Northern Andes Of Colombia Research Articles

Use of anticoagulant rodenticides: a silent threat to biodiversity in a city of Northern Colombian Andes

Use of anticoagulant rodenticides: a silent threat to biodiversity in a city of Northern Colombian Andes

Joining to the web. Predation of Heterophrynus sp. (Amblypygi: Phrynidae) on a catfish Astroblepus sp. (Siluriformes: Astroblepidae), in a premontane river of the northern Andes of Colombia

Riparian food webs are linked by cross-boundary resource fluxes, including the consumption of terrestrial invertebrates and vertebrates by fish and the consumption of aquatic vertebrates by terrestrial invertebrates, mostly arachnids. Amblypygids prey upon a wide array of vertebrates, but no records on fishes are known. Here we report an interesting predation event of an adult Heterophrynus sp., upon a catfish Astroblepus sp. in the Rio Manso, northern Andes of Colombia, and summarized the published information of trophic interactions of this river in a food web framework. A high prey-size ratio (0.87) respect to Heterophrynus sp., highlight that fishes could represent an important food item for amblypygids. This datum, besides other published before, indicates that the consumption of terrestrial and aquatic vertebrates by terrestrial invertebrates can be a substantial cross-boundary flux link in tropical montane streams deserving future ecological studies.

Geochemical Evidence of Water-Fluxed Crustal Melting in the Northern Colombian Andes

Abstract The compositions of crustal magmas are powerful tools for understanding the formation and differentiation of continents. However, the geochemical fingerprints that distinguish the two dominant mechanisms of crustal melting, namely dehydration and water-fluxed melting, are still controversial. To provide new insights into this problem, we discuss the petrogenesis of the Paipa Volcanic Complex (PVC), an isolated Quaternary volcanic field in the Colombian Eastern Cordillera. The PVC is characterized by peraluminous trondhjemite-like rhyolites with exceptionally high Na2O contents (~6 wt %), super-chondritic Nb/Ta (~27), elevated Sr/Y ratios (~120), spoon-shaped REE patterns, and enriched isotopic compositions that overlap with those of the local basement. They also exhibit high pre-eruptive H2O contents (~up to 9.5 wt %) and abundant Paleozoic zircon inheritances. We demonstrate that these characteristics are inconsistent with a process of intra-crustal differentiation from a mafic or intermediate mantle-derived precursor. Instead, we propose that the origin of the PVC is best explained by melting the local (meta)sedimentary basement under H2O-saturated conditions, at middle-crustal pressures (~1.3 GPa) and relatively low temperatures (~690–740°C), following the complete breakdown of plagioclase and biotite, and the formation of reactive peritectic amphibole. This scenario differs from the high-temperature dehydration melting conditions that have been widely proposed for the Andes and globally, which result in the production of water undersaturated magmas in equilibrium with anhydrous lithologies rich in plagioclase and/or garnet. Accordingly, we speculate that an external H2O flux was ultimately sourced from a buoyant, cold, and hydrated mantle wedge that was extensively metasomatized by fluids derived from the Nazca and Caribbean flat-slab fronts. These conditions depressed the asthenospheric mantle potential temperature, likely inhibiting mantle melting. In turn, they facilitated the infiltration and ascent of mantle-derived H2O through pre-existing crustal faults and shear zones. Our results indicate that water-fluxed melting could be a plausible mechanism for generating crustal magmas in orogenic regions where the availability of free H2O has been difficult to confirm.

Structure of the assemblage of fruit-feeding butterflies in a high Andean anthropogenic landscape

The high Andean mountains are ecosystems subject to high human pressure activities, resulting in disturbed areas increasingly dominating the landscapes. However, there needs to have more knowledge about the contributions of different vegetation coverages and species to global diversity at the local level. For three consecutive years, we studied a guild of fruit-feeding butterflies in four different land covers (cloud forests, paramo, mixed anthropogenic habitats, and cattle pastures) in the northern Andes in Colombia, analyzing the diversity and structure of the butterfly assemblage in the region. The assembly showed significant differences between land covers. The mixed habitat was the most diverse in order q1 (exponential of Shannon entropy) and q2 (inverse of Gini-Simpson dominance index) diversity, and the cloud forest contained the higher abundance and species richness. Abundance decreased from forest to pasture, significantly reducing diversity in pastures, with cloud forest and paramo containing the key endemic species. These results indicate the value of landscape diversity in providing resources and conditions required for the diversity conservation of high Andean butterflies.

