The evolution of crypsis when pigmentation is physiologically costly

Comments from Mar Comas, the Associate Editor, two anonymous referees and Sami Merilaita have helped to greatly improve the manuscript.The evolution of crypsis when pigmentation is physiologically costly. Predation is one of the main selective forces in nature, frequently selecting for crypsis in prey. Visual crypsis usually implies the deposition of pigments in the integument. However, acquisition, synthesis, mobilisation and maintenance of pigments may be physiologically costly. Here, I develop an optimisation model to analyse how pigmentation costs may affect the evolution of crypsis. The model provides a number of predictions that are easy to test empirically. It predicts that imperfect crypsis should be common in the wild, but in such a way that pigmentation is less than what is required to maximise crypsis. Moreover, optimal crypsis should be closer to “maximal” crypsis as predation risk increases and/or pigmentation costs decrease. The model predicts for intraspecific variation in optimal crypsis, depending on the difference in the predation risk or the costs of pigmentation experienced by different individuals.La evolución de la cripsis cuando la pigmentación es fisiológicamente costosa. La depredación es una de las principales fuerzas de selección de la naturaleza y a menudo favorece la cripsis en las presas. Por lo general, la cripsis visual implica el depósito de pigmentos en el tegumento. Sin embargo, adquirir, sintetizar, movilizar y mantener los pigmentos puede ser fisiológicamente costoso. En este estudio he elaborado un modelo de optimización para analizar cómo pueden afectar los costes de la pigmentación a la evolución de la cripsis. El modelo proporciona una serie de predicciones que son fáciles de probar empíricamente. Predice que la cripsis imperfecta debería ser común en la naturaleza, pero de manera que la pigmentación fuera inferior a la necesaria para que la cripsis sea máxima. Además, la cripsis óptima debería estar más cerca de la cripsis “máxima” a medida que aumenta el riesgo de depredación o disminuye el coste de la pigmentación. El modelo también predice la existencia de variación intraespecífica en la cripsis óptima, que depende de la diferencia en el riesgo de depredación o de los costes de la pigmentación que soportan los diferentes individuos

Benefits of Extra Begging Fail to Compensate for Immunological Costs in Southern Shrike (Lanius meridionalis) Nestlings

Theoretical models aimed at explaining the evolution of honest, informative begging signals employed by nestling birds to solicit food from their parents, require that dishonest signalers incur a net viability cost in order to prevent runaway escalation of signal intensity over evolutionary time. Previous attempts to determine such a cost empirically have identified two candidate physiological costs associated with exaggerated begging: a growth and an immunological cost. However, they failed to take into account the fact that those costs are potentially offset by the fact that nestlings that invest more in begging are also likely to obtain more food. In this study, we test experimentally whether a 25% increase in ingested food compensates for growth and immunological costs of extra begging in southern shrike (Lanius meridionalis) nestlings. Three nestmates matched by size were given three treatments: low begging, high begging-same food intake, and high begging-extra food intake. We found that, while a higher food intake did effectively compensate for the growth cost, it failed to compensate for the immunological cost, measured as T-cell mediated immune response against an innocuous mitogen. Thus, we show for the first time that escalated begging has an associated physiological net cost likely to affect nestling survival negatively.G.M.-R. was supported by the Spanish Government (Ministerio de Ciencia y Tecnología, “Juan de la Cierva” program), and T.R. was supported by the Consejo Superior de Investigaciones Científicas (CSIC; Proyectos Intramurales Especiales, ref. 201030E079). The study was economically supported by the Spanish government (Ministerio de Ciencia e Innovación; project CGL2011-29694)

Mirlo acuático – Cinclus cinclus (Linnaeus, 1758)

Aves - Orden Passeriformes - Familia Cinclidae en la Enciclopedia Virtual de Vertebrados Españoles, http://www.vertebradosibericos.org/. Versiones anteriores: 12-03-2009; 25-02-2011A comprehensive review of the natural history of the White-breasted Dipper Cinclus cinclus in Spain.Peer reviewe

La richesse spécifique des rongeurs et celle des carnivores sont corrélées en Espagne

