Juan Arroyo - Profile on Academia.edu (original) (raw)
Papers by Juan Arroyo
La necesidad de la experimentación en ecología y conservación: una aproximación para la restaurac... more La necesidad de la experimentación en ecología y conservación: una aproximación para la restauración forestal en el Campo de Gibraltar. VI Jornadas de Flora, Fauna y Ecología del Campo de Gibraltar. Algeciras, Octubre 2003.<br><br>
Reivindicacion de la figura de Darwin como botanico, muchas veces ignorada por el publico en gene... more Reivindicacion de la figura de Darwin como botanico, muchas veces ignorada por el publico en general, ademas el autor llama la atencion sobre la gran deuda que tienen todos los botanicos con el.
Interspecific Pollen Transfer Among Co-Occurring Heteromorphic and Homomorphic Species
Pollen transfer, and hence sharing of pollinators, among Primula veris, Narcissus assoanus, and P... more Pollen transfer, and hence sharing of pollinators, among Primula veris, Narcissus assoanus, and Potentilla tabernaemontani in Northern Spain is demonstrated in the study of pollen loads on their stigmas. The length of style in both P. veris and N. assoanus is dimorphic (the former being a typical distylous species); they resemble each other in flower morphology (narrow-tubed), color, and nectar characteristics. Therefore, interspecific pollen transfer between these two species shows a pattern related to these similarities. It is inferred that the pattern of interspecific pollen transfer is mediated mainly by long-tongued pollinators seeking nectar, and that of intraspecific pollen transfer by long- and short-tongued pollinators feeding on nectar and pollen, respectively. The floral features of P. tabernaemontani are markedly different, especially in flower architecture (open) and reward (pollen). Accordingly, pollen transfer to other species is reduced, the long-styled flowers of N....
X Reunion Anual Ecoflor
Santos-Gally, R., Perez-Barrales, R., Arroyo, J., Jordano, P., Valido, A., Pico, X., Narbona, E. ... more Santos-Gally, R., Perez-Barrales, R., Arroyo, J., Jordano, P., Valido, A., Pico, X., Narbona, E. (2013). X Reunion anual de Ecoflor. Ecosistemas 22(2):125. Doi.: 10.7818/ECOS.2013.22-2.20
PLOS ONE, 2020
The theory of evolution is one of the greatest scientific achievements in the intellectual histor... more The theory of evolution is one of the greatest scientific achievements in the intellectual history of humankind, yet it is still contentious within certain social groups. Despite being as robust and evidence-based as any other notable scientific theory, some people show a strong reluctance to accept it. In this study, we used the Measure of Acceptance of the Theory of Evolution (MATE) and Knowledge of Evolution Exam (KEE) questionnaires with university students from four academic degree programs (Chemistry, English, History, and Biology) of ten universities from Spain to measure, respectively, acceptance and knowledge of evolutionary theory among third-year undergraduate students (n MATE = 978; n KEE = 981). Results show that acceptance of evolution is relatively high (87.2%), whereas knowledge of the theory is moderate (5.4 out of 10) although there are differences across degrees (Biolo-gy>Chemistry>History>English), and even among various universities (ranging from 4.71 to 5.81). Statistical analysis reveals that knowledge of evolutionary theory among Biology students is partially explained by the relative weight of evolutionary themes within the curriculum, suggesting that an increase in the number of hours dedicated to this topic could have a direct influence on students' knowledge of it. We also found that religion may have a significant-although relatively small-negative influence on evolutionary theory acceptance. The moderate knowledge of evolution in our undergraduate students, together with the potential
Acta Botanica Malacitana, 2007
RÉSUMÉ. Structure et diversité de la strate arbustive des forêts de la Péninsule Tingitane (Maroc... more RÉSUMÉ. Structure et diversité de la strate arbustive des forêts de la Péninsule Tingitane (Maroc). Cette étude concerne les communautés végétales arbustives des massifs forestiers sur substrat gréseux couvrant la Péninsule Tingitane au nord ouest du Maroc. La structure et la diversité de ces communautés ont été étudiées sur la base de 98 relevés représentatifs. Les subéraies (Quercus suber) sont les formations forestières naturelles les plus représentatives et les plus diversifiées de l´aire d´étude. L´altitude s’est révélée être un facteur écologique très discriminant, en séparant clairement les communautés arbustives des forêts des hautes montagnes. Au niveau des zones de basses altitudes, la fertilité, l´acidité et la perturbation anthropique jouent un rôle déterminant dans la distribution des communautés végétales arbustives. Cette distribution semble exprimer la dynamique de la végétation selon un gradient de conservation-perturbation. En conclusion, l´étude souligne l´intérêt...
