Genetic Connectivity among Populations of an Endangered Snake Species from Southeastern Australia (Hoplocephalus bungaroides, Elapidae)

For endangered species that persist as apparently isolated populations within a previously more extensive range, the degree of genetic exchange between those populations is critical to conservation and management. A lack of gene flow can exacerbate impacts of threatening processes and delay or prevent colonization of sites after local extirpation. The broad-headed snake, Hoplocephalus bungaroides, is a small venomous species restricted to a handful of disjunct reserves near Sydney, Australia. Mark-recapture studies have indicated low vagility for this ambush predator, suggesting that gene flow also may be low. However, our analyses of 11 microsatellite loci from 163 snakes collected in Morton National Park, from six sites within a 10-km diameter, suggest relatively high rates of gene flow among sites. Most populations exchange genes with each other, with one large population serving as a source area and smaller populations apparently acting as sinks. About half of the juvenile snakes, for which we could reliably infer parentage, were collected from populations other than those in which we collected their putative parents. As expected from the snakes' reliance on rocky outcrops during cooler months of the year, most gene flow appears to be along sandstone plateaux rather than across the densely forested valleys that separate plateaux. The unexpectedly high rates of gene flow on a landscape scale are encouraging for future conservation of this endangered taxon. For example, wildlife managers could conserve broad-headed snakes by restoring habitats near extant source populations in areas predicted to be least affected by future climate change.     

Molecular phylogeny of the Australian venomous snake genus Hoplocephalus (Serpentes, Elapidae) and conservation genetics of the threatened H. stephensii

The Australian elapid snakeHoplocephalus stephensii (Stephens' BandedSnake) is patchily distributed in disjunctforest remnants in eastern Australia and islisted as threatened in both states in which itoccurs (Qld and NSW). Here we focus on thephylogeography of H. stephensii toaddress (1) the genetic distinctiveness of thistaxon within its genus and (2) the level ofgenetic diversity present within and betweendisjunct populations from throughout thespecies' range. We sequenced an approximately900 base pair DNA fragment of the mitochondrialgenome that includes half of the ND4 gene andthree tRNA genes. We obtained sequence datafrom 15 H. stephensii individuals drawnfrom four populations, plus representatives ofthe other Hoplocephalus species.Phylogenetic analyses of the data produced asingle fully resolved tree. The two coastaltaxa (H. bungaroides and H. stephensii)are very closely related (2.6–3.1% sequencedivergence) whereas the inland taxon H.bitorquatus is more distantly related to theother two (7.6% vs H. bungaroides;7.8–8.3% vs H. stephensii). Geneticdiversity is low within H. stephensii(nine mitochondrial haplotypes with 1–3haplotypes with only single base pairdifferences within populations). The largestsplit (1.7% sequence divergence) occursbetween the northern population and the threesouthern populations and corresponds to thespecies distribution north and south of theMcPherson Range on the Queensland-New SouthWales border. The three southern populationsdisplay much less molecular divergence (maximumof 0.6% sequence divergence), consistent withthe presence of generally continuous forestthroughout the species' range until Europeaninvasion of Australia 200 years ago, and withradiotelemetric studies that have found highvagility in these arboreal snakes. Thus, onthe basis of genetic distinctiveness we arguethat (1) Hoplocephalus bitorquatus shouldreceive high conservation priority; and (2)managers should treat the Queensland and NSWpopulations of H. stephensi as separateconservation units.     

Habitat requirements of the threatened snake species Hoplocephalus stephensii (Elapidae) in eastern Australia

