Hatching Success Rate Research Articles

Egg production and hatching patterns of Acartia erythraea (Copepoda, Calanoida), with a note on its two egg types, in a eutrophic bay in Korea

Abstract Acartia erythraea, a copepod species commonly found in the summer, was sampled weekly using a conical net, in Gamak Bay (southern Korea) from 19 July to 14 November 2013. Egg production rate (EPR) and hatching success rate (HS) were estimated weekly during the study period, for egg types with distinct surface morphologies, i.e. smooth or spiny. EPR ranged from 1.0 to 25.0 eggs female−1 day−1 with a mean of 12.0 eggs female−1 day−1. The weight-specific growth rate (WSGR) ranged from 0.01 to 0.19 day−1 with a mean value of 0.09 day−1. Of these, all the eggs were smooth until August, whereas spiny eggs were produced from September, and the spiny eggs contributed 88% of the total eggs in November. Both egg types hatched within 12 to 48 h, and the average HS was 80% or higher. The EPR and WSGR were significantly related to water temperature but weakly related to chlorophyll-a concentration. Contrary to previous studies, our findings suggest that it is impossible to determine whether an egg is subitaneous or diapause based on the egg surface structure. Spines on the surface of A. erythraea eggs in Gamak Bay could be an adaptation to seasonal variations and a rapidly changing coastal environment.

The Effects of Vegetation Type on Oedaleus decorus asiaticus (Orthoptera: Acrididae) Oviposition and Hatching Success.

Oedaleus decorus asiaticus (Bei-Bienko, 1941) has been regarded as one of the most dominant locusts in the northern grassland, the adjacent area of agriculture and animal farmland, in China. The aims of this study were to investigate the effects of vegetation type on the oviposition behavior of this pest in an open field and the hatching success of the offspring in the following year. The results showed that vegetation type did have a significant effect on whether any egg pods were laid by O. d. asiaticus. Once the females laid eggs, vegetation type and cage number had a significant effect on the number of egg pods laid. The highest number of egg pods was found in the Cleistogenes squarrosa treatment, followed by Stipa krylovii and then Leymus chinensis, while the Artemisia frigida treatment contained the lowest number of egg pods. The O. d. asiaticus eggs laid in S. krylovii and C. squarrosa treatments had a significantly higher hatching success rate (over 53%) than the other two grasses (below 40%). In short, habitats with C. squarrosa and S. krylovii grasses are likely to be preferred by ovipositing females, thus population monitoring efforts of O. d. asiaticus should focus on these habitats.

Long-term monitoring of marine turtle nests in northeastern Brazil

Abstract: This study monitored marine turtle nests in a region known as the Potiguar Basin, which stretches from the northern region of Rio Grande do Norte State (5°4’1.15” S, 36°4’36.41” W) to eastern Ceará State (4°38’48.28” S, 37°32’52.08” W) in Brazil. We collected data from January 2011 to December 2019 to identify species of sea turtles that spawn in the basin, to analyze the nesting spatial-temporal pattern and nests characteristics, and to record effects of environmental and anthropic factors on nests. A field team examined sea turtle tracks and nests signs. Turtle clutches were monitored daily until hatchings emerged from the nests. We monitored nests of hawksbill (Eretmochelys imbricata; n = 238) and olive Ridley turtles (Lepidochelys olivacea; n = 103). The nesting season for E. imbricata occurred between December and May and for L. olivacea from March to August. Hawksbills had clutch size, incubation time, number of unhatched eggs, and dead hatchlings higher than olive Ridley turtles; nevertheless, they presented lower hatching success. Precipitation between 0 and 22 mm and relative humidity (RH) higher than 69% increased the hatching success rate for E. imbricata; however, rainfall above 11 mm and RH 64% had the same effect for L. olivacea. Signs of egg theft and human presence (e.g. vehicle traffic and plastic residues on the beach) were recorded and are considered threats to nests. The results of our long-term monitoring study in the Potiguar Basin provide basis for the implementation of mitigation measures and adoption of management policies at nesting beaches in this Brazilian region.

Lack of trade-offs in host offspring produced during fecundity compensation.

