Biology Letters最新文献

Genes from ancient families are sometimes involved in the convergent evolutionary origins of similar traits, even across vast phylogenetic distances. Sulfotransferases are an ancient family of enzymes that transfer sulfate from a donor to a wide variety of substrates, including probable roles in some bioluminescence systems. Here, we demonstrate multiple sulfotransferases, highly expressed in light organs of the bioluminescent ostracod Vargula tsujii, transfer sulfate in vitro to the luciferin substrate, vargulin. We find luciferin sulfotransferases (LSTs) of ostracods are not orthologous to known LSTs of fireflies or sea pansies; animals with distinct and convergently evolved bioluminescence systems compared to ostracods. Therefore, distantly related sulfotransferases were independently recruited at least three times, leading to parallel evolution of luciferin metabolism in three highly diverged organisms. Reuse of homologous genes is surprising in these bioluminescence systems because the other components, including luciferins and luciferases, are completely distinct. Whether convergently evolved traits incorporate ancient genes with similar functions or instead use distinct, often newer, genes may be constrained by how many genetic solutions exist for a particular function. When fewer solutions exist, as in genetic sulfation of small molecules, evolution may be more constrained to use the same genes time and again.

Interspecific interactions are fundamental drivers of animal space use. Yet while non-consumptive effects of predation risk on prey space use are well-known, the risk of aggressive interactions on space use of competitors is largely unknown. We apply the landscape of risk framework to competition-driven space use for the first time, with the hypothesis that less aggressive competitors may alter their behaviour to avoid areas of high competitor density. Specifically, we test how aggressive risk from territorial algal-farming damselfishes can shape the spatial distribution of herbivore fish competitors. We found that only the most aggressive damselfish had fewer competitors in their surrounding area, demonstrating that individual-level behavioural variation can shape spatial distributions. In contradiction to the landscape of risk framework, abundances of farming damselfish and other fishes were positively associated. Our results suggest that reef fishes do not simply avoid areas of high damselfish abundance, but that spatial variation in aggressive behaviour, rather than of individuals, created a competitive landscape of risk. We emphasize the importance of individual-level behaviour in identifying patterns of space use and propose expanding the landscape of risk framework to non-predatory interactions to explore cascading behavioural responses to aggressive risk.

The mechanisms whereby environmental experiences of parents are transmitted to their offspring to impact their behaviour and fitness are poorly understood. Previously, we showed that naive Bicyclus anynana butterfly larvae, whose parents fed on a normal plant feed but coated with a novel odour, inherited an acquired preference towards that odour, which had initially elicited avoidance in the naive parents. Here, we performed simple haemolymph transfusions from odour-fed and control-fed larvae to naive larval recipients. We found that larvae injected with haemolymph from odour-fed donors stopped avoiding the novel odour, and their naive offspring preferred the odour more, compared to the offspring of larvae injected with control haemolymph. These results indicate that factors in the haemolymph, potentially the odour molecule itself, play an important role in odour learning and preference transmission across generations. Furthermore, this mechanism of odour preference inheritance, mediated by the haemolymph, bypasses the peripheral odour-sensing mechanisms taking place in the antennae, mouthparts or legs, and may mediate food plant switching and diversification in Lepidoptera or more broadly across insects.

Ostracod crustaceans originated at least 500 Ma ago. Their tiny bivalved shells represent the most species-abundant fossil arthropods, and ostracods are omnipresent in a wide array of freshwater and marine environments today and in the past. Derima paparme gen. et sp. nov. from the Herefordshire Silurian Lagerstätte (~430 Ma) in the Welsh Borderland, UK, is one of only a handful of exceptionally preserved ostracods (with soft parts as well as the shell) known from the Palaeozoic. A male specimen provides the first evidence of the appendages of Binodicopina, a major group of Palaeozoic ostracods comprising some 135 Ordovician to Permian genera. The appendage morphology of D. paparme, but not its shell, indicates that binodicopes belong to Podocopa. The discovery that the soft-part morphology of binodicopes allies them with podocopes affirms that using the shell alone is an unreliable basis for classifying certain fossil ostracods, and knowledge of soft-part morphology is critical for the task. Current assignment of many fossil ostracods to higher taxa, and therefore the evolutionary history of the group, may require reconsideration.

The transmission efficiency of aphid-vectored plant viruses can differ between aphid populations. Intra-species diversity (genetic variation, endosymbionts) is a key determinant of aphid phenotype; however, the extent to which intra-species diversity contributes towards variation in virus transmission efficiency is unclear. Here, we use multiple populations of two key aphid species that vector barley yellow dwarf virus (BYDV) strain PAV (BYDV-PAV), the grain aphid (Sitobion avenae) and the bird cherry-oat aphid (Rhopalosiphum padi), and examine how diversity in vector populations influences virus transmission efficiency. We use Illumina sequencing to characterize genetic and endosymbiont variation in multiple Si. avenae and Rh. padi populations and conduct BYDV-PAV transmission experiments to identify links between intra-species diversity in the vector and virus transmission efficiency. We observe limited variation in the transmission efficiency of Si. avenae, with transmission efficiency consistently low for this species. However, for Rh. padi, we observe a range of transmission efficiencies and show that BYDV transmission efficiency is influenced by genetic diversity within the vector, identifying 542 single nucleotide polymorphisms that potentially contribute towards variable transmission efficiency in Rh. padi. Our results represent an important advancement in our understanding of the relationship between genetic diversity, vector-virus interactions, and virus transmission efficiency.

