High Adult Densities Research Articles

Factors affecting fruit damage caused by Thrips hawaiiensis (Morgan) (Thysanoptera: Thripidae) in citrus lemon groves in Turkey

The Hawaiian flower thrips, Thrips hawaiiensis (Morgan) (Thysanoptera: Thripidae) is an economically important invasive species in citrus grown in the eastern Mediterranean region of Turkey. The diverse impacts of temperature on arthropods are well documented. This study was conducted with the aim of determining the influence of day-degree on insect population dynamics and crop damage levels in Mersin Province, Turkey during 2018–2019. In 2018, the first damage caused by T. hawaiiensis was observed at 300 degree-days (DD), while in 2019, it occurred at 800 DD. The damage percentage was recorded as 28% in the lemon grove, where the population of second instar larvae briefly reached a high level (approximately 2 individuals per fruit). During 2019, the average temperature remained relatively low, and the initial population density of thrips was below the 33-day development threshold (10.4 °C) from January to April. This pattern was observed even during the mild spring season. Additionally, in both sampling locations, the high adult densities, mainly adult females, led to the shedding of a limited number of flowers that had formed in June.

High densities of large tuaki, the New Zealand cockle Austrovenus stutchburyi, provide a post-settlement predation refuge for conspecific juveniles

Bivalves are ecosystem engineers, and their effective management relies on a full understanding of the mechanisms that influence population dynamics. Juvenile tuaki (New Zealand cockle) Austrovenus stutchburyi, a numerically dominant and ecologically important bivalve in New Zealand estuaries, were found at higher densities when surrounded by high densities of large adults within Waitati Inlet, in southern New Zealand. Consequently, we hypothesised that adults provided a refuge from predation for juveniles, resulting in higher juvenile survival and retention in dense beds. The observed pattern was consistent with post-settlement Allee effects, where declines in density and truncated size distributions may have resulted in unsuccessful recruitment if a density threshold was reached. Field experiments were undertaken in 2020 and 2021 to test the potential sheltering effect of adults on retention and survival of juveniles, with and without the addition of organic loading of sediments. Presence of adults had significant effects on juvenile retention and interaction with organic loading in 2020, but not in 2021. To isolate the effects of adult presence on predation of juveniles, a series of laboratory experiments were carried out using the predatory crab Ovalipes catharus. Juvenile survivorship from crab predation was enhanced in the presence of large adults, consistent with the hypothesised sheltering effect. Further, predation rates increased significantly from winter to summer, which correlated with increasing water temperatures and the breeding and moult cycle of crabs. These findings across surveys, field and laboratory manipulations have significant implications for effective fisheries management and restoration of bed-forming bivalves.

Structure of reef-building corals in tidal pools of a Marine Protected Area on the coastal zone of Royal Charlotte Bank, Eastern Brazil

ABSTRACT Brazilian coral reefs are the largest and richest reefs in the Southwestern Atlantic Ocean. Despite their historical and tourist importance, coral reefs on the east coast of Brazil remained unknown until recently. This study evaluated the structure of the reef-building coral community in three tidal pools along a gradient of anthropogenic disturbance. The pool known as Dolphin Pool is the warmest and has a high abundance of stony coral Siderastrea spp. One endemic species is on the national list of threatened species. Despite the high frequency of water temperatures above the alert threshold for mass bleaching events, the tidal pools have high densities of adults and recruits of reef-building corals. The results highlight the importance of reef formations on the coastal zone of the Royal Charlotte Bank, given the uniqueness of this area, and reinforce the need for further research and adoption of adaptive conservation approaches.

The population fluctuation of European grapevine moth, Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae) in a vineyard in Antalya

European grapevine moth, Lobesia botrana (Denis & Schiffermüller) (Lepidoptera: Tortricidae) is the most serious pest of vineyards on a worldwide scale. The study aimed to determine the adult and larval population fluctuations and the generation number for the control of the L. botrana. The present study was conducted in a 1 ha vineyard in Serik district of Antalya province during 2014 and 2015. After the first adult in traps, adult and larval population of pest monitored, weekly. The study findings revealed that L. botrana adults were initially observed in nature in mid-March and remain active for almost eight months in both years. The second peak in the adult count was observed on June 2 and June 12, in 2014 and 2015, respectively. The highest adult density was observed on July 7, 2014 (72.5 adults trap-1) and July 14, 2015 (54 adults trap-1)) during the third peak. The highest larval count was determined on July 14, 2014 (1.72 larva bunch-1) and on July 22, 2015 (1.45 larva bunch-1). The data obtained show that L. botrana gives four full generations in Antalya province conditions. Based on the data, it could be suggested that pest population could partially generate a fifth generation in September. It is recommended to consider the determined second and third peak dates in the pest control strategy in Antalya province.

