Find research datasets worth reusing

Data from: Natal dispersal of tree sloths in a human-dominated landscape: implications for tropical biodiversity conservation

1. Habitat loss and fragmentation resulting from the conversion of tropical forests are among the most important threats to biodiversity globally. Habitat specialists and species with low dispersal capacity are expected to be the most sensitive to such changes. Relatively little is known, however, about how habitat change and life history interact to impact natal dispersal and population viability in tropical species. 2. Here, we characterized natal dispersal patterns, habitat selection, and survival rates in two-toed (Choloepus hoffmanni) and three-toed (Bradypus variegatus) sloths within a human-dominated tropical landscape in Costa Rica consisting of a shade-grown cacao plantation surrounded by riparian forests and cattle pastures. 3. Radio-marked individuals of both species preferentially selected tropical forests during natal dispersal and were commonly observed using riparian forest buffers for dispersal. The more specialized and sedentary three-toed sloth, however, avoided both pastures and shade-grown cacao for dispersal, whereas two-toed sloths only avoided pastures. 4. Juvenile survival was lower for three-toed than two-toed sloths, and was lowest immediately following maternal independence for both species. Despite interspecific differences, juvenile survival was high and sufficient to maintain stable populations of both species. 5. Synthesis and applications. Our results indicate that tropical forest conversion is more likely to impact the natal dispersal success of specialized and dispersal-limited species. Moreover, riparian forest buffers appear to provide critical corridors for maintaining such species, and biodiversity more broadly, in modified tropical landscapes.07-Feb-2018

Data from: Structure and phylogeography of two tropical predators, spinner (Stenella longirostris) and pantropical spotted (S attenuata) dolphins, from SNP data

Little is known about global patterns of genetic connectivity in pelagic dolphins, including how circumtropical pelagic dolphins spread globally following the rapid and recent radiation of the subfamily delphininae. In this study, we tested phylogeographic hypotheses for two circumtropical species, the spinner dolphin (Stenella longirostris) and the pantropical spotted dolphin (Stenella attenuata), using >3,000 nuclear DNA single nucleotide polymorphisms (SNPs) in each species. Analyses for population structure indicated significant genetic differentiation between almost all subspecies and populations in both species. Bayesian phylogeographic analyses of spinner dolphins showed deep divergence between Indo-Pacific, Atlantic, and eastern tropical Pacific Ocean (ETP) lineages. Despite high morphological variation, our results show very close relationships between endemic ETP spinner subspecies in relation to global diversity. The dwarf spinner dolphin is a monophyletic subspecies nested within a major clade of pantropical spinner dolphins from the Indian and western Pacific Ocean populations. Population-level division among the dwarf spinner dolphins was detected–with the northern Australia population being very different from that in Indonesia. In contrast to spinner dolphins, the major boundary for spotted dolphins is between offshore and coastal habitats in the ETP, supporting the current subspecies-level taxonomy. Comparing these species underscores the different scale at which population structure can arise, even in species that are similar in habitat (i.e., pelagic) and distribution.

Data from: Long-term in situ persistence of biodiversity in tropical sky-islands revealed by landscape genomics

Tropical mountains are areas of high species richness and endemism. Two historical phenomena may have contributed to this: (1) fragmentation and isolation of habitats may have promoted the genetic differentiation of populations and increased the possibility of allopatric divergence and speciation, and; (2) the mountain areas may have allowed long-term population persistence during global climate fluctuations. These two phenomena have been studied using either species occurrence data or estimating species divergence times. However, only few studies have used intraspecific genetic data to analyse the mechanisms by which endemism may emerge at the microevolutionary scale. Here, we use landscape analysis of genomic SNP data sampled from two high-elevation plant species from an archipelago of tropical sky-islands (the Transmexican Volcanic Belt) to test for population genetic differentiation, synchronous demographic changes and habitat persistence. We show that genetic differentiation can be explained by the degree of glacial habitat connectivity among mountains, and that mountains have facilitated the persistence of populations throughout glacial/interglacial cycles. Our results support the ongoing role of tropical mountains as cradles for biodiversity by uncovering cryptic differentiation and limits to gene flow.

