A landmark-free analysis of the pelvic girdle in Sulawesi ricefishes (Adrianichthyidae): How 2D and 3D geometric morphometrics can complement each other in the analysis of a complex structure.

Geometric morphometrics (GM) enable the quantification of morphological variation on various scales. Recent technical advances allow analyzing complex three-dimensional shapes also in cases where landmark-based approaches are not appropriate. Pelvic girdle bones (basipterygia) of Sulawesi ricefishes are 3D structures that challenge traditional morphometrics.

Potential Contribution of Ancient Introgression to the Evolution of a Derived Reproductive Strategy in Ricefishes.

Transitions from no parental care to extensive care are costly and involve major changes in life history, behavior, and morphology. Nevertheless, in Sulawesi ricefishes, pelvic brooding evolved from transfer brooding in two distantly related lineages within the genera Adrianichthys and Oryzias, respectively. Females of pelvic brooding species carry their eggs attached to their belly until the fry hatches.

How to stay attached-Formation of the ricefish plug and changes of internal reproductive structures in the pelvic brooding ricefish, Oryzias eversi Herder et al. (2012) (Beloniformes: Adrianichthyidae).

Teleost fishes show an enormous diversity of parental care, ranging from no care to viviparity with maternal provisioning of embryos. External brooders carry their developing eggs attached to their bodies. This requires the formation of novel morphological structures to support attachment.

The genetic basis of a novel reproductive strategy in Sulawesi ricefishes: How modularity and a low number of loci shape pelvic brooding.

The evolution of complex phenotypes like reproductive strategies is challenging to understand, as they often depend on multiple adaptations that only jointly result in a specific functionality. Sulawesi ricefishes (Adrianichthyidae) evolved a reproductive strategy termed as pelvic brooding. In contrast to the more common transfer brooding, female pelvic brooders carry an egg bundle connected to their body for weeks until the fry hatches.

Inflammation and convergent placenta gene co-option contributed to a novel reproductive tissue.

The evolution of pregnancy exposes parental tissues to new, potentially stressful conditions, which can trigger inflammation. Inflammation is costly and can induce embryo rejection, which constrains the evolution of pregnancy. In contrast, inflammation can also promote morphological innovation at the maternal-embryonic interface as exemplified by co-option of pro-inflammatory signaling for eutherian embryo implantation.

Complex sexually dimorphic traits shape the parallel evolution of a novel reproductive strategy in Sulawesi ricefishes (Adrianichthyidae).

Background: Pelvic brooding is a form of uni-parental care, and likely evolved in parallel in two lineages of Sulawesi ricefishes. Contrary to all other ricefishes, females of pelvic brooding species do not deposit eggs at a substrate (transfer brooding), but carry them until the fry hatches. We assume that modifications reducing the costs of egg carrying are beneficial for pelvic brooding females, but likely disadvantageous in conspecific males, which might be resolved by the evolution of sexual dimorphism via sexual antagonistic selection.

The untapped potential of medaka and its wild relatives.

The medaka is a fish that has served as a model organism for over a century, yet there is still much to learn about its life in the wild. Here we summarize the current knowledge, highlight recent progress and outline remaining gaps in our understanding of the natural history of medaka. It has also become clear over time that rather than being a single species, medaka comprises an entire species complex, so disentangling the species boundaries is an important goal for future research.

A Dense Linkage Map of Lake Victoria Cichlids Improved the Genome Assembly and Revealed a Major QTL for Sex-Determination.

Genetic linkage maps are essential for comparative genomics, high quality genome sequence assembly and fine scale quantitative trait locus (QTL) mapping. In the present study we identified and genotyped markers via restriction-site associated DNA (RAD) sequencing and constructed a genetic linkage map based on 1,597 SNP markers of an interspecific F2 cross of two closely related Lake Victoria cichlids ( and sp. 'red head').

The evolution of scarab beetles tracks the sequential rise of angiosperms and mammals.

