Phenotypic divergence in two sibling species of shorebird: Common Snipe and Wilson’s Snipe (Charadriiformes: Scolopacidae)

Abstract Background The sibling species of the malaria mosquito, Anopheles gambiae (sensu stricto) and Anopheles coluzzii co-exist in many parts of West Africa and are thought to have recently diverged through a process of ecological speciation with gene flow. Divergent larval ecological adaptations, resulting in Genotype-by-Environment (G × E) interactions, have been proposed as important drivers of speciation in these species. In West Africa, An. coluzzii tends to be associated with permanent man-made larval habitats such as irrigated rice fields, which are typically more eutrophic and mineral and ammonia-rich than the temporary rain pools exploited by An. gambiae (s.s.) Methods To highlight G × E interactions at the larval stage and their possible role in ecological speciation of these species, we first investigated the effect of exposure to ammonium hydroxide and water mineralisation on larval developmental success. Mosquito larvae were exposed to two water sources and increasing ammonia concentrations in small containers until adult emergence. In a second experiment, larval developmental success was compared across two contrasted microcosms to highlight G × E interactions under conditions such as those found in the natural environment. Results The first experiment revealed significant G × E interactions in developmental success and phenotypic quality for both species in response to increasing ammonia concentrations and water mineralisation. The An. coluzzii strain outperformed the An. gambiae (s.s.) strain under limited conditions that were closer to more eutrophic habitats. The second experiment revealed divergent crisscrossing reaction norms in the developmental success of the sibling species in the two contrasted larval environments. As expected, An. coluzzii had higher emergence rates in the rice paddy environment with emerging adults of superior phenotypic quality compared to An. gambiae (s.s.), and vice versa, in the rain puddle environment. Conclusions Evidence for such G × E interactions lends support to the hypothesis that divergent larval adaptations to the environmental conditions found in man-made habitats such as rice fields in An. coluzzii may have been an important driver of its ecological speciation.

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Morphological Differences Between Two Sibling Species, Drosophila Pseudoobscura and Drosophila Persimilis

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.37.3.156 ◽

1951 ◽

Vol 37 (3) ◽

pp. 156-159 ◽

Cited By ~ 11

Author(s):

M. T. M. Rizki

Keyword(s):

Sibling Species ◽

Drosophila Pseudoobscura ◽

Drosophila Persimilis ◽

Morphological Differences

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A Quantitative Genetic Analysis of Male Sexual Traits Distinguishing the Sibling Species Drosophila simulans and D. sechellia

Genetics ◽

10.1093/genetics/153.4.1683 ◽

1999 ◽

Vol 153 (4) ◽

pp. 1683-1699 ◽

Cited By ~ 11

Author(s):

Stuart J Macdonald ◽

David B Goldstein

Keyword(s):

Genetic Analysis ◽

Sibling Species ◽

Reproductive Traits ◽

Drosophila Simulans ◽

Directional Selection ◽

Posterior Lobe ◽

Sex Comb ◽

Tooth Number ◽

Comb Tooth ◽

Shape And Size

Abstract A quantitative trait locus (QTL) genetic analysis of morphological and reproductive traits distinguishing the sibling species Drosophila simulans and D. sechellia was carried out in a backcross design, using 38 markers with an average spacing of 8.4 cM. The direction of QTL effects for the size of the posterior lobe was consistent across the identified QTL, indicating directional selection for this trait. Directional selection also appears to have acted on testis length, indicating that sexual selection may have influenced many reproductive traits, although other forms of directional selection cannot be ruled out. Sex comb tooth number exhibited high levels of variation both within and among isofemale lines and showed no evidence for directional selection and, therefore, may not have been involved in the early speciation process. A database search for genes associated with significant QTL revealed a set of candidate loci for posterior lobe shape and size, sex comb tooth number, testis length, tibia length, and hybrid male fertility. In particular, decapentaplegic (dpp), a gene known to influence the genital arch, was found to be associated with the largest LOD peak for posterior lobe shape and size.

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Performance of a points-based scoring system for assessing species limits in birds

The Auk ◽

10.1093/ornithology/ukab016 ◽

2021 ◽

Author(s):

Joseph A Tobias ◽

Paul F Donald ◽

Rob W Martin ◽

Stuart H M Butchart ◽

Nigel J Collar

Keyword(s):

Strong Support ◽

Molecular Data ◽

Sympatric Species ◽

Global Scale ◽

Training Set ◽

Species Limits ◽

Phenotypic Data ◽

Fast Tracking ◽

Extinction Rates ◽

Phenotypic Divergence

AbstractSpecies are fundamental to biology, conservation, and environmental legislation; yet, there is often disagreement on how and where species limits should be drawn. Even sophisticated molecular methods have limitations, particularly in the context of geographically isolated lineages or inadequate sampling of loci. With extinction rates rising, methods are needed to assess species limits rapidly but robustly. Tobias et al. devised a points-based system to compare phenotypic divergence between taxa against the level of divergence in sympatric species, establishing a threshold to guide taxonomic assessments at a global scale. The method has received a mixed reception. To evaluate its performance, we identified 397 novel taxonomic splits from 328 parent taxa made by application of the criteria (in 2014‒2016) and searched for subsequent publications investigating the same taxa with molecular and/or phenotypic data. Only 71 (18%) novel splits from 60 parent taxa have since been investigated by independent studies, suggesting that publication of splits underpinned by the criteria in 2014–2016 accelerated taxonomic decisions by at least 33 years. In the evaluated cases, independent analyses explicitly or implicitly supported species status in 62 (87.3%) of 71 splits, with the level of support increasing to 97.2% when excluding subsequent studies limited only to molecular data, and reaching 100% when the points-based criteria were applied using recommended sample sizes. Despite the fact that the training set used to calibrate the criteria was heavily weighted toward passerines, splits of passerines and non-passerines received equally strong support from independent research. We conclude that the method provides a useful tool for quantifying phenotypic divergence and fast-tracking robust taxonomic decisions at a global scale.

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