Plant biology (Stuttgart, Germany), Jan 4, 2017
Narcissus papyraceus is a style dimorphic species with two floral forms, with anthers at similar ... more Narcissus papyraceus is a style dimorphic species with two floral forms, with anthers at similar height and stigmas above (long-styled L) and below (short-styled S) the anther level. The species is self-incompatible, but intra and inter-morph compatible. Populations are either dimorphic (including both morphs) in the region of the Strait of Gibraltar, or L-monomorphic (with only L plants) in the inland of the Iberian Peninsula. This variation correlates with the most common floral visitors, be these primarily long-tongued and short-tongued pollinators respectively, a rare condition in Mediterranean plants. The maintenance of S-flowers relies on long-tongued insects, as only those deliver pollen to short-styled stigmas. Narcissus flowers present a long and narrow tube, at the bottom of which nectar accumulates, and a floral corona, which has been proposed as an important trait for the attraction of pollinators. Here we tested the importance of the corona on the pollination of L and S...
Changes in floral biology and inbreeding depression in native and invaded regions of Datura stramonium
Plant biology (Stuttgart, Germany), Jan 4, 2017
Plant populations invading new environments might compromise their fitness contribution to the ne... more Plant populations invading new environments might compromise their fitness contribution to the next generation, owing to the lack of native specialist pollinators and/or potential mates. Thus, changes in plant mating system and traits linked to it are expected in populations colonising new environments where selection would favour selfing and floral traits that maximise reproductive output. To test this, we studied native (Mexico) and non-native (Spain) populations of the obligate sex reproducing annual weed Datura stramonium. Flower size, herkogamy, total number of seeds per plant, number of visits by and type of pollinators, and inbreeding depression, were assessed in native and non-native populations. Finally, we measured phenotypic selection on corolla size and herkogamy in each population. Flower size and herkogamy showed wide and similar variation in both ranges. However, the largest average flower size was found in one non-native population whereas the highest average positiv...
Flora, 1990
Results: The project comes with an innovative design that was achieved through the aforementioned... more Results: The project comes with an innovative design that was achieved through the aforementioned methodology using the Araucoply material and solving the initial problem for which the project is made. Conclusions: Two arc options are made where the significant change is in the design of the joints that takes a tensegrity to another, this change is made in order to save material and facilitate the processing of the parts.
Refugios del ojaranzo en las sierras del sur de Cádiz
Quercus, 2004
Biblioteca de la Universidad Complutense de Madrid, Base de datos de artículos de revistas, ...
