skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Defensive structures influence fighting outcomes
Abstract In many animal species, individuals engage in fights with conspecifics over access to limited resources (e.g. mates, food, or shelter). Most theory about these intraspecific fights assumes that damage has an important role in determining the contest winner. Thus, defensive structures that reduce the amount of damage an individual accrues during intraspecific competition should provide a fighting advantage.Examples of such damage‐reducing structures include the dermal shields of goats, the dorsal osteoderms of crocodiles, and the armoured telsons of mantis shrimps. Although numerous studies have identified these defensive structures, no study has investigated whether they influence the outcomes of intraspecific fights.Here we investigated whether inhibiting damage by enhancing an individual's armour influenced fighting behaviour and success in the giant mesquite bug,Thasus neocalifornicus(Insecta: Hemiptera: Coreidae).We found that experimentally manipulated individuals (i.e. those provided with additional armour) were 1.6 times more likely to win a fight when compared to the control. These results demonstrate that damage, and damage‐reducing structures, can influence fighting success.The implications of these results are twofold. First, our results experimentally support a fundamental assumption of most theoretical fighting models: that damage is a fighting cost that can influence contest outcomes. Second, these results highlight the importance of an individual's defensive capacity, and why defence should not be ignored. A freePlain Language Summarycan be found within the Supporting Information of this article.  more » « less
Award ID(s):
1907051
PAR ID:
10443021
Author(s) / Creator(s):
 ;  ;
Publisher / Repository:
Wiley-Blackwell
Date Published:
Journal Name:
Functional Ecology
Volume:
35
Issue:
3
ISSN:
0269-8463
Page Range / eLocation ID:
p. 696-704
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; (, Behavioral Ecology)
    Briffa, Mark (Ed.)
    Abstract When individuals engage in fights with conspecifics over access to resources, injuries can occur. Most theoretical models suggest that the costs associated with these injuries should influence an individual’s decision to retreat from a fight. Thus, damage from intraspecific combat is frequently noted and quantified. However, the fitness-related costs associated with this damage are not. Quantifying the cost of fighting-related damage is important because most theoretical models assume that it is the cost associated with the damage (not the damage itself) that should influence an individual’s decision to retreat. Here, we quantified the cost of fighting-related injuries in the giant mesquite bug, Thasus neocalifornicus. We demonstrate that experimentally simulated fighting injuries result in metabolic costs and costs to flight performance. We also show that flight costs are more severe when the injuries are larger. Overall, our results provide empirical support for the fundamental assumption that damage acquired during intraspecific combat is costly. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al (, Functional Ecology)
    Abstract Plant traits are useful proxies of plant strategies and can influence community and ecosystem responses to climate extremes, such as severe drought. Few studies, however, have investigated both the immediate and lagged effects of drought on community‐weighted mean (CWM) plant traits, with even less research on the relative roles of interspecific vs. intraspecific trait variability in such responses.We experimentally reduced growing season precipitation by 66% in two cold‐semi‐arid grassland sites in northern China for four consecutive years to explore the drought resistance of CWM traits as well as their recovery 2 years following the drought. In addition, we isolated the effects of both interspecific and intraspecific trait variability on shifts in CWM traits.At both sites, we observed significant effects of drought on interspecific and intraspecific trait variability which, in some cases, led to significant changes in CWM traits. For example, drought led to reduced CWM plant height and leaf phosphorous content, but increased leaf carbon content at both sites, with responses primarily due to intraspecific trait shifts. Surprisingly, these CWM traits recovered completely 2 years after the extreme drought. Intraspecific trait variability influenced CWM traits via both positive and negative covariation with interspecific trait variability during drought and recovery phases.These findings highlight the important role of interspecific and intraspecific trait variability in driving the response and recovery of CWM traits following extreme, prolonged drought. Read the freePlain Language Summaryfor this article on the Journal blog. 