Data from: Evaluating mechanisms of diversification in a Guineo-Congolian tropical forest frog using demographic model selection

The accumulation of biodiversity in tropical forests can occur through multiple allopatric and parapatric models of diversification, including forest refugia, riverine barriers and ecological gradients. Considerable debate surrounds the major diversification process, particularly in the West African Lower Guinea forests, which contain a complex geographic arrangement of topographic features and historical refugia. We used genomic data to investigate alternative mechanisms of diversification in the Gaboon forest frog, Scotobleps gabonicus, by first identifying population structure and then performing demographic model selection and spatially explicit analyses. We found that a majority of population divergences are best explained by allopatric models consistent with the forest refugia hypothesis and involve divergence in isolation with subsequent expansion and gene flow. These population divergences occurred simultaneously and conform to predictions based on climatically stable regions inferred through ecological niche modelling. Although forest refugia played a prominent role in the intraspecific diversification of S. gabonicus, we also find evidence for potential interactions between landscape features and historical refugia, including major rivers and elevational barriers such as the Cameroonian Volcanic Line. We outline the advantages of using genomewide variation in a model-testing framework to distinguish between alternative allopatric hypotheses, and the pitfalls of limited geographic and molecular sampling. Although phylogeographic patterns are often species-specific and related to life-history traits, additional comparative studies incorporating genomic data are necessary for separating shared historical processes from idiosyncratic responses to environmental, climatic and geological influences on diversification.

opencc-zeroFeb 2020View details →

Stable species boundaries despite ten million years of hybridization in tropical eels

Genomic evidence is increasingly underpinning that hybridization between taxa is commonplace, challenging our views on the mechanisms that maintain their boundaries. Here, we focus on seven catadromous eel species (genus Anguilla), and use genome-wide sequence data from more than 450 individuals sampled across the tropical Indo-Pacific, morphological information, and three newly assembled draft genomes to compare contemporary patterns of hybridization with signatures of past gene flow across a time-calibrated phylogeny. We show that the seven species have remained distinct entities for up to 10 million years, despite a dynamic scenario of incomplete isolation whereby the current frequencies of hybridization across species pairs (over 5% of all individuals were either F1 hybrids or backcrosses) contrast remarkably with patterns of past introgression. Based on near-complete asymmetry in the directionality of hybridization and decreasing frequencies of later-generation hybrids, we identify cytonuclear incompatibilities and hybrid breakdown as two powerful mechanisms that can support species cohesion even when hybridization has been pervasive throughout the evolutionary history of entire clades.

Data from: Edaphic factors, successional status, and functional traits drive habitat associations of trees in naturally regenerating tropical dry forests

1. Many studies have examined individual environmental drivers of tropical tree species distributions, but edaphic and successional gradients have not been considered simultaneously. Furthermore, determining how functional traits influence species distributions along these gradients may help to elucidate mechanisms behind community assembly. 2. To assess the influence of environmental filtering on tropical dry forest (TDF) tree species distributions we used forest inventory data from sites with large edaphic and successional gradients in NW Costa Rica. Our goals were to determine (1) whether edaphic or successional factors are more important determinants of the abundance of individual tree species in regenerating TDF, (2) how species-level functional traits are related to edaphic and/or successional niche associations of tree species, and (3) correlations between species-level edaphic and successional niche associations. 3. The distributions of 82 focal tree species were strongly driven by both edaphic and successional gradients. Overall, 94% of species responded to soil chemistry, 89% to soil texture, and 94% to stand age gradients. Some functional traits were correlated with the edaphic and successional niche associations of TDF tree species. Species that specialized on soils with high total nutrient concentrations had higher foliar nutrient concentrations (nitrogen and phosphorus) and lower leaf dry matter content (LDMC). Species with wider stand age niches had lower LDMC and wood density. There were no correlations between edaphic and successional niche optima of TDF tree species. 4. Our results indicate that successional and edaphic gradients concurrently drive community assembly in regenerating TDF. Moreover, our work underscores the importance of considering how the functional characteristics of TDF trees dictates species distributions across environmental gradients.

Data from: The demography of a resource specialist in the tropics: Cecropia trees and the fitness of three-toed sloths

Resource specialists persist on a narrow range of resources. Consequently, the abundance of key resources should drive vital rates, individual fitness and population viability. While Neotropical forests feature both high levels of biodiversity and numbers of specialist species, no studies have directly evaluated how the variation of key resources affects the fitness of a tropical specialist. Here, we quantified the effect of key tree species density and forest cover on the fitness of three-toed sloths (Bradypus variegatus), an arboreal folivore strongly associated with Cecropia trees, in Costa Rica using a multi-year demographic, genetic and space use dataset. We found that the density of Cecropia trees was strongly and positively related to both adult survival and reproductive output. A matrix model parameterized with Cecropia-demography relationships suggested positive growth of sloth populations, even at low densities of Cecropia (0.7 trees/ha). Our study shows the first direct link between the density of a key resource to demographic consequences of a tropical specialist, underscoring the sensitivity of tropical specialists to the loss of a single key resource, but also point to targeted conservation measures to increase that resource. Finally, our study reveals that previously disturbed and regenerating environments can support viable populations of tropical specialists.

