Current Biology最新文献

Females control the paternity of their offspring by selectively mating with males they perceive to be of high quality. In species where females mate with multiple males in succession, females may bias offspring paternity by favoring the sperm of one male over another, a process known as cryptic female choice.¹ While evidence of cryptic female choice exists in multiple taxa, the mechanisms underlying this process have remained difficult to unravel.² Understanding cryptic female choice requires demonstration of a female-driven post-mating bias in sperm use and paternity and a causal link between this bias and male cues.³ In this study, we present evidence of cryptic female choice in female Drosophila melanogaster. Through experiments utilizing transgenic males expressing fluorescent sperm, we observed that exposure to attractive males between matings prompts females to expel the ejaculate of their initial mate more rapidly than in the presence of less attractive males. While doing so, females exhibit a bias in sperm storage against their first mate, thereby favoring the paternity of their subsequent mate. Our findings reveal that females adjust the timing of ejaculate expulsion in response to male pheromones in their environment, specifically heptanal and 11-cis-vaccenyl acetate, which are sensed by females through specific odorant receptors. We provide a cryptic female choice mechanism allowing a female to modulate the share of paternity of her first mate depending on the sensing of the quality of potential mates in her environment. These findings showcase that paternity can be influenced by events beyond copulation.

Oxford ragwort (Senecio squalidus) is one of only two homoploid hybrid species known to have originated very recently, so it is a unique model for determining genomic changes and stabilization following homoploid hybrid speciation. Here, we provide a chromosome-level genome assembly of S. squalidus with 95% of the assembly contained in the 10 longest scaffolds, corresponding to its haploid chromosome number. We annotated 30,249 protein-coding genes and estimated that ∼62% of the genome consists of repetitive elements. We then characterized genome-wide patterns of linkage disequilibrium, polymorphism, and divergence in S. squalidus and its two parental species, finding that (1) linkage disequilibrium is highly heterogeneous, with a region on chromosome 4 showing increased values across all three species but especially in S. squalidus; (2) regions harboring genetic incompatibilities between the two parental species tend to be large, show reduced recombination, and have lower polymorphism in S. squalidus; (3) the two parental species have an unequal contribution (70:30) to the genome of S. squalidus, with long blocks of parent-specific ancestry supporting a very rapid stabilization of the hybrid lineage after hybrid formation; and (4) genomic regions with major parent ancestry exhibit an overrepresentation of loci with evidence for divergent selection occurring between the two parental species on Mount Etna. Our results show that both genetic incompatibilities and natural selection play a role in determining genome-wide reorganization following hybrid speciation and that patterns associated with homoploid hybrid speciation—typically seen in much older systems—can evolve very quickly following hybridization.

The evolution of intracellular organelles by endosymbiosis is considered rare. Two recent studies suggest that endosymbioses between nitrogen-fixing bacteria and eukaryotic algae are approaching levels of integration comparable to cellular organelles, helping to solve the problem of oceanic nitrogen limitation.

‘Jump scares’ are particularly robust when visuals are paired with coherent sound. A new study demonstrates that connectivity between the superior colliculus and parabigeminal nucleus generates multimodal enhancement of visually triggered defensiveness, revealing a novel multisensory threat augmentation mechanism.

The partnership between corals and their intracellular algal symbionts has long been a textbook example of a mutually beneficial association. Here I argue that this view has been made obsolete by a steady accumulation of evidence over the past three decades. The coral–algal relationship is perhaps better viewed as one of domestication — think of it like a cattle farm, in which the coral is the farmer and the algae are the cows. I synthesize old and new evidence in support of this updated view and highlight remaining knowledge gaps, the largest of which continues to be the natural history of algal symbionts.

Long-term memory — information retention over long timescales — can allow animals to retain foraging skills and efficiently respond to seasonally available resources and changing environments¹. Most long-term memory research is with captive species, focusing on spatial, individual or object recognition, with less known about wild species and the retention of motor task abilities, as in the case of complex foraging skills^2,3. We have examined whether wild striated caracaras (Phalcoboenus australis), recently shown to rapidly and flexibly innovate with an eight-task puzzle box⁴, retain task memories one year later. We found that, despite no reinforcement, caracaras repeated motor techniques that led to their most recent success on tasks the year prior, solving nearly twice as fast as a naïve control group and four times faster than when naïve. Our results suggest long-term memory may be important for non-migratory opportunistic generalists, particularly in remote island environments with seasonally available resources, and further highlight how striated caracaras are promising candidates for avian cognitive studies.

The word ‘medicine’ is typically associated with humans, but scientists are increasingly realizing that non-human animals also use medication to deal with infections and other health issues. Medication behaviors are shared by a wide diversity of animal species, ranging from ants to apes, from bees to bears, and from caterpillars to capuchins. These animals use a wide variety of medicines provided by nature, ranging from plant chemicals to other animals and clay (Box 1). The targets of medication are equally diverse: while many animals use medication as protection against internal and external parasites and pathogens, animals may also use medicine to reduce inflammation and stress or to improve reproductive function.

Some species have evolved the ability to use the sense of hearing to modify existing vocalizations, or even create new ones, which enlarges their repertoires and results in complex communication systems.¹ This ability corresponds to various forms of vocal production learning that are all possessed by humans and independently displayed by distantly related vertebrates.^{1,2,3,4,5,6,7} Among mammals, a few species, including the Egyptian fruit bat,^8,9,10 would possess such vocal production learning abilities.⁷ Yet the necessity of an intact auditory system for the development of the Egyptian fruit bat typical vocal repertoire has not been tested. Furthermore, a systematic causal examination of learned and innate aspects of the entire repertoire has never been performed in any vocal learner. Here we addressed these gaps by eliminating pups’ sense of hearing at birth and assessing its effects on vocal production in adulthood. The deafening treatment enabled us to both causally test these bats’ vocal learning ability and discern learned from innate aspects of their vocalizations. Leveraging wireless individual audio recordings from freely interacting adults, we show that a subset of the Egyptian fruit bat vocal repertoire necessitates auditory feedback. Intriguingly, these affected vocalizations belong to different acoustic groups in the vocal repertoire of males and females. These findings open the possibilities for targeted studies of the mammalian neural circuits that enable sexually dimorphic forms of vocal learning.

Social aging — the change in social behavior across an individual’s lifespan — has been found in many animals. A new study in African lions shows that female and male lions differ in their pattern of social aging.