Abstract Genetic color polymorphism is widespread in nature. There is an increasing interest in u... more Abstract Genetic color polymorphism is widespread in nature. There is an increasing interest in understanding the adaptive value of heritable color variation and tradeoff resolution by differently colored individuals. Melaninbased pigmentation is often associated with variation in many different life history traits. These associations have recently been suggested to be the outcome of pleiotropic effects of the melanocortin system. Although pharmacological research supports that MC1R, a gene with a major role in vertebrate pigmentation, has important immunomodulatory effects, evidence regarding pleiotropy at MC1R in natural populations is still under debate. We experimentally assessed whether MC1R-based pigmentation covaries with both inflammatory and humoral immune responses in the color polymorphic Eleonora’s falcon. By means of a cross-fostering experiment, we disentangled potential genetic effects from environmental effects on the covariation between coloration and immunity. Variation in both immune responses was primarily due to genetic factors via the nestlings’ MC1R-related color genotype/phenotype, although environmental effects via the color morph of the foster father also had an influence. Overall, dark nestlings had lower immune responses than pale ones. The effect of the color morph of the foster father was also high, but in the opposite direction, and nestlings raised by dark eumelanic foster fathers had higher immune responses than those raised by pale foster fathers. Although we cannot completely discard alternative explanations, our results suggest that MC1R might influence immunity in this species. Morph-specific variation in immunity as well as pathogen pressure may therefore contribute to the long-term maintenance of genetic color polymorphism in natural populations.
Background: The adaptive transition between behavioral strategies, such as the shift from migrato... more Background: The adaptive transition between behavioral strategies, such as the shift from migratoriness to sedentariness, remains an outstanding question in evolutionary ecology. Density-dependent variation in the age of first breeding has been proposed as a feasible mechanism through which long-lived migratory birds with deferred sexual maturity should become sedentary to persist on islands. Although this pattern seems to hold for most raptors and herons, a few exceptions have been identified. One of these exceptions is the Eleonora's falcon, a long-distance migratory bird, which shows one of the most peculiar adaptations in the timing of reproduction and food requirements among raptors.
Bone lead accumulation decreases the degree of bone mineralization in vultures exposed to ammunit... more Bone lead accumulation decreases the degree of bone mineralization in vultures exposed to ammunition sources. a b s t r a c t Long-lived species are particularly susceptible to bioaccumulation of lead in bone tissues. In this paper we gain insights into the sublethal effects of lead contamination on Egyptian vultures (Neophron perc-nopterus). Our approach was done on the comparison of two populations (Canary Islands and Iberian Peninsula) differing in exposures to the ingestion of lead ammunition. Blood lead levels were higher in the island population (Canary Islands range: 5.10–1780 mg L À1 n ¼ 137; Iberian Peninsula range: 5.60– 217.30 mg L À1 n ¼ 32) showing clear seasonal trends, peaking during the hunting season. Moreover, males were more susceptible to lead accumulation than females. Bone lead concentration increased with age, reflecting a bioaccumulation effect. The bone composition was significatively altered by this contaminant: the mineralization degree decreased as lead concentration levels increased. These results demonstrate the existence of long-term effects of lead poisoning, which may be of importance in the declines of threatened populations of long-lived species exposed to this contaminant.
Colour polymorphism results from the expression of multiallelic genes generating phenotypes with ... more Colour polymorphism results from the expression of multiallelic genes generating phenotypes with very distinctive colourations. Most colour polymorphisms are due to differences in the type or amount of melanins present in each morph, which also differ in several behavioural, morphometric and physiological attributes. Melanin-based colour morphs could also differ in the levels of glutathione (GSH), a key intracellular antioxidant, because of the role of this molecule in melanogenesis. As GSH inhibits the synthesis of eumelanin (i.e. the darkest melanin form), individuals of darker morphs are expected to have lower GSH levels than those of lighter morphs. We tested this prediction in nestlings of two polymorphic raptors, the booted eagle Hieraaetus pennatus and the Eleonora's falcon Falco eleonorae, both of which occur in two morphs differing in the extent of eumelanic plumage. As expected, melanic booted eagle nestlings had lower blood GSH levels than light morph eagle nestlings. In the Eleonora's falcon, however, melanic nestlings only had lower GSH levels after controlling for the levels of other antioxidants. We also found that melanic female eagle nestlings had higher levels of antioxidants other than GSH and were in better body condition than light female eagle nestlings. These findings suggest an adaptive response of melanic nestlings to compensate for reduced GSH levels. Nevertheless, these associations were not found in falcons, indicating species-specific particularities in antioxidant machinery. Our results are consistent with previous work revealing the importance of GSH on the expression of melanic characters that show continuous variation, and suggest that this pathway also applies to discrete colour morphs. We suggest that the need to maintain low GSH levels for eumelanogenesis in dark morph individuals may represent a physiological constraint that helps regulate the evolution and maintenance of polymorphisms.
