In the tropical Indian Ocean, the Maldive Islands lack surface freshwater, so are unsuitable for dragonfly reproduction. Nevertheless, millions of dragonflies (Insecta, Odonata; mostly globe skimmer, Pantala flavescens) appear suddenly every year starting in October. Arrival dates in the Maldives and India demonstrate that the dragonflies travel from southern India, a distance of some 500–1000 km. Dates of arrival and occurrence coincide with the southward passage of the Inter-tropical Convergence Zone (ITCZ). Circumstantial evidence suggests that the dragonflies fly with north-easterly tail winds, within and behind the ITCZ, at altitudes over 1000 m. It is proposed that this massive movement of dragonflies is part of an annual migration across the western Indian Ocean from India to East Africa. Arrival dates in the Seychelles support this hypothesis. Dragonflies also appear (in smaller numbers) in the Maldives in May, with the onset of the southwest monsoon, suggesting a possible return migration from Africa. These proposed migrations of dragonflies, regularly crossing 3500 km or more of open ocean, were previously unknown. It is known that these dragonflies exploit ephemeral rain pools for reproduction; the monsoons and ITCZ bring not only alternating, seasonal rains to India and Africa, but also appropriate winds for dragonflies to follow those rains. Several bird species migrate from India across the western Indian Ocean to wintering grounds in Africa. They do so at the same time as the dragonflies, presumably taking advantage of the same seasonal tail winds. Many of these birds also eat dragonflies; the possible significance of this was not previously appreciated.

Estimation of tree growth is generally based on repeated diameter measurements. A buttress at the height of measurement will lead to overestimates of tree diameter. Because buttresses grow up the trunk through time, it has become common practice to increase the height of measurement, to ensure that measurements remain above the buttress. However, tapering of the trunk means that increasing measurement height will bias estimates of diameter downward by up to 10% per m of height. This bias could affect inference concerning species differences and climate effects on tree demography and on biomass accumulation. Here we introduce a hierarchical state space method that allows formal integration of data on diameter taken at different heights and can include individual variation, temporal effects or other covariates. We illustrate our approach using species from Barro Colorado Island, Panama, and La Selva, Costa Rica. Results include trends that are consistent with some of those previously reported for climate responses and changes over time, but differ in relative magnitude. By including the full data-set and accounting for bias and variation among individuals and over time, our approach allows for quantification of climate responses and the uncertainty associated with measurements and the underlying growth process.

The abundance of epiphytes has been assumed to be important in explaining the high diversity of tropical canopy arthropods. In this study we assessed the possible role that the presence of epiphytes may have on the diversity and abundance of canopy insects in an experimental study conducted in a coffee plantation in Coatepec, Veracruz, Mexico. Epiphytes were removed from trees in one of two plots in two sites of the coffee plantation. In each plot we collected insects from three Inga jinicuil trees by knockdown insecticide fogging. Insects were sorted to morphospecies, counted and measured. Trees with epiphytes had significantly higher numbers of species and individuals and insects larger than 5 mm were also more species-rich and abundant in trees with epiphytes. The magnitude of the enhancement was surprisingly large with the epiphyte plot samples having on average 90% more individuals and 22% more species than plots without epiphytes. These differences were even greater for large (>5 mm) insects (184% and 113% respectively). Our results support the tenet that epiphytes provide valuable resources to arthropods, which we have illustrated for canopy insects in shade trees of coffee plantations.

Lowland forests of western Amazonia contain the most species-rich primate communities in the Neotropics, which begs the question of what mechanisms operate to promote species coexistence. This study examines habitat occupancy and its relationship to phylogeny in a primate community in Amazonian Ecuador. First, as potential factors that shape community structure, we determined whether (1) mean height in the forest canopy differed among species; (2) within each species, habitat occupancy was disproportional to habitat availability; and (3) species diverged in habitat occupancy. We then tested hypotheses regarding ecological distance and its relationship to phylogenetic distance among species pairs within this community. We tested these hypotheses primarily with data derived from 15 censuses of primate species on two 100-ha plots in eastern Ecuador. In these censuses, we observed eight primate species over nearly 200 encounters. We observed larger species at greater heights in the forest canopy than smaller ones. Although they occupied habitat types at frequencies proportionate to their availability in the study area, species diverged in habitat occupancy. Although a clear relationship was not observed between phylogenetic and ecological distances among species pairs, this study suggests that ecological differences among the species in this community facilitate their coexistence.

