Understorey predicts the spatial distribution of Ixodes hirsti in South Australia

2008 ◽  
Vol 56 (2) ◽  
pp. 123 ◽  
Author(s):  
Margot Oorebeek ◽  
Sonia Kleindorfer
Keyword(s):  
Spatial Distribution ◽  
Mortality Rate ◽  
Reproductive Success ◽  
Preliminary Investigation ◽  
South Australia ◽  
Saturation Deficit ◽  
Questing Ticks ◽  
Tick Survival ◽  
Vegetation Characteristics ◽  
Study Sites

Ticks reduce the fitness of their host by increasing mortality rate and reducing reproductive success. Understanding the distribution of ticks is therefore crucial in assessing the vulnerability of host populations. The distribution of ticks is dependent on the dispersal capabilities of their hosts as well as the suitability of the new habitat. In this study, we examine the spatial distribution of Ixodes hirsti in South Australia and investigate the influence of vegetation characteristics on the presence of ticks. Additionally, we conducted a preliminary investigation into the effects of vegetation characteristics on the microclimate experienced by questing ticks. Ticks were present in six of the nine study sites. We found that the number of shrubs and the percentage of ground covered by shrubs were significant predictors of the presence of ticks: ticks were present only at sites with a dense cover of shrubs. Additionally, our preliminary data showed that dense understorey was associated with a low saturation deficit and, as such, provided a suitable microclimate for tick survival.

scholarly journals Host density predicts the probability of parasitism by avian brood parasites

2019 ◽  
Vol 374 (1769) ◽  
pp. 20180204 ◽  
Author(s):  
Iliana Medina ◽  
Naomi E. Langmore
Keyword(s):  
Spatial Distribution ◽  
Reproductive Success ◽  
Host Species ◽  
Field Data ◽  
Host Density ◽  
Brood Parasites ◽  
Parasitism Rates ◽  
Analyse Data ◽  
First Time ◽  
Determining Factor

The spatial distribution of hosts can be a determining factor in the reproductive success of parasites. Highly aggregated hosts may offer more opportunities for reproduction but can have better defences than isolated hosts. Here we connect macro- and micro-evolutionary processes to understand the link between host density and parasitism, using avian brood parasites as a model system. We analyse data across more than 200 host species using phylogenetic comparative analyses and quantify parasitism rate and host reproductive success in relation to spatial distribution using field data collected on one host species over 6 years. Our comparative analysis reveals that hosts occurring at intermediate densities are more likely to be parasitized than colonial or widely dispersed hosts. Correspondingly, our intraspecific field data show that individuals living at moderate densities experience higher parasitism rates than individuals at either low or high densities. Moreover, we show for the first time that the effect of host density on host reproductive success varies according to the intensity of parasitism; hosts have greater reproductive success when living at high densities if parasitism rates are high, but fare better at low densities when parasitism rates are low. We provide the first evidence of the trade-off between host density and parasitism at both macro- and micro-evolutionary scales in brood parasites. This article is part of the theme issue ‘The coevolutionary biology of brood parasitism: from mechanism to pattern’.

scholarly journals Seasonal activity of Dermacentor reticulatus ticks in the era of progressive climate change in eastern Poland

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zbigniew Zając ◽  
Joanna Kulisz ◽  
Aneta Woźniak ◽  
Katarzyna Bartosik ◽  
Adil Khan
Keyword(s):  
Climate Change ◽  
Local Population ◽  
Weather Conditions ◽  
Dermacentor Reticulatus ◽  
Seasonal Activity ◽  
Saturation Deficit ◽  
Annual Basis ◽  
Questing Ticks ◽  
The Mean

AbstractDermacentor reticulatus ticks are one of the most important vectors and reservoirs of tick-borne pathogens in Europe. Changes in the abundance and range of this species have been observed in the last decade and these ticks are collected in areas previously considered tick-free. This may be influenced by progressive climate change. Eastern Poland is an area where the local population of D. reticulatus is one of the most numerous among those described so far. At the same time, the region is characterized by a significant increase in the mean air temperature in recent years (by 1.81 °C in 2020) and a decrease in the average number of days with snow cover (by 64 days in 2020) and in the number of days with frost (by 20 days in 2020) on an annual basis compared to the long-term average. The aim of our research was to investigate the rhythms of seasonal activity and the population size of D. reticulatus in the era of progressive climate change. To this end, questing ticks were collected in 2017–2020. Next, the weather conditions in the years of observation were analyzed and compared with multi-year data covering 30 years preceding the study. The research results show that, in eastern Poland, there is a stable population of D. reticulatus with the peak of activity in spring or autumn (up to a maximum of 359 individuals within 30 min of collection) depending on the year of observation. Ticks of this species may also be active in winter months. The activity of D. reticulatus is influenced by a saturation deficit.

