RESUMO
Genetic differentiation depends on ecological and evolutionary processes that operate at different spatial and temporal scales. While the geographical context is likely to determine large-scale genetic variation patterns, habitat disturbance events will probably influence small-scale genetic diversity and gene flow patterns. Therefore, the genetic diversity patterns that we observe today result from the combination of both processes, but they are rarely assessed simultaneously. We determined the population structure and genetic diversity of a hemiparasitic mistletoe (Tristerix corymbosus) from the temperate rainforests of southern Chile to determine the effects of geographical context and habitat disturbance at a regional scale and if it is affected by the abundance and occurrence of its seed disperser mutualist (the arboreal marsupial Dromiciops gliroides). We genotyped 359 individuals from 12 populations using single nucleotide polymorphisms, across three different geographical contexts and four disturbance conditions. We also used camera traps to estimate the abundance and occurrence of the seed disperser. Our results suggest that genetic differences among populations are related more to geographical context than to habitat disturbance. However, as disturbance increased, D. gliroides abundance and occurrence decreased, and mistletoe inbreeding index (FIS ) increased. We also found highly uneven gene flow among study sites. Despite the high levels of disturbance that these temperate rainforests are facing, our results suggest that mistletoe genetic differentiation at a regional scale was more influenced by historical events. However, habitat disturbance can indirectly affect mistletoe population genetic differentiation via the seed dispersal process, which may increase levels of inbreeding.
Assuntos
Erva-de-Passarinho , Dispersão de Sementes , Ecossistema , Fluxo Gênico , Variação Genética/genética , Genética Populacional , Erva-de-Passarinho/genética , ÁrvoresRESUMO
En ecosistemas boscosos, numerosas especies de aves insectívoras usan ciertas especies de árboles como sustrato de alimentación y de nidificación. Evaluamos el uso de Pygarrhichas albogularis King, 1831 por componentes florísticos utilizados como sustrato de alimentación en un bosque nativo en el sur de Chile entre el 2009 y 2010. De 13 especies de árboles y arbustos P. albogularis utilizó seis especies de árboles como sustrato de alimentación. El uso de los árboles se limitó a alturas intermedias (11-20 m) y principalmente utilizó el tronco (40% observaciones) y las ramas secundarias (26%) de los árboles como sustrato de alimentación. Pygarrhichas albogularis mostró un uso desproporcionado por Nothofagus dombeyi y un uso importante por árboles con la mayor estructura etárea (DAP 81-100 cm). Por su parte, N. dombeyi presentó una profundidad de las grietas de la corteza significativamente mayor que E. cordifolia. A su vez, la profundidad de las grietas covarió positiva y significativamente con la oferta de invertebrados en la corteza de los árboles. Consideramos la profundidad de la corteza y la oferta de invertebrados como las causas próximas que podrían explicar el uso desproporcionado de P. albogularis por Nothofagus dombeyi.(AU)
In forest ecosystems, numerous species of insectivorous birds use certain tree species as feeding and nesting substrates. Between 2009 and 2010, the use of different floristic components as feeding substrate by the Pygarrhichas albogularis King, 1831 was evaluated in a southern Chilean secondary native forest. From a total of 13 trees and bush species, six tree species were used by P. albogularis as a feeding substrate. Tree use was limited to intermediate heights (11-20 m) and, mainly, to the trunk (40% of observations) and secondary branches (26%). Pygarrhichas albogularis showed a disproportionated use of N. dombeyi and an important use of trees with a greater age structure (DBH 81-100 cm). Nothofagus dombeyi presented a significantly greater tree bark crevice depth than E. cordifolia. In turn, covariance between crevice depth and invertebrate supply in tree bark was positive and significant. We consider bark depth and invertebrate supply to be the proximate causes explaining P. albogularis disproportionated use of Nothofagus dombeyi.(AU)
Assuntos
Animais , Passeriformes , Árvores , Comportamento Animal , Florestas , ChileRESUMO
En ecosistemas boscosos, numerosas especies de aves insectívoras usan ciertas especies de árboles como sustrato de alimentación y de nidificación. Evaluamos el uso de Pygarrhichas albogularis King, 1831 por componentes florísticos utilizados como sustrato de alimentación en un bosque nativo en el sur de Chile entre el 2009 y 2010. De 13 especies de árboles y arbustos P. albogularis utilizó seis especies de árboles como sustrato de alimentación. El uso de los árboles se limitó a alturas intermedias (11-20 m) y principalmente utilizó el tronco (40% observaciones) y las ramas secundarias (26%) de los árboles como sustrato de alimentación. Pygarrhichas albogularis mostró un uso desproporcionado por Nothofagus dombeyi y un uso importante por árboles con la mayor estructura etárea (DAP 81-100 cm). Por su parte, N. dombeyi presentó una profundidad de las grietas de la corteza significativamente mayor que E. cordifolia. A su vez, la profundidad de las grietas covarió positiva y significativamente con la oferta de invertebrados en la corteza de los árboles. Consideramos la profundidad de la corteza y la oferta de invertebrados como las causas próximas que podrían explicar el uso desproporcionado de P. albogularis por Nothofagus dombeyi.
In forest ecosystems, numerous species of insectivorous birds use certain tree species as feeding and nesting substrates. Between 2009 and 2010, the use of different floristic components as feeding substrate by the Pygarrhichas albogularis King, 1831 was evaluated in a southern Chilean secondary native forest. From a total of 13 trees and bush species, six tree species were used by P. albogularis as a feeding substrate. Tree use was limited to intermediate heights (11-20 m) and, mainly, to the trunk (40% of observations) and secondary branches (26%). Pygarrhichas albogularis showed a disproportionated use of N. dombeyi and an important use of trees with a greater age structure (DBH 81-100 cm). Nothofagus dombeyi presented a significantly greater tree bark crevice depth than E. cordifolia. In turn, covariance between crevice depth and invertebrate supply in tree bark was positive and significant. We consider bark depth and invertebrate supply to be the proximate causes explaining P. albogularis disproportionated use of Nothofagus dombeyi.