Forest Systems, Aug 1, 2003
El paisaje forestal mediterráneo que vemos en la actualidad es el resultado de la actuación del h... more El paisaje forestal mediterráneo que vemos en la actualidad es el resultado de la actuación del hombre y su gestión de los recursos a lo largo de la Historia (Le Houérou, 1981; McNeill, 1992; Marañón y Ojeda, 1998). Entre los procesos que han contribuido a la deforestación de la Cuenca Mediterránea, Thirgood (1981) ha destacado los siguientes: la transformación del bosque en cultivos y pastos, la explotación de ma-dera para la construcción de barcos, la extracción de combustible para uso doméstico o para la minería, las guerras e invasiones, los incendios y el sobrepastoreo. Los bosques del Rif, y en particular de la Península Tingitana (norte de Marruecos), han sufrido episodios intensos de perturbación que han sido más acentuados en la época reciente (Mikesell, 1960; Reille, 1977; Taiqui, 1997). La mayor parte de los bosques actuales de Marruecos son testigos de una explotación intensa, que se refleja en su estructura y composición. Excepcionalmente, los morabitos o «bosques sagrados» han sido respetados en señal de respeto hacia el santo musul
Evolution, 2015
Evolution to reduce inbreeding can favor disassortative (inter-morph) over assortative (intramorp... more Evolution to reduce inbreeding can favor disassortative (inter-morph) over assortative (intramorph) mating in hermaphroditic sexually polymorphic plant species. Heterostyly enhances disassortative pollination through reciprocal placement of stigmas and anthers of morphs and appropriate pollinators. Stylar dimorphism in which there is not reciprocal anther placement may compromise disassortative mating, particularly when there is not intra-morph incompatibility. Variable rates of disassortative mating along with differential female fecundity or siring success among floral morphs could lead to variation in morph ratio. We investigated mating patterns, female fecundity and siring success of style-length morphs in Narcissus papyraceus, a self-incompatible but morph-compatible species with dimorphic (long-and short-styled) and monomorphic (long-styled) populations in central and north regions of its range respectively. We established experimental populations in both regions and exposed them to ambient pollinators. Using paternity analysis, we found similar siring success of morphs and high disassortative mating in most populations. Female fecundity of morphs was similar in all populations. Although these results could not completely explain the loss of dimorphism in the species' northern range, they provided evidence for the evolutionary stability of stylar dimorphism in N. papyraceus in at least some populations. Our findings support the hypothesis that prevailing inter-morph mating is key for the maintenance of stylar dimorphism.
Proceedings. Biological sciences / The Royal Society, Aug 22, 2015
Many of the macroevolutionary processes that have shaped present-day phylogenetic patterns were c... more Many of the macroevolutionary processes that have shaped present-day phylogenetic patterns were caused by geological events such as plate tectonics and temporary land-bridges. The study of spatial patterns of phylogenetic diversity can provide insights into these past events. Here we focus on a western Mediterranean biodiversity hotspot located in the southern Iberian Peninsula and northwest Africa, two regions that are separated by the Strait of Gibraltar. We explore the spatial structure of the phylogenetic relationships within and across large-scale plant assemblages. Significant turnover in terminal lineages tends to occur between landmasses, whereas turnover in deep lineages tends to occur within landmasses. Plant assemblages in the western ecoregions of this hotspot tend to be phylogenetically overdispersed but are phylogenetically clustered on its eastern margins. We discuss our results in the light of potential scenarios of niche evolution (or conservatism) and lineage diver...
Estudio de la flora rara y endemica del parque nacional de Talasemtane (Norte de Marruecos)
Diversité et structures des forêts du Nord-ouest du Maroc
98 relevés représentatifs des massifs forestiers du nord du Maroc ont été réalisés. Les subéraies... more 98 relevés représentatifs des massifs forestiers du nord du Maroc ont été réalisés. Les subéraies sont les formations forestières les plus représentatives et les plus diversifiées dans l'aire d'étude. En effet, elles représentent une richesse spécifique et une richesse en taxons endémiques remarquables. Chez les formations forestières dominées par Quercus suber et Q. canariensis, l'altitude, la fertilité du sol et la perturbation anthropique jouent un rôle primordial dans la distribution des espèces. Cette distribution semble exprimer la dynamique de la végétation selon un gradient de conservation-perturbation. D'autres parts, la structure démographique des subéraies étudiées a montré un déficit évident de régénération naturelles.