Temporal and spatial distribution and abundance of blue swimmer crab (Portunus pelagicus) larvae in a temperate gulf

2004 ◽  
Vol 55 (8) ◽  
pp. 809 ◽  
Author(s):  
Simon R. Bryars ◽  
Jon. N. Havenhand
Keyword(s):  
Spatial Distribution ◽  
Surface Waters ◽  
Vertical Migration ◽  
South Australia ◽  
Temporal And Spatial Distribution ◽  
Portunus Pelagicus ◽  
Limited Sampling ◽  
Sampling Programme ◽  
Temporal And Spatial ◽  
Stage 1

A plankton-sampling programme for blue swimmer crab (Portunus pelagicus) larvae was conducted in the temperate waters of Gulf St Vincent, South Australia, to investigate: (1) if larval hatching is seasonal; (2) if larvae are restricted to surface waters; (3) if larvae are hatched offshore; and (4) if larval development occurs offshore. The temporal and spatial distribution and abundance of larvae indicated that hatching and zoeal development occur mainly in deeper offshore waters during the warmer months of November to March, and that zoeal development occurs in a range of depths from the neuston to at least 14 m. Although peaks in abundance usually occurred in the upper 3 m, zoeae were distributed throughout the water column, with the majority occurring in sub-surface waters below 1 m depth. There was no evidence for a daylight ontogenetic or tidal vertical migration in the four zoeal stages. Limited sampling revealed no evidence for a diurnal vertical migration in stage-1 zoea. Although the seasonal and inshore-offshore patterns of hatching observed in the study were typical for a portunid species, the broad vertical distribution differed from that observed for P. pelagicus in previous studies.

scholarly journals Do metrics of sexual selection conform to Bateman's principles in a wind-pollinated plant?

2019 ◽  
Vol 286 (1905) ◽  
pp. 20190532 ◽  
Author(s):  
Jeanne Tonnabel ◽  
Patrice David ◽  
John R. Pannell
Keyword(s):  
Spatial Distribution ◽  
Sexual Selection ◽  
Reproductive Success ◽  
Pollen Dispersal ◽  
Male Fitness ◽  
Female Fitness ◽  
Dioecious Plant ◽  
Common Gardens ◽  
Mate Acquisition ◽  
Mercurialis Annua

Bateman's principles posit that male fitness varies more, and relies more on mate acquisition, than female fitness. While Bateman's principles should apply to any organism producing gametes of variable sizes, their application to plants is potentially complicated by the high levels of polyandry suspected for plants, and by variation in the spatial distribution of prospective mates. Here we quantify the intensity of sexual selection by classical Bateman metrics using two common gardens of the wind-pollinated dioecious plant Mercurialis annua . Consistent with Bateman's principles, males displayed significantly positive Bateman gradients (a regression of fitness on mate number), whereas the reproductive success of females was independent of their ability to access mates. A large part of male fitness was explained by their mate number, which in turn was associated with males' abilities to disperse pollen. Our results suggest that sexual selection can act in plant species in much the same way as in many animals, increasing the number of mates through traits that promote pollen dispersal.

The effect of temperature and moisture on the Immature Stages of Aphodius tasmaniae Hope (Scarabaeidae) in the lower South-east of South Australia.

1961 ◽  
Vol 9 (2) ◽  
pp. 173 ◽  
Author(s):  
DA Maelzer
Keyword(s):  
Mortality Rate ◽  
Water Content ◽  
South Australia ◽  
Effect Of Temperature ◽  
Annual Rainfall ◽  
Field Observations ◽  
Immature Stages ◽  
Rate Of Increase ◽  
Lower South ◽  
Third Instar Larvae