Exceptionally preserved subfossil woods from late Pleistocene volcanic deposits from the Northern Andes of Colombia

The recent geological history of the Northern Andes is characterized by the interaction of dynamic surface processes such as volcanic activity, fluvial erosion, mass movements, etc. that have shaped landscapes for millennia. Despite its great geological and biological importance, the long-term ecological history of middle-elevation tropical habitats (between 1000 and 2500 m.a.s.l.) is unknown, due to the scarcity of suitable paleo archives preserving the paleoecological signal, leading to a critical data gap. This manuscript reports well-preserved subfossil woods of the Pleistocene volcanoclastic deposits from the Central Cordillera of Colombia. Four wood specimens are described and identified as Terminalioxylon gumminae sp.nov., Andesanthus risaraldense sp.nov., Anacardium quindiuense sp.nov., and Chrysochlamys colombiana. This report demonstrates the potential of volcanic deposits in the Northern Andes as paleo archives, and contributes to the fossil record of the tropical Andes, as it contains elements of mid-altitude vegetation preserved in association with the Pleistocene volcanic activity of the Central Cordillera. The environments where these subfossil species lived resemble present environmental conditions. This is a baseline for future paleobotanical exploration and paleoenvironmental analyses.

Tectono-stratigraphic and sedimentological analysis of the Early to Middle Devonian Floresta Formation: Insights from the Floresta Massif, Northern Andes, Colombia

A comprehensive tectono-stratigraphic and sedimentological investigation of Early to Middle Devonian rocks was conducted in the southern Floresta Massif and adjacent regions in the Northern Andes of Colombia. A substantially reduced thickness of the Floresta Formation compared to prior studies is suggested here, attributable to pronounced stratal deformation and the prevalence of recumbent folds throughout the area. The deformation in the Floresta Formation manifests as atypical recumbent folds, diverging from the structural behavior observed in the underlying and overlying strata of the El Tibet and Cuche formations respectively, which exhibit minimal deformation. Our findings also reveal that the Floresta Formation accumulated under shallow-water platform conditions, subject to eustatic sea-level fluctuations. This resulted in distinct episodes of carbonate and siliciclastic deposition, with terrigenous sediments sourced from continental origins, potentially encompassing a combination of cratonic areas and uplifted blocks. The identification of a plausible stage of carbonate silicification signifies a post-diagenetic transformation. The sedimentary rocks of the Floresta Formation reached the upper epizone conditions, in proximity to the transition between the epizone and the upper anchizone, which suggests a maximum depth and temperature of ~5-7 km and ~300 °C, respectively. This contribution provides new insights into the geological history of the region, emphasizing the importance of scrutinizing Early to Middle Devonian rocks within the broader geological context of the Northern Andes.

Landslide susceptibility assessment in scarce-data regions using remote sensing data

Landslides triggered by rainfall are among the most frequent causes of natural disasters in mountainous terrains. However, landslide susceptibility assessments are often limited due to the scarcity of reliable observations. Due to this lack of data, especially in developing countries, remote sensing is used for landslide susceptibility analysis. This study presents the application of remote sensing data and a logistic regression model to assess landslide susceptibility in a basin on a remote terrain in the northern Colombian Andes, where a rainstorm on May 18th, 2015, triggered more than 40 landslides and an associated debris flow afterwards. The methodology applied is based on free access remote sensing tools, since the study area is considered a scarce-data zone. The results show that free remote sensing tools provide enough information to run a model as logistic regression and achieve a successful first approach to the landslide susceptibility map of complex terrains as the study area. This suggests that the proposed methodology could be implemented in several regions with similar characteristics based only on free access information.

