scholarly journals Coevolution of group-living and aposematism in caterpillars: warning colouration may facilitate the evolution from group-living to solitary habits

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Lingzi Wang ◽  
Stephen J. Cornell ◽  
Michael P. Speed ◽  
Kevin Arbuckle
Keyword(s):  
Evolutionary Dynamics ◽  
Strong Support ◽  
Chemical Defence ◽  
Group Living ◽  
Warning Signal ◽  
Comparative Approach ◽  
Transition Rates ◽  
Aggregation Behaviour ◽  
Solitary Living ◽  
Antipredator Mechanisms

Abstract Background Animals use diverse antipredator mechanisms, including visual signalling of aversive chemical defence (aposematism). However, the initial evolution of aposematism poses the problem that the first aposematic individuals are conspicuous to predators who have not learned the significance of the warning colouration. In one scenario, aposematism evolves in group-living species and originally persisted due to kin selection or positive frequency-dependent selection in groups. Alternatively, group-living might evolve after aposematism because grouping can amplify the warning signal. However, our current understanding of the evolutionary dynamics of these traits is limited, leaving the relative merit of these scenarios unresolved. Results We used a phylogenetic comparative approach to estimate phenotypic evolutionary models to enable inferences regarding ancestral states and trait dynamics of grouping and aposematic colouration in a classic model system (caterpillars). We find strong support for aposematism at the root of the clade, and some (but weaker) support for ancestral solitary habits. Transition rates between aposematism and crypsis are generally higher than those between group-living and solitary-living, suggesting that colouration is more evolutionarily labile than aggregation. We also find that the transition from group-living to solitary-living states can only happen in aposematic lineage, suggesting that aposematism facilitates the evolution of solitary caterpillars, perhaps due to the additional protection offered when the benefits of grouping are lost. We also find that the high frequency of solitary, cryptic caterpillars is because this state is particularly stable, in that the transition rates moving towards this state are substantially higher than those moving away from it, favouring its accumulation in the clade over evolutionary time. Conclusions Our results provide new insights into the coevolution of colour and aggregation in caterpillars. We find support for an aposematic caterpillar at the root of this major clade, and for the signal augmentation hypothesis as an explanation of the evolution of aposematic, group-living caterpillars. We find that colouration is more labile than aggregation behaviour, but that the combination of solitary and cryptic habits is particularly stable. Finally, our results reveal that the transitions from group-living to solitary-living could be facilitated by aposematism, providing a new link between these well-studied traits.

scholarly journals Dynamical analysis of the global elevational diversity gradient in passerine birds reveals a prominent role for highlands as species pumps

2020 ◽  
Author(s):  
Paul van Els ◽  
Leonel Herrera-Alsina ◽  
Alex L. Pigot ◽  
Rampal Etienne
Keyword(s):  
Evolutionary Dynamics ◽  
Strong Support ◽  
High Elevation ◽  
Dynamical Analysis ◽  
Reverse Direction ◽  
Passerine Birds ◽  
Diversification Rates ◽  
Diversity Gradient ◽  
As Species ◽  
Almost All

Abstract Low elevation regions harbor the majority of the world’s species diversity compared to high elevation areas. This global elevational diversity gradient, suggests that lowland species have had more time to diversify, or that net diversification rates have been higher in the lowlands (either due to higher ecological limits or intrinsically higher diversification rates). However, highlands seem to be cradles of diversity as they contain many young endemics, suggesting that their rates of speciation are exceptionally fast. Here, we use a phylogenetic diversification model that accounts for the dispersal of species between different elevations to examine the evolutionary dynamics of the elevational diversity gradient in passerine birds, a group that has radiated globally to occupy almost all elevations and latitudes. We find strong support for a model where passerines diversify at the same rate in the highlands and the lowlands but where the rate of dispersal from high to low elevations is more than twice as fast as in the reverse direction. This suggests that while there is no consistent trend in diversification across elevations, highland regions act as species pumps because the diversity they generate migrates into the lowlands, thus setting up the observed gradient in passerine diversity. This species pump is particularly strong in the tropics, where the inferred rate of speciation is 1.4 times faster than in the temperate zone. We conclude that despite their lower diversity, highland regions are disproportionally important for maintaining diversity in the adjacent lowlands. The extinction of species in the tropical highlands due to rapid climate change this century could thus have major and long-lasting impacts on global passerine diversity.

scholarly journals Solitary bees reduce investment in communication compared with their social relatives

2017 ◽  
Vol 114 (25) ◽  
pp. 6569-6574 ◽  
Author(s):  
Bernadette Wittwer ◽  
Abraham Hefetz ◽  
Tovit Simon ◽  
Li E. K. Murphy ◽  
Mark A. Elgar ◽  
...  
Keyword(s):  
Social Behavior ◽  
Communication Systems ◽  
Group Membership ◽  
Group Living ◽  
Signal Perception ◽  
Eusocial Insects ◽  
Social Species ◽  
Solitary Living ◽  
Social Animals ◽  
Signal Production