Introduction of alien herbivores in sensitive island systems has resulted in massive effects on v... more Introduction of alien herbivores in sensitive island systems has resulted in massive effects on vegetation cover, floristic richness and composition of communities; some species can be even totally extirpated by grazing pressure. Goats Capra hircus and wild rabbits Oryctolagus cuniculus were introduced in the Canary Islands around 500 B.C. Barbary ground squirrels Atlantoxerus getulus were introduced in 1967. Traditional extensive livestock exploitations have been maintained to the present but in the last decades the number of goats has sharply increased up to densities of 53 heads/km 2. Overgrazing and trampling have heavily affected eleven island endemic plant species. Some populations have been reduced to less than 10 viable individuals. On the other hand, goat carcasses and wild rabbit and squirrel populations help to maintain populations of three endangered endemic subspecies of birds. This conflict presents important economic and social ramifications: whereas public funds (mainly through European LIFE projects) are devoted to conservation of plant and avian endemic taxa, the number of goats increases rapidly thanks to subventions derived from the European Common Agricultural Policy (CAP). Similar conflicts are apparent in other Mediterranean Basin insular systems. It is urgently necessary to harmonize farming and conservation objectives in the Canary Islands. The impact of goats on the vegetation should be minimized through limitation of grazing in sensitive areas with high degree of endemism. Creation of 'vulture restaurants' may reduce the dependence of scavengers on extensive livestock exploitations. We recommend a careful study of ecological relationships within island communities where non-native species are susceptible of playing a keystonrole as occurs in the Mediterranean Basin archipelagos.
Abstract Genetic color polymorphism is widespread in nature. There is an increasing interest in u... more Abstract Genetic color polymorphism is widespread in nature. There is an increasing interest in understanding the adaptive value of heritable color variation and tradeoff resolution by differently colored individuals. Melaninbased pigmentation is often associated with variation in many different life history traits. These associations have recently been suggested to be the outcome of pleiotropic effects of the melanocortin system. Although pharmacological research supports that MC1R, a gene with a major role in vertebrate pigmentation, has important immunomodulatory effects, evidence regarding pleiotropy at MC1R in natural populations is still under debate. We experimentally assessed whether MC1R-based pigmentation covaries with both inflammatory and humoral immune responses in the color polymorphic Eleonora’s falcon. By means of a cross-fostering experiment, we disentangled potential genetic effects from environmental effects on the covariation between coloration and immunity. Variation in both immune responses was primarily due to genetic factors via the nestlings’ MC1R-related color genotype/phenotype, although environmental effects via the color morph of the foster father also had an influence. Overall, dark nestlings had lower immune responses than pale ones. The effect of the color morph of the foster father was also high, but in the opposite direction, and nestlings raised by dark eumelanic foster fathers had higher immune responses than those raised by pale foster fathers. Although we cannot completely discard alternative explanations, our results suggest that MC1R might influence immunity in this species. Morph-specific variation in immunity as well as pathogen pressure may therefore contribute to the long-term maintenance of genetic color polymorphism in natural populations.
Background: The adaptive transition between behavioral strategies, such as the shift from migrato... more Background: The adaptive transition between behavioral strategies, such as the shift from migratoriness to sedentariness, remains an outstanding question in evolutionary ecology. Density-dependent variation in the age of first breeding has been proposed as a feasible mechanism through which long-lived migratory birds with deferred sexual maturity should become sedentary to persist on islands. Although this pattern seems to hold for most raptors and herons, a few exceptions have been identified. One of these exceptions is the Eleonora's falcon, a long-distance migratory bird, which shows one of the most peculiar adaptations in the timing of reproduction and food requirements among raptors.