Mesocarnivores activity patterns in the Northern Colombian Andes

Temporal segregation plays an important role as a coexistence mechanism between potentially competing and closely related species, especially in species with similar morphology and ecological requirements, such as mesocarnivores. This study investigates the temporal niche ecology of mesocarnivores coexisting in the southeastern Aburrá Valley, northern Colombian Andes. Specifically, this study i) evaluated the daily activity patterns of six mesocarnivore species, ii) analyzed the influence of the lunar cycle on the activity patterns of nocturnal species, iii) estimated the temporal overlap between pairs of mesocarnivores, and iv) estimated the functional similarities of these species. We hypothesized that mesocarnivores with similar functional traits exhibit greater temporal niche segregation, thus showing low overlap in their activity patterns to reduce competition. We used data from tracking cameras (10,744 camera-days) and estimated daily activity patterns using Kernel density analysis, non-negative trigonometric summation, and overlap analysis with the Overlap package in R. Also, lunar influence was evaluated using circular statistics in the software Oriana 4.02. Functional similarity was analyzed by similarity clustering using Jaccard's index in PAST. Nine species were recorded; six were included in the analyses of daily activity patterns. Activity patterns were not uniform throughout the circadian cycle. Cerdocyon thous, Leopardus tigrinus, and Nasuella olivacea showed mainly nocturnal activity, while Eira barbara, Nasua nasua, and Neogale frenata displayed a diurnal activity pattern. Only Leopardus tigrinus showed significant activity related to the lunar cycle. The activity overlap between pairs of species was variable, with a tendency to a low overlap, showing a high ecological similarity between species. This study represents the first estimate of the activity patterns of mesocarnivore species in the southeastern Aburrá Valley. The observed activity patterns are similar to those reported in other works. Species with high overlap showed ecological differences, especially in size and diet. The low number of records for some species may be associated with poor detectability but also with low abundance as a result of urban development and anthropogenic disturbance (e. g., roadkills). Our results suggest that temporal segregation contributes to mediating intra-gremial interactions and coexistence between sympatric and potentially competing species. These results will hopefully contribute to the knowledge of the ecology of mesocarnivores, mainly in ecosystems surrounding large cities in the northern Andes.

Erosion rate maps highlight spatio-temporal patterns of uplift and quantify sediment export of the Northern Andes

Erosion rates are widely used to assess tectonic uplift and sediment export from mountain ranges. However, the scarcity of erosion rate measurements often hinders detailed tectonic interpretations. Here, we present 25 new cosmogenic nuclide-derived erosion rates from the Northern Andes of Colombia to study spatio-temporal patterns of uplift along the Central and Eastern Cordillera. Specifically, we combine new and published erosion rate data with precipitation-corrected normalized channel steepness measurements to construct high-resolution erosion rate maps. We find that erosion rates in the southern Central Cordillera are relatively uniform and average ∼0.3 mm/a. In the northern Central Cordillera rapidly eroding canyons dissect slowly eroding, low-relief surfaces uplifting since 8.3−2.6+3.7 Ma, based on a block uplift model. We interpret that persistent steep slab subduction has led to an erosional steady-state in the southern Central Cordillera, whereas in the northern Central Cordillera, Late Miocene slab flattening caused an acceleration in uplift, to which the landscape has not yet equilibrated. The Eastern Cordillera also displays pronounced erosional disequilibrium, with a slowly eroding central plateau rimmed by faster eroding western and eastern flanks. Our maps suggest Late Miocene topographic growth of the Eastern Cordillera, with deformation focused along the eastern flank, which is also supported by balanced cross-sections and thermochronologic data. Spatial gradients in predicted erosion rates along the eastern flank of the Eastern Cordillera suggest transient basin-ward migration of thrusts. Finally, sediment fluxes based on our erosion maps, suggest that the Eastern Cordillera exports nearly four times more sediment than the Central Cordillera. Our analysis shows that accounting for spatial variations in erosion parameters and climate reveals important variations in tectonic forcing that would otherwise be obscured in traditional river profile analyses. Moreover, given relationships between tectonic and topographic evolution, we hypothesize that spatio-temporal variations in slab dip are the primary driver of the dynamic landscape evolution of the Northern Andes, with potentially superposed effects from inherited Mesozoic rift structures.