Social animals must communicate to define group membership and coordinate social organization. For social insects, communication is predominantly mediated through chemical signals, and as social complexity increases, so does the requirement for a greater diversity of signals. This relationship is particularly true for advanced eusocial insects, including ants, bees, and wasps, whose chemical communication systems have been well-characterized. However, we know surprisingly little about how these communication systems evolve during the transition between solitary and group living. Here, we demonstrate that the sensory systems associated with signal perception are evolutionarily labile. In particular, we show that differences in signal production and perception are tightly associated with changes in social behavior in halictid bees. Our results suggest that social species require a greater investment in communication than their solitary counterparts and that species that have reverted from eusociality to solitary living have repeatedly reduced investment in these potentially costly sensory perception systems.

scholarly journals Stronger net selection on males across animals

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Lennart Winkler ◽  
Maria Moiron ◽  
Edward H Morrow ◽  
Tim Janicke
Keyword(s):  
Sex Differences ◽  
Sexual Selection ◽  
Natural Selection ◽  
Environmental Change ◽  
Evolutionary Dynamics ◽  
Comparative Approach ◽  
Sex Bias ◽  
Adaptive Potential ◽  
Stressful Environment ◽  
Preliminary Support

Sexual selection is considered the major driver for the evolution of sex differences. However, the eco-evolutionary dynamics of sexual selection and their role for a population’s adaptive potential to respond to environmental change have only recently been explored. Theory predicts that sexual selection promotes adaptation at a low demographic cost only if sexual selection is aligned with natural selection and if net selection is stronger on males compared to females. We used a comparative approach to show that net selection is indeed stronger in males and provide preliminary support that this sex bias is associated with sexual selection. Given that both sexes share the vast majority of their genes, our findings corroborate the notion that the genome is often confronted with a more stressful environment when expressed in males. Collectively, our study supports one of the long-standing key assumptions required for sexual selection to bolster adaptation, and sexual selection may therefore enable some species to track environmental change more efficiently.

scholarly journals Solitary Living Brings a Decreased Weight and an Increased Agility to the Domestic Silkworm, Bombyx mori

Insects ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 809
Author(s):  
Zhenglin Zhu ◽  
Yuting Tan ◽  
Siyu Xiao ◽  
Zhufen Guan ◽  
Wen Zhao ◽  
...  
Keyword(s):  
Bombyx Mori ◽  
Group Living ◽  
Modern Society ◽  
Comprehensive Investigation ◽  
Solitary Living ◽  
Microrna Sequencing ◽  
The Difference ◽  
Pathway Analyses ◽  
Differently Expressed Genes ◽  
Silkworm Bombyx Mori

The domestic silkworms, Bombyx mori, always live in groups and little is known of the outcomes of solitary living. We bred solitary silkworms and performed a comprehensive investigation of the difference between solitary and group-living silkworms. The results show that solitary silkworms had significantly lower weights than group-living counterparts. Moreover, solitary silkworms had faster movements under food luring or heat stress than the group-living ones, supported by extensive behavior experiments. These findings inferred that an increased agility resulted from solitary living. For an understanding of the molecular mechanism associated with solitary living, we performed integrated mRNA and miRNA (microRNA) sequencing of tissues for solitary and group-living silkworms. We identified 165 differently expressed genes (DEGs) and 6 differently expressed miRNAs between the solitary and group-living silkworms. Functional and pathway analyses indicated that these DEGs are associated with weight loss and agility increase. These findings compose a sketch depicting an association between the phenotypes and genes resulted from solitary living and refresh the understanding of solitary living and loneliness, which has an increased prevalence in our modern society.

scholarly journals Switching spatial scale reveals dominance-dependent social foraging tactics in a wild primate

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3462 ◽  
Author(s):  
Alexander E.G. Lee ◽  
Guy Cowlishaw
Keyword(s):  
Evolutionary Dynamics ◽  
Spatial Scales ◽  
Social Rank ◽  
Group Living ◽  
Social Foraging ◽  
Potential Cost ◽  
Papio Ursinus ◽  
Theoretical Predictions ◽  
Lower Ranking ◽  
Foraging Tactics

When foraging in a social group, individuals are faced with the choice of sampling their environment directly or exploiting the discoveries of others. The evolutionary dynamics of this trade-off have been explored mathematically through the producer-scrounger game, which has highlighted socially exploitative behaviours as a major potential cost of group living. However, our understanding of the tight interplay that can exist between social dominance and scrounging behaviour is limited. To date, only two theoretical studies have explored this relationship systematically, demonstrating that because scrounging requires joining a competitor at a resource, it should become exclusive to high-ranking individuals when resources are monopolisable. In this study, we explore the predictions of this model through observations of the natural social foraging behaviour of a wild population of chacma baboons (Papio ursinus). We collected data through over 800 h of focal follows of 101 adults and juveniles across two troops over two 3-month periods. By recording over 7,900 social foraging decisions at two spatial scales we show that, when resources are large and economically indefensible, the joining behaviour required for scrounging can occur across all social ranks. When, in contrast, dominant individuals can aggressively appropriate a resource, such joining behaviour becomes increasingly difficult to employ with decreasing social rank because adult individuals can only join others lower ranking than themselves. Our study supports theoretical predictions and highlights potentially important individual constraints on the ability of individuals of low social rank to use social information, driven by competition with dominant conspecifics over monopolisable resources.