Host-parasite coevolution may result in life-history changes in hosts that can limit the detrimental effects of parasitism. Fecundity compensation is one such life-history response, occurring when hosts increase their current reproductive output to make up for expected losses in future reproduction due to parasitic infection. However, the potential trade-offs between this increase in quantity and the quality of offspring have been relatively unexplored. This study uses the trematode, Schistosoma mansoni, and its snail intermediate host, Biomphalaria glabrata, to better understand how this host life-history response, fecundity compensation, impacts host reproduction. Measures of host reproductive output as well as offspring hatching success and survival were collected to assess the reproductive consequences of infection. Infected snails exhibited fecundity compensation by increasing the number of eggs laid and the overall probability of laying eggs compared to uninfected snails. Parental infection status did not play a significant role in hatching or offspring survival to maturity. Offspring from a later reproductive bout demonstrated a higher hatching success rate. Overall, the lack of an apparent trade-off between quantity and quality of offspring suggests that infected parental snails invest more resources towards reproduction not only to increase reproductive output, but also to maintain the fitness of their offspring, possibly at the expense of their own longevity.

Effects of temperature and salinity on egg development and larval settlement of an invasive ascidian species, <i>Herdmania momus</i> (Savigny, 1816)

The effects of temperature and salinity on egg development and settlement of the ascidian Herdmania momus were investigated. Adult specimens were collected from the Dodu Yacht facility in Jeju Island, Korea (33°30′30.54″N, 126°27′55.46″E) in August 2018. Egg development and larval settlement were observed and recorded at 8 h intervals using a stereomicroscope, under nine temperature (10, 13, 16, 19, 22, 25, 28, 31, and 34°C), and four salinity regimens (28, 30, 32, and 34 psu). The highest hatching rate (82.8±7%) was observed at 32 psu and 25°C and the lowest hatching rate (1.0±2%) was at 34 psu and 13°C. The developmental rate (0.222±0.0994) was highest at 28 psu and 28°C, and lowest (0.016±0.008) at 30 psu and 13°C. The highest settlement success rate (77.1±5%) was at 32 psu and 25°C and the lowest (0.1±1.0%) was at 30 psu, and 13°C. The rate of settlement (0.080±0.000) was highest at 28 psu and 28°C, and lowest (0.013±0.000) at 30 psu and 13°C. Both hatching and settlement success rates increased as temperature increased and tended to decrease beyond an optimal temperature range. Herdmania momus preferred 30-34 psu salinity and 22-25°C temperature. This study provides baseline information about the life history of H. momus, and important data to control the damage caused by the increase in number and distribution of this invasive ascidian.

The Effect of Invertebrate Infestation on Green Turtle (<i>Chelonia mydas</i>) Nests on Kazanlı Beach, Mersın, Turkey

In this study invertebrate infestation in green turtle (Chelonia mydas) nests were recorded for the first time for Kazanlı beach, Mersin, Turkey. For this aim, in 2006 nesting season, 294 natural intact green turtle nests were sampled to examine their contents and invertebrate infestation was found in 76 (25.85% of the total sampling green turtle nests). These infested nests were examined in terms of the invertebrate faunal composition. The specimens found in the green sea turtle nests were identified to order, family or genus levels and they were represented in 5 orders. These invertebrate groups are Elater sp. larvae (Elateridae; Coleoptera), Pimelia sp. larvae (Tenebrionidae; Coleoptera), Enchytraeidae (Oligochaeta), Cyrptostigmata (Acari), Oniscidae (Isopoda), Formicidae (Hymenoptera). Elater sp. was the most common invertebrate group in the green turtle nests. According to student t test, we found statistically significant differences between 7 independent variables and invertebrate species presence. Furthermore, logistic regression analysis explained that there is a negative relationship between hatching success rate and invertebrate species presence.

Post-Natal Movement, Habitat Use, and Hibernacula Selection of Eastern Box Turtles (Terrapene carolina carolina) in Southern New England