The sampling of epiphytes is fraught with methodological difficulties. We present a protocol to sample and analyse vascular epiphyte richness and abundance in forests of different structure (SVERA). Epiphyte abundance is estimated as biomass by recording the number of plant components in a range of size cohorts. Epiphyte species biomass is estimated on 35 sample-trees, evenly distributed over six trunk diameter-size cohorts (10 trees with dbh > 30 cm). Tree height, dbh and number of forks (diameter > 5 cm) yield a dimensionless estimate of the size of the tree. Epiphyte dry weight and species richness between forests is compared with ANCOVA that controls for tree size. SChao1 is used as an estimate of the total number of species at the sites. The relative dependence of the distribution of the epiphyte communities on environmental and spatial variables may be assessed using multivariate analysis and Mantel test. In a case study, we compared epiphyte vegetation of six Mexican oak forests and one Colombian oak forest at similar elevation. We found a strongly significant positive correlation between tree size and epiphyte richness or biomass at all sites. In forests with a higher diversity of host trees, more trees must be sampled. Epiphyte biomass at the Colombian site was lower than in any of the Mexican sites; without correction for tree size no significant differences in terms of epiphyte biomass could be detected. The occurrence of spatial dependence, at both the landscape level and at the tree level, shows that the inclusion of spatial descriptors in SVERA is justified.

Post-dispersal fate of seeds dispersed by large primates is well studied but little is known about this process in small frugivores like tamarins. This study in the Amazonian forest of Peru aimed at investigating if characteristics related to the defecation patterns of tamarins (Saguinus mystax and Saguinus fuscicollis) affected short-term post-dispersal seed fate, through secondary seed dispersal by dung beetles and removal by seed predators. Data on dung beetle activity were based on direct observations of 49 defecations while seed fate was studied using semi-controlled experiments (N = 458 for secondary dispersal and N = 398 for predation). Tamarins produce small defecations with a low number of seeds. Thirty-five per cent of defecations were visited by an average of 1.5 dung beetles that usually transport the faeces as pellets. Twenty-four per cent of seeds were buried by beetles at a mean depth of 3.5 cm. With increasing quantities of faecal matter, the probability of secondary seed dispersal increased but not the depth of burial. Seed predation pressure was low (17.6%) after 4 d and higher in faeces of S. mystax than in faeces of S. fuscicollis. Despite their small size, tamarins could be considered as high-quality seed dispersers, with a potential role for forest regeneration.

We studied the impact of dung deposition by the red howler monkey (Alouatta seniculus), and subsequent burial by dung beetles and other biotic and abiotic processes, on the distribution of small seeds in the soil seed bank (Nouragues Reserve, French Guiana). Seeds were collected from 54 soil samples taken under three sleeping sites and adjoining control sites, at three positions according to a fixed grid and at three different depths (0–2, 2–4 and 4–6 cm). Despite large differences between the three sites, defecation areas (latrines) were found to contain more seeds and higher seed diversity than control areas. Seed density decreased with depth in the top 6 cm in two sites but not in the third. Shannon diversity decreased with depth in both defecation and control areas. Differences in the distribution of seeds of different species were found according to size and growth habits (pioneer vs non-pioneer species). The viability of seeds, ascertained from toughness and integrity of the seed coat, varied according to depth, site and defecation. Seed viability was on average higher in defecation areas compared with control areas.

Ecological and temporal factors can influence animal foraging patterns and may obscure our understanding of how native and exotic species interact. To understand how such factors affect foraging, the visitation of native and exotic bees and wasps was observed at nectar feeders within Mexican agroforestry systems, while documenting (1) vegetation management (low-shade vs. high-shade coffee), (2) light and floral resource levels and (3) recruiting ability, as measured by the change in visitation between two consecutive experimental days. On day one, Africanized honeybee visitation was significantly greater in low-shade habitats, and native solitary bee abundance was significantly greater in high-shade habitats, while native social bee and solitary wasp visitation were not significantly different between habitat types. After 24 h, Africanized honeybee visitation increased significantly in both habitat types, while native social bee visitation increased significantly only in high-shade coffee. In contrast, native solitary bee and native solitary wasp visitation decreased in both habitat types. Overall, this study reveals that Africanized honeybees exhibit only initial foraging preference for low-shade habitats, while native bees exhibit both initial and delayed recruitment-based foraging preferences for high-shade habitats.