Population development of Acanthiophilus helianthi (Rossi) (Diptera: Tephritidae) On Five Different Safflower Varieties in Van, Turkey

Acanthiophilus helianthi (Rossi, 1794) (Diptera: Tephritidae) also known as safflower fly, is an oligophagous species that cause significant damage to safflower plants. Safflower Carthamus tinctorius (L.) (Asterales: Asteraceae) plant, which is among its hosts, is an important energy plant whose cultivation has increased in recent years in our country resistant to drought and has high adaptability. This study investigated the population growth of A. helianthi on different safflower varieties (Asol, Ayaz, Balcı, Dinçer and Göktürk) in Van Yuzuncu Yıl University, Faculty of Agriculture for two years (2019-2020) in Van province. Result of the study, it was determined that the pest showed a similar population change in both years, the adult individuals were seen at the end of June - mid-August, and their pupae from this date to the beginning of September. It was seen that the insect density was statistically different between the varieties at different sampling dates and the highest adult density was found in Asol pupae in both years, and in Göktürk variety. It was determined that Ormyrus sp. (Hymenoptera: Ormyridae), Microdontomerus annulatus (Spinola, 1808) (Hymenoptera: Torymidae), Eurytoma acroptilae (Zerova, 1986) (Hymenoptera: Eurytomidae) and Bracon sp. (Hymenoptera: Braconidae) are essential parasitoids of A. helianthi and show different densities on varieties. It has been observed that thorn, color, vegetative development, climatic factors, and parasitoids play an active role in the population development of safflower cultivars.

Phenology, population size, and factors influencing variation in density of an endangered butterfly, the mottled duskywing Erynnis martialis

Understanding the natural history and ecology of endangered species is critical for developing effective, evidence-based conservation and management plans. The mottled duskywingErynnismartialisis a skipper butterfly inhabiting oak savanna, oak woodlands, alvars, and tallgrass prairie habitats containing their host plants,Ceanothusspp. Listed as endangered in Canada, few populations persist in Ontario and Manitoba, but there are no formal estimates of population size or what influences spatial variation in adult density, and we have limited knowledge of phenology. To address these knowledge gaps, we conducted spatially explicit mark-re-sighting over multiple years at 2 of the largest known populations in Ontario (specific locations withheld). Population sizes at Site A were estimated to be 1159 individuals (confidence limit [CL] = 845-1598) in 2021 and at Site B, 626 individuals (CL = 466-851) in 2020 and 2227 individuals (CL = 1110-4463) in 2021. Most (81%) re-sightings occurred within 5 d of marking, suggesting that adults likely live less than 1 wk. High densities of adults were generally associated with highCeanothusspp. abundance and open canopy, but relationships varied by site and year. Peak flight across sites and years ranged from 5-13 June. We recommend that existing and prospective habitat managers prevent succession with brush-cutting and/or prescribed burns, specifically in areas of abundantCeanothusspp. This work provides valuable information for future management and recovery efforts, including planned translocations to both historically occupied and newly restored sites.

Social stratification reflected in bone mineral density and stature: Spectral imaging and osteoarchaeological findings from medieval Norway.

This study presents skeletal material from five medieval burial sites in Eastern Norway, confined to one royal burial church, one Dominican monastery, and three burial sites representing parish populations. We combine osteological analysis and Dual Energy X-Ray Absorptiometry, studying the remains of 227 individuals (102 females and 125 males) employing young, middle, and old adult age categories. The aim is to assess bone mineral density as a skeletal indicator of socioeconomic status including stature as a variable. We detected that socioeconomic status significantly affected bone mineral density and stature. Individuals of high status had higher bone mineral density (0.07 g/cm2, p = 0.003) and taller stature (1.85 cm, p = 0.017) than individuals from the parish population. We detected no significant relationship between young adult bone mineral density and socioeconomic status (p = 0.127 and 0.059 for females and males, respectively). For males, high young adult bone mineral density and stature varied concordantly in both status groups. In contrast, females of high status were significantly taller than females in the parish population (p = 0.011). Our findings indicate quite different conditions during growth and puberty for the two groups of females. The age-related pattern of bone variation also portrayed quite different trajectories for the two socioeconomic status groups of both sexes. We discuss sociocultural practices (living conditions during childhood and puberty, as well as nutritional and lifestyle factors in adult life), possibly explaining the differences in bone mineral density between the high-status and parish population groups. The observation of greater differences in bone mineral density and stature for females than males in the medieval society of Norway is also further discussed.

