scholarly journals Parallel morphological evolution and habitat‐dependent sexual dimorphism in cave‐ vs. surface populations of the Asellus aquaticus (Crustacea: Isopoda: Asellidae) species complex

2021 ◽  
Author(s):  
Gergely Balázs ◽  
Anna Biró ◽  
Žiga Fišer ◽  
Cene Fišer ◽  
Gábor Herczeg
Keyword(s):  
Sexual Dimorphism ◽  
Species Complex ◽  
Morphological Evolution ◽  
Asellus Aquaticus

scholarly journals Deceleration of morphological evolution in a cryptic species complex and its link to paleontological stasis

Evolution ◽  
2019 ◽  
Vol 74 (1) ◽  
pp. 116-131 ◽  
Author(s):  
José Cerca ◽  
Christian Meyer ◽  
Dave Stateczny ◽  
Dominik Siemon ◽  
Jana Wegbrod ◽  
...  
Keyword(s):  
Cryptic Species ◽  
Species Complex ◽  
Morphological Evolution ◽  
Cryptic Species Complex

scholarly journals Incomplete lineage sorting and ancient admixture, and speciation without morphological change in ghost-worm cryptic species

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e10896
Author(s):  
José Cerca ◽  
Angel G. Rivera-Colón ◽  
Mafalda S. Ferreira ◽  
Mark Ravinet ◽  
Michael D. Nowak ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Cryptic Species ◽  
Species Complex ◽  
Population Genomics ◽  
Incomplete Lineage Sorting ◽  
Morphological Evolution ◽  
Population Level ◽  
Similar Species ◽  
Lineage Sorting ◽  
Amplification Method

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.

Description of four new species from the Haploniscus unicornis Menzies, 1956 complex (Isopoda: Asellota: Haploniscidae)

Zootaxa ◽  
2010 ◽  
Vol 2536 (1) ◽  
pp. 1 ◽  
Author(s):  
WIEBKE BRÖKELAND
Keyword(s):  
Puerto Rico ◽  
New Species ◽  
Sexual Dimorphism ◽  
Deep Sea ◽  
Species Complex ◽  
Wide Distribution ◽  
Adult Males ◽  
Southwest Atlantic ◽  
Walvis Ridge ◽  
Iceland Basin

Based on the adult males the four species Haploniscus bihastatus n. sp., H. monoceros n. sp., H. machairis n. sp. and H. angolensis n. sp. are described from the deep sea of the Southeast Atlantic. These belong to a species complex, which also includes H. unicornis Menzies from the Puerto Rico Trench and H. aduncus Lincoln from the Iceland Basin and shares several characters with species from the genus Mastigoniscus Lincoln. While males of the species complex can be reasonably well distinguished by their habitus and pleopods 1 and 2, the discrimination of female specimens is hampered by the pronounced sexual dimorphism. The Haploniscus unicornis complex has a wide distribution in the Atlantic Ocean, but appears to be absent from basins south of the Walvis Ridge and also from the southwest Atlantic basins.

scholarly journals Quantification of sexual dimorphism in Asellus aquaticus (Crustacea: Isopoda) using outline approaches

2002 ◽  
Vol 77 (4) ◽  
pp. 523-533 ◽  
Author(s):  
ANGÉLINE BERTIN ◽  
BRUNO DAVID ◽  
FRANK CÉZILLY ◽  
PAUL ALIBERT
Keyword(s):  
Sexual Dimorphism ◽  
Asellus Aquaticus

Two new species in the annelid genus Stygocapitella (Orbiniida, Parergodrilidae) with comments on their biogeography

Zootaxa ◽  
2017 ◽  
Vol 4286 (3) ◽  
pp. 301 ◽  
Author(s):  
TORSTEN H. STRUCK ◽  
JENS KOCZULA ◽  
DAVE STATECZNY ◽  
CHRISTIAN MEYER ◽  
GÜNTER PURSCHKE
Keyword(s):  
New Species ◽  
Cryptic Species ◽  
Southern Hemisphere ◽  
Species Complex ◽  
Morphological Evolution ◽  
Principal Component ◽  
European Population ◽  
Dispersal Capacity ◽  
Two New Species ◽  
Limited Dispersal

Many interstitial species with limited dispersal capacity are in fact complexes of cryptic species showing a seemingly cosmopolitan distribution. The interstitial annelid Stygocapitella subterranea (Orbiniida, Parergodrilidae) is such a complex with populations in Northern America, Europe, Australia, and New Zealand and a tropical distribution gap. Herein we present new records of Stygocapitella from South Africa, which is morphologically substantially different from S. subterranea. Additionally, using specimens from both hemispheres and morphological, nuclear and mitochondrial data as well as principal component analyses and a newly developed measurement for morphological disparity we show furthermore that the cryptic species complex of S. subterranea is not as cryptic as assumed as the Australian populations are morphologically and genetically different from the European population. Hence, we herein describe two new species, S. minuta and S. australis, within this complex from the Southern hemisphere. Additionally, we assigned a neotype for S. subterranea. This increases numbers of species known for Stygocapitella from one to three and for Parergodrilidae from two to four. Moreover, our results support an origin of this species complex on the Southern hemisphere and that both the split of S. minuta from the other two and S. subterranea from S. australis was several tens of millions years ago. Hence, the distribution of this complex was not driven by recent events, but rather it represents a strong case of decelerated morphological evolution as only slight differences in the morphology could be observed after all. 