Understanding movement patterns of hatchling Terrapene carolina carolina (Eastern Box Turtle) may be critical to guide conservation and management efforts since little is known about this early life-history stage. We used radio-telemetry to track 10 hatchling Eastern Box Turtles from 28 August 2012 to 21 August 2013 in Hamden, CT, to investigate postnatal movement patterns, habitat use, and hibernacula selection. We also report nest characteristics, clutch size, incubation length, hatching success, hibernation length, and overwintering mortality rates. The mean number of eggs laid in each of 5 nests was 5 (min–max = 1–6 eggs). Incubation varied from 83 to 97 days (mean = 90 days), and the overall hatching success rate was 63%. Hatchling movement (n = 6) was directional towards the north-northeast prior to hibernation. The mean distance hatchlings moved per day was 3.8 m. Mean total distance traveled was 131 m and mean straight-line distance from nest to hibernacula was 95 m. Average total distance turtles moved between observations in 2013 was significantly less than 2012 (P = 0.0001). The post-natal period averaged 35 days, with hibernation occurring before 12 October 2012. Hibernacula locations varied between partially canopied sites within the open fields and closed-canopy conditions on the forest/open-field interface. Hibernation duration averaged 177 days, with all juveniles emerging from hibernation before 6 April 2013. Movement patterns ceased to be directional after hibernation, suggesting the initiation of a home range. While dispersing from their nests, hatchlings selected microsites higher in shrub cover, and just before hibernation, microsites with higher sapling and tree cover. Following hibernation, juveniles did not return to pre-hibernation microhabitats, either in the woods or in fields. Following hibernation, juveniles continued to occupy open fields, but occupied microhabitats with partial canopy cover. A strong preference for microhabitats higher in shrub cover did not persist into the second year.

Perancangan Mesin Tetas Telur Otomatis Menggunakan Sensor Suhu dan Sensor Udara

ABSTRACTThe design of quail egg incubators is intended to facilitate the hatching process. The heat source used in the incubator is produced from heaters that use incandescent lamps and humidifiers are used as humidity regulators. The temperature regulator uses a fan to maintain air circulation and reduce the temperature when the temperature has exceeded the setpoint. This tool is equipped with a DHT11 temperature and humidity sensor, an incubator motor is used for the egg turning process, a sound sensor is used to detect if an egg has hatched and a GSM module will send an SMS notification to the farmer. The whole system is controlled by Arduino Mega 2560. During the hatching period, the temperature needed to incubate quail eggs is 39oC and humidity is 60%. The eggs in the hatching machine are rotated once every 3 hours with a 45o rotation angle. This is so that the egg can be heated evenly. The hatching process takes 18 days, with a hatching success rate of 98% of 50 eggs. The use of power in the hatching machine is on average 62.44 watts up to 83.45 watts and for 1 hatching period for 18 days, that is 25.2392kWh.Keywords: Arduino Mega 2560, DHT11, humidifier, GSM module

Caretta caretta nesting activity on Akumal Beaches, Mexico

Mexico has made substantial contributions to marine turtle protection and conservation, especially since 1990. Several conservation projects entail monitoring efforts to recover nesting territories for marine turtles. The Sea Turtle Protection Program of Akumal, in the Mexican state of Quintana Roo, was created in 1993 and was developed by the Akumal Ecological Center. This paper provides the nesting ecology parameters for Caretta caretta over a protection period of 24 years (1995–2018). A well-defined nesting peak was observed in June, with a nesting success rate of 75.2 ± 23.0%. Nesting females showed a mean curved carapace length of 99.0 ± 5.6 cm. The mean clutch size was 108.6 ± 24.6 eggs, with variation among years. The mean incubation period was 57.2 ± 6.2 days. The hatching and emergence success rates were 87.2 ± 16.9% and 78.8 ± 24.4%, respectively. For the 926 tagged females that returned, the remigration interval peaked at 726 days, with a 12-day inter-nesting period. The results show not only the recovery of the nesting population over time but also a decrease in female size; we postulate that this decrease is due to the recruitment of young females, which has been increasingly pronounced since 2010. Hence, the Akumal rookery plays an important role in its corresponding regional management unit (Atlantic Northwest).

The Breeding Success of Lesser Kestrels Falco naumanni in Mongolia

We examined the breeding success of Lesser Kestrels Falco naumanni in Ikh Nart Nature Reserve, a semi-desert zone in southeast Mongolian. We found that the mean number of nests per colony was 7.4. Lesser Kestrels laid eggs between 24 May and 2 June each year. Mean clutch size was 4.0±0.7 SE, with a mean incubation period of 28±2 SE days. We recorded an overall hatching success rate of 84.2% and overall fledgling success rate of 89.7%, hence a mean fledgling per breeding attempt was 2.79. Our findings revealed relatively high hatching and fledgling rates for our study population, and bode well for the conservation of this small falcon in its poorly-known breeding range.