Data from: Disentangling competitive versus climatic drivers of tropical forest mortality

1. Tropical forest mortality is controlled by biotic and abiotic processes, but how these processes interact to determine forest structure is not well understood. Using long-term demography data from permanent forest plots at the Paracou Tropical Forest Research Station in French Guiana, we analyzed the relative influence of competition and climate on tree mortality. We found that self-thinning is evident at the stand level, and is associated with clumped mortality at smaller scales (< 2 m) and regular spacing of living trees at intermediate (2.5-7.5 m) scales. A competition index based on spatial clustering of dead trees was used to build predictive mortality models, which also accounted for climate interactions. 2. The model that most closely fitted observations included both the competition index and climatic variables, with climate-only and competition-only models performing worse than the full model. There was strong evidence for size-specific mortality, with highest mortality for small and very large trees, as well as sensitivity of trees to drought, especially when temperatures were high, and when soils were water saturated. The effect of the competition index was more complex than expected a priori: a higher CI index was associated with lower mortality odds, which we hypothesize is caused by gap-phase dynamics, but there was also evidence for competition-induced mortality at very high index values. 3. The strong signature of competition as a control over mortality at the stand and individual scales confirms that it plays a very important role in determining tropical forest structure. The complexity of the competition-mortality relationship and its interaction with climate indicates that a thorough consideration of the scale of analysis is needed when inferring the role of competition in tropical forests, but demonstrates that climate-only mortality models can be significantly improved by including competition effects, even when ignoring species-specific effects. 4. Synthesis Empirical models such as the one developed here can help constrain and improve process-based vegetation models, serving both as a benchmark and as a means to disentangle mortality processes. Tropical ecosystem dynamic models would benefit greatly from explicitly considering the role of competition in stand development and self-thinning while modeling demography, as well as its interaction with climate.

opencc-zeroMar 2020View details →

River dams and the stability of bird communities: A hierarchical Bayesian analysis in a tropical hydroelectric power plant

<ol> <li>The effects of anthropogenic disturbance upon the stability of wildlife communities depend on the heterogeneity and connectivity of habitat remnants on multiple scales. The number of hydroelectric dams in biodiversity hotspots (Africa, South America and Asia) is growing rapidly. To establish their environmental impact, it is essential to understand the dynamics of wildlife communities before and following the establishment of dams.</li> <li>We evaluated the impacts of the filling of the Serra do Facão hydroelectric reservoir in the São Marcos river, central Brazil, upon the bird community. Using data from 1,145 surveys across 20 sampling sites over eight years, two years before and six years after the filling of the reservoir, we assessed the resistance, i.e., maintenance close to an equilibrium state during the disturbance, and resilience, i.e., ability to return to the original state following the disturbance, of the bird community. We used spatiotemporal hierarchical Bayesian models to assess the effects of reservoir filling on five community parameters: abundance, richness, phylogenetic diversity, functional diversity and species composition.</li> <li>In the period subsequent to reservoir filling, there was (i) a marked reduction in bird abundance, richness, phylogenetic diversity and functional diversity, and (ii) a reduction in the proportion of forest species, coupled with an increase in the proportion of savanna species. Except for bird abundance, none of the other community attributes returned to their original levels, even after six years. Our findings indicate that Cerrado bird communities have both low resistance and low resilience to habitat loss associated with the establishment of hydroelectric reservoirs.</li> <li> Synthesis and applications. The environmental costs of hydroelectric dams are still underestimated or neglected in Brazil. A new paradigm in the assessment of their environmental impacts is warranted, incorporating (i) models of spatiotemporal variations based on long-term monitoring with surveys initiated before disturbances and (ii) measures of functional and phylogenetic diversity, such that society can understand the costs and benefits of the establishment of new hydroelectric dams and make informed decisions. Biodiversity loss could be minimized by ensuring the preservation and connectivity of alluvial habitats, capable of maintaining the supply of resources and the functional and phylogenetic attributes of bird communities associated with such habitats.</li> </ol>

