Reproductive isolation among cryptic species in the ectomycorrhizal genus Strobilomyces: Population-level CAPS marker-based genetic analysis

Morphologically similar species, that is cryptic species, may be similar or quasi-similar owing to the deceleration of morphological evolution and stasis. While the factors underlying the deceleration of morphological evolution or stasis in cryptic species remain unknown, decades of research in the field of paleontology on punctuated equilibrium have originated clear hypotheses. Species are expected to remain morphologically identical in scenarios of shared genetic variation, such as hybridization and incomplete lineage sorting, or in scenarios where bottlenecks reduce genetic variation and constrain the evolution of morphology. Here, focusing on three morphologically similar Stygocapitella species, we employ a whole-genome amplification method (WGA) coupled with double-digestion restriction-site associated DNA sequencing (ddRAD) to reconstruct the evolutionary history of the species complex. We explore population structure, use population-level statistics to determine the degree of connectivity between populations and species, and determine the most likely demographic scenarios which generally reject for recent hybridization. We find that the combination of WGA and ddRAD allowed us to obtain genomic-level data from microscopic eukaryotes (∼1 millimetre) opening up opportunities for those working with population genomics and phylogenomics in such taxa. The three species share genetic variance, likely from incomplete lineage sorting and ancient admixture. We speculate that the degree of shared variation might underlie morphological similarity in the Atlantic species complex.

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Neural Basis of Acoustic Species Recognition in a Cryptic Species Complex

Journal of Experimental Biology ◽

10.1242/jeb.243405 ◽

2021 ◽

Author(s):

Saumya Gupta ◽

Rishi K. Alluri ◽

Gary J. Rose ◽

Mark A. Bee

Keyword(s):

Reproductive Isolation ◽

Cryptic Species ◽

Temporal Processing ◽

Species Recognition ◽

Species Difference ◽

Mechanistic Explanation ◽

Pulse Number ◽

Neural Basis ◽

Cryptic Species Complex ◽

Species Specific

Sexual traits that promote species recognition are important drivers of reproductive isolation, especially among closely related species. Identifying neural processes that shape species differences in recognition is crucial for understanding the causal mechanisms of reproductive isolation. Temporal patterns are salient features of sexual signals widely used in species recognition by several taxa, including anurans. Recent advances in our understanding of temporal processing by the anuran auditory system provide an opportunity to investigate the neural basis of species-specific recognition. The anuran inferior colliculus (IC) consists of neurons that are selective for temporal features of calls. Of potential relevance are auditory neurons known as interval-counting neurons (ICNs) that are often selective for the pulse rate of conspecific advertisement calls. Here, we tested the hypothesis that ICNs mediate acoustic species recognition by exploiting the known differences in temporal selectivity in two cryptic species of gray treefrog (Hyla chrysoscelis and Hyla versicolor). We examined the extent to which the threshold number of pulses required to elicit behavioral responses from females and neural responses from ICNs was similar within each species but potentially different between the two species. In support of our hypothesis, we found that a species difference in behavioral pulse number thresholds closely matched the species difference in neural pulse number thresholds. However, this relationship held only for ICNs that exhibited band-pass tuning for conspecific pulse rates. Together, these findings suggest that differences in temporal processing of a subset of ICNs provide a mechanistic explanation for reproductive isolation between two cryptic treefrog species.

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A comparison of cone and needle characters in Abies: a test of a new theory of evolution

Canadian Journal of Botany ◽

10.1139/b83-205 ◽

1983 ◽

Vol 61 (7) ◽

pp. 1926-1930 ◽

Cited By ~ 6

Author(s):

Jack Maze

Keyword(s):

Reproductive Isolation ◽

Population Level ◽

Dynamic Interaction ◽

General Sense ◽

Theory Of Evolution ◽

Allopatric Populations ◽

Evolutionary Event ◽

Different Levels

One part of a new theory of evolution proposed by Wiley and Brooks is that evolution results in continually increasing complexity. This leads to the unique prediction that once speciation occurs and species are embarked on independent histories, developmentally independent characters will become more correlated. This was tested by comparing cone and needle characters for some Abies species from different levels in a hierarchy, i.e., from the population level, where one would predict low correlations, to the supraspecific level, where one would predict high correlations. In a general sense, these predictions were realized. The results also indicated approximately equal correlations between cone and needle characters at levels below the species. These results were unexpected since one would predict that allopatric populations in the analyses would be embarked on independent histories because they are reproductively isolated and this would show correlations between cone and needle characters. This implies that reproductive isolation may not be a basic evolutionary event but that the dynamic interaction between entropic decay of information and reproductive linkages, the view presented in the new theory of evolution mentioned above, may be.

