Trends in evolution of the Rhodniini tribe (Hemiptera, Triatominae): experimental crosses between Psammolestes tertius Lent & Jurberg, 1965 and P. coreodes Bergroth, 1911 and analysis of the reproductive isolating mechanisms

Background The tribe Rhodniini is a monophyletic group composed of 24 species grouped into two genera: Rhodnius and Psammolestes. The genus Psammolestes includes only three species, namely P. coreodes, P. tertius and P. arthuri. Natural hybridization events have been reported for the Rhodniini tribe (for genus Rhodnius specifically). Information obtained from hybridization studies can improve our understanding of the taxonomy and systematics of species. Here we report the results from experimental crosses performed between P. tertius and P. coreodes and from subsequent analyses of the reproductive and morphological aspects of the hybrids. Methods Crossing experiments were conducted between P. tertius and P. coreodes to evaluate the pre- and post-zygotic barriers between species of the Rhodniini tribe. We also performed cytogenetic analyses of the F1 hybrids, with a focus on the degree of pairing between the homeologous chromosomes, and morphology studies of the male gonads to evaluate the presence of gonadal dysgenesis. Lastly, we analyzed the segregation of phenotypic characteristics. Results Interspecific experimental crosses demonstrated intrageneric genomic compatibility since hybrids were produced in both directions. However, these hybrids showed a high mortality rate, suggesting a post-zygotic barrier resulting in hybrid unviability. The F1 hybrids that reached adulthood presented the dominant phenotypic segregation pattern for P. tertius in both directions. These insects were then intercrossed; the hybrids were used in the cross between P. tertius ♀ × P. coreodes ♂ died before oviposition, and the F1 hybrids of P. coreodes ♀ x P. tertius ♂ oviposited and their F2 hybrids hatched (however, all specimens died after hatching, still in first-generation nymph stage, pointing to a hybrid collapse event). Morphological analyses of male gonads from F1 hybrids showed that they did not have gonadal dysgenesis. Cytogenetic analyses of these triatomines showed that there were metaphases with 100% pairing between homeologous chromosomes and metaphases with pairing errors. Conclusion The results of this study demonstrate that Psammolestes spp. have intrageneric genomic compatibility and that post-zygotic barriers, namely unviability of hybrid and hybrid collapse, resulted in the breakdown of the hybrids of P. tertius and P. coreodes, confirming the specific status of species based on the biological concept of species. Graphical abstract

Niche shifts and hybridization in two Amazona parrot sister-species introduced to Southern California

ABSTRACTHybridization involving introduced species is becoming more common as humans modify landscapes and ecosystems. When two closely related species are introduced to the same area, their niche dynamics will dictate the level of sympatry and potential for hybridization. Amazona parrots offer a rare case where multiple closely related species have established as breeders in Southern California. Red-crowned Parrots (A. viridigenalis) and Lilac-crowned Parrots (A. finschi) are particularly interesting because they are sister species with allopatric native ranges in Mexico. In Southern California, where they established in the 1980s and have since grown in numbers, they appear to occupy the same urban habitat. We sought to test whether introduced Red-crowned and Lilac-crowned parrots have shifted their niches compared to their native ranges, and if so, whether sympatry has led to hybridization. Using broad-scale environmental data collected from weather stations and orbiting satellites, we found that Red- crowned and Lilac-crowned parrots have partially divergent environmental niches in their native ranges, but now occupy the same environmental niche in their introduced range in Southern California. This new niche is largely different from what they experience in their respective home ranges, supporting a niche- shift model of species introduction. Due to this niche shift, the two species now come into contact across Southern California, leading to hybridization. Genomic markers support the existence of some recent hybrids as well as advanced backcrosses resulting from older hybridization events closer to the time of first introduction. Photographs from community scientists included as part of the Free-flying Los Angeles Parrot Project (FLAPP) also document hybrids, but underestimate their frequency compared to genetic data. Despite evidence for ongoing hybridization, the bimodal distribution of ancestry among the introduced population points to the existence of reproductive isolating mechanisms keeping the two species distinct. Further study is needed to understand if reproductive isolating mechanisms result from behavioral factors, such as conspecific flocking preferences, suggested by the community science data, or from genomic incompatibilities built up from a long history of isolation in Mexico. The integrity of these genetic lineages in Southern California carries important conservation implications, as both species are listed as endangered in their native ranges due to trapping for the pet trade and habitat loss.

Courtship and mating behavior in four Pachytroctidae species (Psocodea: ‘Psocoptera’: Troctomorpha: Nanopsocetae: Pachytroctidae)

Courtship and mating behavior were investigated in four species, representing three different genera, in the family Pachytroctidae. All exhibited a lengthy courtship in the male-above position followed by brief copulation in the female-above position with both facing in the same direction. This courtship behavior has not previously been observed in ‘Psocoptera’ and may be unique to Pachytroctidae. In three of the species in this study, the spermatophore remnant protruded from the tip of the male’s abdomen after copulation, and was immediately deposited on the surface of the experimental enclosure. Differences in courtship behavior of the two closely related and sympatric Tapinella species, described in this report, may represent reproductive isolating mechanisms. Under experimental conditions, we observed a male of each Tapinella species mount, court, and attempt to mate with a virgin female of the other species. In each case the female rejected the male and failed to mate. Implications relative to these behaviors are discussed. DOI links to videos are provided for easy access.