Continuous egg separation of the copepod Acartia tonsa. Implications for increasing adult density at an intensive level

The concept of continuous egg and adult separation was studied to evaluate the possibility of cultivating the copepod Acartia tonsa at high density (> 2.5 adults mL−1). First experiment: Densities of 5, 10, 15, 30, and 45 adults mL−1 were evaluated. For this, eggs spawned were allowed to settle quickly, harvested, and counted to determine the specific and relative egg production (SEP and REP, eggs female−1 day−1 and eggs mL−1 day−1, respectively). Second experiment: Mature females were spawned on slides to observe the shape of the freshly spawned eggs. Third experiment: respiratory rate under four corporal velocities in the filter system were evaluated (57, 115, 173 and 231 PL min−1; PL, prosome length), corresponding to four water exchange rates (50, 100, 150 and 200 volumes day−1). Fourth experiment: A high-density (7 adults mL−1) prototype based on continuous egg separation was designed and compared with daily egg harvest for siphon (control system). The specific egg production (SEP, egg female−1 day−1) and relative egg production were determined (REP, eggs mL−1 day−1). The SEP decreased with culture density (p < .05), but quickly egg separation allowed a high REP when a density of 10 adults mL−1 was used. Freshly spawned eggs were elongated for the first 7 min, which suggests fragility when freshly spawned. Water velocity increased adult respiratory rate (p < .05), and egg production reached a maximum at 100 volumes per day (p < .05). The above suggested a great potential to increase egg production at a high adult density (>2.5 mL−1), which was confirmed by higher REP in the prototype (100 eggs mL−1 day−1) than in the control system. This study contributes to intensive A. tonsa culture; a superior density of 5 mL−1 is possible with a high water exchange rate and careful egg harvesting.

An evaluation of strategies for restoring a degraded New Zealand scallop fishery using stochastic dynamic simulation modelling

A decision-theoretical approach was used to evaluate strategies to rebuild a severely depleted scallop (Pecten novaezelandiae) populations in the Tasman Bay and Golden Bay of New Zealand. These strategies were: no intervention, cessation of seabed bottom contact fishing, and reduction of sediment and nutrient runoff from surrounding land through on-farm practices. Our approach combined outputs of estimated effects of on-farm practices on erosion and nutrient reduction with a stochastic dynamic model of the scallop populations. The most effective individual intervention is eliminating bottom contact fishing through dredging and trawling which increased scallop biomass on average by 73% compared to the no intervention scenario. Although on-farm practices have reduced sedimentation and nutrient runoff significantly (28–36% and 2%, respectively), they have no effect on scallop biomass if implemented individually and led to only marginal improvements in scallop biomass if implemented alongside cessation of bottom contact fishing (2–4%). Although our results showed, on average, substantial recovery in the scallop population when reducing seabed bottom contact and water pollution, the large uncertainty boundaries makes it unclear whether these improvements would be realized. The long-term success of such strategies will depend on the available habitat being able to sustain high densities of healthy scallop adults and recruits, a situation that has been posited in our analysis. Where scallop juvenile survival is compromised by sedimentation, nutrient pollution, or other exogenous influences, proposed interventions may be insufficient to aid recovery.

Spawning Parvocalanus crassirostris at a high adult density: Explaining low adult population numbers and means for improving their intensive culture