Data from: Leaf-cutter ants engineer large nitrous oxide hot spots in tropical forests

Though tropical forest ecosystems are among the largest natural sources of the potent greenhouse gas nitrous oxide (N2O), the spatial distribution of emissions across landscapes is often poorly resolved. Leaf-cutter ants (LCA, Atta and Acromyrmex, Myrmicinae) are dominant herbivores throughout Central and South America and influence multiple aspects of forest structure and function. In particular, their foraging creates spatial heterogeneity by concentrating large quantities of organic matter (including nitrogen, N) from the surrounding canopy into their colonies, and ultimately, into colony refuse dumps. Here, we demonstrate that refuse piles created by LCA species Atta colombica in tropical rainforests of Costa Rica provide ideal conditions for extremely high rates of N2O production (high microbial biomass, potential denitrification enzyme activity, N content, and anoxia), and may represent an unappreciated source of heterogeneity in tropical forest N2O emissions. Average instantaneous refuse pile N2O fluxes surpassed background emissions by more than three orders of magnitude (in some cases exceeding 80,000 μg N2O-N m-2 h-1) and generating fluxes comparable to or greater than those produced by engineered systems such as wastewater treatment tanks. Refuse-concentrating Atta species are ubiquitous in tropical forests, pastures and production ecosystems, and increase density strongly in response to disturbance. As such, LCA colonies may represent an unrecognised greenhouse gas point source throughout the Neotropics.

Data from: How temporal patterns in rainfall determine the geomorphology and carbon fluxes of tropical peatlands

Tropical peatlands now emit hundreds of megatons of carbon dioxide per year because of human disruption of the feedbacks that link peat accumulation and groundwater hydrology. However, no quantitative theory has existed for how patterns of carbon storage and release accompanying growth and subsidence of tropical peatlands are affected by climate and disturbance. Using comprehensive data from a pristine peatland in Brunei Darussalam, we show how rainfall and groundwater flow determine a shape parameter (the Laplacian of the peat surface elevation) that specifies, under a given rainfall regime, the ultimate, stable morphology, and hence carbon storage, of a tropical peatland within a network of rivers or canals. We find that peatlands reach their ultimate shape first at the edges of peat domes where they are bounded by rivers, so that the rate of carbon uptake accompanying their growth is proportional to the area of the still-growing dome interior. We use this model to study how tropical peatland carbon storage and fluxes are controlled by changes in climate, sea level, and drainage networks. We find that fluctuations in net precipitation on timescales from hours to years can reduce long-term peat accumulation. Our mathematical and numerical models can be used to predict long-term effects of changes in temporal rainfall patterns and drainage networks on tropical peatland geomorphology and carbon storage.

Data from: Rising CO2 accelerates phosphorus and molybdenum limitation of N2-fixation in young tropical trees

Background and Aims: Nitrogen fixation may be critical for supplying the nitrogen (N) needed to maintain the tropical carbon sink in a world of rising atmospheric CO2. However, we do not know whether increased CO2 acts to exacerbate nutrient limitation on the fixation process itself. We experimentally test this idea by growing N2-fixing plants in pre-Industrial (280 ppm), present-day (400 ppm), and doubled (800 ppm) atmospheric CO2. Methods: In a greenhouse experiment, we grew tree seedlings from N2-fixing species and a non-fixing species at three CO2 concentrations with control, +P (phosphorus), +Mo (molybdenum), and +P+Mo nutrient treatments. Results: We found nutrient limitation to be minimal at pre-Industrial CO2, but with increasing CO2 fixer growth and fixation became increasingly limited by P and by a P-by-Mo interaction. At 400 ppm, plants with +P grew ~50% faster and fixed 10-15x more N2 based on nodule mass and nitrogenase activity. At 800 ppm, plants with +P+Mo grew 200% more, and fixed 25x more N2, suggesting Mo-P co-limitation at elevated CO2. Conclusion: Our findings imply that complex patterns of nutrient limitation can develop as CO2 rises, potentially suppressing tropical N2-fixation and new inputs of N needed to sustain the tropical carbon sink.

opencc-zeroJan 2020View details →

Differences in architecture and performance between two sub-canopy congeneric tropical tree species

We report architectural divergence between two congeneric tropical tree species coexisting in the same stratum which suggests different strategies: reducing self-shading and support costs, or maximizing light foraging. We found species-specific differential performance across light environments, suggesting that architectural differentiation could facilitate the coexistence of species with similar vertical habitat.