Breeding biology of the Little Egret Egretta garzetta on the southern coast of the Bay of Biscay

ABSTRACT Capsule: Annual reproductive parameters of Little Egrets Egretta garzetta in an Atlantic coastal colony showed strong variation in a 20-year study, mainly due to extreme events. Aims: To describe the breeding biology of Little Egrets in the Bay of Biscay and compare it with that of the Mediterranean basin. Also, to explore relationships between breeding parameters and colony size with some climatic indicators. Methods: Phenology, number of nests, clutch size, number of hatchlings, brood size, and hatching and breeding success were recorded over 20 years. Results: Median laying date of 214 nests was 1 May (range: 1 April–25 June) and 54% of the clutches were laid in the second half of April and the first half of May. Over the 20-year study period mean clutch size of 270 nests was 4.0, mean number of hatchlings was 3.1, and mean brood size was 2.3. Hatching success ranged from 46.1% to 100% and breeding success from zero to 100%. Number of nests was negatively associated with clutch and brood size. The highest clutch size and lowest brood size were recorded at the beginning of the season. Significant relationships were found between the number of hatchlings and the rainfall during the pre-breeding season, and between brood size and the summer rainfall. Conclusions: Reproductive parameters showed significant variation over the study period, which highlights the importance of using long-term data sets. Breeding occurred one month later than in natural colonies of the Mediterranean basin. Negative relationships between the number of nests and clutch and brood size suggest some degree of density-dependent effects. Ranges of clutch size, number of hatchlings, and brood size were within those reported in Mediterranean populations. The effect of rainfall on reproductive parameters was weak. Extreme weather and predation events caused low rates of hatching and breeding success that affected the growth of the colony.

Nesting ecology and hatching success of the hawksbill turtle (2004–2014) on Cousine Island, Seychelles

Populations of the Critically Endangered hawksbill turtle Eretmochelys imbricata in the Seychelles showed significant declines in the past. They have since recovered and nesting numbers are increasing because of increased protection and management intervention. Data on their nesting ecology on Cousine Island were collected and analysed for the breeding seasons from 2004/2005 to 2013/2014 with the aim of improving management methods. The findings indicate that the number of nesting individuals increased during the study period (from x̅ = 34.3 nesters between 2004 and 2009, to x̅ = 55.4 nesters between 2010 and 2014); however, the clutch frequency was relatively low compared with other study areas. Night-time nesting increased, most likely because of increased disturbances across the study period. Clutch sizes decreased significantly across the nesting season, and there was a significant drop in hatching success in clutch sizes exceeding 200 eggs. The predation rate and infertility rate each showed an increasing trend over time. Nests incubating in full sun showed the highest mean hatching success rate and had the shortest mean incubation duration. The present study provides insight into the species’ nesting ecology on Cousine Island and will better inform management decisions aimed at increasing hatching success and minimising threats such as beach erosion and predation.

The Effects of Short Freshwater Bath Treatments on the Susceptibility to Different Stages of Neobenedenia girellae Infecting Barramundi (Lates calcarifer)

Neobenedenia girellae is one of the most pathogenic parasites affecting marine fish in captivity conditions. The use of chemicals for parasite prevention and treatment have several benefits; however, they can cause various negative side-effects. In an effort to discover cost-effective and sustainable practices, our current study was aimed at investigating the efficiency of freshwater treatments on N. girellae. A challenge test was conducted to produce infected fish which became materials for the freshwater immersion experiments. The duration and reaction of the parasites at different development stages from eggs to adult parasites were examined. Our findings revealed that 100% of the adults and oncomiracidia of N. girellae were killed quickly in freshwater. The eggs of N. girellae, however, were highly resistant to freshwater with a hatching success rate of more than 95% in all the freshwater immersion treatments (2, 5, 10 and 30min). The eggs hatched mainly on day 7 and finished hatching on day 8. Thus, the freshwater immersion method can be applied to treat N. girellae at most stages excepted for the egg stage. The best practical treatment for this parasite is to perform a replicated immersion recommended 8 days following the first treatment.