AoB Plants, 2015
When plants are introduced into new regions, the absence of their co-evolved natural enemies can ... more When plants are introduced into new regions, the absence of their co-evolved natural enemies can result in lower levels of attack. As a consequence of this reduction in enemy pressure, plant performance may increase and selection for resistance to enemies may decrease. In the present study, we compared leaf damage, plant size and leaf trichome density, as well as the direction and magnitude of selection on resistance and plant size between non-native (Spain) and native (Mexico) populations of Datura stramonium. This species was introduced to Spain about five centuries ago and constitutes an ideal system to test four predictions of the enemy release hypothesis. Compared with native populations, we expected Spanish populations of D. stramonium to have (i) lower levels of foliar damage; (ii) larger plant size; (iii) lower leaf trichome density that is unrelated to foliar damage by herbivores; and (iv) weak or no selection on resistance to herbivores but strong selection on plant size. Our results showed that, on average, plants from non-native populations were significantly less damaged by herbivores, were less pubescent and were larger than those from native populations. We also detected different selection regimes on resistance and plant size between the non-native and native ranges. Positive selection on plant size was detected in both ranges (though it was higher in the non-native area), but consistent positive selection on relative resistance was detected only in the native range. Overall, we suggest that changes in selection pressure on resistance and plant size in D. stramonium in Spain are a consequence of 'release from natural enemies'.
Santos-Gally et al Annals of Botany
Botanical Journal of the Linnean Society, 2015
Heterostyly and related polymorphisms (e.g. stigma-height dimorphism) have been used as model sys... more Heterostyly and related polymorphisms (e.g. stigma-height dimorphism) have been used as model systems for studying the origin and maintenance of plant population variability. Stigma-height dimorphism frequently occurs in Narcissus and is associated with a particular flower shape. In the present study, we describe a new, peculiar case of stigma-height dimorphism in Narcissus broussonetii, a species on the margin of the geographical distribution of the genus. We determined the stylar condition of N. broussonetii and its variation across populations, analyzed perianth morphology and its relationship with stylar variation, and compared this species with other stylar dimorphic species of the genus. We also studied the incompatibility system and pollination ecology of the species. Narcissus broussonetii is a style-dimorphic species, as suggested in early studies that were subsequently neglected, and displays unusual flower morphology, with a long floral tube and a virtual absence of a corona. The species shows a late-(ovarian) acting incompatibility system and crosses within and between morphs are fertile. We observed short-tongued diurnal and long-tongued nocturnal pollinators. Our findings confirm that the presence of the observed dimorphism across populations is most probably the result of the joint action of a nonheteromorphic incompatibility system, extremely long and narrow floral tubes, and a combined role of short-and long-tongued pollinators.
La necesidad de la experimentación en ecología y conservación: una aproximación para la restaurac... more La necesidad de la experimentación en ecología y conservación: una aproximación para la restauración forestal en el Campo de Gibraltar. VI Jornadas de Flora, Fauna y Ecología del Campo de Gibraltar. Algeciras, Octubre 2003.<br><br>
Reivindicacion de la figura de Darwin como botanico, muchas veces ignorada por el publico en gene... more Reivindicacion de la figura de Darwin como botanico, muchas veces ignorada por el publico en general, ademas el autor llama la atencion sobre la gran deuda que tienen todos los botanicos con el.
Interspecific Pollen Transfer Among Co-Occurring Heteromorphic and Homomorphic Species
Pollen transfer, and hence sharing of pollinators, among Primula veris, Narcissus assoanus, and P... more Pollen transfer, and hence sharing of pollinators, among Primula veris, Narcissus assoanus, and Potentilla tabernaemontani in Northern Spain is demonstrated in the study of pollen loads on their stigmas. The length of style in both P. veris and N. assoanus is dimorphic (the former being a typical distylous species); they resemble each other in flower morphology (narrow-tubed), color, and nectar characteristics. Therefore, interspecific pollen transfer between these two species shows a pattern related to these similarities. It is inferred that the pattern of interspecific pollen transfer is mediated mainly by long-tongued pollinators seeking nectar, and that of intraspecific pollen transfer by long- and short-tongued pollinators feeding on nectar and pollen, respectively. The floral features of P. tabernaemontani are markedly different, especially in flower architecture (open) and reward (pollen). Accordingly, pollen transfer to other species is reduced, the long-styled flowers of N....
