Detecting life by behavior, the overlooked sensitivity of behavioral assays.

Detecting life has driven research and exploration for centuries, but recent attempts to compile and generate a framework that summarizes life features, aimed to develop strategies for life detection missions beyond planet Earth, have disregarded a key life feature: behavior. Yet, some behaviors such as biomineralization or motility have occasionally been proposed as biosignatures to detect life. Here, we capitalize on a specific taxis' motility behavior, magnetotaxis, to experimentally provide insights in support of behavior as an unambiguous, sensitive biosignature, and magnetic forces as a prescreening option.

Fetal endocrine axes mRNA expression levels are related to sex and intrauterine position.

Background: The hypothalamic-pituitary-adrenal (HPA) and -gonadal (HPG) axes are two major pathways that connect the neural and endocrine systems in vertebrates. Factors such as prenatal stress and maternal exposure to exogenous steroids have been shown to affect these pathways during fetal development. Another less studied factor is the transfer of hormones across fetuses in multifetal pregnancies.

THE EFFECT OF 4-VINYLCYCLOHEXENE DIEPOXIDE ON FEMALE NUTRIA () FERTILITY IN CAPTIVITY-A PILOT STUDY.

The nutria () is a globally widespread invasive species. Attempts to eradicate nutria by shooting, poisoning, and trapping have been mostly unsuccessful, leading to calls for the development of new control methods. The compound 4-vinylcyclohexene diepoxide (VCD) is known to cause follicular atresia in mammals and may control conception when administered orally.

Fathers and sons, mothers and daughters: Sex-specific genetic architecture for fetal testosterone in a wild mammal.

Testosterone plays a critical role in mediating fitness-related traits in many species. Although it is highly responsive to environmental and social conditions, evidence from several species show a heritable component to its individual variation. Despite the known effects that in utero testosterone exposure have on adult fitness, the heritable component of individual testosterone variation in fetuses is mostly unexplored.

Paternity share predicts sons' fetal testosterone.

Multiple paternity is common in many species. While its benefits for males are obvious, for females they are less clear. Female indirect benefits may include acquiring 'good genes' for offspring or increasing litter genetic diversity.

The evidence for divergent sexual selection among closely related barn swallow populations is strong.

Lifjeld's comment provides an opportunity to illustrate the intricacies of the "regression to the mean" (RTM) effect, to clarify the difficulty in teasing apart RTM from allocation bias, and to re-examine our results in relation to RTM and in the context of related evidence. Here, we show that (a) the correlations between paternity change and initial paternity are mathematically expected and can equally be produced when changes are caused by the experimental manipulation itself. (b) The approach taken by Lifjeld to control for RTM is overly conservative because it is based on the unrealistic assumption of zero correlation between individuals' repeated measurements.

Identification, Analysis and Characterization of Base Units of Bird Vocal Communication: The White Spectacled Bulbul () as a Case Study.

Animal vocal communication is a broad and multi-disciplinary field of research. Studying various aspects of communication can provide key elements for understanding animal behavior, evolution, and cognition. Given the large amount of acoustic data accumulated from automated recorders, for which manual annotation and analysis is impractical, there is a growing need to develop algorithms and automatic methods for analyzing and identifying animal sounds.

Symbiotic magnetic sensing: raising evidence and beyond.

The identity of a magnetic sensor in animals remains enigmatic. Although the use of the geomagnetic field for orientation and navigation in animals across a broad taxonomic range has been well established over the past five decades, the identity of the magnetic-sensing organ and its structure and/or apparatus within such animals remains elusive-'a sense without a receptor'. Recently, we proposed that symbiotic magnetotactic bacteria (MTB) may serve as the underlying mechanism behind a magnetic sense in animals-'the symbiotic magnetic-sensing hypothesis'.

Divergent sexual signals reflect costs of local parasites.

Many closely related populations are distinguished by variation in sexual signals and this variation is hypothesized to play an important role in reproductive isolation and speciation. Within populations, there is considerable evidence that sexual signals provide information about the incidence and severity of parasite infections, but it remains unclear if variation in parasite communities across space could play a role in initiating or maintaining sexual trait divergence. To test for variation in parasite-associated selection, we compared three barn swallow subspecies with divergent sexual signals.

Non-model species deliver a non-model result: Nutria female fetuses neighboring males in utero have lower testosterone.

Neighboring fetuses may impact their siblings in various respects, depending on their in utero location and sex. The effects of the intrauterine position (IUP) are widely studied in model organisms, especially laboratory bred murine strains that are characterized by short gestations and altricial offspring. In some species, the proximity to a male fetus and its higher circulating testosterone masculinizes neighboring female fetuses.

The symbiotic magnetic-sensing hypothesis: do underlie the magnetic sensing capability of animals?

The ability to sense Earth's magnetic field has evolved in various taxa. However, despite great efforts to find the '' in vertebrates, the results of these scientific efforts remain inconclusive. A few decades ago, it was found that bacteria, known as magnetotactic bacteria (MTB), can move along a magnetic field using nanometric chain-like structures.

The maintenance of phenotypic divergence through sexual selection: An experimental study in barn swallows Hirundo rustica.

Previous studies have shown that sexual signals can rapidly diverge among closely related species. However, we lack experimental studies to demonstrate that differences in trait-associated reproductive performance maintain sexual trait differences between closely related populations, in support for a role of sexual selection in speciation. Populations of Northern Hemisphere distributed barn swallows Hirundo rustica are closely related, yet differ in two plumage-based traits: ventral color and length of the outermost tail feathers (streamers).

Expression of multiple sexual signals by fathers and sons in the East-Mediterranean barn swallow: are advertising strategies heritable?

The level of expression of sexually selected traits is generally determined by genes, environment and their interaction. In species that use multiple sexual signals which may be costly to produce, investing in the expression of one sexual signal may limit the expression of the other, favoring the evolution of a strategy for resource allocation among signals. As a result, even when the expression of sexual signals is condition dependent, the relative level of expression of each signal may be heritable.

Multiple sexual signals and behavioral reproductive isolation in a diverging population.

Sexual trait divergence has been shown to play a role in the evolution of reproductive isolation. While variation in multiple sexual signals is common among closely related species, little is known about the role of these different axes of phenotype variation with respect to the evolution of behavioral reproductive isolation. Here we study a unique population of barn swallows (Hirundo rustica transitiva) that can be distinguished phenotypically from its neighboring populations only on the basis of two features of male plumage: exaggerated expression of both long tail streamers and dark ventral coloration.

Low variation in the polymorphic Clock gene poly-Q region despite population genetic structure across barn swallow (Hirundo rustica) populations.

Recent studies of several species have reported a latitudinal cline in the circadian clock gene, Clock, which influences rhythms in both physiology and behavior. Latitudinal variation in this gene may hence reflect local adaptation to seasonal variation. In some bird populations, there is also an among-individual association between Clock poly-Q genotype and clutch initiation date and incubation period.

Population genetics and morphological comparisons of migratory European (Hirundo rustica rustica) and sedentary East-Mediterranean (Hirundo rustica transitiva) barn swallows.

Speciation processes are largely determined by the relative strength of divergent selection versus the magnitude of gene flow. The barn swallow (Hirundo rustica) has a broad geographic distribution that encompasses substantial geographic variation in morphology and behavior. The European (H.