Abstract Although forested habitats in eastern Australia have attracted significant conservation‐related research, this work has focused strongly on endothermic vertebrates. Threatened reptile taxa have received less attention, but information on their habitat requirements should be central to management planning. The arboreal elapid snake Hoplocephalus stephensii is largely restricted to remnant forests in eastern Australia, and is listed as a threatened species under wildlife legislation. We collated 84 records of the current New South Wales geographical distribution of H. stephensii, and compared attributes of these locations to those of randomly chosen points within the same forests, in adjacent forests, in timber plantations and on freehold land across the geographical range of the taxon. Data on climatic and topographic characteristics of these sites were obtained from Geographic Information Systems databases and entered into a principal components analysis. Unsurprisingly, locations where snakes were recorded differed from the random sites in several respects (e.g. rainfall, elevation, seasonality of precipitation). Within a given forest, H. stephensii was generally found in areas similar to randomly chosen points. Comparison of vegetation communities used with those available within forests provided no evidence for active habitat selection. Comparisons of Geographic Information Systems‐derived data for snake‐collection localities along roads versus those within the forest revealed significant biases, and we warn that such methodological errors could generate spurious conclusions about non‐random habitat use by threatened species. In combination with previous data from radio‐tracking, we conclude that although H. stephensii is highly specialized in its arboreality and dependence upon hollow trees, its broad tolerance with respect to other factors (climatic conditions, vegetation communities, food types, etc.) allows populations to persist so long as large areas of forest with high numbers of hollow‐bearing trees are available. These requirements are similar to those of many other components of the Australian forest fauna. Thus, the findings of this study support the idea that the same kinds of management programmes can effectively conserve a wide range of taxa, if such programmes protect critical habitat components at suitable spatial scales.     

Novel microsatellite loci identified from the Australian eastern small‐eyed snake (Elapidae: Rhinocephalus nigrescens) and cross species amplification in the related genus Suta

A total of 15 microsatellite primers pairs were developed for the Australian small‐eyed snake Rhinoplocephalus nigrescens. Five primers were used to screen 93 individuals of R. nigrescens and were also tested against eight species of the closely related genus Suta. Allelic diversity in R. nigrescens was high in three loci (12–27) and there was high heterozygosity (0.58–0.82). Observed heterozygosity did not deviate from Hardy–Weinberg expectations for the five loci tested. These primers will be useful in studies of population genetics and mating systems of small‐eyed snakes and related species.     

Isolation and characterization of novel microsatellite markers from the Australian tiger snakes (Elapidae: Notechis) and amplification in the closely related genus Hoplocephalus

We provide details of seven microsatellite loci (out of 20 primer pairs designed) that exhibited the cleanest and strongest banding patterns for the Eastern tiger snake Notechis scutatus. These loci were used to screen 76 individuals from across the geographical range of N. scutatus and a further 14 individuals of the closely related and endangered broadheaded snake Hoplocephalus bungaroides. We observed large numbers of alleles per locus (14–52) and relatively high levels of heterozygosity (0.270–0.696) within the N. scutatus sample. These markers are also likely to be informative for work on H. bungaroides.     

Reproductive mode may determine geographic distributions in Australian venomous snakes (Pseudechis,Elapidae)

Summary Why are viviparous squamate reptiles more common in cold climates, and oviparous ones in warmer areas? The usual explanation is that (1) oviparous squamates cannot reproduce successfully in cold areas because soil temperatures are too low for embryonic development; and (2) viviparous squamates experience lower survivorship or reproductive success than oviparous taxa in warmer areas. These hypotheses suggest that the boundaries of geographic distributions of congeneric oviparous and viviparous squamates should be predictable from data on thermal tolerances of embryos, and estimated temperatures of soils and gravid female reptiles throughout the potential geographic range of the taxon. In large venomous Australian snakes of the genus Pseudechis, distributional boundaries of oviparous and viviparous taxa can be accurately predicted from such data. This predictive ability, if substantiated by studies of other reproductively biomodal squamate taxa, would support the putative role of reproductive mode as a direct determinant of reptilian geographic distributions.     

Integrating phylogeny,environment and space to explore variation in macroecological traits of Viperidae and Elapidae (Squamata: Serpentes)

We used eigenvector mapping in space and phylogeny to investigate the relationships among space, phylogeny and environment on body size and range size variation across two groups of venomous snakes – Viperidae and Elapidae – from the New World. Data on species geographic range sizes, maximum body sizes and phylogenetic relationships were compiled from the available literature. The distributional data were also used to calculate the latitudinal and longitudinal midpoint and the environmental centroids for each species. The eigenvectors extracted from the pair wise spatial and phylogenetic distance matrices were integrated with environmental variables into a method of variation partitioning where the variation in each trait was quantitatively attributed to ‘pure’ and/or shared effects of phylogeny, environment and space. Our results showed that variation in body size was predominantly determined by phylogeny in both groups of snakes. For Viperidae, we found that pure ‘effects’ of phylogeny were the strongest, indicating that most of the body size evolution that was phylogenetically determined in this group occurred independently of environment and geographical proximity. Regarding range sizes, pure phylogenetic influences were very low in both groups, whereas the largest single fraction of explained variation corresponded to overlapped influences of the three sets of predictors, especially for Elapidae. Along with this, we found evidence that niche conservatism is an important processes underlying variation in body size and range size in both groups of snakes.     