Several South-East Asian anuran species can breed year-round near the equator (due to abundant rainfall in all months in Singapore, for example) but are limited to a 6-mo breeding season in other areas (including central Thailand). In order to investigate the extent to which such differences in breeding season length are associated with differences in reproductive measures such as clutch size, reproduction of three common species, Polypedates leucomystax, Microhyla heymonsi and Hylarana erythraea, was compared in Singapore and Thailand over a 2-y period. All three species produce nearly twice as many eggs per clutch in seasonal environments compared with aseasonal environments, although annual fecundity may be similar in both environments. In Polypedates leucomystax, increased clutch size and volume are associated with larger female size, but in the other two species female size is unchanged with respect to latitude. In H. erythraea, the increased clutch size in Thailand was observed early in the breeding season; later clutches were not significantly different between sites. Collectively, these data suggest that these widespread species have adapted to shortened breeding season length by increasing clutch size.

The factors that influence food choice have implications for animal survival, reproduction and population growth. We conducted a 1-y study of food choice by four mountain gorilla groups that consumed herbs and fruit at two locations differing spatially and temporally in food availability in Bwindi Impenetrable National Park, Uganda. We collected data on 45 important foods consumed by the gorillas, the availability of those foods in each gorilla group's home range and their corresponding nutrient and phenolic concentrations. Employing a linear multiple regression, we tested three hypotheses regarding the influence of food availability and the nutritional and phenolic concentrations of food on food choice. Regardless of changes in herb availability, the choice of herbs was positively influenced by their abundance and sugar concentrations and negatively influenced by their fibre, condensed tannin and protein concentrations. Furthermore, regardless of changes in fruit availability, the choice of fruit was positively influenced by its abundance and negatively influenced by its condensed tannin concentrations. During periods of low fruit availability, the gorillas did not increase the consumption of herbs high in fibre and sugar. The choice of herbs low in fibre had less of an influence on food choice at the location with lower fruit availability than the other location. Our results underscore the importance of incorporating both availability and nutrient concentrations into studies of food choice; by doing so we found Bwindi gorillas were able to choose abundant, relatively high-quality foods year round.

Photosynthetic responses of 12 species including six fern species (Neottopteris nidus, Microsorum punctatum, Pseudodrynaria coronans, Asplenium finlaysonianum, Paraleptochilus decurrens and Tectaria fauriei) and seedlings of six fig species (Ficus curtipes, F. gibbosa, F. altissima, F. auriculata, F. oligodon and F. hookeriana) in different life forms to lightfleck were investigated, to test whether epiphytes and hemiepiphytes display a slower response to lightfleck and fast induction loss after a lightfleck compared with their terrestrial counterparts, and whether ferns display a slower response to lightfleck and slower induction loss compared to figs. The measurements of functional traits and physiological parameters were determined in a screenhouse of 4% full sunlight. Epiphytic ferns and hemiepiphytic figs had thicker leaves compared with their terrestrial counterparts. Compared with figs, ferns had thicker fronds, larger stomata with a low density, and lower stomatal conductance and photosynthetic capacity; ferns had lower light compensation point and dark respiration rate, conferring a positive carbon gain under low diffuse light beneath the canopy. The induction time to reach 90% maximum net photosynthetic rate (T90) upon the exposure to a saturated light varied strongly among life forms. Epiphytic ferns had slower T90 than terrestrial ferns (19.9–26.3 vs 5.9–16.3 min, respectively), and hemiepiphytic figs had slower T90 than terrestrial figs (13.1–20.4 vs 5.2–7.8 min, respectively). Compared with figs, ferns showed a slower response to lightfleck. Across ferns and figs, the induction time was negatively correlated with initial stomatal conductance. No significant difference in induction loss was found between two life forms within ferns or figs, whereas ferns had a significantly slower induction loss compared with figs. These results showed that the inherent conservative water use strategy of the epiphytes and hemiepiphytes constrain their lightfleck utilization.

