Host contributions to the force of Borrelia burgdorferi and Babesia microti transmission differ at edges of and within a small habitat patch

In the northeastern United States, the emergence of Lyme disease has been associated, in part, with the increase of small forest patches. Such disturbed habitat is exploited by generalist species, such as white-footed mice, which are considered the host with the greatest reservoir capacity for the agents of Lyme disease ( Borrelia burgdorferi sensu stricto) and human babesiosis ( Babesia microti ). Spatial risk analyses have identified edge habitat as particularly risky. Using a retrotransposon-based quantitative PCR assay for host bloodmeal remnant identification, we directly measured whether the hosts upon which vector ticks fed differed at the edge or within the contiguous small habitat patch. Questing nymphal deer ticks, Ixodes dammini , the northern clade of Ixodes scapularis , were collected from either the edge or within a thicket on Nantucket Island over 3 transmission seasons and tested for evidence of infection as well as bloodmeal hosts. Tick bloodmeal hosts significantly differed by site as well as by year. Mice and deer were identified most often (49.9%), but shrews, rabbits and birds were also common. Ticks from the edge fed on a greater diversity of hosts than those from the thicket. Surprisingly, mice were not strongly associated with either infection at either sampling site (OR<2 for all). Although shrews were not the most common host utilized by ticks, they were highly associated with both infections at both sites (OR= 4.5 and 7.9 B. burgdorferi and 7.9 and 19.0 B. microti , edge and thicket). We conclude that reservoir hosts may differ in their contributions to infecting ticks between edge and contiguous vegetated patches. Importance Habitat fragmentation is thought to be a main factor in the emergence of Lyme disease and other of the deer tick-transmitted infections. The patchwork of forest and edges promotes altered biodiversity, favoring the abundance of generalist rodents such as white footed mice, heretofore considered a key tick and reservoir host in the northeastern U.S. We used tick bloodmeal analyses to directly identify the hosts from which nymphal deer ticks became infected. We demonstrate that there is considerable microfocality in host contributions to the cohort of infected ticks and that shrews, although they fed fewer ticks than mice, disproportionately influenced the force of pathogen transmission in our site. The venue of transmission of certain deer tick-transmitted agents may comprise a habitat scale of 10 meters or fewer and depend on alternative small mammal hosts such as shrews.

Avian Species Abundance and Richness in a Variably Urbanised Landscape in Wellington City, New Zealand

<p>Avian community composition fluctuates across the landscape at different scales of space and time. These fluctuations may be modified at the broader scale of landscape and at the local scale of habitat patch. A species' ecology also influences its occurrence and abundance in the landscape. This thesis investigates the spatial and temporal distribution of the avian community in Wellington. Wellington is an interesting case study because it has a diverse range of landscapes influenced by the proximity of hills to the coast (see Appendix 3). I assess the effect of landscape classification on the richness and abundance of birds and the role of fine patch structure in shaping this distribution. My study was located within a 5-km radius of Wellington City's central business district (41 degrees 16' S, 174 degrees 46' E). I used six strip-transects divided into 400m length segments that traversed through high to lower density residential suburbs and green space inter-digitated with built habitat, and established five-minute count (FMBC) points at each segment interval along these routes for a total of 49 points. I used ArcGIS to analyse the habitat patch types in the 100-m areas surrounding the FMBC. I recorded avian species type and abundance along the strips and at the FMBC during the morning and evening. A total of 35 bird species and 10966 individuals were recorded along the strip-transects and 34 bird species and 5960 individuals at the FMBCs. House sparrow, then starling and blackbacked gull, rock pigeon, blackbird and silvereye were the most common and widely spread species. Results indicated that landscape type modified avian biodiversity with the highest number of species (S) recorded in green landscapes (n = 10, S = 15.9) and the lowest in wharf littoral (n = 2, S = 7.5) and low-density commercial sites (n = 3, S = 6.67). The diversity of the landscape within an area did not influence avian biodiversity. I found that total species abundance did not change across the landscape but that the species' ecology did influence where it occurred and its abundance in the landscape. Dietary diversity particularly influenced a species' abundance. Both season and time of day altered species richness and abundance, with lower values of richness recorded in autumn (morning period = 13.5, evening period = 10.7). I found that avian communities in the Wellington urban area were dominated by six common species but that many more species were present in much lower numbers at fewer sites. Results showed an inverse relationship between species richness and abundance - while the greater biomass (abundance) of birds concentrated at FMBC within the built commercial centre and surrounding higher density housing areas, richness increased with distance from the built centre to residential and green sites. I found no relationship between species richness and the total number of individuals present at any point, and the total biomass and abundance of birds was also independent of patch size. Neither habitat patch diversity nor average patch size influenced species diversity across the community of birds, but the effect of average patch size was less at patches between 300 and 1500 metres. The abundance of some individuals in their favoured patch type did vary in response to patch structure with the strongest relationships seen for blackbird and house sparrow. These results suggest that birds are responding to cues at the larger scale of landscape first rather than to fine patch structure within the urban setting, and therefore that landscape is a more important influence in driving bird biodiversity.</p>

Avian Species Abundance and Richness in a Variably Urbanised Landscape in Wellington City, New Zealand