X Reunion Anual Ecoflor
Santos-Gally, R., Perez-Barrales, R., Arroyo, J., Jordano, P., Valido, A., Pico, X., Narbona, E. ... more Santos-Gally, R., Perez-Barrales, R., Arroyo, J., Jordano, P., Valido, A., Pico, X., Narbona, E. (2013). X Reunion anual de Ecoflor. Ecosistemas 22(2):125. Doi.: 10.7818/ECOS.2013.22-2.20
PLOS ONE, 2020
The theory of evolution is one of the greatest scientific achievements in the intellectual histor... more The theory of evolution is one of the greatest scientific achievements in the intellectual history of humankind, yet it is still contentious within certain social groups. Despite being as robust and evidence-based as any other notable scientific theory, some people show a strong reluctance to accept it. In this study, we used the Measure of Acceptance of the Theory of Evolution (MATE) and Knowledge of Evolution Exam (KEE) questionnaires with university students from four academic degree programs (Chemistry, English, History, and Biology) of ten universities from Spain to measure, respectively, acceptance and knowledge of evolutionary theory among third-year undergraduate students (n MATE = 978; n KEE = 981). Results show that acceptance of evolution is relatively high (87.2%), whereas knowledge of the theory is moderate (5.4 out of 10) although there are differences across degrees (Biolo-gy>Chemistry>History>English), and even among various universities (ranging from 4.71 to 5.81). Statistical analysis reveals that knowledge of evolutionary theory among Biology students is partially explained by the relative weight of evolutionary themes within the curriculum, suggesting that an increase in the number of hours dedicated to this topic could have a direct influence on students' knowledge of it. We also found that religion may have a significant-although relatively small-negative influence on evolutionary theory acceptance. The moderate knowledge of evolution in our undergraduate students, together with the potential
Acta Botanica Malacitana, 2007
RÉSUMÉ. Structure et diversité de la strate arbustive des forêts de la Péninsule Tingitane (Maroc... more RÉSUMÉ. Structure et diversité de la strate arbustive des forêts de la Péninsule Tingitane (Maroc). Cette étude concerne les communautés végétales arbustives des massifs forestiers sur substrat gréseux couvrant la Péninsule Tingitane au nord ouest du Maroc. La structure et la diversité de ces communautés ont été étudiées sur la base de 98 relevés représentatifs. Les subéraies (Quercus suber) sont les formations forestières naturelles les plus représentatives et les plus diversifiées de l´aire d´étude. L´altitude s’est révélée être un facteur écologique très discriminant, en séparant clairement les communautés arbustives des forêts des hautes montagnes. Au niveau des zones de basses altitudes, la fertilité, l´acidité et la perturbation anthropique jouent un rôle déterminant dans la distribution des communautés végétales arbustives. Cette distribution semble exprimer la dynamique de la végétation selon un gradient de conservation-perturbation. En conclusion, l´étude souligne l´intérêt...
Plant biology (Stuttgart, Germany), Jan 4, 2017
Narcissus papyraceus is a style dimorphic species with two floral forms, with anthers at similar ... more Narcissus papyraceus is a style dimorphic species with two floral forms, with anthers at similar height and stigmas above (long-styled L) and below (short-styled S) the anther level. The species is self-incompatible, but intra and inter-morph compatible. Populations are either dimorphic (including both morphs) in the region of the Strait of Gibraltar, or L-monomorphic (with only L plants) in the inland of the Iberian Peninsula. This variation correlates with the most common floral visitors, be these primarily long-tongued and short-tongued pollinators respectively, a rare condition in Mediterranean plants. The maintenance of S-flowers relies on long-tongued insects, as only those deliver pollen to short-styled stigmas. Narcissus flowers present a long and narrow tube, at the bottom of which nectar accumulates, and a floral corona, which has been proposed as an important trait for the attraction of pollinators. Here we tested the importance of the corona on the pollination of L and S...
Changes in floral biology and inbreeding depression in native and invaded regions of Datura stramonium
Plant biology (Stuttgart, Germany), Jan 4, 2017
Plant populations invading new environments might compromise their fitness contribution to the ne... more Plant populations invading new environments might compromise their fitness contribution to the next generation, owing to the lack of native specialist pollinators and/or potential mates. Thus, changes in plant mating system and traits linked to it are expected in populations colonising new environments where selection would favour selfing and floral traits that maximise reproductive output. To test this, we studied native (Mexico) and non-native (Spain) populations of the obligate sex reproducing annual weed Datura stramonium. Flower size, herkogamy, total number of seeds per plant, number of visits by and type of pollinators, and inbreeding depression, were assessed in native and non-native populations. Finally, we measured phenotypic selection on corolla size and herkogamy in each population. Flower size and herkogamy showed wide and similar variation in both ranges. However, the largest average flower size was found in one non-native population whereas the highest average positiv...