Tropical tree wood density is often related to other species-specific functional traits, e.g. size, growth rate and mortality. We would therefore expect significant associations within tropical forests between the spatial distributions of stand-level wood density and micro-environments when interspecific variation in wood density is larger than intraspecific variation and when habitat-based species assembly is important in the forest. In this study, we used wood cores collected from 515 trees of 72 species in a 15-ha plot in northern Thailand to analyse intra- and interspecific variation in wood density and the spatial association of stand-level wood density. Intraspecific variation was lower than interspecific variation (20% vs. 80% of the total variation), indicating that species-specific differences in wood density, rather than phenotypic plasticity, are the major source of variation in wood density at the study site. Wood density of individual species was significantly negatively related to maximum diameter, growth rate of sapling diameter and mortality of saplings. Stand-level mean wood density was significantly negatively related to elevation, slope convexity, sapling growth rate and sapling mortality, and positively related to slope inclination. East-facing slopes had significantly lower stand-level mean wood densities than west-facing slopes. We hypothesized that ridges and east-facing slopes in the study forest experience strong and frequent wind disturbance, and that this severe impact may lead to faster stand turnover, creating conditions that favour fast-growing species with low wood density.

In this study we examined the size-structures and allometric relationships between height and diameter over 2 y in populations of the pioneer tree Trema micrantha on a large landslide (Casita Volcano, Nicaragua). The landslide comprised three different zones (erosional, depositional and transitional) based on fertility and geomorphological stability. We attempted to analyse the development of canopy hierarchies and intraspecific competition, and the existence of different growth strategies, within the T. micrantha populations of the different landslide zones. Vegetation was surveyed in 2810 × 10-m plots in which a total number of 307 T. micrantha individuals were recorded and tagged. In the depositional zones, size-hierarchies and one-sided competition for light were apparent and, among the short stems (0.0–2.5 m) of the understorey, plastic responses to shade consisting in a marked increase in height in relation to diameter were evident. In the erosional zones, size-hierarchies were not apparent. All stems were small and, among them, the shortest ones (0.0–1.0 m) were dead whereas the tallest (>1.5 m) grew slowly, increasing their diameter to a greater extent than their height. Our study shows that T. micrantha individuals developed different growth strategies in the different areas of the landslide and suggests that this species allocates resources to growth and survival differently depending on environmental conditions. Trema micrantha is a highly versatile species capable of dealing not only with extremely infertile substrates and conditions of high light availability, but also with partially shaded environments such as those in secondary forests.

We developed allometric relationships between tree size parameters (stem diameter at breast height (dbh), at ground surface (D0) and tree height) and leaf, stem, small-root (diameter <5 mm) and total root biomass in various tropical secondary-forest trees in Sarawak, Malaysia. In total, 136 individuals from 23 species were harvested to measure above-ground parts. Root systems of 77 individuals of 16 species were also excavated. The coefficients of correlation for the obtained allometric relationships between tree diameter and plant-part biomass showed high values, ranging from 0.83 to 0.99. In addition, there were few interspecific differences in relationships for all biomass parts, except for leaves. We also found relatively high coefficients of allometric relationships between tree height and plant-part biomass ranging from 0.83 to 0.94. Comparison of above- and below-ground biomass equations for various tropical rainforests implies that our allometric equations differ largely from the equations for tropical primary forests. Thus, choosing both above- and below-ground allometric equations for biomass estimation in tropical secondary forests of South-East Asia requires careful consideration of their suitability.

Above-ground biomass (AGB) is increasing in most of the Amazon forests. One hypothesis is that forests are responding to widespread and intense human intervention prior to the European conquest (>500 y ago). In this study we confront this hypothesis with changes in AGB over 6.3 y in a large western Amazonian forest plot (>150 000 shrubs and trees and 1100 species with dbh ≥ 10 mm in 25 ha). We examined AGB flux in different habitats and across diameter classes. The forest lost small stems (4.6%), gained large trees (2.6%), and gained biomass (0.7%). The change in AGB stock was due entirely to this upward shift in size leading to more canopy trees and fewer saplings after just 6 y. Across habitats, the biggest increment in biomass was in the secondary-forest patch (3.4% y−1) which we know was cleared about 27 y ago, whereas mature forest on ridges and valleys had small increases (0.10% and 0.09% y−1, respectively). In both censuses, AGB stocks were >50% higher on the ridge than in the valley while relative growth and mortality were higher in the valley. Mean wood specific gravity (WSG) decreased with increasing diameter class; WSG did not change much between censuses in mature forests and did not contribute to the change in AGB stocks. Our forest increased its standing biomass, but far less than the average reported for other Amazonian forests (i.e. 0.30 vs. 0.98 Mg ha−1 y−1). We find no evidence to support the notion that this forest is recovering from long-past human intervention. Instead of a long-term recovery, we believe the forest changed in response to natural fluctuations of the environment (e.g. changes in precipitation, higher CO2), windstorms or other more recent events. The significant differences in AGB stocks between valley and ridge suggest that the terra firme forests are a mosaic of natural habitats, and that this mosaic is in part responsible for the variation in biomass stocks detected in Amazonian terra firme forests.

