Biology Letters最新文献

Altruistic behaviour is evolutionarily favoured through the action of kin selection. A simple mechanism for kin selection is population viscosity, whereby individuals do not move very far over the course of their lives, such that even indiscriminate helping of neighbours is liable to benefit one's genetic relatives. However, population viscosity is also associated with intensified resource competition among kin, which acts to inhibit the evolution of altruism. In standard models of population structure, these opposing effects of viscosity exactly cancel so that the evolutionary potential for altruism is completely invariant with respect to the rate of dispersal. Here, we investigate the consequences of load-balancing dispersal-whereby dispersers exhibit a preference for settling in less-crowded areas-for the evolution of altruism. Using mathematical modelling and individual-based computer simulations, we find that load-balancing dispersal dramatically reduces the kin-competition consequences of altruism, and thereby strongly promotes the evolution of altruism in viscous populations. We discuss other implications of such load-balancing dispersal for social evolution.

Food availability determines where and how animals use space across a landscape and, therefore, affects the risk of encounters leading to zoonotic spillover. This relationship is evident in Australian flying foxes (Pteropus spp.; fruit bats), where acute food shortages precede clusters of Hendra virus spillovers. Using machine learning, we predicted months of food shortages from climatological and ecological covariates (1996-2022) in subtropical Australia. Overall accuracy in predicting months of low food availability on a test set from 2018 up to 2022 reached 93.33 and 92.59% based on climatological and bat-level features, respectively. Seasonality and the Oceanic El Niño Index were the most important environmental features, while the number of bats in rescue centres and their body weights were the most important bat-level features. These models support predictive signals up to nine months in advance, facilitating action to mitigate spillover risk.

While many verte brates breed annually, there are a few that do not. Female sea turtles are a classic example of a generally non-annual nester, with often intervals between breeding seasons (termed the remigration interval) of 2-4 years. Non-annual nesting in sea turtles is believed to be due to long migration distances. While this hypothesis holds for populations where females migrate large distances (e.g. sometimes several 1000 km), it is harder to reconcile with cases where migration distances are short (e.g. sometimes <50 km). We show that even with very short breeding migrations, there are invariant time and energy costs to breeding. The time involved in the breeding process (migration, mating, nesting, internesting and returning to the foraging grounds) also comes with the opportunity cost of an individual being away from its foraging grounds and so lost foraging time. We show that this strategy of non-annual nesting is linked to high survival rates for adult sea turtles, a feature that is common across other non-annual breeders such as albatrosses and southern right whales.

Physical contests are critical in most animals in determining access to limited resources such as territories, food and sexual partners. Individuals should base their decision to engage and escalate a contest on the potential returns and the probability of winning against a specific opponent. Although variation in competitive ability should maintain variation in contest behaviour within populations, empirical evidence linking contest behaviour to competitive ability at the among- and within-individual levels remains limited. Here, we used an inbred line of the highly territorial and aggressive fly Drosophila prolongata to test how pre-existing variation in competitive ability drives phenotypic variation in contest behaviour. Specifically, we quantified the degree to which individual differences (i.e. individuality) in two key traits determining competitive ability, body size and weapon size, contribute to variation in territoriality and aggressiveness. Although territoriality and aggressiveness were repeatable, we found that behavioural plasticity in response to both focal and opponent morphological traits largely explains variation in both behaviours. Thus, even in the absence of genetic differences and under identical laboratory conditions, individuals consistently differ in contest behaviour while still adjusting their responses to the social context. We suggest that variation in the micro-environment, by shaping competitive ability through body size and weapon size, plays a crucial role in driving both between- and within-individual variation in social behaviour.

Infectious disease plays a key role in shaping marine communities, including in seagrass meadows, which form biodiverse coastal habitats. Eelgrass (Zostera marina) is the most widespread seagrass species and is susceptible to seagrass wasting disease, caused by the protist Labyrinthula zosterae. As a foundation species, eelgrass strongly influences ecosystem structure, function and services; recent work has begun to explore the links between critical community interactions and seagrass wasting disease. Here, we highlight recent advances about how the eelgrass community regulates and responds to seagrass wasting disease, from the microbiome to herbivores and filter feeders. We further show how efforts to model seagrass wasting disease progression can build on prior efforts to predict eelgrass growth and productivity and can inform our understanding of ecosystem health, resilience and vulnerability. As climate change alters environmental conditions, potentially favouring the wasting disease pathogen, efforts to integrate community interactions with disease ecology will be critical to forecast ecosystem dynamics and to develop effective coastal management strategies. We offer guidance on addressing major knowledge gaps in the study of eelgrass wasting disease in order to deepen both ecological theory and applied practices and identify how an integrated marine-disease-community ecology can inform a broader, cross-cutting understanding of disease.