Ecology and Diversity of Weed Communities in the Northern Andes under Different Anthropogenic Pressures

Weeds can have both positive and negative effects on agricultural environments. However, despite the growing interest in the ecology of weed communities in agricultural areas, a few studies have been carried out in the northern region of the Andes of Colombia, where urban and agricultural expansion have generated highly disturbed scenarios. The aim of this study was to analyze the diversity of vegetation and weed seed banks in three agricultural production systems and a forest ecosystem in the northern Andes of Colombia. Hill numbers were used to compare diversity, Beta diversity to assess changes in composition, and range—abundance–dominance curves at different sites. Likewise, indicator species were analyzed to find species associations to each system. The results revealed differences in the composition of weeds between the forest ecosystem and the agricultural production systems, with higher equitability in the forest ecosystem and higher dominance in agricultural systems. Significant differentiation was observed among the dominant species within each agricultural system, particularly highlighting those species considered pests due to their unique life history traits. These traits confer them with a greater advantage in the face of various anthropogenic selection pressures. These findings highlight the impact of anthropogenic disturbances on the ecological dynamics of weed communities in different ecosystems, which should be considered when planning integrated weed management techniques.

Middle-late Eocene to Early Miocene micropaleontology of the ANH–TIERRALTA–2–X–P well: Biostratigraphic implications for southwestern deposits of the Sinú-San Jacinto belt (Colombian Caribbean)

The Eocene and Oligocene deposits of the southwestern region of the Sinú-San Jacinto Belt (SSJB) in NW South America were formed in marine environments influenced by fluvial discharges from the northern Andes of Colombia. However, these deposits are not well-exposed on the surface, which has limited the study of micropaleontological assemblages that could improve our understanding of the chronostratigraphic and paleoenvironmental characteristics of these rocks. In this study, we analyzed two cores of one of the thickest Cenozoic stratigraphic sections in the Caribbean region, from the ANH-TIERRALTA-2-X-P stratigraphic well, using palynomorphs and calcareous nannofossils. Our analysis allowed us to determine the age of deposition and understand the biostratigraphic patterns of marine and terrestrial microfossils in these nearshore deposits. We found that the first cored interval, from 2122 m to 2026.9 m, corresponds to marine rocks accumulated between the middle and late Eocene. The second interval, from 1130 m to 731.6 m, showed patterns of terrestrial and marine microfossils, which indicate the middle-late Eocene to the Early Miocene age. Palynological and calcareous nannofossil biostratigraphy were consistent in the middle to upper Eocene and Lower Miocene deposits, but discrepancies were observed in the Oligocene deposits. We attributed this to reworking or broader biostratigraphic ranges of certain palynological markers used in the biozones. Determining the age of the middle to upper Eocene and upper Eocene to lower Oligocene deposits was challenging due to the limited number of well-calibrated biostratigraphic markers. As a result, accurate correlation with the late Eocene – early Oligocene stratigraphic record from other parts of the SSJB is hindered, demonstrating that regional stratigraphic correlations based on biostratigraphy alone are problematic.

Caribbean–South America interactions since the Late Cretaceous: Insights from zircon U–Pb and Lu–Hf isotopic data in sedimentary sequences of the northwestern Andes

The Northern Andes in Colombia developed along an active, convergent margin with a complex subduction-accretion/collision history since Triassic times. Sedimentary basins that developed within, or close to, the evolving margin provide an important record for the tectonic history. Here we present U–Pb and Hf isotopic data of detrital zircons from Late Cretaceous and Miocene sedimentary strata. Two sedimentary sequences deposited in an active margin setting are analyzed in this study along two roughly E–W trending transects. Targeted sedimentary sequences are the Late Cretaceous-Paleocene siliciclastic member of the Penderisco Formation outcropping in the Western Cordillera and the hemipelagic Miocene Beibaviejo Formation overlying the suture zone between the Western Cordillera and the Panama-Chocó Block (PCB). Provenance and Hf isotopic signatures for sediments and volcaniclastic sandstones associated with the Penderisco Formation indicate a maximum depositional age of ca. 57 Ma with input of detrital material from mixed sources from two major domains: an eastern ancient continental domain, and a western Cretaceous oceanic domain that defines the present Western Cordillera. The record from continental sources suggests a para-autochthonous to autochthonous syn-tectonic history. For the Beibaviejo Formation provenance and Hf isotopic data suggest the Penderisco Formation and Eocene rocks with oceanic affinity within the PCB as the main sources and define a middle Miocene maximum depositional age (∼16 Ma). Our results provide a new insight into the evolution of volcaniclastic sequences at the northwestern margin of South America and provide a new constraint on the timing of collision between the PCB and the Andean margin during the middle Miocene.

