Dominant Species In Sites Research Articles

Structure of ground beetle (Coleoptera, Carabidae) community in the spring wheat crops of the northern forest-steppe of the Ob region

The species composition of the ground beetle community (Coleoptera, Carabidae) in the spring wheat crop area in the forest-steppe zone of Western Siberia was researched for the period of 2019-2020. The ground beetle population was represented by 36 species from 14 genera. The genera Poecilus, Dolichus, and Harpalus were the most abundant, while the genera Pterostichus, Poecilus, Harpalus, and Amara had the highest species diversity. It was revealed that the dominant species in sites with conventional technology of spring wheat cultivation, are: Harpalus rufipes, Poecilus cupreus, Dolichus halensis, Harpalus calceatus, and in 2020 Agonum gracilipes appeared along with them. In 2020, the species abundance increased by 25%, and the dynamic density of most species in the second year of the study was also higher than in the first year. This may be caused by the influence of agrometeorological conditions of the studied area. The vegetation period of 2020 differed by conditions of heat and moisture supply in comparison with 2019, as indicators of 2020 are much higher than the previous year and average long-term values for the area. The dominant and subdominant complex of carabidofauna was found to be relatively stable for two years.

Association between temporal patterns in helminth assemblages and successful range expansion of exotic Mus musculus domesticus in Senegal

Relationships between parasitism and invasion success are increasingly evidenced in the literature. However, the dynamic nature of the major parasite-related processes has been rarely taken into account until now, while the residence time of invaders in colonized regions was shown to be associated to crucial changes in parasite communities. Here, we strive to bridge this gap using a temporal survey of rodent populations along one invasion route of the exotic house mouse Mus musculus domesticus that currently invades North Senegal. In this study, we investigated whether gastrointestinal helminth (GIH) assemblages changed over time in native (Mastomys erythroleucus) and/or invasive (M. m. domesticus) rodent populations sampled at an invasion front, and whether these potential changes may be associated to the invasion success of the exotic mouse. Four years separated two rodent sampling campaigns (2013 and 2016/17) in six localities. Despite being relatively short, the timeframe considered here allowed to evidence significant patterns in rodent communities and their GIH assemblages. At the host community level, we showed that the exotic mouse was now established at all sites, becoming the dominant species in sites where it was not recorded before. At the GIH community level, increased infection of the single shared cestode (Mathevotaenia symmetrica) in both rodent species brought support to the “spill-back” hypothesis. Infection levels of GIH that remained low at the invasion front in invading mice over time also supported the “enemy release” hypothesis. Both hypotheses should deserve further experimental work to demonstrate their role in the invasion success of the house mouse in Senegal.

Ecology and Diversity of Plankton in Kotmale Reservoir, Sri Lanka

Present study investigated the relationship between plankton communities and environmental variables in five different locations of the Kotmale Reservoir during the period of June 2008 to May 2011. A total of 123 plankton species were recorded with 85 species of phytoplankton and 38 species of zooplankton. The relative abundance data indicate that Aulacoseira granulata (31.06%), Botryococcus braunii (12.34%) and Microcystis sp. (11.93%) were the dominant phytoplankton species while Acanthocystis turfacea (52.22%) was the dominant zooplankton species. Staurastrum cingulum was the dominant species in sites where the immediate catchment is covered with reservation forest with no significant inflow streams. Aulacoseira granulata, Fragellaria capucina and Navicula sp. were abundant in locations where the highest total phosphorus (TP) values were recorded. The main inflow streams, Puna Oya and Pundalu Oya appear to bring nutrient rich waters from its catchment with dense tea estates, agricultural lands, industries and villages. Microcystis sp. was abundant in locations where the highest values for TP, dissolved phosphorus (DP), ammonia, conductivity and turbidity were recorded. Botryococcus braunii was dominant in the location where Puna Oya reaches the reservoir. Staurastrumlepta canthum was abundant in the location located closer to the dam where the water body mostly contains limnetic characteristics. Among the zooplankton, cladocera species were abundant in sites where Staurastrum cingulum was identified. Rotifers and ciliate protozoans were identified closer to the dam and at the sites with high dominance of Microcystis sp. Accordingly, it was apparent that the distribution and abundance of these plankton species depend on the prevailing environmental conditions which ultimately show their ability to use as environmental indicators.

Studies on influence of human activities on the species diversity of Odonata in parts of Lagos metropolis

This study was conducted to determine dragonfly species diversity in a fish pond in Igbaga, Ikorodu (6.6671°N and 3.5983°E)and a large expanse of farm land in Ipaja (6.6044°N and 3.2660°E), southwestern Nigeria from January, 2016 to July, 2016 to as well as the effect of anthropogenic activities on the dragonflies at both sites. A total of 1002 dragonflies were collected belonging to20 species, 15 genera, and two families (Libellulidae and Aesnidae), were found at the two locations. The most dominant species in Site 1 (Ikorodu fish farm) was Chalcostephia flavifrons (36%) followed by Palpopleura lucia (15%) and the least were Palpopleura albifrons, Gynacantha nigeriensis, Diplacodes lefebvrii and Trithemis grouti which were one percent of the total numbers sampled. On the other hand, the most dominant species in Site 2 (Agricultural Farm in Ipaja) was Pantala flavescens (92%) and the least was Urothemis asignata (1%). Similarity test using Soerensen's quotient revealed a strong dissimilarity in the community structures of the two areas surveyed. The fish pond had a more even distribution of the dragonflies(e^H/S=0.508) and a higher concentration (H´=1.808) of dragonflies than Ipaja agricultural farm.

Population dynamics and dispersal of two exotic biological control agents of spotted knapweed, Urophora affinis and U. quadrifasciata (Diptera: Tephritidae), in southwestern Virginia from 1986 to 2000

Abstract A gall fly, Urophora affinis Frfld. (Diptera: Tephritidae), released at two sites in southwestern Virginia in 1986 for the biological control of spotted knapweed, Centaurea maculosa Lam., was monitored annually through 2000 to determine its population density and dispersal rate. Between 1986 and 1991, the mean number of U. affinis per knapweed capitulum increased 10-fold at these original release sites. By spring 2000, it was recovered at 44 of 55 sites sampled but its density at each original release site has not exceeded the 1991 level. Rate of spread averaged 1.3 km/year. A second species, Urophora quadrifasciata (Meigen) that was not released in Virginia, was first recovered in 1995 comprising 30% of the two Urophora species. From 1996 to 2000 it was recovered at all sites sampled. Its rapid increase made it the dominant species, comprising 87.5% of the two species within two years. Although U. quadrifasciata has spread more rapidly than U. affinis, the proportion of the two species has stabilized since 1998 with the population of U. quadrifasciata being three times that of U. affinis. Eighty-two percent of the capitula of spotted knapweed sampled were infested. Each infested capitulum contained 1–3 U. affinis or 1–6 U. quadrifasciata with 11.7% of the capitula being infested by both species. Sex ratio consistently showed a slightly higher number of males than females in both species. Comparison of both species present in 20 sites showed that despite a 9-year head start, U. affinis was the dominant species in only 2.6, 2.4, and 3.5% of the capitula in 1998, 1999, and 2000, respectively. The highest number of each species recorded per capitulum was a mean for all sampled sites of 1.68 U. quadrifasciata in 1997 and 0.4 U. affinis in 1991. Although U. quadrifasciata quickly became the dominant species in sites occupied by U. affinis, the latter has persisted, suggesting that the two species can coexist. Data derived from two sample sizes of 100 and 1000 capitula were not significantly different.