Movements and Habitat Use of an Endangered Snake,Hoplocephalus bungaroides (Elapidae): Implications for Conservation

A detailed understanding of how extensively animals move through the landscape, and the habitat features upon which they rely, can identify conservation priorities and thus inform management planning. For many endangered species, information on habitat use either is sparse, or is based upon studies from a small part of the species’ range. The broad-headed snake (Hoplocephalus bungaroides) is restricted to a specialized habitat (sandstone outcrops and nearby forests) within a small geographic range in south-eastern Australia. Previous research on this endangered taxon was done at a single site in the extreme south of the species’ geographic range. We captured and radio-tracked 9 adult broad-headed snakes at sites in the northern part of the species’ distribution, to evaluate the generality of results from prior studies, and to identify critical habitat components for this northern population. Snakes spent most of winter beneath sun-warmed rocks then shifted to tree hollows in summer. Thermal regimes within retreat-sites support the hypothesis that this shift is thermally driven. Intervals between successive displacements were longer than in the southern snakes but dispersal distances per move and home ranges were similar. Our snakes showed non-random preferences both in terms of macrohabitat (e.g., avoidance of some vegetation types) and microhabitat (e.g., frequent use of hollow-bearing trees). Despite many consistencies, the ecology of this species differs enough between southern and northern extremes of its range that managers need to incorporate information on local features to most effectively conserve this threatened reptile.     

Spatial ecology of jaguars,pumas, and ocelots: a review of the state of knowledge

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Roost preferences and foraging ranges of the eastern forest bat Vespadelus pumilus under two disturbance histories in northern New South Wales,Australia

Little is known about the habitat requirements of Australian bats; however, this information is needed to make better‐informed decisions when systems are disturbed. This study contrasts the roosting and foraging ecology of the eastern forest bat Vespadelus pumilus (Vespertilionidae), one of Australia’s smallest bats, between two sites of differing disturbance history on the mid‐north coast of New South Wales. Lorne Flora Reserve (182 ha) is primarily old‐growth forest surrounded by regrowth forest and eucalypt plantations, while Swans Crossing is dominated by regrowth and eucalypt plantations established on part of an old dairy farm. A total of 38 bats were tracked during the maternity and mating seasons at the two sites. Roost preferences were determined by comparing trees used as roosts with those randomly available, while foraging bats were triangulated from fixed stations at night. Bats tracked at Lorne Flora Reserve typically roosted in hollows within large, mature trees and showed a strong preference for roosting and foraging (females only) within the Reserve. Lactating females at Swans Crossing roosted in hollows of remnant rainforest trees within a gully and dead eucalypts, while males often roosted in understorey trees (such as Acacia). Dead trees were frequently used as roosts at both sites. Under both disturbance histories, the mean distance of female maternity roosts from creeks was 20 m, indicating that riparian zones provide important roosting habitat for V. pumilus. However, roosts shifted to the mid‐slope prior to winter when bats mate. Retention of mature trees in a variety of topographic locations may allow behavioural adjustments with the seasons. Bats caught in the regrowth forest also foraged there, with foraging ranges averaging just 5.3 ha (n = 10), indicating that regrowth is used by this bat for both foraging and roosting.     

