Publications

Habitat loss and fragmentation may impact animal-mediated dispersal of seed and pollen, and a key question is how the genetic attributes of plant populations respond to these changes. Theory predicts that genetic diversity may be less sensitive to such disruptions in the short term, whereas inbreeding and genetic structure may respond more strongly. However, results from studies to date vary in relation to species, context and the parameter being assessed, triggering calls for more empirical studies, especially from the tropics, where plant–animal dispersal mutualisms are both disproportionately common and at risk. We compared the genetic characteristics of adults and recruits in a long-lived palm Oenocarpus bataua in a recently fragmented landscape (o2 generations) in northwest Ecuador using a suite of 10 polymorphic microsatellite markers. We sampled individuals from six forest fragments and one nearby continuous forest. Our goal was to assess short-term consequences of fragmentation, with a focus on how well empirical data from this system follow theoretical expectations. Mostly congruent with predictions, we found stronger genetic differentiation and fine-scale spatial genetic structure among recruits in fragments compared with recruits in continuous forest, but we did not record differences in genetic diversity or inbreeding, nor did we record any differences between adults in fragments and adults in continuous forest. Our findings suggest that genetic characteristics of populations vary in their sensitivity to change in response to habitat loss and fragmentation, and that fine-scale spatial genetic structure may be a particularly useful indicator of genetic change in recently fragmented landscapes. Heredity (2015) advance online publication, 29 April 2015; doi:10.1038/hdy.2015.35

Manakins (Pipridae) are well know for elaborate male sexual displays and ornate plumage coloration, both of which are thought to have evolved as a consequence of lekking breeding, the prevalent mating system in the family. Less attention has been paid to a handful of ‘drab’ manakin species, in which sexual dimorphism appears to be reduced or absent. Using character reconstruction, we show that these ‘exceptions to the rule’ represent phylogenetically independent cases of losses in sexual dimorphism, and as such could provide a focal group to investigate the link between changes in morphology and in life history (e.g. mating system). We take a first step in this direction by focusing on two subspecies of the putatively monomorphic green manakin Xenopipo holochlora to formally confirm that the species is sexually monomorphic in size and plumage color and test the prediction that sexual monomorphism is associated with the loss of lekking behavior in this species. Our results show that size dimorphism is present but limited in the green manakin, with substantial overlap in male and female morphometric measures, and that sexes are largely monochromatic (including from an avian perspective), despite marked coloration differences between subspecies. Behavioral observations indicate that males do not form leks and do not engage in elaborate sexual displays, that there is no stable pair bond formation, and that females provide parental care alone. These findings are consistent with the idea that changes in mating behavior may have driven changes in morphology in Pipridae, and we encourage similar studies on other drab manakins to better understand this relationship

Anthropogenic activities are influencing, and in many cases decreasing, biodiversity in the tropics. In Australia’s tropical savanna, mismanaged fire regimes and the introduction of nonnative species are of major concern, and climate change may worsen the situation. Already very fire-prone, Australia’s wet-dry northern tropical savanna ecosystem is experiencing intensive burn regimes and also suffers from an invasive grass species which may influence the severity and frequency of fires. This study investigates relationships between fire history, vegetation, arthropods, and a grassland-dwelling insectivorous bird, the red-backed fairy-wren (Malurus melanocephalus). We found that fire history predicts grass cover, which in turn influences arthropod abundance and diversity and the presence of red-backed fairy-wrens. In the context of intensive fire regimes, we argue that this species may be suitable as an indicator of ecosystem health in Australia’s tropical savanna.

Amphibians are facing extinctions worldwide as a result of numerous factors. Habitat alteration has long been implicated in the loss of biodiversity; however, we still do not know how different animal assemblages respond to habitat alteration. To investigate the impacts of anthropogenic habitat alteration on diversity, we studied amphibian assemblages across different habitats in the Choco´ rainforest of northwest Ecuador. Amphibian diversity was estimated using intensive surveys along transects in primary and altered (historically logged) forest and riparian habitats, as well as along roads with varying levels of ongoing human activity. Our results suggest an interaction between habitat type and alteration on the diversity and composition of amphibian assemblages. Amphibian assemblages along rivers were the richest as well as the least impacted by habitat alteration. In addition, riparian zones harbored amphibian assemblages distinct from other habitat types, including rare and endangered species. Diversity and species richness were lower in secondary than in primary forest, suggesting that amphibian assemblages in interior forest habitat may be more vulnerable to alterations caused by logging. These findings suggest that amphibian assemblages in different habitat types (i.e., riparian vs. interior forest) may vary in vulnerability to habitat alteration. We discuss these findings in relation to land management plans that promote amphibian diversity in northwest Ecuador and recognize a good potential indicator species, Oophaga sylvatica, for identifying pristine habitat

Marine oil spills may have extensive and deleterious effects on coastal waterbirds, but pre-spill data sets are often not available for making comparisons of demographics to the period following a spill. The 2010 Deepwater Horizon oil spill allowed us to compare Brown Pelican (Pelecanus occidentalis) demographics during pre- and post-spill years. We banded 1114 pelicans on Louisiana barrier islands from 2007 to 2009, tracked their distribution via band re-sighting surveys from 2008 to 2011, and conducted age-structure surveys. Across Louisiana coastal islands in 2011, we detected 7% of pelicans that had been oiled during the 2010 spill and released following rehabilitation. Similarly, 6% of pelicans (not oiled) banded at the same release site in 2007 were observed across coastal islands 1 yr after banding. We observed variation in proportions of pelicans that were 1, 2, and 3 or more years old among years (2008–2011) and across islands, but little variation could readily be assigned to spill-related mortality. These Brown Pelican demographic trends one year following the Deepwater Horizon oil spill are contrary to other assessments of the impacts of oil contamination on marine birds. However, additional research is required to evaluate potential long-term population trends.