    more » « less
  3. ; ; ; ; ; ; ; ; ; ; et al (, Functional Ecology)
    Abstract Soil nutrients and water availability are strong drivers of tropical tree species distribution across scales. However, the physiological mechanisms underlying environmental filtering along these gradients remain incompletely understood. Previous studies mostly focused on univariate variation in structural traits, but a more integrative approach combining multiple physiological traits is needed to fully portray species functional strategies.We measured nine leaf functional traits related to trees' resource capture and hydraulic strategies for 552 individuals belonging to 21 tropical tree species across an environmental gradient in Amazonian forests. Our sampling included generalist and specialist species fromterra firme(TF) and seasonally flooded (SF) forests. We tested the influence of the topographic wetness index, a proxy for soil moisture and nutrient gradients, on each trait separately and on the trait integration through multivariate indices computed from the eigenvalues of a principal component analysis on the traits of the species. Finally, we evaluated intraspecific trait variability (ITV) for generalists and specialists by calculating the coefficient of variation for each trait.Results showed that (1) the environment had a greater influence on trait syndromes than single trait variation. Moreover, (2) SF specialist species expressed a stronger leaf trait coordination than TF specialist species. Furthermore, (3) the ability of generalist species to occupy a broader range of environments was not reflected by a larger ITV than specialist species but by the capacity to change trait coordination across environments.Our work highlights the need to investigate functional strategies as multidimensional syndromes in physiological trait space to fully understand and predict species distribution along environmental gradients. Read the freePlain Language Summaryfor this article on the Journal blog. 
    more » « less
  4. ; ; ; ; ; ; (, Functional Ecology)
    Abstract The ability to cope with heat is likely to influence species success amidst climate change. However, heat coping mechanisms are poorly understood in wild endotherms, which are increasingly pushed to their thermoregulatory limits.We take an organismal approach to this problem, unveiling how behavioural and physiological responses may allow success in the face of sublethal heat. We experimentally elevated nest temperatures for 4 h to mimic a future climate scenario (+4.5°C) during a critical period of post‐natal development in tree swallows (Tachycineta bicolor).Heat‐exposed nestlings exhibited marked changes in behaviour, including movement to cooler microclimates in the nest. They panted more and weighed less than controls at the end of the four‐hour heat challenge, suggesting panting‐induced water loss. Physiologically, heat induced high levels of heat shock protein (HSP) gene expression in the blood, alongside widespread transcriptional differences related to antioxidant defences, inflammation and apoptosis.Critically, all nestlings survived the heat challenge, and those exposed to milder heat weremorelikely to recruit into the breeding population. Early life but sub‐lethal heat may therefore act as a selective event, with the potential to shape population trajectories.Within the population, individuals varied in their physiological response to heat, namely in HSP gene expression, which exhibited higher mean and higher variance in heat‐exposed nestlings than in controls. Heat‐induced HSP levels were unrelated to individual body mass, or among‐nest differences in brood size, temperature, and behavioural thermoregulation. Nest identity explained a significant amount of HSP variation, yet siblings in the same nest differed by an average of ~4‐fold and individuals in the population differed by as much as ~100‐fold in their HSP response. This massive variation extends previous laboratory work in model organisms showing that heat shock proteins may harbour cryptic phenotypic variation.These results shed light on oft‐ignored elements of thermotolerance in wild birds at a critical stage of post‐natal development. By highlighting the scope of heat‐induced HSP gene expression and coupling it with a suite of organismal traits, we provide a framework for future testing of the mechanisms that shape species success in the face of change. Read the freePlain Language Summaryfor this article on the Journal blog. 
    more » « less
  5. (, Functional Ecology)
    Abstract Plant functional strategies change considerably as plants develop, driven by intraindividual variability in anatomical, morphological, physiological and architectural traits.Developmental trait variation arises through the complex interplay among genetically regulated phase change (i.e. ontogeny), increases in plant age and size, and phenotypic plasticity to changing environmental conditions. Although spatial drivers of intraspecific trait variation have received extensive research attention, developmentally driven intraspecific trait variation is largely overlooked, despite widespread occurrence.Ontogenetic trait variation is genetically regulated, leads to dramatic changes in plant phenotypes and evolves in response to predictable changes in environmental conditions as plants develop.Evidence has accumulated to support a general shift from fast to slow relative growth rates and from shade to sun leaves as plants develop from the highly competitive but shady juvenile niche to the stressful adult niche in the systems studied to date.Nonetheless, there are major gaps in our knowledge due to examination of only a few environmental factors selecting for the evolution of ontogenetic trajectories, variability in how ontogeny is assigned, biogeographic sampling biases on trees in temperate biomes, dependencies on a few broadly sampled leaf morphological traits and a lack of longitudinal studies that track ontogeny within individuals. Filling these gaps will enhance our understanding of plant functional ecology and provide a framework for predicting the effects of global change threats that target specific ontogenetic stages. Read the freePlain Language Summaryfor this article on the Journal blog. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email