The distribution and abundance of the univoltine species A. tasmaniae in the lower south-east of South Australia appears to be related to annual rainfall. The effects of moisture on the mortality rates of the immature stages were consequently studied and observations were made of the effects of variations in moisture in the field. Laboratory experiments and field observations suggested that variations in soil moisture have little effect on the eggs and the diapausing prepupae in the field. Eggs absorbed water and hatched normally within a pF range of 2.50-3.75 in a sand and in a clay loam. At pF 4.0 in both soils, eggs lost weight and did not hatch. The adults, however, tend to lay the eggs well within the pF range in which the eggs can develop, and soil samples suggested that eggs would develop with little mortality in the kinds of places in which they are usually laid. When prepupae enter diapause they have a water content of c. 77%. When desiccated in the laboratory, few prepupae died until their water content fell below 62%. The mortality rate then increased sharply, and it was estimated that 50% of the prepupae died when their water content dropped to 57%. Droughts of sufficient duration and intensity to kill 50% of the prepupae have never been recorded from the study area, and field observations suggested that few prepupae died of desiccation in summer. Unlike the two stages above, the first and third instar larvae may be markedly affected by variations in moisture in the field. The first instar larvae, after hatching, do not move to the surface of the soil and do not feed much until the soil is saturated with rain. As rainfall is variable at this time of the year, the larvae may be in dry soil for many weeks before they are stimulated to extend their burrows to the surface and search for food. Many larvae may die of starvation during this time, and the mortality rate of the larvae was related empirically to the length of the autumn "drought". Third instar larvae may be affected, on the other hand, by excessive water. In wet winters, vast numbers of larvae are drowned when extensive flooding occurs on the poorly-drained soils, and on well-drained soils a large proportion of larvae are killed by the entomophagous fungus Cordyceps aphodii. The above data have suggested that moisture is one of the major factors affecting the distribution and abundance of the species. Temperature has little effect on the rate of increase of the species.

scholarly journals Meningococcal disease in South Australia: incidence and serogroup distribution 1971–1980

1983 ◽  
Vol 90 (1) ◽  
pp. 49-54 ◽  
Author(s):  
D. Hansman
Keyword(s):  
Mortality Rate ◽  
Meningococcal Disease ◽  
Single Case ◽  
South Australia ◽  
Neisseria Lactamica ◽  
Annual Prevalence ◽  
Group A ◽  
Overall Mortality

SUMMARYDuring the ten-year period 1971–80 isolates of meningococci from 85 cases of meningococcal disease (MD) in South Australia, from 66 children, 6 adolescents and 13 adults, were examined. These comprised 69 cases of meningitis and 16 cases of bacteraemia without meningitis. Thirty-three (39%) of all cases of MD occurred in children less than 1 year of age, the median age was 19 months. Serogroup B accounted for 61 (72%) cases of MD, group A seven (8%), group C seven (8%), group W135 five (6%), group Y three (4%) and group X one (1%); in addition there was a single case of Neisseria lactamica infection.The annual prevalence of MD in South Australia for the period was 11 cases per 100000 for children under the age of 2 years and 0·7 cases per 100000 overall. The prevalence was highest in winter (45% cases) and spring (26%) and lowest in summer (13%). The overall mortality rate was 8%. Four of the 21 infants under the age of 6 months died (mortality rate 19 %) whereas none of the 32 children aged from 6 months to 14 years died (P = 0·02). Amongst the survivors, three children had deafness, which was bilateral and severe in two.

Social organization, spatial distribution, and population density of wolves in relation to moose density

1985 ◽  
Vol 63 (5) ◽  
pp. 1068-1077 ◽  
Author(s):  
François Messier
Keyword(s):  
Spatial Distribution ◽  
Mortality Rate ◽  
Population Density ◽  
Social Organization ◽  
Prey Density ◽  
Territory Size ◽  
Wolf Population ◽  
Pack Size ◽  
Behavioral Attributes ◽  
Density Threshold

This 4-year study compared population density and related behavioral attributes of wolves (14 packs) at two different moose densities: 0.23 (LP, low prey density), and 0.37 (HP, high prey density) moose∙km−2. Wolf densities in January averaged 0.8 and 1.4 animals∙100 km−2, packs consisted of 3.7 and 5.7 individuals, year-long territory sizes were 255 and 390 km2, and interstices between territories represented 30 and [Formula: see text] of available area, for the LP and HP areas, respectively. Territory size increased significantly with pack size. The LP wolf population suffered from a higher mortality rate owing to a higher occurrence of deaths from malnutrition and intraspecific strife, and from a lower success in producing pups (61% of the possible occasions, compared with 93% in HP). When no other ungulate species is present, a density of 0.2 moose∙km−2 would approximate the density threshold below which a pack could not subsist and (or) reproduce successfully. The study reveals that naturally regulated moose–wolf systems may stabilize at low prey and low predator densities.

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