In calanoid copepods, intensive culture is preferred, but currently, densities do not exceed a few adults per milliliter. Several explanations exist, but none have allowed increasing the density of adults. This study proposes a new explanation for the problem of adult density in intensive culture, using the copepod Parvocalanus crassirostris as a model. First: eggs (2 h old) were supplied to adults kept at 20 adults mL−1 in 1 L containers with and without microalgae; constant aeration was supplied to determine egg survival to damage caused by the adults. Different samples were taken up to 175 min. Second: A high-density spawning test (5–80 adults mL−1) was performed, using shallow depth (2.5 cm) and supersaturation level of oxygen for rapid egg separation and sufficient oxygen for adults, respectively. The SEP (egg female−1 day−1) and REP (egg mL−1 day−1) were determined. Third: two systems of continuous egg harvesting, filtration and sedimentation, were evaluated under a high density of adults culture (10 adults mL−1). The adults of P. crassirostris quickly damaged the eggs, but the presence of food reduces the damage caused. Adults presented high SEP up to 10 adults mL−1; however, REP increased significantly to more than 170 eggs mL−1 day-1 using densities of 20 and 30 adults mL−1 (p <.05). A continuous harvesting system by filtration generated deformation of the eggs and a lower SEP and REP compared to the passive harvesting system by sedimentation (p <.01). The present study showed that even P. crassirostris, considered herbivore copepod, can damage its eggs. The fragility of newly spawned eggs (without hardened chorion) can generate difficulties when increasing adult density in culture. This new explanation contributes to the generation of new egg harvesting strategies in calanoid copepods of aquaculture importance.

Spatiotemporal Variation in the Magnitude of Reproduction by Invasive, Pelagically Spawning Carps in the Illinois Waterway

AbstractThe relationship between the magnitude of reproduction and adult density of pelagically spawning carp (PSC) species (bigheaded carp Hypophthalmichthys spp., Grass Carp Ctenopharyngodon idella, and Black Carp Mylopharyngodon piceus) and the influence of environmental factors on this relationship are valuable information for management and control of these highly invasive cyprinids. Six years of standardized monitoring for PSC reproduction and adult density in navigation pools of the Illinois Waterway (IWW; the Illinois River and its connection to Lake Michigan through the Des Plaines River and Chicago Area Waterway System), in conjunction with removal efforts in the upper IWW, where there is limited fish movement between pools, provided an opportunity to deepen our understanding of factors affecting the reproductive productivity of this invasive assemblage. Reproductive activity most commonly occurred in May and June, with the magnitude of reproduction in June far exceeding that occurring in other months. The highest egg counts were found within a 72‐km zone containing the hydromorphological transition between the upper and lower Illinois River, with the majority of PSC larval drift occurring below this zone in the lower Illinois River. Magnitude of reproduction increased nonlinearly with adult PSC density, declining at high adult densities. Annual egg counts were also higher in years that combined more variable spring discharge with higher accumulated degree‐days through June. The density‐dependent reproduction exhibited by PSC implies that any stock–recruitment variation observed for these species needs to be interpreted cautiously before being ascribed to environmental factors affecting survival from hatching to juvenile stages. An increased understanding of which life stages of PSC are subject to density dependence can refine projections of how these species respond to harvest and other control measures.

Unique reproductive biology of the broadcasting sea cucumber Holothuria floridana: facultative recruitment on adults inside nursery grounds

ABSTRACT Information on newly settled juveniles and recruitment processes in sea cucumbers is sparse for most commercial species, impeding protection of nursery habitats, which are key to management. Here, the ecology of early life stages of Holothuria floridana was investigated. In laboratory experiments, females released a small number of oocytes, which underwent abbreviated lecithotrophic development. During broadcast spawning, some of the negatively buoyant and sticky oocytes settled on the adults where they remained anchored up to the pentactula stage (encapsulated). Several wild adults collected in the Placencia Lagoon (Belize) each hosted ~2 propagules (eggs, blastulae, pentactulae, juveniles). The nursery habitat was characterized by high adult density, shallow seagrass beds close to mangroves, and mud dominated substrata. The present work illustrates a unique facultative offspring-adult association in a free-spawning lecithotrophic species of Holothuroidea, possibly representing a hybrid state between broadcasting and external brooding. This uncommon reproductive feature may ensure successful local recruitment in one of the most competitive habitats of the tropical Americas, where predation pressure is likely to be very high.

Feeling the Squeeze: Adult Run Size and Habitat Availability Limit Juvenile River Herring Densities in Lakes