Extant terrestrial biodiversity arguably is driven by the evolutionary success of angiosperm plants, but the evolutionary mechanisms and timescales of angiosperm-dependent radiations remain poorly understood. The Scarabaeoidea is a diverse lineage of predominantly plant- and dung-feeding beetles. Here, we present a phylogenetic analysis of Scarabaeoidea based on four DNA markers for a taxonomically comprehensive set of specimens and link it to recently described fossil evidence.

Genomics and the origin of species.

Speciation is a fundamental evolutionary process, the knowledge of which is crucial for understanding the origins of biodiversity. Genomic approaches are an increasingly important aspect of this research field. We review current understanding of genome-wide effects of accumulating reproductive isolation and of genomic properties that influence the process of speciation.

Isolation and characterization of nine polymorphic microsatellite markers for the deep-sea shrimp Nematocarcinus lanceopes (Crustacea: Decapoda: Caridea).

Background: The shrimp Nematocarcinus lanceopes Bate, 1888 is found in the deep sea around Antarctica and sub-Antarctic islands. Previous studies on mitochondrial data and species distribution models provided evidence for a homogenous circum-Antarctic population of N. lanceopes.

Repeated trans-watershed hybridization among haplochromine cichlids (Cichlidae) was triggered by Neogene landscape evolution.

The megadiverse haplochromine cichlid radiations of the East African lakes, famous examples of explosive speciation and adaptive radiation, are according to recent studies, introgressed by different riverine lineages. This study is based on the first comprehensive mitochondrial and nuclear DNA dataset from extensive sampling of riverine haplochromine cichlids. It includes species from the lower River Congo and Angolan (River Kwanza) drainages.

Speciation within genomic networks: a case study based on Steatocranus cichlids of the lower Congo rapids.

Hybridization in animals is a much more common phenomenon as previously thought and may have profound implications for speciation research. The cichlid genus Steatocranus (Teleostei: Cichlidae), a close relative to members of the East African cichlid radiations, radiated under riverine conditions in the lower Congo rapids and produced a small species flock. Previous phylogenetic analyses suggested that hybridization occurred and contributed to speciation in this genus.

Microsatellite support for active inbreeding in a cichlid fish.

In wild animal populations, the degree of inbreeding differs between species and within species between populations. Because mating with kin often results in inbreeding depression, observed inbreeding is usually regarded to be caused by limited outbreeding opportunities due to demographic factors like small population size or population substructuring. However, theory predicts inclusive benefits from mating with kin, and thus part of the observed variation in inbreeding might be due to active inbreeding preferences.

Time and origin of cichlid colonization of the lower Congo rapids.

Most freshwater diversity is arguably located in networks of rivers and streams, but, in contrast to lacustrine systems riverine radiations, are largely understudied. The extensive rapids of the lower Congo River is one of the few river stretches inhabited by a locally endemic cichlid species flock as well as several species pairs, for which we provide evidence that they have radiated in situ. We use more that 2,000 AFLP markers as well as multilocus sequence datasets to reconstruct their origin, phylogenetic history, as well as the timing of colonization and speciation of two Lower Congo cichlid genera, Steatocranus and Nanochromis.

The root of the East African cichlid radiations.

Background: For decades cichlid fishes (Perciformes: Cichlidae) of the East African cichlid radiations (Teleostei: Cichlidae) have served as natural experimental subjects for the study of speciation processes and the search for potential speciation key factors. Despite numerous phylogenetic studies dealing with their intragroup relationships, surprisingly little is known about the phylogenetic placement and time of origin of this enigmatic group. We used multilocus DNA-sequence data from five nuclear and four mitochondrial genes and refined divergence time estimates to fill this knowledge gap.

Adaptive radiation and hybridization in Wallace's Dreamponds: evidence from sailfin silversides in the Malili Lakes of Sulawesi.

Adaptive radiations are extremely useful to understand factors driving speciation. A challenge in speciation research is to distinguish forces creating novelties and those relevant to divergence and adaptation. Recently, hybridization has regained major interest as a potential force leading to functional novelty and to the genesis of new species.