The Effects of Short Freshwater Bath Treatments on the Susceptibility to Different Stages of Neobenedenia girellae Infecting Barramundi (Lates calcarifer)

Neobenedenia girellae is one of the most pathogenic parasites affecting marine fish in captivity conditions. The use of chemicals for parasite prevention and treatment have several benefits; however, they can cause various negative side-effects. In an effort to discover cost-effective and sustainable practices, our current study was aimed at investigating the efficiency of freshwater treatments on N. girellae. A challenge test was conducted to produce infected fish which became materials for the freshwater immersion experiments. The duration and reaction of the parasites at different development stages from eggs to adult parasites were examined. Our findings revealed that 100% of the adults and oncomiracidia of N. girellae were killed quickly in freshwater. The eggs of N. girellae, however, were highly resistant to freshwater with a hatching success rate of more than 95% in all the freshwater immersion treatments (2, 5, 10 and 30min). The eggs hatched mainly on day 7 and finished hatching on day 8. Thus, the freshwater immersion method can be applied to treat N. girellae at most stages excepted for the egg stage. The best practical treatment for this parasite is to perform a replicated immersion recommended 8 days following the first treatment.

Nematode community characteristics are associated to loggerhead turtle hatching success

Abstract Nematodes represent an important group of animals in the decomposer food web, because of high diversities, abundances and functional roles supporting ecological processes, such as decomposition. They have been relatively well studied in numerous ecosystems, but have rather skipped attention in sea turtle nests at sandy shores, where a massive supply of nutrients is taking place after turtle egg hatching. Being excellent indicators of ecological functioning, we hypothesized that nematode community characteristics could be indicative of the ecological/functional state of sea turtle nests as affected by hatching characteristics (e.g. number of eggs, hatching success rate etc.). In our study, conducted in Zakynthos (Greece), we perform a pioneer in-depth analyses of nematode communities in Caretta caretta nests after egg hatching. We further explore whether turtle reproductive success, measured through a number of metrics reflecting stages and portion of alive/dead hatchlings, are linked to nematode community characteristics. We found 14 different nematode genera in total. Our analyses demonstrate that nematodes play a critical role in functionality and energy flow in sandy shore ecosystems and that sea turtle nests present an ephemeral micro-habitat hosting communities with specific characteristics. These include rather high nematode abundances and communities in early successional stages with a simple trophic structure, almost exclusively dominated by bacterivore nematodes (mostly opportunistic/c-p 1) and without top-down control. Variables either showing success or failure of hatching explained a large amount of variability of nematode community characteristics, supporting our hypothesis. The nematode Metabolic Footprint was strongly associated with the amount of dead hatchlings concentrated in the turtle nest. Nematode taxonomic diversity and richness were closely associated with an increased hatching success rate at nest level. Our findings can offer a base for developing a framework for comprehensive and standardized assessments of sea turtle nests that could ensure comparability of results over spatial or temporal scales in monitoring projects. Further research might show how increased diversity of nematode communities could be achieved so to improve reproduction output and success of loggerhead sea turtles.

Breeding biology of the chaffinch Fringilla coelebs africana in the El Kala National Park (North East Algeria)

This work focused on monitoring the reproductive phenology of the chaffinch Fringilla coelebs africana for two successive seasons (2016 and 2017) in the mountains of the El Kala National Park (North East Algeria). We searched for nests in the tree stratum or by direct observation of breeding pairs carrying building materials from mid-March to the end of June and found a total of 34 nests that were measured without affecting the breeding process. The results show that nests were built at an average height of 6.3m from the ground. The laying period was 46 days (Early April to mid-May) and the average laying date was May 2. The mean of clutch size is 3.2 eggs per brood. All the previous traits are similar to those recorded in Europe. The mean hatching success rate was 43.1% and the average breeding success rate was 36.3%. These two values are relatively low compared to those found in European populations.

Exceptional preservation of a Late Cretaceous dinosaur nesting site from Mongolia reveals colonial nesting behavior in a non-avian theropod