opencc-zeroMar 2022View details →

Data from: Relaxation of putative plant defenses in a tropical agroecosystem

Evidence of the effects of agriculture on natural systems is widespread, but potential evolutionary responses in non-target species are largely uncharacterized. To explore whether exposure to agrochemicals may influence selective pressures and phenotypic expression in non-agricultural plant populations, we characterized the expression of putative anti-herbivore defense phenotypes in three non-agricultural species found upstream and downstream of irrigated rice fields in Guanacaste Province, Costa Rica. We found that plants downstream of chemically intensive agriculture showed shifts toward reduced expression of putative anti-herbivore defenses relative to upstream counterparts. In two of three tested species, leaf extracts from downstream plants were more palatable to a generalist consumer, suggesting a possible reduction of chemical defenses. In one species with multiple modes of putative defenses, we observed parallel reductions of three metrics of putative biotic and physical defenses. These reductions were concurrent with reduced herbivore damage on downstream plants. Together, these results suggest that agriculture has the potential to alter intraspecific phenotypic expression, ecological interactions, and natural selection in non-target plant populations.

opencc-zeroDec 2018View details →

Data from: Genomic, ecological, and morphological approaches to investigating species limits: a case study in modern taxonomy from Tropical Eastern Pacific surgeonfishes

A wide variety of species are distinguished by slight color variations. However, molecular analyses have repeatedly demonstrated that coloration does not always correspond to distinct evolutionary histories between closely related groups, suggesting that this trait is labile and can be misleading for species identification. In the present study, we analyze the evolutionary history of sister species of Prionurus surgeonfishes in the Tropical Eastern Pacific (TEP), which are distinguished by the presence or absence of dark spots on their body. We examined the species limits in this system using comparative specimen-based approaches, a mitochondrial gene (COI), more than 800 nuclear loci (Ultraconserved Elements), and abiotic niche comparisons. The results indicate there is a complete overlap of meristic counts and morphometric measurements between the two species. Further, we detected multiple individuals with intermediate spotting patterns suggesting that coloration is not diagnostic. Mitochondrial data recovered a single main haplotype shared between the species and all locations resulting in a complete lack of structure (ST = 0). Genomic analyses also suggest low levels of genetic differentiation (FST = 0.013), and no alternatively fixed SNPs were detected between the two phenotypes. Furthermore, niche comparisons could not reject niche equivalency or similarity between the species. These results suggest that these two phenotypes are conspecific and widely distributed in the TEP. Here we recognize Prionurus punctatus Gill 1862 as a junior subjective synonym of P. laticlavius (Valenciennes 1846). The underlying causes of phenotypic variation in this species is unknown. However, this system gives insight into general evolutionary dynamics within the TEP.

Data from: Demographic costs and benefits of natural regeneration during tropical forest restoration

For tropical forest restoration to result in long‐term biodiversity gains, native trees must establish self‐sustaining populations in degraded sites. While many have asked how seedling recruitment varies between restoration treatments, the long‐term fate of these recruits remains unknown. We address this research gap by tracking natural recruits of 27 species during the first 7 years of a tropical forest restoration experiment that included both planted and naturally regenerating plots. We used an individual‐based model to estimate the probability that a seedling achieves reproductive maturity after several years of growth and survival. We found an advantage for recruits in naturally regenerating plots, with up to 40% increased probability of reproduction in this treatment, relative to planted plots. The demographic advantage of natural regeneration was highest for mid‐successional species, with relatively minor differences between treatments for early‐successional species. Our research demonstrates the consequences of restoration decision making across the life cycle of tropical tree species.

Data from: Apparent annual survival estimates of tropical songbirds better reflect life history variation when based on intensive field methods