AbstractMaximum densities of juvenile river herring (Alewife Alosa pseudoharengus and Blueback Herring A. aestivalis) vary among freshwater lakes, likely due to densities of adult spawners. Differences in habitat availability and lake water quality may also contribute to variation in juvenile river herring productivity between populations, yet these relationships have not been tested across a large geographic scope. In this study we investigated relationships between juvenile river herring densities and (1) spawning adult river herring densities, (2) lake habitat availability, and (3) lake water quality in 29 freshwater lakes in the northeastern USA. Purse seines were used at night to sample juvenile river herring monthly in June–August 2014 and 2015, with concurrent collection of lake‐specific physical (e.g., lake surface area, mean depth, depth to thermocline), chemical (e.g., nitrogen, phosphorus, dissolved organic carbon [DOC]), and biological (chlorophyll a, adult spawning density) data. Spawning adult density (number of adults per surface area of lake) explained 66.6% of the variation in juvenile densities using a generalized additive model. Juvenile densities increased with increasing adult density, peaking at roughly 1,000 adults/ha, and then declined at higher adult densities, suggesting a limit to carrying capacity in juvenile production. Linear mixed‐effects models revealed that differences in water quality and habitat across lakes explained additional variation in juvenile densities. Specifically, DOC was negatively related to juvenile densities, suggesting that DOC limits the amount of suitable, well‐oxygenated epilimnion habitat available to juvenile river herring in late summer. Our results can be used to help understand expected juvenile production based on adult density within a lake, to inform expectations about juvenile growth and survival, and to understand the mechanisms for how changes in habitat availability and water quality affect river herring populations.

How many generations does Epischura baikalensis (Copepoda, Calanoida) have in Lake Baikal?

Abstract Epischura baikalensis Sars is a dominant pelagic species of the Lake Baikal zooplankton. We empirically determined the duration of the development of Epischura from field data, as it is not possible to determine this experimentally. Based on our data, we conclude that the central pelagic food web of metazoan species in Lake Baikal has not two, as was previously accepted, but three generations during a year and each lasts not 6 but instead 3 to 4 months. The life cycle of the species also possibly includes a 3-months long winter embryonic diapause, starting in November and ending in late February with the start of the under-ice algae bloom. The high nauplii density in spring is not the result of high adult density, suggesting the presence of resting eggs in the E. baikalensis life cycle. We also found a large morphological difference between the pelagic eggs of the species in the winter and in the summertime. The possible participation of diatom algal toxins in the regulation of the seasonal dynamics of their main consumer in Lake Baikal, similar to those known in marine ecosystems, is discussed. The population dynamics in a year with relatively low diatom algae density show four peaks of reproduction, i.e., in February, June, September, and December. In years with significant (more than 15 000 cells/l) diatom blooming we found mass mortality of E. baikalensis juveniles in the plankton, with only two clear peaks of nauplii density. A negative correlation was found between the number of population density peaks for E. baikalensis and the spring-blooming of diatom algae.

Tree species traits affect which natural enemies drive the Janzen-Connell effect in a temperate forest

A prominent tree species coexistence mechanism suggests host-specific natural enemies inhibit seedling recruitment at high conspecific density (negative conspecific density dependence). Natural-enemy-mediated conspecific density dependence affects numerous tree populations, but its strength varies substantially among species. Understanding how conspecific density dependence varies with species’ traits and influences the dynamics of whole communities remains a challenge. Using a three-year manipulative community-scale experiment in a temperate forest, we show that plant-associated fungi, and to a lesser extent insect herbivores, reduce seedling recruitment and survival at high adult conspecific density. Plant-associated fungi are primarily responsible for reducing seedling recruitment near conspecific adults in ectomycorrhizal and shade-tolerant species. Insects, in contrast, primarily inhibit seedling recruitment of shade-intolerant species near conspecific adults. Our results suggest that natural enemies drive conspecific density dependence in this temperate forest and that which natural enemies are responsible depends on the mycorrhizal association and shade tolerance of tree species.

Genetic and Spatial Structuring of Populus tremuloides in a Mixed-Species Forest of Southwestern Utah, USA

Populus tremuloides Michx. (aspen) is an iconic species of the southwestern United States, where it is known for its extensive clonality. The size of clones and pattern of clonal distribution within and among stands can provide important clues to the species' evolution and ecology, but there are very few studies that have conducted the type of sampling necessary to define these features. We examined the genetic composition and habitat associations of aspen in a mixed-species forest in Cedar Breaks National Monument on the Markagunt Plateau, southwestern Utah. Genetic analysis of 94 stems ≥1 cm diameter at breast height (dbh) selected from a population census of 2742 stems within a contiguous 13.64-ha plot revealed 2 spatially cohesive triploid genets and 2 diploid genets (all differing in 8 to 15 alleles). Aspen abundance within the 13.64 ha varied between 0 and 634 stems/ha across 8 distinct habitat types. Regenerating aspen stems (1 cm ≤ dbh < 5 cm) varied between 0 and 112 stems/ha, with higher levels of regeneration in habitats with greater aspen dominance relative to other tree species. Recent regeneration may have been stimulated by a Dendroctonous rufipennis outbreak in the 1990s, which killed a high proportion of Picea engelmannii. Even though the visual impression is of a single aspen clone, the 4 identified genets suggest a higher-than-expected level of genetic diversity in this mixed-species stand which may confer resilience to increasing climate variability and drought. Furthermore, aspen regeneration in areas of both low and high adult aspen densities show that these mixed stands can support vigorous aspen populations.

