would be raised and sexually imprinted on Laysan Albatrosses, and two unmated hybrids in a previous study courted only Laysan Albatrosses.

Reproductive Isolation in Sympatric Species of Dayflying Moths (Hemileuca: Saturniidae)

Evolution ◽  
1979 ◽  
Vol 33 (2) ◽  
pp. 728 ◽  
Author(s):  
Michael M. Collins ◽  
Paul M. Tuskes
Keyword(s):  
Reproductive Isolation ◽  
Sympatric Species

Evolution of Flowers, Pollination, and Plant Diversity

2011 ◽  
Author(s):  
Pat Willmer
Keyword(s):  
Reproductive Isolation ◽  
Genetic Drift ◽  
Plant Diversity ◽  
Character Displacement ◽  
Good Evidence ◽  
Early Evolution ◽  
Evolutionary Divergence ◽  
Floral Variation ◽  
Character Correlations ◽  
Animal Pollination

This chapter examines the evolution of flowers, pollination, and plant diversity. There is good evidence for pollinator-mediated selection and appropriate trait heritability in flowers, and there are well-established mechanisms by which this could bring about floral change, reproductive isolation, and evolutionary divergence or specialization. The chapter first considers the origin and early evolution of flowers before discussing the diversification of angiosperms. It then explores the advantages of animal pollination and goes on to discuss the extent to which pollination may have contributed to floral variation, plant speciation, and plant diversification. In particular, it explains whether pollinators select for floral divergence and describes five ways in which floral divergence could arise by selection: adaptation to distinct niches, character displacement, adaptive “wandering,” character correlations, and genetic drift.

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