Abstract Colonial nesting behavior has been inferred in a variety of non-avian dinosaurs based on high concentrations of nests preserved in an area, but sedimentologic and taphonomic evidence demonstrating the contemporaneity of the nests is often lacking. A new nesting site discovered in the Upper Cretaceous Javkhlant Formation of the eastern Gobi Desert, Mongolia, preserves at least 15 egg clutches laid by a probable non-avian theropod, and provides strong evidence for colonial nesting in a non-avian dinosaur. The occurrence of the clutches at the top of a common paleosurface, the distribution of eggshell fragments within clutches, the presence of a consistent two-layer sediment infill within eggs, and a thin marker lithologic unit blanketing all the clutches indicate the clutches were laid and hatched in a single nesting season. Despite the absence of sedimentologic evidence indicative of nest structure, statistical analyses of egg characteristics and facies association reveal the clutches were likely incubated in covered or buried nests. Based on the number of hatched clutches, the hatching success rate of the colony was high (60%), similar to that of extant crocodylian populations and bird species that attend and/or protect their nests during the incubation period, which indicates nest attendance behavior in the Javkhlant theropods. Thus, colonial nesting with parental attendance, widespread in extant birds, likely evolved initially among non-brooding, non-avian dinosaurs to increase nesting success.

Differential reproductive investment in co-occurring oviparous and viviparous common lizards (Zootoca vivipara) and implications for life-history trade-offs with viviparity

Live-bearing reproduction (viviparity) has evolved from egg-laying (oviparity) independently many times and most abundantly in squamate reptiles. Studying life-history trade-offs between the two reproductive modes is an inherently difficult task, as most transitions to viviparity are evolutionarily old and/or are confounded by environmental effects. The common lizard (Zootoca vivipara) is one of very few known reproductively bimodal species, in which some populations are oviparous and others viviparous. Oviparous and viviparous populations can occur in sympatry in the same environment, making this a unique system for investigating alternative life-history trade-offs between oviparous and viviparous reproduction. We find that viviparous females exhibit larger body size, smaller clutch sizes, a larger reproductive investment, and a higher hatching success rate than oviparous females. We find that offspring size and weight from viviparous females was lower compared to offspring from oviparous females, which may reflect space constraints during pregnancy. We suggest that viviparity in common lizards is associated with increased reproductive burden for viviparous females and speculate that this promoted the evolution of larger body size to create more physical space for developing embryos. In the context of life-history trade-offs in the evolution of viviparity, we suggest that the extent of correlation between reproductive traits, or differences between reproductive modes, may also depend on the time since the transition occurred.

Breeding ecology and causes of nest failure in the Indian Skimmer Rynchops albicollis

ABSTRACTCapsule: The breeding success of the Indian Skimmer Rynchops albicollis in eastern India is significantly reduced by human activities at the breeding sites.Aim: To investigate the breeding ecology of Indian Skimmer and factors affecting breeding success along the Mahanadi River in eastern India.Methods: A total of 230 Indian Skimmer nests were monitored in 2017 and 2018. Population, breeding phenology, clutch size, egg dimensions and factors affecting breeding success rates were determined.Results: Indian Skimmers arrived at the breeding sites during January–February followed by breeding activities during March–May. On a small scale, nests were more likely to be closer to water and ground vegetation than expected by chance, probably as mitigation against hot afternoon temperatures. Hatching success rate was higher (72.27%) in 2017 and chick survival rate was higher (33.15%) in 2018. Factors that affected breeding success were flooding, nest desertion, egg collecting by humans, predation and trampling.Conclusion: The breeding success rate of Indian Skimmer could be increased by protecting the breeding sites and minimizing disturbances through community awareness.

Dispersal of rotifers and cladocerans by waterbirds: seasonal changes and hatching success

Aquatic invertebrates can be geographically dispersed by abiotic vectors (wind, rain and water flow) or organisms (mainly by insects, fishes and waterbirds). However, there is a lack of information on the dispersal by waterbirds of cladocerans and especially rotifers, and on the hatching success of the dispersed propagules. Here, we quantify the dispersal of cladocerans and rotifers by waterbirds through analysis of their faecal droppings collected in a wetland formed by two natural lakes located in Donana National Park (Spain). We also study the influence of different photoperiod and temperature conditions on the hatching success of the dispersal propagules. Diapausing propagules of 22 species of rotifers or cladocerans were identified in waterbird faecal droppings, with a mean number of 0.9 diapausing propagules per dropping. The hatching success rate, which was not influenced by photoperiod or temperature, was low (~ 12.5%). Nevertheless, the role of rotifer dispersal by waterbirds appears to have been underestimated in the past. In this study area, the dispersal of rotifers by waterbirds may be at least as relevant as their dispersal by air currents. Further studies are needed to evaluate the relative importance of dispersal mechanisms (mainly air currents and animal vectors) in different geographical areas.