<p>Avian community composition fluctuates across the landscape at different scales of space and time. These fluctuations may be modified at the broader scale of landscape and at the local scale of habitat patch. A species' ecology also influences its occurrence and abundance in the landscape. This thesis investigates the spatial and temporal distribution of the avian community in Wellington. Wellington is an interesting case study because it has a diverse range of landscapes influenced by the proximity of hills to the coast (see Appendix 3). I assess the effect of landscape classification on the richness and abundance of birds and the role of fine patch structure in shaping this distribution. My study was located within a 5-km radius of Wellington City's central business district (41 degrees 16' S, 174 degrees 46' E). I used six strip-transects divided into 400m length segments that traversed through high to lower density residential suburbs and green space inter-digitated with built habitat, and established five-minute count (FMBC) points at each segment interval along these routes for a total of 49 points. I used ArcGIS to analyse the habitat patch types in the 100-m areas surrounding the FMBC. I recorded avian species type and abundance along the strips and at the FMBC during the morning and evening. A total of 35 bird species and 10966 individuals were recorded along the strip-transects and 34 bird species and 5960 individuals at the FMBCs. House sparrow, then starling and blackbacked gull, rock pigeon, blackbird and silvereye were the most common and widely spread species. Results indicated that landscape type modified avian biodiversity with the highest number of species (S) recorded in green landscapes (n = 10, S = 15.9) and the lowest in wharf littoral (n = 2, S = 7.5) and low-density commercial sites (n = 3, S = 6.67). The diversity of the landscape within an area did not influence avian biodiversity. I found that total species abundance did not change across the landscape but that the species' ecology did influence where it occurred and its abundance in the landscape. Dietary diversity particularly influenced a species' abundance. Both season and time of day altered species richness and abundance, with lower values of richness recorded in autumn (morning period = 13.5, evening period = 10.7). I found that avian communities in the Wellington urban area were dominated by six common species but that many more species were present in much lower numbers at fewer sites. Results showed an inverse relationship between species richness and abundance - while the greater biomass (abundance) of birds concentrated at FMBC within the built commercial centre and surrounding higher density housing areas, richness increased with distance from the built centre to residential and green sites. I found no relationship between species richness and the total number of individuals present at any point, and the total biomass and abundance of birds was also independent of patch size. Neither habitat patch diversity nor average patch size influenced species diversity across the community of birds, but the effect of average patch size was less at patches between 300 and 1500 metres. The abundance of some individuals in their favoured patch type did vary in response to patch structure with the strongest relationships seen for blackbird and house sparrow. These results suggest that birds are responding to cues at the larger scale of landscape first rather than to fine patch structure within the urban setting, and therefore that landscape is a more important influence in driving bird biodiversity.</p>

Habitat Patch Size and Landscape Structure Influence, Although Weakly, the Parasite Richness of an Arboreal Folivorous-frugivorous Primate in Anthropogenic Landscapes

ContextAnthropogenic habitat disturbances that affect the ecology and behavior of parasites and hosts can either facilitate or compromise their interactions and modulate the parasite richness.ObjectivesWe assessed if the size of the habitat patch, the composition and configuration of the landscape (forest cover, patch density and mean distance to the nearest patch) and host group size influence the parasite richness of brown howler monkeys (Alouatta guariba clamitans) inhabiting forest fragments immersed in an anthropogenic matrix.MethodsWe collected fecal samples from 60 howler monkey groups inhabiting distinct forest fragments (one group/fragment) from January to July 2019. We used generalized linear models to assess the power of the independent variables in predicting parasite richness at the patch- and patch-landscape scales.ResultsWe found 10 parasite taxa (five basal eukaryotes, four nematodes and one platyhelminth), nine of which also infect humans or domestic animals. Overall parasite richness showed an inverse relationship with habitat patch size and forest cover, and a direct relationship with the mean distance to the nearest patch and group size. Patch-landscape metrics and host group size also influenced the infection with parasites with direct cycle and transmission via ingestion of the infective stage in the arboreal environment or with parasites with indirect cycle and transmission via ingestion of intermediate hosts. However, all significant models presented low weight.ConclusionsWe suggest that characteristics of parasite and host populations among other factors are more critical modulators of the relationship between howler monkeys and their parasites in anthropogenic landscapes.

Habitat requirements of the endangered heath bush-cricket Gampsocleis glabra (Orthoptera, Tettigoniidae) in an isolated population

Steppes and xerothermic grasslands are hotspots of biodiversity, but are threatened by habitat destruction and fragmentation. The heath bush-cricket, Gampsocleis glabra, is considered to be a specialist of xerothermic habitats and appears in national red lists as a threatened species in several European countries. The goal of the current research was to determine the habitat requirements of G. glabra in an isolated habitat patch in Poland, at the northern edge of its range. By comparing the composition of plant species and vegetation architecture of vacant and occupied sites in the summers of 2018 and 2019, it was found that this population of G. glabra still maintained a strict specialisation for the xerothermofilous Festuco-Brometea plant community. On the contrary to previous studies, however, Stipa-type grasses were not essential for the occurrence of the species and the majority of occupied areas were based on the plant Brachypodium pinnatum. The physiognomy of plant communities was crucial for the abundance of stridulating males, which showed a preference for dense grasses at 10 cm high. The habitat characteristics of patches occupied by males and females did not differ significantly. The study of habitat requirements of this endangered Orthoptera species in an isolated habitat patch could serve as a prelude to the restoration of similar locations before it becomes extinct. This study may also underpin the development of a global conservation strategy for G. glabra.