Spatial ecology of female bighorn sheep in a prairie landscape in Nebraska

Understanding the spatial ecology of small populations at the periphery of their range is important for identifying factors limiting population growth and developing sound management strategies. Bighorn sheep were reintroduced to Nebraska in 1981 and persist in a small population at the easternmost extent of the distribution of the species, where 1 of the 2 subpopulations is declining. Bighorn sheep space use and movement has been studied extensively in mountain and desert populations, but information is sparse from prairie populations in the Northern Great Plains. We investigated the spatial ecology of female bighorn sheep in Nebraska, USA, with global positioning system (GPS) telemetry. We tested the hypothesis that space use and movements would vary across seasons, years, and individuals but predicted that migration would involve relatively short distances in this translocated population (relative to native populations) occupying a fragmented landscape. Overall, females used smaller seasonal home ranges (3.3–7.8 km²) than most of those reported previously for the species and exhibited a high degree of variability in space use and movements across seasons, subpopulations, and individuals. Most females (92–100%) exhibited fidelity to their home ranges across seasons and years. Six females migrated between spatially distinct core lambing and winter ranges, although the distances (range = 7.9–8.7 km) and mean elevations (range = 31–41 m) between these core seasonal ranges were less than those reported for most native, migratory bighorn sheep populations. After accounting for variation in season, subpopulation, and years, home range size was positively associated with road density in both subpopulations (P < 0.001), suggesting that females incur greater energetic costs associated with greater space use in areas of higher fragmentation. Our results establish the basic spatial ecology of female bighorn sheep in Nebraska where their behavior appears to reflect the isolated nature of suitable habitat in this fragmented prairie landscape.     

Spatial ecology of bluetongue lizards (Tiliqua spp.) in the Australian wet–dry tropics

New technologies for quantifying animal locations enable us to document habitat‐selection patterns of cryptic taxa in extraordinary detail. Northern bluetongues (Tiliqua scincoides intermedia) and centralian bluetongues (Tiliqua multifasciata) are large heavy‐bodied scincid lizards that are broadly sympatric in the wet–dry tropics of north‐western Australia. We used data from GPS‐based radiotelemetry (n = 49 lizards, tracked for 2–121 days, total n = 61 640 locations) to examine the size, internal structure and overlap of lizard home ranges. Despite substantial habitat differences at our two study sites (semi‐arid and relatively pristine habitat at Keep River National Park, Northern Territory, vs. highly disturbed and fragmented flood plain habitat in an agricultural area near Kununurra, Western Australia), home ranges were similar between the two areas, and between the two species. Our radio‐tracked lizards continued to disperse into previously unused areas throughout the duration of the study, so that the total areas used by lizards continued to increase. Based on the minimum convex polygon method, total home ranges averaged 4 ha (range 2–12 ha), but only about two‐thirds of each home range was used intensively. Each home range had multiple core areas, and overlap of core as well as peripheral areas (especially with same‐sex conspecifics) was high at the disturbed (Western Australia) site where lizard densities were high. The concentration of lizard activity within small core areas, often used by multiple individuals, suggests that these heavily used sites are critical to lizard conservation. However, the lizards' infrequent long‐distance displacements also make them vulnerable to changes in the wider landscape mosaic. Because GPS‐based radiotelemetry can quantify habitat use at finer spatial and temporal scales than earlier technologies, it can provide a robust base for management of at‐risk fauna.     

Home-range use and intergroup encounters in western gorillas (Gorilla g. gorilla) at Lossi forest, North Congo

I present data on home-range use and types of intergroup encounters for one group (Apollo) of western gorillas (Gorilla gorilla gorilla) from a new study site in the Republic of Congo. The total home-range size of the focal group, which I calculated by superimposing a 100 m x 100 m grid over the mapped daily path traveled, was 11 km2. The majority (73%) of the group's home range was used exclusively, although at the periphery it overlapped with the ranges of three other groups. Most encounters (86%) with other groups (n = 14) took place in the periphery of the home range, and appeared to involve access to fruit trees. The focal group silverback's encounters with solitary silverbacks occurred throughout the focal group's home range, did not involve access to fruit, and typically resulted in aggressive or avoidance behavior. The focal group silverback's response to other group males was more varied: it included tolerance (64%), avoidance (14%), and aggression (21%), and was dependent upon the identity of the extragroup male. The focal group exhibited an unusual form of tolerant behavior toward some other groups by occasionally forming "nesting supergroups" (two groups nested together overnight at distances of 30-50 m). The western gorillas at Lossi were somewhat fluid in their grouping. Subgrouping and supergrouping occurred, although more infrequently than reported previously, and with a new twist: subgrouping did not necessarily require a silverback's presence. I stress the need for intraspecific comparisons and more complete data sets on western gorilla social organization.     