The keystone plant resources (KPR) concept describes certain plant species in tropical forests as vital to community stability and diversity because they provide food resources to vertebrate consumers during the season of scarcity. Here, we use an 8-y, continuous record offruitfallfrom a 1.44-hamatureforest stand toidentify potential KPRs in a lowland western Amazonian rain forest. KPRs were identified based on four criteria: temporal non-redundancy; year-to-year reliability; abundance of reproductive-size individuals and inferred fruit crop size; and the variety of vertebrate consumers utilizing their fruit. Overall, seven species were considered excellent KPRs: two of these belong to the genus Ficus, confirming that this taxon is a KPR as previously suggested. Celtis iguanaea (Cannabaceae) – a canopy liana – has also been previously classified as a KPR; in addition, Pseudomalmea diclina (Annonaceae), Cissus ulmifolia (Vitaceae), Allophylus glabratus (Sapindaceae) and Trichilia elegans (Meliaceae) are newly identified KPRs. Our results confirm that a very small fraction (<5%) of the plant community consistently provides fruit for a broad set of consumers during the period of resource scarcity, which has significant implications for the conservation and management of Amazonian forests.

Hybrid zones are geographic regions where differentiated taxa meet and potentially exchange genes. Increasingly, genomic analyses have demonstrated that many hybrid zones are semipermeable boundaries across which introgression is highly variable. In some cases, certain alleles penetrate across the hybrid zone in only one direction, recombining into the alternate genome. We investigated this phenomenon using genomic (genotyping-by-sequencing) and morphological (plumage reflectance spectrophotometry) analyses of the hybrid zone between two subspecies of the red-backed fairy-wren (Malurus melanocephalus) that differ conspicuously in a sexual signal, male back plumage color. Geographic cline analyses revealed a highly variable pattern of differential introgression, with many narrow coincident clines combined with several significantly wider clines, suggesting that the hybrid zone is a semipermeable tension zone. The plumage cline was shifted significantly into the genomic background of the orange subspecies, consistent with sexual selection driving asymmetrical introgression of red plumage alleles across the hybrid zone. This interpretation is supported by previous experimental work demonstrating an extra-pair mating advantage for red males, but the role of genetic dominance in driving this pattern remains unclear. This study highlights the potential for sexual selection to erode taxonomic boundaries and promote gene flow, particularly at an intermediate stage of divergence.

During the breeding season, seabird foraging behaviors are driven by a combination of individual- and external-based factors. This study evaluated how two individual-based factors (body condition and sex) and two external factors (nest stage and colony size), and their interactions, were related to movement. To do so, we used movement data obtained from 22 GPS-tagequipped Brown Pelicans (Pelecanus occidentalis L., 1766) breeding in the northern Gulf of Mexico. In Brown Pelicans, the postegg-hatching phase imposes increased foraging demands on breeding adults relative to the prehatching phase. This study demonstrates that the progression of the breeding period affects the nature and intensity of the relationship between individualbased factors and movement patterns. In particular, birds in relatively lower condition traveled greater distances during foraging trips during the energetically demanding posthatching phase, but not during the incubation stage. Contrary to many seabird species studied to date, neither colony size nor sex appeared to affect Brown Pelican movement patterns. Our results suggest that nest stage is the most important factor influencing foraging movements, and that it may modulate relationships between condition and movement. More refined measures of body condition and foraging behavior will allow further insights into the movement ecology of this seabird.

We report on the avifauna of the 120,000 ha Mache Chindul Ecological Reserve (REMACH), northwest Ecuador. The study area is located in a poorly studied transition zone between three major Neotropical biogeographic regions - the Chocó, Tumbesian, and Tropical Andes - each of which contains exceptional diversity and endemism in birds and other organisms. We collected data from 1998^99 and 2004^11 from the Bilsa Biological Station (a 3500 ha private reserve) and several farms, forest fragments, and communities distributed across the central portion of REMACH using observations (aural and visual), audio recordings, mist netting, point counts and photographs. We recorded 360 species of bird (263 genera, 51 families), including 57 threatened species on the Red List of Ecuador, 14 of which are also globally threatened; 23 drestricted rangee endemic species (15 Chocó and 8 Tumbesian); and 16 migratory species. We recorded breeding activity for 130 species, and documented two distinctive peaks of reproduction, corresponding to the wet and dry seasons, respectively. Our results suggest that REMACH represents a transition zone between Chocó and Tumbesian biogeographic zones, and as such should be considered a priority for conservation of avifauna and other taxa. Accepted 7 November 2013. Key words: Avifauna, conservation, Chocó, Ecuador, endangered species, endemism, Neotropical migration, Tropical Andes, Tumbesian.