Bone lead accumulation decreases the degree of bone mineralization in vultures exposed to ammunit... more Bone lead accumulation decreases the degree of bone mineralization in vultures exposed to ammunition sources. a b s t r a c t Long-lived species are particularly susceptible to bioaccumulation of lead in bone tissues. In this paper we gain insights into the sublethal effects of lead contamination on Egyptian vultures (Neophron perc-nopterus). Our approach was done on the comparison of two populations (Canary Islands and Iberian Peninsula) differing in exposures to the ingestion of lead ammunition. Blood lead levels were higher in the island population (Canary Islands range: 5.10–1780 mg L À1 n ¼ 137; Iberian Peninsula range: 5.60– 217.30 mg L À1 n ¼ 32) showing clear seasonal trends, peaking during the hunting season. Moreover, males were more susceptible to lead accumulation than females. Bone lead concentration increased with age, reflecting a bioaccumulation effect. The bone composition was significatively altered by this contaminant: the mineralization degree decreased as lead concentration levels increased. These results demonstrate the existence of long-term effects of lead poisoning, which may be of importance in the declines of threatened populations of long-lived species exposed to this contaminant.
Colour polymorphism results from the expression of multiallelic genes generating phenotypes with ... more Colour polymorphism results from the expression of multiallelic genes generating phenotypes with very distinctive colourations. Most colour polymorphisms are due to differences in the type or amount of melanins present in each morph, which also differ in several behavioural, morphometric and physiological attributes. Melanin-based colour morphs could also differ in the levels of glutathione (GSH), a key intracellular antioxidant, because of the role of this molecule in melanogenesis. As GSH inhibits the synthesis of eumelanin (i.e. the darkest melanin form), individuals of darker morphs are expected to have lower GSH levels than those of lighter morphs. We tested this prediction in nestlings of two polymorphic raptors, the booted eagle Hieraaetus pennatus and the Eleonora's falcon Falco eleonorae, both of which occur in two morphs differing in the extent of eumelanic plumage. As expected, melanic booted eagle nestlings had lower blood GSH levels than light morph eagle nestlings. In the Eleonora's falcon, however, melanic nestlings only had lower GSH levels after controlling for the levels of other antioxidants. We also found that melanic female eagle nestlings had higher levels of antioxidants other than GSH and were in better body condition than light female eagle nestlings. These findings suggest an adaptive response of melanic nestlings to compensate for reduced GSH levels. Nevertheless, these associations were not found in falcons, indicating species-specific particularities in antioxidant machinery. Our results are consistent with previous work revealing the importance of GSH on the expression of melanic characters that show continuous variation, and suggest that this pathway also applies to discrete colour morphs. We suggest that the need to maintain low GSH levels for eumelanogenesis in dark morph individuals may represent a physiological constraint that helps regulate the evolution and maintenance of polymorphisms.
Introduction of alien herbivores in sensitive island systems has resulted in massive effects on v... more Introduction of alien herbivores in sensitive island systems has resulted in massive effects on vegetation cover, floristic richness and composition of communities; some species can be even totally extirpated by grazing pressure. Goats Capra hircus and wild rabbits Oryctolagus cuniculus were introduced in the Canary Islands around 500 B.C. Barbary ground squirrels Atlantoxerus getulus were introduced in 1967. Traditional extensive livestock exploitations have been maintained to the present but in the last decades the number of goats has sharply increased up to densities of 53 heads/km 2. Overgrazing and trampling have heavily affected eleven island endemic plant species. Some populations have been reduced to less than 10 viable individuals. On the other hand, goat carcasses and wild rabbit and squirrel populations help to maintain populations of three endangered endemic subspecies of birds. This conflict presents important economic and social ramifications: whereas public funds (mainly through European LIFE projects) are devoted to conservation of plant and avian endemic taxa, the number of goats increases rapidly thanks to subventions derived from the European Common Agricultural Policy (CAP). Similar conflicts are apparent in other Mediterranean Basin insular systems. It is urgently necessary to harmonize farming and conservation objectives in the Canary Islands. The impact of goats on the vegetation should be minimized through limitation of grazing in sensitive areas with high degree of endemism. Creation of 'vulture restaurants' may reduce the dependence of scavengers on extensive livestock exploitations. We recommend a careful study of ecological relationships within island communities where non-native species are susceptible of playing a keystonrole as occurs in the Mediterranean Basin archipelagos.
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Papers by Laura Gangoso
foster fathers had higher immune responses than those raised by pale foster fathers. Although we cannot completely discard alternative explanations, our results suggest that MC1R might influence immunity in this species. Morph-specific variation in immunity as well as pathogen pressure may therefore contribute to the long-term maintenance of genetic color polymorphism in natural populations.
foster fathers had higher immune responses than those raised by pale foster fathers. Although we cannot completely discard alternative explanations, our results suggest that MC1R might influence immunity in this species. Morph-specific variation in immunity as well as pathogen pressure may therefore contribute to the long-term maintenance of genetic color polymorphism in natural populations.