Based on an interspecific comparison, Fernández-Martinez et al. (Fernández-Martinez et al. 2019 Nat. Plants5, 1222-1228 (doi:10.1038/s41477-019-0549-y)) found that masting is stronger in populations growing under conditions of nutrient scarcity, a relationship potentially providing a mechanistic link to resource-budget models of mast fruiting. Using comparisons among individual Quercus lobata, a common California masting oak species, we tested whether access to groundwater, foliar nitrogen (N) and foliar phosphorus (P) correlate with greater interannual acorn crop variability, increased synchrony of acorn production with other trees in the population and more negative lag-1 autocorrelations with acorn production the prior year-metrics indicative of masting-like behaviour. Our analyses failed to support the nutrient scarcity hypothesis. Three of the significant correlations between masting metrics and resources were in the opposite direction predicted by the hypothesis-trees with greater foliar N showed greater variability and synchrony in acorn production-while the other two (more water-stressed trees exhibited larger coefficient of variation (CV) in interannual acorn production) were apparently due to the inverse relationship between CV and mean overall productivity. More studies at different geographic and taxonomic scales and of other potentially important nutrients are needed to understand the relationship between masting and resources.

Exceptional preservation within the Mazon Creek Konservat-Lagerstätte has yielded unprecedented insights into Late Carboniferous flora and fauna including a wealth of information on extinct horseshoe crabs (Xiphosurida). Here, we document a unique specimen of the xiphosurid species Euproops danae that exhibits numerous dimple-like structures across the prosomal region. Comparison with modern horseshoe crabs suggests that these dimples may represent an algal or parasitic infestation that impacted the organism during life. This is the only known example of this infestation within the xiphosurid fossil record and provides evidence of life-stage-specific vulnerability, with dimpling indicating a terminal moult individual. These observations highlight the palaeobiological significance of pathological features within the fossil record and reinforce the value of Konservat-Lagerstätten in documenting ancient host-parasite interactions.

Copulation duration is a variable behaviour that is often extended by males beyond the time needed for sperm transfer. In many insect species, these prolonged matings have been linked to higher male reproductive success with virgin females. However, most matings in multiply mating species involve non-virgin females, whose role in shaping the evolution of this behaviour remains underexplored. Using hemiclonal analysis in Drosophila melanogaster, we tested whether males benefit from extended matings with non-virgin females by comparing competitive fertilization success (P2) between males from three long-mating and three short-mating hemiclone lines. We confirmed that differences among hemiclone lines in male mating duration with virgin females persisted with non-virgin females and that these longer matings were associated with higher P2, demonstrating a clear fitness benefit to males. These findings build on past work showing that longer matings increase male defensive reproductive success, highlighting the adaptive value of prolonged matings for males in multiply mating species and underscoring the importance of including non-virgin females in studies of sexual selection and reproductive behaviour.

The human menopause is hypothesized to be an adaptive trait that allows post-reproductive females to invest in, and avoid reproductive conflict with, their existing offspring and grand-offspring, thereby increasing their survival. Thus, the sacrifice of an early cessation of reproduction can result in increased inclusive fitness. However, the genetic basis of menopause remains largely unknown. Given that a mid-life menopause is a rare trait in terrestrial social species, there is a need to consider alternative taxa to move beyond a single datapoint to test theoretical frameworks upon. One aquatic taxonomic group, toothed whales, comprises five matrilineal species with menopause, thereby providing a crucial comparative system for understanding the evolution of menopause. The kinship dynamics in killer whale Orcinus orca societies, maximize the inclusive fitness of post-reproductive females when they invest in their son's reproductive success. Specifically, inclusive fitness is maximized at the X-chromosome (over the autosomes) through a post-reproductive female's son siring daughters. This raises the question of how selection favours a female trait that primarily benefits male offspring? Due to its inheritance pattern and ploidy, the X-chromosome is a candidate target for sexual antagonistic selection, which could act on the female-specific traits of increased lifespan and reproductive cessation. We therefore propose that the X-chromosome is a promising marker to explore the genetic underpinning of menopause in matrilineal whale species and could provide a key comparison (and contrast) to the genetic basis of menopause in humans. Lastly, we expand these ideas to autosomal regions with female biased recombination.

In this study, we used a multi-faceted approach to understand patterns of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission and persistence in a wild white-tailed deer (Odocoileus virginianus) population. Serology data indicated transmission of SARS-CoV-2 and persistence during the seven-month sampling period. Traditional disease modelling based on deer-to-deer transmission indicated relatively low prevalence with an R0 of 1.9 and recovery period of 7 days; however, individual-based modelling informed by GPS tracked-movement data captured a potential transmission event. Phylogenetic analyses revealed a recurring pattern of divergent groups of deer-derived sequences with human-derived sequences falling close to each deer-derived cluster. Further, human-derived sequences were frequently sampled months prior to the deer-derived sequences, indicating repeated human to deer spillover. Using multiple types of data as well as both fine and broad scale analyses, we have characterized a pattern of localized outbreaks of SARS-CoV-2 within white-tailed deer populations that are likely recurring due to frequent spillover events. Our results suggest that while deer-to-deer transmission occurs over small spatiotemporal scales, SARS-CoV-2 persistence over longer periods and across larger regions is likely driven by repeated spillover from human populations.