Integrated Characterization of Mudstones in the Andes of Colombia: Understanding Its Complexities for Risk Mitigation

This article presents a comprehensive vision of particularities and constraints of the Paja Formation in the Northern Andes of Colombia, supported by personal, institutional, and academic experiences, including a doctoral thesis in completion (geomorphology and risks research line). Such fine-grained marine rocks cause severe damage in diverse zones, with little spread, and are very unfavorable, especially within the Eastern Cordillera (departments of Santander and Cundinamarca), whose socio-environmental problems motivated a popular legal action in the municipality of Vélez due to the cracking and collapse of houses, damage to roads and landslides in the urban area, as well as flows, subsidence, and high hydrogeochemical dynamism or rare earths, although they also presented spontaneous ignition at the rural area. Understanding how these problems originate and interrelate is the main objective of the work. At the beginning, we include some brief definitions, terms, and key approaches to understand the consolidated geomaterials, location, and background of the problem; then, the results of meso–macro–micro studies, obtained by combining the field techniques and conventional instrumental laboratory analyses (tests on the chemistry of water and soil, description of samples with magnifying glasses, petrography with a polarized light microscope, micromorphology of regoliths–colluvions) of nanoscientists (emphasizing RXD-RXF, SEM, IR-Raman spectroscopy, TOC-TS) are presented. These characterizations and new knowledge must be socially and institutionally appropriated and applied in land use planning and risk management for the sustainability of challenging environments with the stratiforms of Lower Cretaceous rocks and associated Quaternary deposits in populated mountainous areas and contrasting intertropical hydroclimatological regimes, geologically active, so unstable and insecure.

Landscape genetics across the Andes mountains: Environmental variation drives genetic divergence in the leaf-cutting ant Atta cephalotes.

Distinguishing among the mechanisms underlying the spatial distribution of genetic variation resulting from the environmental or physical barriers from those arising due to simple geographic distance is challenging in complex landscapes. The Andean uplift represents one of the most heterogeneous habitats where multiple mechanisms may interact, confounding their relative roles. We explore this broad question in the leaf-cutting ant Atta cephalotes, a species that is distributed across the Andes mountains, using nuclear microsatellite markers and mtCOI gene sequences. We investigate spatial genetic divergence across the western range of the northern Andes in Colombia by testing the relative role of alternative scenarios of population divergence, including isolation by geographic distance (IBD), climatic conditions (IBE), and the physical barriers presented by the Andes mountains (IBB). Our results reveal substantial genetic differentiation among A. cephalotes populations for both types of markers, but only nuclear divergence followed a hierarchical pattern with multiple models of genetic divergence imposed by the western range. Model selection showed that the IBD, IBE (temperature and precipitation), and IBB (Andes mountains) models, often proposed as individual drivers of genetic divergence, interact, and explain up to 33% of the genetic divergence in A. cephalotes. The IBE model remained significant after accounting for IBD, suggesting that environmental factors play a more prominent role than IBB. These factors, in combination with the idiosyncratic dispersal patterns of ants, appear to determine the hierarchical patterns of gene flow. This study enriches our understanding of the forces shaping population divergence in complex habitat landscapes.

Petrogenetic constraints of the La Quinta Formation igneous rocks, Serranía del Perijá, northern Colombian Andes

La Quinta Formation is a Triassic-Jurassic volcano-sedimentary unit that crops out along both flanks of the Serranía de Perijá, in Cesar and La Guajira departments of Colombia, and Zulia state in Venezuela. It is mainly composed of red clastic sedimentary rocks (siltstones, sandstones, and minor conglomerates), interbedded with volcanic rocks and cut by small stocks. The volcanic horizons are mainly formed by rhyolitic tuffs and lava flows (basalts and andesites).
 
 Andesites and basalts are constituted by plagioclase, clinopyroxene, biotite, magnetite, apatite, and zircon, whereas rhyolites and tuffs are formed by plagioclase, ß quartz, biotite, and sanidine. EMPA analyses revealed that plagioclase display varying compositions from labradorite-andesine in intermediate and basic rocks to oligoclase in rhyolites. Besides, clinopyroxene from basalts was classified as augite, and several hydrothermal mineral phases were also recognized, such as epidote, Ca-zeolites, and andradite-grossular. Using ILMAT (ilmenite-magnetite) geothermometer, temperature and oxygen fugacity conditions of 700-730°C and +1.2 ∆NNO were determined for dolerite.
 