Intergenerational paternal effect of adult density in Drosophila melanogaster.

Notwithstanding recent evidences, paternal environment is thought to be a potential but unlikely source of fitness variation that can affect trait evolution. Here we studied intergenerational effects of males’ exposure to varying adult density in Drosophila melanogasterlaboratory populations.We held sires at normal (N), medium (M) and high (H) adult densities for 2 days before allowing them to mate with virgin females. This treatment did not introduce selection through differential mortality. Further, we randomly paired males and females and allowed a single round of mating between the sires and the dams. We then collected eggs from the dams and measured the egg size. Finally, we investigated the effect of the paternal treatment on juvenile and adult (male) fitness components.We found a significant treatment effect on juvenile competitive ability where the progeny sired by the H‐males had higher competitive ability. Since we did not find the treatment to affect egg size, this effect is unlikely to be mediated through variation in female provisioning.Male fitness components were also found to have a significant treatment effect: M‐sons had lower dry weight at eclosion, higher mating latency, and lower competitive mating success.While being the first study to show both adaptive and non‐adaptive effect of the paternal density in Drosophila, our results highlight the importance of considering paternal environment as important source of fitness variation.

Extremely High Biting Densities of Aedes albopictus (Skuse) (Diptera: Culicidae) at a University Campus in Nagasaki, Japan.

Aedes albopictus (Skuse) transmits several arboviral diseases. This mosquito was the vector responsible for both the past and recent dengue outbreaks in Japan. Sites with a high density of A. albopictus are at risk of outbreaks of arboviral diseases. This study describes extremely high biting densities of A. albopictus at a campus of Nagasaki University, southwestern Japan. In August of 2015 and 2016, an 8 min human-bait-sweep collection obtained on average 33.4 and 38.9 females, respectively. In both 2015 and 2016, the highest and the second highest biting densities were observed at sites densely shaded by trees and covered with a large number of understory plants. In addition, major A. albopictus breeding sites were identified near these locations in 2016. A predaceous larval mosquito, Lutzia vorax Edwards, appeared to strongly suppress the breeding of A. albopictus in catch basins near the site with the highest adult density, although its effect was insufficient to maintain A. albopictus density at a low level. After the catch basins had been cleaned, A. albopictus immatures became more abundant, especially in shallow catch basins in shaded sites.

Density-dependent adult recruitment in a low-density tropical tree

The Janzen-Connell hypothesis is a well-known explanation for why tropical forests have large numbers of tree species. A fundamental prediction of the hypothesis is that the probability of adult recruitment is less in regions of high conspecific adult density, a pattern mediated by density-dependent mortality in juvenile life stages. Although there is strong evidence in many tree species that seeds, seedlings, and saplings suffer conspecific density-dependent mortality, no study has shown that adult tree recruitment is negatively density dependent. Density-dependent adult recruitment is necessary for the Janzen-Connell mechanism to regulate tree populations. Here, we report density-dependent adult recruitment in the population of Handroanthus guayacan, a wind-dispersed Neotropical canopy tree species. We use data from high-resolution remote sensing to track individual trees with proven capacity to flower in a lowland moist forest landscape in Panama and analyze these data in a Bayesian framework similar to capture-recapture analysis. We independently quantify probabilities of adult tree recruitment and detection and show that adult recruitment is negatively density dependent. The annualized probability of adult recruitment was 3.03% ⋅ year-1 Despite the detection of negative density dependence in adult recruitment, it was insufficient to stabilize the adult population of H. guayacan, which increased significantly in size over the decade of observation.

Comment on "Plant diversity increases with the strength of negative density dependence at the global scale".

LaManna et al (Reports, 30 June 2017, p. 1389) claim that subadult trees are proportionally less common at high conspecific adult density (CNDD) and that this effect increases toward the tropics and for rare species. We show that the CNDD-abundance correlation may have arisen from a methodological artifact and that a range of processes can explain the reported latitudinal pattern.