Resumen: La biomasa aérea de la mayoría de los bosques amazónicos está incrementando. Una hipótesis es que los bosques están respondiendo a un disturbio humano intenso y ampliamente distribuido, anterior a la llegada de los conquistadores europeos (>500 años atrás). En este estudio se confronta esta hipótesis con los cambios en biomasa encontrados en 6.3 años en una parcela de gran escala de la Amazonia occidental (>150.000 arbustos y árboles con diámetro a la altura del pecho ≥10 mm y 1100 especies en 25 ha). Los resultados se examinan por categorías de diámetro y hábitat. En este período el bosque perdió tallos pequeños (4.6%), ganó árboles grandes (2.6%) y ganó biomasa (0.7%). La ganancia en biomasa fue debida enteramente al incremento de árboles de gran tamaño que significó más árboles de dosel y menos juveniles en apenas 6 años. Entre los hábitats, el mayor incremento en biomasa se encontró en un parche de bosque secundario de colina (3.4%/año), cuya edad es de 27 años, mientras el bosque maduro de las colinas y los valles incrementó escasamente (0.10% y 0.09%/año, respectivamente). Tanto al inicio como al final del estudio, el stock de biomasa fue >50% más grande en la colina que en el valle mientras que el crecimiento y la mortalidad relativa fueron mayores en el valle. La media de la gravedad específica de la madera (GEM) fue menor a mayor clase diamétrica; en el bosque maduro, el cambio en la GEM fue insignificante y no contribuyó al aumento en stocks de biomasa. El bosque incrementó la biomasa aérea pero mucho menos que el promedio reportado para otros bosques amazónicos (i.e. 0.30 vs. 0.98 Mg ha−1/año). No se encontró evidencia que apoye la noción de que el bosque se está recuperando de un disturbio de gran escala ocurrido en el pasado. En su lugar, se cree que el bosque cambió en respuesta a fluctuaciones naturales del ambiente (e.g. cambios en precipitación, mayor concentración de CO2), vendavales u otro tipo de eventos más recientes. La diferencia significativa en los stocks de biomasa encontrada entre el valle y la colina sugiere que la tierra firme es un mosaico de hábitats naturales y que este mosaico podría explicar en parte la variación encontrada en los stocks de biomasa de bosques amazónicos de tierra firme.

Knowledge of the population dynamics of tropical trees has expanded considerably in the past 20 years. An important observation deriving from these investigations is the confirmation that population behaviour varies both in time and space. A tool recently developed to evaluate the potential for variation in vital rates, and therefore in population growth rate, is variance-standardized perturbation analysis (VSPA). In this paper we report the results of a 2-y demographic analysis of a population of the tropical tree Manilkara zapota in a subtropical rain forest in the Mexican state of Veracruz, in which variance-standardized perturbation analysis was applied and compared with the results of the traditional elasticity analyses. To build population projection matrices, we tagged and followed a sample of 91 juvenile and adult individuals, and 635 seedlings. We subdivided the sample in nine size classes (defined by tree height and dbh; as well as leaf size, in the case of seedlings) and estimated transition probabilities and fecundity for each class. The demography of M. zapota varied greatly from the first to the second year of study (in 1998–1999, λ = 0.987, while in 1999–2000, λ = 1.038) due to negligible seed production during the first year and a massive reproductive event during the second. The largest elasticity values for both years corresponded to persistence of large juveniles and adults. Although the fecundity entries showed very low elasticity values, the variance-standardized perturbation analysis revealed the importance of these matrix entries; transition to larger categories and retrogression to smaller ones of saplings and juveniles were also important demographic processes contributing to variation in λ according to the VSPA. Thus, although the results of elasticity analysis and VSPA were similar for the 1998–1999 matrix, they differed substantially for the 1999–2000 matrix. In the latter, the VSPA enhanced the importance of demographic processes that are intuitively relevant for the population studied. This points toward the necessity of further exploring the use of VSPA, since it offers several advantages over the traditional elasticity analysis: it concentrates on the impact on λ of vital rates that actually vary, and the interpretation of the results is more realistic and straightforward.