Spatial and temporal changes in bird assemblages in forest fragments in an eastern Amazonian savannah

We investigated the effects of forest fragmentation on bird assemblages in an Amazonian savannah landscape with forest fragments that have been isolated for more than 100 years. The study was conducted in areas surrounding the village of Alter do Chão (2°31′S, 55°00′W), Santarém, Brazil. Bird surveys and measurements of tree density were undertaken in 25 areas, with 19 plots in forest fragments of different sizes and six in an area of continuous forest. Data on forest‐fragment size, perimeter, and isolation were obtained from a georeferenced satellite image. Variation in number of bird species recorded per plot was not related to vegetation structure (tree density). The number of bird species recorded per plot increased significantly only with fragment area, but was not influenced by fragment shape or degree of isolation, even when considering species from the savannah matrix in the analysis. Fragments had fewer rare species. Multivariate ordination analyses (multiple dimensional scaling, [MDS]) indicated that bird species composition changed along a gradient from small to large forest fragments and continuous‐forest areas. In the Amazonian savannah landscapes of Alter do Chão, the organization and composition of bird assemblages in forest fragments are affected by local long‐term forest‐fragmentation processes. Differences in the number of bird species recorded per plot and assemblage composition between forest fragments and continuous forest were not influenced by forest structure, suggesting that the observed patterns in species composition result from the effects of fragmentation per se rather than from preexisting differences in vegetation structure between sites. Nevertheless, despite their long history of isolation, the forest fragments still preserve a large proportion (on average 80%) of the avifauna found in continuous‐forest areas. The fragments at Alter do Chão are surrounded by natural (rather than planted) grassland, with many trees in the savannah matrix and the landscape has vast areas covered by forest, which may have helped to ameliorate the influences of forest fragmentation.     

Terrestrial activity,movements and spatial ecology of an Australian freshwater turtle,Chelodina longicollis,in a temporally dynamic wetland system

Animal movements, use of space, activity patterns and habitat use are in part determined by proximal factors such as the landscapes they occupy, seasonal or environmental cues and individual attributes such as sex and body size. Using radio‐telemetry and a drift fence, we examined the contribution of these factors to variation in movements, use of space and terrestrial activity in a freshwater turtle, Chelodina longicollis (Testudines: Chelidae), in south‐east Australia. Movements and use of space depended strongly on landscape attributes, while sex and body size were less important. Movements and use of space also varied seasonally and were partly correlated with rainfall. The high overall vagility of turtles, irrespective of sex and adult body size (13.8 ± 2.8 ha (±SE) home range, 2608 ± 305 m total distance moved, 757 ± 76 m range length), probably reflects a common need to be mobile in a landscape characterized by fluctuating resources in temporary wetlands. Use of temporary wetlands also drives C. longicollis into terrestrial habitats for movements between wetlands and extended refuge. Timing of inter‐wetland movements was associated with rainfall, but most notably for immature individuals and for those moving towards temporary wetlands. Movements of adults, evacuation of the drying wetland and periods of extended refuge (i.e. aestivation) were less dependent upon rainfall if at all. We conclude that movements about and use of the landscape by C. longicollis are under the strong influence of several interacting factors such as patch configuration, seasonal and environmental cues, and in part, body size. We argue that such behaviours are also ultimately under selection from the costs and benefits of these behaviours in the context of fluctuating resources.     

Spatial and temporal patterns of home range use by olive baboons (Papio anubis) in eastern Laikipia,Kenya

The study investigated the relationship between topography, seasonal food availability and home range use by a troop of olive baboons (Papio anubis) in a dry savannah environment. Valleys were the most utilized parts of the home range in dry seasons while old boma sites were more frequently used in the wet season. Herb‐layer food biomass decreased significantly in dry seasons. The flowers of both Acacia tortilis and Acacia etbaica were available only in dry seasons with valleys having the highest biomass. The biomass of Acacia nilotica seeds was higher in valleys than on other locations. Leaves of the shrub Lycium europaeum were available on all locations in the wet season but valleys had the highest biomass of this food type. Herb‐layer baboon food biomass at ridge tops, slopes, valleys and old boma sites showed similar trends in productivity between seasons. Baboons tracked food along the soil catenas by feeding at ridge tops and old boma sites where foods were available during the wet season and exploiting food sources at the valleys during the dry seasons. Food availability was related to the catena effect and baboons used the catenas in the home range in a predictable manner.