Aim: Adult survival is central to theories explaining latitudinal gradients in life history strategies. Life history theory predicts higher adult survival in tropical than north temperate regions given lower fecundity and parental effort. Early studies were consistent with this prediction, but standard-effort netting studies in recent decades suggested that apparent survival rates in temperate and tropical regions strongly overlap. Such results do not fit with life history theory. Targeted marking and resighting of breeding adults yielded higher survival estimates in the tropics, but this approach is thought to overestimate survival because it does not sample social and age classes with lower survival. We compared the effect of field methods on tropical survival estimates and their relationships with life history traits. Location: Sabah, Malaysian Borneo. Time period: 2008–2016. Major taxon: Passeriformes. Methods: We used standard-effort netting and resighted individuals of all social and age classes of 18 tropical songbird species over 8 years. We compared apparent survival estimates between these two field methods with differing analytical approaches. Results: Estimated detection and apparent survival probabilities from standard-effort netting were similar to those from other tropical studies that used standard-effort netting. Resighting data verified that a high proportion of individuals that were never recaptured in standard-effort netting remained in the study area, and many were observed breeding. Across all analytical approaches, addition of resighting yielded substantially higher survival estimates than did standard-effort netting alone. These apparent survival estimates were higher than for temperate zone species, consistent with latitudinal differences in life histories. Moreover, apparent survival estimates from addition of resighting, but not from standard-effort netting alone, were correlated with parental effort as measured by egg temperature across species. Main conclusions: Inclusion of resighting showed that standard-effort netting alone can negatively bias apparent survival estimates and obscure life history relationships across latitudes and among tropical species.

opencc-zeroDec 2019View details →

Data from: Evolutionary diversity in tropical tree communities peaks at intermediate precipitation

Global patterns of species and evolutionary diversity in plants are primarily determined by a temperature gradient, but precipitation gradients may be more important within the tropics, where plant species richness is positively associated with the amount of rainfall. The impact of precipitation on the distribution of evolutionary diversity, however, is largely unexplored. Here we detail how evolutionary diversity varies along precipitation gradients by bringing together a comprehensive database on the composition of angiosperm tree communities across lowland tropical South America (2,025 inventories from wet to arid biomes), and a new, large-scale phylogenetic hypothesis for the genera that occur in these ecosystems. We find a marked reduction in the evolutionary diversity of communities at low precipitation. However, unlike species richness, evolutionary diversity does not continually increase with rainfall. Rather, our results show that the greatest evolutionary diversity is found in intermediate precipitation regimes, and that there is a decline in evolutionary diversity above 1,490 mm of mean annual rainfall. If conservation is to prioritise evolutionary diversity, areas of intermediate precipitation that are found in the South American 'arc of deforestation', but which have been neglected in the design of protected area networks in the tropics, merit increased conservation attention.

Data from: Direct fitness benefits and kinship of social foraging groups in an Old World tropical babbler

Molecular studies have revealed that social groups composed mainly of non-relatives may be widespread in group-living vertebrates, but the benefits favoring such sociality are not well understood. In the Old World, birds often form conspecific foraging groups that are maintained year-round and offspring usually disperse to other social groups. We tested the hypothesis that non-breeding group members are largely unrelated and gain direct fitness benefits through breeding opportunities (males) and brood parasitism (females) in the tropical grey-throated babbler, Stachyris nigriceps, in Malaysian Borneo. Babblers foraged in social groups containing one or more breeding pairs (median = 8 group members of equal sex ratio), but group members rarely assisted with breeding (9% of 67 breeding pairs had a third helper; exhibiting facultative cooperative breeding). Although 20% of 266 group member dyads were first-order relatives of one or both members of the breeding pairs, 80% were unrelated. Male group members gained direct fitness benefits through extra-pair and extra-group paternity (25% of 73 offspring), which was independent of their relatedness to the breeding pair and increased with decreasing group size. In contrast, females did not gain direct fitness benefits through brood parasitism. The low levels of relatedness and helping in social groups suggest that most group members do not gain indirect fitness benefits by helping to raise unrelated offspring. These findings highlight the importance of examining benefits of sociality for unrelated individuals that largely do not help and broaden the direct fitness benefits of group foraging beyond assumed survival benefits.

Data from: Vertical differentiation in tropical forest butterflies: a novel mechanism generating insect diversity?

Many tropical fruit-feeding nymphalid butterflies are associated with either the forest canopy or the understory, however, the exceptions offer insights into the origins of tropical diversity. As it occurs in both habitats of tropical forests in Ecuador and Peru, Archaeoprepona demophon is one such exception. We compared patterns of occurrence of A. demophon in the canopy and understory and population genomic variation for evidence of ecological and genetic differentiation between habitats. We found that butterfly occurrences in the canopy were largely uncorrelated with occurrences in the understory at both localities, indicating independent demographic patterns in the two habitats. We also documented modest, significant genome-level differentiation at both localities. Genetic differentiation between habitat types (approximately 20m in elevation) were comparable to levels of differentiation between sampling locations (approximately 1500km). We conclude that canopy and understory populations of A. demophon represent incipient independent evolutionary units. These findings support the hypothesis that divergence between canopy and understory-associated populations might be a mechanism generating insect diversity in the tropics.