Flora, 1990
Results: The project comes with an innovative design that was achieved through the aforementioned... more Results: The project comes with an innovative design that was achieved through the aforementioned methodology using the Araucoply material and solving the initial problem for which the project is made. Conclusions: Two arc options are made where the significant change is in the design of the joints that takes a tensegrity to another, this change is made in order to save material and facilitate the processing of the parts.
Refugios del ojaranzo en las sierras del sur de Cádiz
Quercus, 2004
Biblioteca de la Universidad Complutense de Madrid, Base de datos de artículos de revistas, ...
Forest Systems, Aug 1, 2003
El paisaje forestal mediterráneo que vemos en la actualidad es el resultado de la actuación del h... more El paisaje forestal mediterráneo que vemos en la actualidad es el resultado de la actuación del hombre y su gestión de los recursos a lo largo de la Historia (Le Houérou, 1981; McNeill, 1992; Marañón y Ojeda, 1998). Entre los procesos que han contribuido a la deforestación de la Cuenca Mediterránea, Thirgood (1981) ha destacado los siguientes: la transformación del bosque en cultivos y pastos, la explotación de ma-dera para la construcción de barcos, la extracción de combustible para uso doméstico o para la minería, las guerras e invasiones, los incendios y el sobrepastoreo. Los bosques del Rif, y en particular de la Península Tingitana (norte de Marruecos), han sufrido episodios intensos de perturbación que han sido más acentuados en la época reciente (Mikesell, 1960; Reille, 1977; Taiqui, 1997). La mayor parte de los bosques actuales de Marruecos son testigos de una explotación intensa, que se refleja en su estructura y composición. Excepcionalmente, los morabitos o «bosques sagrados» han sido respetados en señal de respeto hacia el santo musul
Evolution, 2015
Evolution to reduce inbreeding can favor disassortative (inter-morph) over assortative (intramorp... more Evolution to reduce inbreeding can favor disassortative (inter-morph) over assortative (intramorph) mating in hermaphroditic sexually polymorphic plant species. Heterostyly enhances disassortative pollination through reciprocal placement of stigmas and anthers of morphs and appropriate pollinators. Stylar dimorphism in which there is not reciprocal anther placement may compromise disassortative mating, particularly when there is not intra-morph incompatibility. Variable rates of disassortative mating along with differential female fecundity or siring success among floral morphs could lead to variation in morph ratio. We investigated mating patterns, female fecundity and siring success of style-length morphs in Narcissus papyraceus, a self-incompatible but morph-compatible species with dimorphic (long-and short-styled) and monomorphic (long-styled) populations in central and north regions of its range respectively. We established experimental populations in both regions and exposed them to ambient pollinators. Using paternity analysis, we found similar siring success of morphs and high disassortative mating in most populations. Female fecundity of morphs was similar in all populations. Although these results could not completely explain the loss of dimorphism in the species' northern range, they provided evidence for the evolutionary stability of stylar dimorphism in N. papyraceus in at least some populations. Our findings support the hypothesis that prevailing inter-morph mating is key for the maintenance of stylar dimorphism.
Proceedings. Biological sciences / The Royal Society, Aug 22, 2015
Many of the macroevolutionary processes that have shaped present-day phylogenetic patterns were c... more Many of the macroevolutionary processes that have shaped present-day phylogenetic patterns were caused by geological events such as plate tectonics and temporary land-bridges. The study of spatial patterns of phylogenetic diversity can provide insights into these past events. Here we focus on a western Mediterranean biodiversity hotspot located in the southern Iberian Peninsula and northwest Africa, two regions that are separated by the Strait of Gibraltar. We explore the spatial structure of the phylogenetic relationships within and across large-scale plant assemblages. Significant turnover in terminal lineages tends to occur between landmasses, whereas turnover in deep lineages tends to occur within landmasses. Plant assemblages in the western ecoregions of this hotspot tend to be phylogenetically overdispersed but are phylogenetically clustered on its eastern margins. We discuss our results in the light of potential scenarios of niche evolution (or conservatism) and lineage diver...