The diversity of ecological niches favours species coexistence, increasing species richness. Therefore, carnivore species richness should increase with prey species richness, as this represents more trophic niches for carnivores. We evaluated this hypothesis with data from peninsular Spain, by using General Linear Models. We controlled for five alternative explanations for such a relationship: climate, human activity, spatial autocorrelation, habitat heterogeneity, and spurious chance, which might prompt a positive correlation between carnivore and rodent species richness (its main prey). Results show that rodent species richness was positively correlated with carnivore species richness (r = 0.62). The correlation between carnivore species richness and rodent species richness was not caused by climate, human activity, spatial autocorrelation or habitat heterogeneity. Together, these factors explained 13.6 % of variation in carnivore species richness, while rodent species richness alone explained 26.2 % of variation (50.4 % of explained variance). Moreover, carnivore species richness was more correlated with rodent species richness than with 28 other vertebrate taxa, with a probability of 0.034 of this being by chance. In conclusion, this study presents evidence that higher prey species richness may promote higher carnivore species richness. The conservation of prey diversity, thus, may contribute to the conservation of carnivoresLa diversité des niches écologiques favorise la coexistence des espèces, accroissant la richesse spécifique. La richesse spécifique des carnivores devrait donc croître avec celle de leurs proies, en raison des niches trophiques ainsi ouvertes. Cette hypothèse a été évaluée à l'aide de modèles linéaires généralisés utilisant des données de l'Espagne péninsulaire. Cinq facteurs susceptibles de générer une corrélation positive entre la richesse spécifique des carnivores et celle de leurs principales proies, les rongeurs, ont été contrôlés: le climat, l'activité humaine, l'autocorrélation spatiale, l'hétérogénéité de l'habitat et les effets du hasard. Les résultats montrent que la richesse spécifique des rongeurs et celle des carnivores sont positivement corrélées (r 0,62) et que cette corrélation n'est due ni au climat, ni à l'activité humaine, ni à l'autocorrélation spatiale, ni à l'hétérogénéité de l'habitat. Ensemble, ces facteurs n'expliquent que 13,6 % de la variation de la richesse spécifique des carnivores alors que les rongeurs en expliquent 26,2 % (soit 50,4 % de la variance expliquée). De plus, la richesse spécifique des carnivores s'avère plus corrélée à celle des rongeurs qu'à celle de 28 autres taxons de vertébrés, la probabilité que ce soit le produit du hasard n'étant que de 0,034. En conclusion, cette étude met en évidence qu'une plus forte richesse spécifique des proies engendrerait une plus forte richesse spécifique des carnivores. La conservation de la densité des proies contribuerait ainsi à celle des carnivores

The son-killer microbe Arsenophonus nasoniae is a widespread associate of the parasitic wasp Nasonia vitripennis in Europe

Heritable microbes that exhibit reproductive parasitism are common in insects. One class of these are the malekilling bacteria, which are found in a broad range of insect hosts. Commonly, our knowledge of the incidence of these microbes is based on one or a few sampling sites, and the degree and causes of spatial variation are unclear. In this paper, we examine the incidence of the son-killer microbe Arsenophonus nasoniae across European populations of its wasp host, Nasonia vitripennis. In preliminary work, we noticed two female N. vitripennis producing highly female biased sex ratios in a field study from the Netherlands and Germany. When tested, the brood from Germany was revealed to be infected with A. nasoniae. We then completed a broad survey in 2012, in which fly pupal hosts of N. vitripennis were collected from vacated birds’ nests from four European populations, N. vitripennis wasps allowed to emerge and then tested for A. nasoniae presence through PCR assay. We then developed a new screening methodology based on direct PCR assays of fly pupae and applied this to ethanolpreserved material collected from great tit (Parus major) nests in Portugal. These data show A. nasoniae is found widely in European N. vitripennis, being present in Germany, the UK, Finland, Switzerland and Portugal. Samples varied in the frequency with which they carry A. nasoniae, from being rare to being present in 50% of the pupae parasitised by N. vitripennis. Direct screening of ethanol-preserved fly pupae was an effective method for revealing both wasp and A. nasoniae infection, and will facilitate sample transport across national boundaries. Future research should examine the causes of variation in frequency, in particular testing the hypothesis that N. vitripennis superparasitism rates drive the variation in A. nasoniae frequency through providing opportunities for infectious transmission.The NERC (NE/I01067X/1)BBSRC (BB/S017534/1)Grants lzp-2021/1-02772022/1-0348 from the Latvian Council of Science to IKGrant from Academy of Finland (338180)Grants from the Fundaçao para a Ciencia e a Tecnologia to ACN (UIDB/04292/2020; UIDP/04292/2020LA/P/0069/2020; DL57/2016/CP1370/CT89)Grants from AUIP and Spanish Ministry of Education (FPU18/03034