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Genetic investigations of laboratory stocks of the complex of Anopheles balabacensis Baisas (Diptera: Culicidae)

Bulletin of Entomological Research ◽

10.1017/s0007485300014279 ◽

1985 ◽

Vol 75 (2) ◽

pp. 185-197 ◽

Cited By ~ 9

Author(s):

Jeffrey L. K. Hii

Keyword(s):

Genetic Analysis ◽

Reproductive Isolation ◽

X Chromosome ◽

Polytene Chromosomes ◽

Natural Populations ◽

Peninsular Malaysia ◽

Distinct Population ◽

Anopheles Dirus ◽

Genetic Changes ◽

Anopheles Balabacensis

AbstractExamination of the polytene chromosomes and cross-breeding data confirmed the specific status of Anopheles dirusPeyton & Harrison within the complex of A. balabacensis Baisas. The data also strongly suggested that A. dirus itself is a complex of at least two species, one of which, a hitherto unrecognized species, provisionally designated A. dirus species B, previously known as the Perlis form, occurs in northern Peninsular Malaysia. A distinct population from Thailand was designated A. dirus species A. The mosquitoes studied also include material from natural populations in Sabah, here provisionally designated A. balabacensis s.s., and may represent the first genetic analysis of this species. The Sabah material is distinct from either of the A. dirus forms. Hybrid males from crosses of A. balabacensis × A. dirus species A and of A. dirus species B females × A. dirus species A males were sterile. Chromosome studies also showed that reproductive isolation was accompanied by genetic changes in both the autosomesand X chromosome in the hybrid larvae.

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Genomic, chromosomal, and ecological differentiation between the cryptic Eurasian malaria vector-species Anopheles messeae and Anopheles daciae

10.21203/rs.2.10780/v1 ◽

2019 ◽

Author(s):

Anastasia N. Naumenko ◽

Dmitriy A. Karagodin ◽

Andrey A. Yurchenko ◽

Anton V. Moskaev ◽

Olga I. Martin ◽

...

Keyword(s):

Reproductive Isolation ◽

Cryptic Species ◽

X Chromosome ◽

Malaria Vector ◽

Genomic Sequence ◽

Wide Distribution ◽

Its2 Sequence ◽

Genetic Introgression ◽

Nucleotide Substitutions ◽

Ecological Differentiation

Abstract Background A dominant malaria vector, Anopheles messeae, is a highly polymorphic species with wide distribution throughout Eurasia. Five highly polymorphic inversions associated with the geographical distribution of the species have been reported. A sister species, An. daciae, was described and discriminated from An. messeae based on five fixed nucleotide substitutions in the internal transcribed spacer 2 (ITS2) of ribosomal DNA. However, the levels of genomic divergence, chromosomal variation, and ecological differentiation between these two cryptic species remain unexplored. Results In this study, we sequenced ITS2 and analyzed the inversion frequencies of 289 Anopheles larvae specimens collected from three locations in the Moscow region. We identified a high abundance of both An. messeae and An. daciae in all three locations. Five individual genomes for each species of An. messeae and An. daciae from one location were sequenced. Our study confirmed five previously described nucleotide substitutions in the ITS2 of An. messeae. However, we found that the ITS2 sequence in An. daciae was heterogenic in three of the five positions. Fixed nucleotide differences between An. messeae and An. daciae were found only in the last two positions. One mosquito was identified as a hybrid between An. messeae and An. daciae based on heterogeneous substitutions in all five positions. Although, the genomic sequence comparison demonstrated genome-wide divergence between the two species, which is especially pronounced on the X chromosome, an ADMIXTURE cluster analysis demonstrated the presence of two admixed individuals suggesting ongoing hybridization. Cytogenetic analysis demonstrated that An. messeae and An. daciae significantly differ from each other by their frequency of polymorphic inversions. Inversion X1 was fixed in An. messeae but was polymorphic in all An. daciae populations. The frequency of polymorphic autosomal inversions was higher in An. messeae than in An. daciae. The species composition was different among the studied locations suggesting species-specific ecological preferences. Conclusions Our study demonstrated that An. messeae and An. daciae represent closely related cryptic species with incomplete reproductive isolation that are able to maintain genomic differentiation in sympatry despite ongoing genetic introgression. The X chromosome plays an important role in the reproductive isolation between the species.

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