How Firms Build Isolating Mechanisms for Knowledge: A Study in Offshore Research and Development Captives

Understanding how firms protect their knowledge from leakage is becoming increasingly important, especially when knowledge is not well protected by legal mechanisms such as patents. The rapid rise in research and development (R&D) activities taking place in offshore locations that only offer weak legal protection for intellectual property provides the ideal context to study this question. Using interview and survey data from captive R&D centers of multinational firms in India, we (1) identify five organizational practices that firms use to protect their knowledge from leaking to competitors in offshore locations, (2) consider whether these practices limit knowledge leakage or limit damage from leaked knowledge, and (3) explore whether they are complements or substitutes.

Taboo on spiritual incest: justification of the anthropic principle

This article makes an attempt to demonstrate that the evolution of culture is isomorphic to the evolution of life, and thus, such isomorphism can be considered a basic metaphor for studying the evolution of culture. Such research allows explicating the key cultural processes, which are imperceptible to other methods, and suggest algorithms for adjusting these processes. Leaning on fact that life due to the impact of isolating mechanisms of nature constantly forms different taxa, in which the evolution rapidly fades, it is proven that isolation of cultural memes leads to their degeneration. The emergence of certain taboos, such as the taboo on incest, cause fusion of taxa, which accelerates the evolution and results in structural revolutions. Such evolutionary pattern can be described with Freud’s metaphor from the eponymous book “Totem and Taboo». Totemism explicates teleologicity of evolution as the need for uniting all taxa into one. The work displays that culture has already formed the plurality of “semantic taxa”, which require unification, or at least, interaction with each other; such interaction should stimulate the taboo on “spiritual incest, which means limitation of evolution within a single semantic taxon.

Allopatric divergence and secondary contact with gene flow: a recurring theme in rattlesnake speciation

The study of recently diverged lineages whose geographical ranges come into contact can provide insight into the early stages of speciation and the potential roles of reproductive isolation in generating and maintaining species. Such insight can also be important for understanding the strategies and challenges for delimiting species within recently diverged species complexes. Here, we use mitochondrial and nuclear genetic data to study population structure, gene flow and demographic history across a geographically widespread rattlesnake clade, the western rattlesnake species complex (Crotalus cerberus, Crotalus viridis, Crotalus oreganus and relatives), which contains multiple lineages with ranges that overlap geographically or contact one another. We find evidence that the evolutionary history of this group does not conform to a bifurcating tree model and that pervasive gene flow has broadly influenced patterns of present-day genetic diversity. Our results suggest that lineage diversity has been shaped largely by drift and divergent selection in isolation, followed by secondary contact, in which reproductive isolating mechanisms appear weak and insufficient to prevent introgression, even between anciently diverged lineages. The complexity of divergence and secondary contact with gene flow among lineages also provides new context for why delimiting species within this complex has been difficult and contentious historically.

Epigenetic and genetic variation between two behaviorally isolated species of Neoconocephalus (Orthoptera: Tettigonioidea)

Epigenetic variation allows for rapid changes in phenotypes without alterations to nucleotide sequences. These epigenetic signatures may diverge over time among isolated populations. Epigenetic incompatibility following secondary contact between these populations could result in the evolution of reproductive isolating mechanisms. If epigenetic incompatibility drove the evolution of species isolating mechanisms, we expect to see significant epigenetic differentiation between these species. Alternatively, epigenetic variation could be the result of predominantly environmental variables and not align along species boundaries. A methylation sensitive amplified fragment length polymorphism analysis was performed on individuals of the closely related katydid species Neoconocephalusrobustus and N.bivocatus. We observed significant variation in total methylation levels between species. However, genetic differentiation remained larger than epigenetic differentiation between species groups. We measured a significant correlation between the epigenetic and genetic distance between individuals. Epigenetic differentiation is therefore likely the result of an interaction between genetic and epigenetic loci and not a mechanism for species differentiation. We therefore did not find evidence to support our hypothesis of an epigenetically mediated mechanism for speciation between N.robustus and N.bivocatus.

The Resource-Based View of the Firm

The Resource-Based View of the firm (RBV) is a set of related theories sharing the assumptions of resource heterogeneity and resource immobility across firms. In this view, a firm is a bundle of resources, capabilities, or routines which create value and cannot be easily imitated or appropriated by competitors due to isolating mechanisms. Grounded in the economic traditions of the “Chicago School” of economic efficiency, the “Austrian School” of economics, and organizational economics, the RBV comprises theories that explain the existence of (sustained) competitive advantage and of economic rents. Empirical research from this perspective addresses both firm performance and firm behavior at the level of business strategy (e.g., within-industry competition) and corporate strategy (e.g., acquisitions). Initially developed through a series of papers by several authors in the 1980s–1990s, major extensions and refinements of the RBV include the knowledge-based view of the firm (KBV), dynamic capabilities, and the relational view, which recognizes capabilities can be developed and shared through alliances between firms.