La richesse spécifique des vertébrés varie selon l’assemblage des espèces dans le sud-est de l’Espagne : implications pour la conservation

Species richness in an area is the result of environmental factors (e.g. primary productivity or habitat heterogeneity), historical factors (colonization, extinction, and human influences), and species interactions within the species assemblage. However, the relative importance of species assemblage, in respect to other factors, on species richness has rarely been analysed. This study analyses the relative importance of environment and species assemblage on vertebrate species richness in south-eastern Spain. The results show that 37 % of the variance in species richness was explained by the correlation between species assemblage and environmental-spatial variables. Species richness increased with habitat heterogeneity (habitat diversity and altitude range), but this effect was independent of species assemblage. Species richness differed among species assemblages in the study area, independently of the effect of environmental and spatial variables. Therefore, the findings suggest that species richness is also influenced by species composition per se, regardless of the influence of other variables. These findings imply that the use of species richness in indices for prioritizing conservation zones may bias conservation priorities towards species assemblages having more species richness. This problem, however, is solved when complementarity algorithms are used to prioritize conservation zonesDans une zone donnée, la richesse spécifique résulte de facteurs environnementaux (e.g. la productivité primaire ou l'hétérogénéité de l'habitat), de facteurs historiques (colonisation, extinction, et influences humaines) et des interactions entre espèces au sein de l'assemblage de ces dernières. Toutefois, par rapport aux autres facteurs, l'importance relative de l'assemblage des espèces pour la richesse spécifique a été rarement analysée. La présente étude analyse l'importance relative de l'environnement et de l'assemblage des espèces pour la richesse spécifique des vertébrés dans le sud-est de l'Espagne. Les résultats montrent que 37 % de la variance de la richesse spécifique sont expliqués par la corrélation entre l'assemblage des espèces et les variables spatiales et environnementales. La richesse spécifique augmente avec l'hétérogénéité de l'habitat (diversité de l'habitat et étages altitudinaux) mais cet effet est indépendant de l'assemblage des espèces. La richesse spécifique diffère entre les assemblages d'espèces de la zone d'étude, indépendamment de l'effet des variables environnementales et spatiales. Les résultats suggèrent donc que la richesse spécifique est également influencée par la composition spécifique per se, quelle que soit l'influence des autres variables. Ils impliquent que l'emploi de la richesse spécifique pour des indices de priorité de zones de conservation peut biaiser les priorités en faveur des assemblages d'espèces ayant les plus fortes richesses spécifiques. Ce problème peut néanmoins être résolu quand des algorithmes de complémentarité sont utilisés pour établir les priorités des zones à conserver

Habitat-dependent breeding biology of the Blue Tit (Cyanistes caeruleus) across a continuous and heterogeneous Mediterranean woodland