 Whole-rock geochemistry results evidence that La Quinta Formation volcanic rocks belong to the sub-alkaline (calc-alkaline) series, displaying compositions from basaltic andesites to rhyolites. Chondrite normalized REE and incompatible elements spidergrams show typical features of subduction-related magmatism and depict three groups of rocks (basic, intermediate, and acid) with contrasting geochemical behaviors. Hence, each group could have formed during single magmatic events associated with different magmatic suites. Nevertheless, the three groups have features that suggest a genesis related to an Andean-type supra-subduction zone, which agrees with the regional tectonic assemblage during Triassic-Jurassic times.

Interplay between conservatism and divergence in climatic niche evolution of Brassicaceae tribe Eudemeae shaped their distribution across the different environments of the Andes

Abstract The Andean region is one of the most biodiverse areas, displaying high levels of endemism and spatial turnover of species. Tribe Eudemeae includes nine genera and 40 species distributed from the northern Andes in Colombia to the southernmost portion of the Andes in Argentina and Chile. Here, we generated a species-level phylogenetic tree to study their climatic niche evolution. We first analysed phylogenetic structure and evolutionary shifts among the main climatic spaces using model-based estimates. Second, we estimated climatic niches for each species and compared them in a phylogenetic context. In Eudemeae, three main groups of climatic spaces were found, mainly related to the northern and central Andes, the north-central portion of the southern Andes and the central-southern portion of the southern Andes. Results suggest that initial colonization of new climatic spaces in the evolution of the tribe appears to be promoted through shifts in adaptive regimes, whereas subsequent diversification of genera occurred predominantly under the same climatic regimes. This trade-off between niche conservatism and divergence appears to have modulated their diversification across the Andes and contributed to their current geographical distribution.

Magnetic fabric of deformed Quaternary sediments: contributions to the understanding of the neotectonic activity in the surroundings of the Aburrá Valley, Central Cordillera, Colombia

The origin of the Aburrá Valley (AV) is proposed as a set of coalescent tectonic subbasins located along the northern portion of the Central Cordillera of Colombia, the Northern Andes of Colombia. The Itagüí, Medellín, Bello, and Barbosa subbasins have developed between the Romeral Shear Zone (RSZ) and the Antioqueño Batholith starting in the Late Cenozoic. The aim of this study is to contribute to the understanding of the AV neotectonic framework using the anisotropy of magnetic susceptibility (AMS) and structural analysis. For this, we measure the magnetic fabric ellipsoid shape of faulted sediments and compare them with the geometry and kinematics of fault planes to determine their relationship with the present-day stress field and the regional fault architecture. The principal directions of the elongation axes along the La Brizuela and Yarumalito sites were NE-SW, following the magnetic lineation trend and marking a normal displacement with a dextral component. A marked NW-SE magnetic cleavage was found for the La Caimana site along a strike-slip tectonic setting. Holocene ruptures of the principal displacement zone (i.e., the RSZ) and their surroundings, may indicate normal faulting, with fault bends and steps over basins controlled primarily by R´ and P structures. Moreover, the active faults located to the east of the AV indicate post Plio-Pleistocene deformations with normal faulting through 90/80 to 150/70 antithetic faults. This work identifies the AMS technique as a powerful tool, for understanding the neotectonic framework along urban and surrounding areas.

Phylogeographic structure suggests environmental gradient speciation in a montane frog from the northern Andes of Colombia

Phylogeographic structure suggests environmental gradient speciation in a montane frog from the northern Andes of Colombia

Extending the geographic and altitudinal range of Popilius gibbosus (Burmeister, 1847) (Coleoptera: Passalidae) with taxonomical comments

Popilius gibbosus (Burmeister, 1847) was known only from localities in the Cordillera Oriental of the northern Andes in Colombia and Venezuela and the southern section in Colombia between 1,350-3,000 m. Herein, we provide the first record for Bolivia at low elevations (< 1,000 m), thus extending the geographic and altitudinal range of this species. Information about characters not yet used and the first description of the aedeagus are provided, accompanied with figures of those characters that facilitate the identification of the species. An identification key for Popilius species in Bolivia and a P. gibbosus distribution map are also provided.

Bigger and stronger bury deeper: the role of dung beetles as secondary seed dispersers in the northern Colombian Andes

Bigger and stronger bury deeper: the role of dung beetles as secondary seed dispersers in the northern Colombian Andes