How organisms produce organs with robust shapes and sizes is still an open question. In recent years, the Arabidopsis sepal has been used as a model system to study this question because of its highly reproducible shape and size. One interesting aspect of the sepal is that its epidermis contains cells of very different sizes. Previous reports have qualitatively shown that sepals with more or less giant cells exhibit comparable final size and shape. Here, we investigate this question using quantitative approaches. We find that a mixed population of cell size modestly contribute to the normal width of the sepal but is not essential for its shape robustness. Furthermore, in a mutant with increased cell and organ growth variability, the change in final sepal shape caused by giant cells is exaggerated but the shape robustness is not affected. This formally demonstrates that sepal shape variability is robust to cell size heterogeneity.

Autotomy refers to self-amputation where the loss of a limb or organ is generally said to be (1) in response to stressful external stimuli; (2) voluntary and nervously mediated; (3) supported by adaptive features that increase efficiency and simultaneously mediate the cost; and (4) morphologically delineated by a predictable breakage plane. It is estimated that this phenomenon has evolved independently nine different times across the animal kingdom, appearing in many different taxa, including vertebrate and invertebrate as well as aquatic and terrestrial animals. Marine invertebrates use this behaviour in a diversity of manners that have yet to be globally reviewed and critically examined. Here, published data from marine invertebrate taxa were used to explore instances of injury as an evolutionary driver of autotomy. Findings suggest that phyla (e.g. Echinodermata and Arthropoda) possibly experiencing high rates of injury (tissue damage or loss) are more likely to be able to perform autotomy. Additionally, this review looks at various morphological, physiological and environmental conditions that have either driven the evolution or maintained the behaviour of autotomy in marine invertebrates. Finally, the use of autotomic abilities in the development of more sustainable and less ecologically invasive fisheries is explored.

Animal play encompasses a variety of aspects, with kinematic and social aspects being particularly prevalent in mammalian play behaviour. While the developmental effects of play have been increasingly documented in recent decades, understanding the specific contributions of different play aspects remains crucial to understand the function and evolutionary benefit of animal play. In our study, developing male rats were exposed to rough-and-tumble play selectively reduced in either the kinematic or the social aspect. We then assessed the developmental effects of reduced play on their appraisal of standardized human-rat play ('tickling') by examining their emission of 50 kHz ultrasonic vocalizations (USVs). Using a deep learning framework, we efficiently classified five subtypes of these USVs across six behavioural states. Our results revealed that rats lacking the kinematic aspect in play emitted fewer USVs during tactile contacts by human and generally produced fewer USVs of positive valence compared with control rats. Rats lacking the social aspect did not differ from the control and the kinematically reduced group. These results indicate aspects of play have different developmental effects, underscoring the need for researchers to further disentangle how each aspect affects animals.

Echolocating bats and their eared insect prey are in an acoustic evolutionary war. Moths produce anti-bat sounds that startle bat predators, signal noxiousness, mimic unpalatable models and jam bat sonar. Tiger beetles (Cicindelidae) also purportedly produce ultrasound in response to bat attacks. Here we tested 19 tiger beetle species from seven genera and showed that they produce anti-bat signals to playback of authentic bat echolocation. The dominant frequency of beetle sounds substantially overlaps the sonar calls of sympatric bats. As tiger beetles are known to produce defensive chemicals such as benzaldehyde and hydrogen cyanide, we hypothesized that tiger beetle sounds are acoustically advertising their unpalatability. We presented captive big brown bats (Eptesicus fuscus) with seven different tiger beetle species and found that 90 out of 94 beetles were completely consumed, indicating that these tiger beetle species are not aposematically signalling. Instead, we show that the primary temporal and spectral characteristics of beetle warning sounds overlap with sympatric unpalatable tiger moth (Arctinae) sounds and that tiger beetles are probably Batesian mimics of noxious moth models. We predict that many insect taxa produce anti-bat sounds and that the acoustic mimicry rings of the night sky are hyperdiverse.

Recent molecular taxonomic advancements have expanded our understanding of crocodylian diversity, revealing the existence of previously overlooked species, including the Congo dwarf crocodile (Osteolaemus osborni) in the central Congo Basin rainforests. This study explores the genomic divergence between O. osborni and its better-known relative, the true dwarf crocodile (Osteolaemus tetraspis), shedding light on their evolutionary history. Field research conducted in the northwestern Republic of the Congo uncovered a locality where both species coexist in sympatry/syntopy. Genomic analysis of sympatric individuals reveals a level of divergence comparable to that between ecologically similar South American dwarf caimans (Paleosuchus palpebrosus and Paleosuchus trigonatus), suggesting parallel speciation in the Afrotropics and Neotropics during the Middle to Late Miocene, 10-12 Ma. Comparison of the sympatric and allopatric dwarf crocodiles indicates no gene flow between the analysed sympatric individuals of O. osborni and O. tetraspis. However, a larger sample will be required to answer the question of whether or to what extent these species hybridize. This study emphasizes the need for further research on the biology and conservation status of the Congo dwarf crocodile, highlighting its significance in the unique biodiversity of the Congolian rainforests and thus its potential as a flagship species.