scholarly journals Gene duplication, tissue-specific gene expression and sexual conflict in stalk-eyed flies (Diopsidae)

2012 ◽  
Vol 367 (1600) ◽  
pp. 2357-2375 ◽  
Author(s):  
Richard H. Baker ◽  
Apurva Narechania ◽  
Philip M. Johns ◽  
Gerald S. Wilkinson
Keyword(s):  
Gene Expression ◽  
Sexual Dimorphism ◽  
Gene Duplication ◽  
Sexual Conflict ◽  
Morphological Evolution ◽  
Expression Patterns ◽  
Genetic Material ◽  
Genomic Research ◽  
Specific Gene ◽  
Duplicated Genes

Gene duplication provides an essential source of novel genetic material to facilitate rapid morphological evolution. Traits involved in reproduction and sexual dimorphism represent some of the fastest evolving traits in nature, and gene duplication is intricately involved in the origin and evolution of these traits. Here, we review genomic research on stalk-eyed flies (Diopsidae) that has been used to examine the extent of gene duplication and its role in the genetic architecture of sexual dimorphism. Stalk-eyed flies are remarkable because of the elongation of the head into long stalks, with the eyes and antenna laterally displaced at the ends of these stalks. Many species are strongly sexually dimorphic for eyespan, and these flies have become a model system for studying sexual selection. Using both expressed sequence tag and next-generation sequencing, we have established an extensive database of gene expression in the developing eye-antennal imaginal disc, the adult head and testes. Duplicated genes exhibit narrower expression patterns than non-duplicated genes, and the testes, in particular, provide an abundant source of gene duplication. Within somatic tissue, duplicated genes are more likely to be differentially expressed between the sexes, suggesting gene duplication may provide a mechanism for resolving sexual conflict.

Wing shape variations in an invasive moth are related to sexual dimorphism and altitude

2010 ◽  
Vol 100 (5) ◽  
pp. 529-541 ◽  
Author(s):  
N. Hernández-L. ◽  
Á.R. Barragán ◽  
S. Dupas ◽  
J.-F. Silvain ◽  
O. Dangles
Keyword(s):  
Invasive Species ◽  
Sexual Dimorphism ◽  
High Altitude ◽  
Morphological Changes ◽  
Morphological Evolution ◽  
Empirical Support ◽  
Wing Shape ◽  
Invasion Success ◽  
Wing Morphology ◽  
Invasive Insects

AbstractWing morphology has great importance in a wide variety of aspects of an insect's life. Here, we use a geometric morphometric approach to test the hypothesis that variation, in insect wing morphology patterns, occurs between sexes and along altitudinal gradients for invasive species, despite their recent association to this environment. We explored the variation in wing morphology between 12 invasive populations of the invasive potato pest, Tecia solanivora, at low and high altitude in the central highlands of Ecuador. After characterizing sexual dimorphism in wing shape, we investigated if moths at higher elevations differ in wing morphology from populations at lower altitudes. Results indicate wing shape and size differences between sexes and between altitudinal ranges. Females showed larger, wider wings than males, while high altitude moths showed larger, narrow-shaped wings by comparison to low-altitude moths. GLM analyses confirmed altitude was the only significant determinant of this gradient. Our study confirms a sexual dimorphism in size and wing shape for the potato moth. It also confirms and extends predictions of morphological changes with altitude to an invasive species, suggesting that wing morphology variation is an adapted response contributing to invasion success of the potato moth in mountainous landscapes. Ours is one of the first studies on the morphology of invasive insects and represents a valuable contribution to the study of insect invasions because it both offers empirical support to previous genetic studies on T. solanivora as well as proving broader insight into the mechanisms behind morphological evolution of a recently introduced pest.

A quantitative image analysis method for the determination of cocontinuity in polymer blends

1993 ◽  
Vol 51 ◽  
pp. 894-895
Author(s):  
William A. Heeschen
Keyword(s):  
Image Analysis ◽  
Polymer Blends ◽  
Quantitative Measurement ◽  
Morphological Evolution ◽  
Phase Ratio ◽  
Irregular Shapes ◽  
Quantitative Image ◽  
Discrete Domains ◽  
A Domains

Two new morphological measurements based on digital image analysis, CoContinuity and CoContinuity Balance, have been developed and implemented for quantitative measurement of morphology in polymer blends. The morphology of polymer blends varies with phase ratio, composition and processing. A typical morphological evolution for increasing phase ratio of polymer A to polymer B starts with discrete domains of A in a matrix of B (A/B < 1), moves through a cocontinuous distribution of A and B (A/B ≈ 1) and finishes with discrete domains of B in a matrix of A (A/B > 1). For low phase ratios, A is often seen as solid convex particles embedded in the continuous B phase. As the ratio increases, A domains begin to evolve into irregular shapes, though still recognizable as separate domains. Further increase in the phase ratio leads to A domains which extend into and surround the B phase while the B phase simultaneously extends into and surrounds the A phase.

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