This study was funded by two projects in the National Plan of the Spanish Ministry of Economy and Competition (CGL2014-55969-P and CGL2017-84938-P) and a project of the Andalusian Regional Government (A-RNM-48-UGR20), financed with ERDF funds from the European Union (EU). JGB was supported by a FPU pre-doctoral contract from the Spanish Ministry of Education (FPU18/03034) and MC by a grant from the Spanish Ministry of Economy and Competition through the Severo & nbsp;Ochoa Programme for Centres of Excellence in Research, Development and Innovation (R+D+I) (SEV-2012-0262), contract No. SVP-2014-068620. JLRS and EP were funded by Erasmus+ grants from the EU.Mediterranean woodland environments are characterised by high spatial and temporal heterogeneity, which means the inhabiting species face a wide variety of selective pressures. Species may respond differently to habitat heterogeneity and so distinct eco-evolutionary scenarios may be responsible for the inter-habitat variability in reproductive strategies observed in certain species. The inter-forest variability of some reproductive traits in passerines has been examined by comparing forest patches or separated fragments. However, there is still little information regarding how such highly mobile animals adjust their breeding performance across continuous and heterogeneous woodlands. Here we studied the reproductive performance of a population of Blue Tits (Cyanistes caeruleus) in an area of continuous Mediterranean woodland that included two mountain slopes and four different types of forest, ranging from deciduous oak forests to perennial non-oak forests. We studied the habitat hetero-geneity and inter-forest phenotypic variation in terms of reproductive performance and adult and nestling biometry, besides also exploring the effects of ectoparasites on Blue Tit reproduction. Eggs were laid earliest in deciduous Pyrenean Oak (Quercus pyrenaica) forests, while clutch size and the number of fledglings were highest in the humid Pyrenean Oak forest, which had the greatest tree coverage and most humid climate, and lowest in the coniferous Scots Pine (Pinus sylvestris) forest. There were no inter-forest differences in hatching (percentage of nests with at least one egg hatched) and fledging (percentage of nests in which at least one nestling fledged) success. Similarly, there were no inter-forest differences in adult and nestling biometry, but adults that raised more fledglings had a lower body mass, while males whose females laid larger clutches had smaller tarsi. Most ectoparasites did not affect Blue Tit reproduction, although Culicoides had a negative impact on nestling body mass. These results suggest that Blue Tits can adjust their reproductive effort to the forest where they breed even across a very small spatial scale. Different eco-evolutionary scenarios, such as phenotypic plasticity or genetic structuring and local adaptation, might explain the phenotypic differentiation in the reproductive strategies observed over small areas in woodlands.National Plan of the Spanish Ministry of Economy and Competition CGL2014-55969-P, CGL2017-84938-PAndalusian Regional Government A-RNM-48-UGR20ERDF funds from the European Union (EU)German Research Foundation (DFG) FPU18/03034Spanish Ministry of Economy and Competition through the Severo~Ochoa Programme for Centres of Excellence in Research, Development and Innovation (R+D+I) SEV-2012-0262, SVP-2014-068620Erasmus+ grants from the E

Age structure of a lizard along an elevational gradient reveals nonlinear lifespan patterns with altitude

We thank the personnel from the Espacio Natural de Sierra Nevada for their constant support. We are also grateful to Concepción Herna´ndez, from the Centre of Scientific Instrumentation at the University of Granada, for her help with the freezing microtome. We are also in debt to Humbert Salvadó (University of Barcelona) for allowing us to use the microscope. Comments from 3 anonymous referees greatly improved the manuscript.Lifespan is one of the main components of life history. Shorter lifespans can be expected in marginal habitats. However, in the case of ectotherms, lifespan typically increases with altitude, even though temperature—one of the main factors to determine ectotherms’ life history—declines with elevation. This pattern can be explained by the fact that a shorter activity time favors survival. In this study, we analyzed how lifespan and other life-history traits of the lizard Psammodromus algirus vary along a 2,200m elevational gradient in Sierra Nevada (SE Spain). Populations at intermediate altitudes (1,200–1,700 m), corresponding to the optimal habitat for this species, had the shortest lifespans, whereas populations inhabiting marginal habitats (at both low and at high altitudes) lived longest. Therefore, this lizard did not follow the typical pattern of ectotherms, as it also lived longer at the lower limit of its distribution, nor did it show a longer lifespan in areas with optimal habitats. These results might be explained by a complex combination of different gradients along the mountain, namely that activity time decreases with altitude whereas food availability increases. This could explain why lifespan was maximum at both high (limited activity time) and low (limited food availability) altitudes, resulting in similar lifespans in areas with contrasting environmental conditions. Our findings also indicated that reproductive investment and body condition increase with elevation, suggesting that alpine populations are locally adapted.Junta de AndalucíaParque Nacional de Sierra Nevada (referencias GMN / GyB / JMIF y ENSN / JSG / JEGT / MCF