Estudio de la flora rara y endemica del parque nacional de Talasemtane (Norte de Marruecos)
Diversité et structures des forêts du Nord-ouest du Maroc
98 relevés représentatifs des massifs forestiers du nord du Maroc ont été réalisés. Les subéraies... more 98 relevés représentatifs des massifs forestiers du nord du Maroc ont été réalisés. Les subéraies sont les formations forestières les plus représentatives et les plus diversifiées dans l'aire d'étude. En effet, elles représentent une richesse spécifique et une richesse en taxons endémiques remarquables. Chez les formations forestières dominées par Quercus suber et Q. canariensis, l'altitude, la fertilité du sol et la perturbation anthropique jouent un rôle primordial dans la distribution des espèces. Cette distribution semble exprimer la dynamique de la végétation selon un gradient de conservation-perturbation. D'autres parts, la structure démographique des subéraies étudiées a montré un déficit évident de régénération naturelles.
AoB Plants, 2015
When plants are introduced into new regions, the absence of their co-evolved natural enemies can ... more When plants are introduced into new regions, the absence of their co-evolved natural enemies can result in lower levels of attack. As a consequence of this reduction in enemy pressure, plant performance may increase and selection for resistance to enemies may decrease. In the present study, we compared leaf damage, plant size and leaf trichome density, as well as the direction and magnitude of selection on resistance and plant size between non-native (Spain) and native (Mexico) populations of Datura stramonium. This species was introduced to Spain about five centuries ago and constitutes an ideal system to test four predictions of the enemy release hypothesis. Compared with native populations, we expected Spanish populations of D. stramonium to have (i) lower levels of foliar damage; (ii) larger plant size; (iii) lower leaf trichome density that is unrelated to foliar damage by herbivores; and (iv) weak or no selection on resistance to herbivores but strong selection on plant size. Our results showed that, on average, plants from non-native populations were significantly less damaged by herbivores, were less pubescent and were larger than those from native populations. We also detected different selection regimes on resistance and plant size between the non-native and native ranges. Positive selection on plant size was detected in both ranges (though it was higher in the non-native area), but consistent positive selection on relative resistance was detected only in the native range. Overall, we suggest that changes in selection pressure on resistance and plant size in D. stramonium in Spain are a consequence of 'release from natural enemies'.
Santos-Gally et al Annals of Botany
Botanical Journal of the Linnean Society, 2015
Heterostyly and related polymorphisms (e.g. stigma-height dimorphism) have been used as model sys... more Heterostyly and related polymorphisms (e.g. stigma-height dimorphism) have been used as model systems for studying the origin and maintenance of plant population variability. Stigma-height dimorphism frequently occurs in Narcissus and is associated with a particular flower shape. In the present study, we describe a new, peculiar case of stigma-height dimorphism in Narcissus broussonetii, a species on the margin of the geographical distribution of the genus. We determined the stylar condition of N. broussonetii and its variation across populations, analyzed perianth morphology and its relationship with stylar variation, and compared this species with other stylar dimorphic species of the genus. We also studied the incompatibility system and pollination ecology of the species. Narcissus broussonetii is a style-dimorphic species, as suggested in early studies that were subsequently neglected, and displays unusual flower morphology, with a long floral tube and a virtual absence of a corona. The species shows a late-(ovarian) acting incompatibility system and crosses within and between morphs are fertile. We observed short-tongued diurnal and long-tongued nocturnal pollinators. Our findings confirm that the presence of the observed dimorphism across populations is most probably the result of the joint action of a nonheteromorphic incompatibility system, extremely long and narrow floral tubes, and a combined role of short-and long-tongued pollinators.