Temporal niche partitioning can be a viable mechanism for coexistence, but has received less attention than other niche axes. We characterized and compared patterns of activity, and overlap of temporal activity among the five common rodent species from a tropical semideciduous forest (TSF) and between the two common rodent species from cloud forest (CF) at El Cielo Biosphere Reserve in Mexico. Capture frequencies over 2-h intervals, obtained via live trapping (6850 trap-nights) in chosen months over 3 y formed the empirical basis for analyses. Trap transects were set from 19h00 to 07h00 and checked every 2 h. Analyses of 484 captures evinced two distinct assemblages. The TSF assemblage was diverse and with non-random temporal niche segregation, whereas the CF assemblage was depauperate with its two dominant species evincing the same activity pattern. Predator avoidance between open- and closed-microhabitat species, as well as niche complementarity may explain temporal segregation at TSF. This is the first documentation of assemblage-wide non-random temporal segregation of neotropical rodents. Time of activity may be a largely under-appreciated mechanism in other species-rich tropical rodent assemblages as well as in other species-rich biotas.

Deforestation rates in South-East Asia are among the highest of any tropical region, with expansion of oil palm being one important factor. Despite this, few studies have investigated the impact of oil palm expansion on the arthropod fauna. We report here the first study on the impact of forest conversion to oil palm on overall arthropod abundance, biomass and composition. We compared arthropod abundance and biomass, collected from epiphytic bird's nest ferns, the canopy, and leaf litter between primary forest, logged forest and oil palm plantation. Epiphytes, canopy and litter all contained a lower abundance (epiphytes: 67.2%, canopy: 2.3% and litter: 77.1% reduction) and biomass (epiphytes: 87.5%, canopy: 37.9% and litter: 72.4% reduction) of arthropods in oil palm compared with primary forest. However, not all orders of arthropods showed the same level of decline, with some groups having higher abundance and biomass in oil palm, resulting in an altered community composition in the epiphytes and canopy in oil palm compared with forest. Our results show that forest conversion to oil palm impacts detrimentally on invertebrates in all compartments of the forest ecosystem.

It has long been suggested that species might exhibit their highest densities at the centre of their geographic range and decline in density towards their range limits. If true, this pattern would have important implications for ecological theory and for conservation management. However, empirical support for this pattern remains equivocal. Furthermore, most research on this topic has emphasized temperate taxa, as is true of much of ecology. Therefore, we here test for a decline in population density from centre to edge of the geographic range of a tropical taxon, primates. In the literature we found data on 30 species and 27 genera from a total of 115 studies with duration of at least 3 mo. Mixed-effects linear models and Wilcoxon matched-pairs signed-rank tests indicated no centre–edge gradient in primate densities. However, densities were significantly lower in more disturbed sites, independent of position in the geographic range.

Population structure and dynamics of the black-cheeked gnateater (Conopophaga melanops) were studied at Salto Morato Nature Reserve, in Paraná, southern Brazil, from October 2006 to September 2007. Territory size and population density, breeding season (timing and length), reproductive success and annual survival rates were estimated from sightings of 18 marked adult birds and the success of 18 nesting attempts. The black-cheeked gnateater is socially monogamous and territorial, with a breeding-season length of approximately 3 mo beginning in early October. Predation caused most nest failures, nest survival was 0.96 d−1 and apparent annual nesting success was 22%, resulting in annual productivity of 0.36 individuals per adult. Apparent adult annual survival was ~0.44 y−1. Seventy-five per cent of fledglings survived at least 2 mo after fledging. Two methods of estimating population growth rate suggest very different rates: r = −0.04 (~ stable), or λ varies between 0.475–0.616 (declining). Yet, low apparent adult survival suggests that territories are not permanent, perhaps abandoned after nest failure. We find that by estimating population growth, even in short-term studies, testable hypotheses can be generated that will allow better understanding of population dynamics.