scholarly journals The Evolutionary Dynamics of Negative Existentials in Indo-European

2021 ◽  
Vol 6 ◽  
Author(s):  
Shahar Shirtz ◽  
Luigi Talamo ◽  
Annemarie Verkerk
Keyword(s):  
Evolutionary Dynamics ◽  
Skewed Distribution ◽  
Phylogenetic Comparative Methods ◽  
Transition Rates ◽  
Evolutionary Models ◽  
Posterior Distributions ◽  
European Languages ◽  
Family Based ◽  
Negative Existentials ◽  
Phylogenetic Modeling

Where in earlier work diachronic change is used to explain away exceptions to typologies, linguistic typologists have started to make use of explicit diachronic models as explanations for typological distributions. A topic that lends itself for this approach especially well is that of negation. In this article, we assess the explanatory value of a specific hypothesis, the Negative Existential Cycle (NEC), on the distribution of negative existential strategies (“types”) in 106 Indo-European languages. We use Bayesian phylogenetic comparative methods to infer posterior distributions of transition rates and parameters, thus applying rational methods to construct and evaluate a set of different models under which the attested typological distribution could have evolved. We find that the frequency of diachronic processes that affect negative existentials outside of the NEC cannot be ignored—the unidirectional NEC alone cannot explain the evolution of negative existential strategies in our sample. We show that non-unidirectional evolutionary models, especially those that allow for different and multiple transitions between strategies, provide better fit. In addition, the phylogenetic modeling is impacted by the expected skewed distribution of negative existential strategies in our sample, pointing out the need for densely sampled and family-based typological research.

scholarly journals Avian predators taste–reject aposematic prey on the basis of their chemical defence

2006 ◽  
Vol 2 (3) ◽  
pp. 348-350 ◽  
Author(s):  
John Skelhorn ◽  
Candy Rowe
Keyword(s):  
Chemical Defence ◽  
Warning Signal ◽  
Selective Advantage ◽  
Evolutionary Stability ◽  
Theoretical Problem ◽  
Chemical Production ◽  
Warning Coloration ◽  
Avian Predators ◽  
Unpalatable Prey ◽  
Evolutionarily Stable

Avian predators learn to avoid defended insects on the basis of their conspicuous warning coloration. In many aposematic species, the level of chemical defence varies, with some individuals being more defended than others. Sequestration and production of defence chemicals is often costly and therefore less defended individuals enjoy the benefits of the warning signal without paying the full costs of chemical production. This is a fundamental theoretical problem for the evolutionary stability of aposematism, since less defended individuals appear to be at a selective advantage. However, if predators sample aposematic prey and selectively reject individuals on the basis of their chemical investment, aposematism could become evolutionarily stable. Previous research aimed at testing whether birds can use taste to discriminate between palatable and unpalatable prey has been confounded by other experimental factors. Here, we show that birds can taste and reject prey entirely on the basis of an individual's level of chemical defence and more importantly, they can make decisions on whether or not to consume a defended individual based upon their level of chemical investment. We discuss these results in relation to the evolution of aposematism, mimicry and defence chemistry.

scholarly journals Coevolution of Snake Venom Toxic Activities and Diet: Evidence that Ecological Generalism Favours Toxicological Diversity

Toxins ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 711 ◽  
Author(s):  
Emma-Louise Davies ◽  
Kevin Arbuckle
Keyword(s):  
Snake Venom ◽  
Strong Support ◽  
Global Scale ◽  
Comparative Approach ◽  
General Effect ◽  
Functional Link ◽  
Selection Pressures ◽  
Functional Activities ◽  
Toxicological Effects ◽  
Toxicological Activity

Snake venom evolution is typically considered to be predominantly driven by diet-related selection pressures. Most evidence for this is based on lethality to prey and non-prey species and on the identification of prey specific toxins. Since the broad toxicological activities (e.g., neurotoxicity, coagulotoxicity, etc.) sit at the interface between molecular toxinology and lethality, these classes of activity may act as a key mediator in coevolutionary interactions between snakes and their prey. Indeed, some recent work has suggested that variation in these functional activities may be related to diet as well, but previous studies have been limited in geographic and/or taxonomic scope. In this paper, we take a phylogenetic comparative approach to investigate relationships between diet and toxicological activity classes on a global scale across caenophidian snakes, using the clinically oriented database at toxinology.com. We generally find little support for specific prey types selecting for particular toxicological effects except that reptile-feeders are more likely to be neurotoxic. We find some support for endothermic prey (with higher metabolic rates) influencing toxic activities, but differently from previous suggestions in the literature. More broadly, we find strong support for a general effect of increased diversity of prey on the diversity of toxicological effects of snake venom. Hence, we provide evidence that selection pressures on the toxicological activities of snake venom has largely been driven by prey diversity rather than specific types of prey. These results complement and extend previous work to suggest that specific matching of venom characteristics to prey may occur at the molecular level and translate into venom lethality, but the functional link between those two is not constrained to a particular toxicological route.

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