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opencc-zeroDec 2016View details →

Data from: Spatial dynamics of habitat use informs reintroduction efforts in the presence of an invasive predator

1. Islands experience major impacts from introduced species, especially nocturnal predators. The Brown Treesnake (Boiga irregularis) extirpated almost the entire native avifauna on Guam shortly after introduction. Reintroductions from neighboring islands can restore bird communities but will take place in heavily managed units where snake populations can be controlled. Yet reintroductions often proceed without relevant biological information such as nocturnal habitat and space use when nocturnal predators are present. To guide efforts, we studied diurnal and nocturnal habitat and space use by the avian frugivore community on the nearby island of Saipan where the snake is absent. 2. Using radio telemetry and a Bayesian framework, we first compared data typically accessible to resource managers (diurnal home range [DHR] and habitat selection) and which often forms the basis of reintroduction plans. We contrast this with data on nocturnal habitat use that is often not available but relevant when nocturnal predation threat is high. 3. DHR size varied within and among species with Micronesian Starlings (Aplonis opaca) having DHRs at least 45 ha larger than other species. For all species, night roost locations were generally spatially clustered within a DHR and covered a smaller spatial extent. Two species had higher probabilities of roosting outside DHR boundaries but, when outside, roosts were often within 200 m of the DHR boundary. All species selected forested habitats during day and night, with some species choosing native forest over non-native habitat. 4. Synthesis and applications If individuals roosted randomly throughout DHR's, landscape-level suppression of B. irregularis might be the only viable option for reintroductions of some species. However, individuals of all species showed clustered roosting and high site fidelity. If site fidelity is common, then individuals that roost within fenced areas where snake populations are severely reduced or eliminated will experience high survivorship even if DHRs extend into surrounding unprotected matrix. There was large overlap in habitat selection during day and night indicating managed areas should be composed of native forest with non-native forests of secondary importance. In systems with nocturnal predators, understanding variability in diurnal and nocturnal habitat use could lead to better informed decisions.

FIG. 4 in Staggered-Entry Analysis of Breeding Phenology and Occupancy Dynamics of Arizona Toads from Historically Occupied Habitats of New Mexico, USA

FIG. 4. Estimated detection probability from the simple multi-season model fitted with calling data from historical and control sites, based on the relationship between detection and Julian date from the simple multi-season occupancy model. Julian values represent only the values present in our data set and range from 1 March to 30 May (Julian days 60–150).

FIG. 3 in Staggered-Entry Analysis of Breeding Phenology and Occupancy Dynamics of Arizona Toads from Historically Occupied Habitats of New Mexico, USA

FIG. 3. Estimated probabilities of yearly occupancy (y-axis; 6 95% CI) from the historically occupied (orange) and control (blue) sites for the (A) staggered-entry model (SE) and the (B) simple multi-season (SMS) model. Dotted error bars represent years when surveys were not conducted.

FIG. 2 in Staggered-Entry Analysis of Breeding Phenology and Occupancy Dynamics of Arizona Toads from Historically Occupied Habitats of New Mexico, USA

FIG. 2. Estimated probabilities of Arizona Toads entering sites between subsequent surveys (orange), given that they have not previously entered, based on the estimated relationship between entry and Julian date. Estimated probabilities of Arizona Toad departing sites between subsequent surveys (blue), given that they are already present, based on the estimated relationship between departure and Julian date. Yellow points show the probabilities that toads were available to be detected for each day. Julian values range from 1 March to 30 May.

FIG. 1 in Staggered-Entry Analysis of Breeding Phenology and Occupancy Dynamics of Arizona Toads from Historically Occupied Habitats of New Mexico, USA

FIG. 1. Study area in southwestern New Mexico showing historically occupied (n ¼ 86; red circles) and control (n ¼ 59; blue triangles) waterbodies sampled during the 2013–2016 and 2019 breeding seasons for the Arizona Toads (Anaxyrus microscaphus). Filled shapes represent sites where we detected toads at least once, and open shapes represent sites where we never detected toads. Basemap by Stamen Design, under CC BY 3.0.

opencc-zeroDec 2013View details →

Data from: Epigenetic variation reflects dynamic habitat conditions in a rare floodplain herb

Variation of DNA-methylation is thought to play an important role for rapid adjustments of plant populations to dynamic environmental conditions, thus compensating for the relatively slow response time of genetic adaptations. However, genetic and epigenetic variation of wild plant populations has not yet been directly compared in fast changing environments. Here we surveyed populations of Viola elatior from two adjacent habitat types along a successional gradient characterized by strong differences in light availability. Using AFLP and MSAP analyses we found relatively low levels of genetic (H'gen=0.19) and epigenetic (H'epi=0.23) diversity and high genetic (ϕST=0.72) and epigenetic (ϕST=0.51) population differentiation. Diversity and, respectively, differentiation were significantly correlated, suggesting that epigenetic variation partly depends on the same driving forces as genetic variation. Correlation based genome scans detected comparable levels of genetic (17.0%) and epigenetic (14.2%) outlier markers associated with site specific light availability. However, as revealed by separate differentiation based genome scans for AFLP, only few genetic markers seemed to be actually under positive selection (0-4.5%). Moreover, PCoA and Mantel tests showed that overall epigenetic variation was more closely related to habitat conditions, indicating that environmentally-induced methylation changes may lead to convergence of populations experiencing similar habitat conditions and may thus play a major role for the transient and/or heritable adjustment to changing environments. Additionally, using a new MSAP scoring approach, we found that mainly the unmethylated (ϕST=0.60) and CG-methylated states (ϕST=0.46) of epiloci contributed to population differentiation and putative habitat related adaptation, whereas CHG-hemimethylated states (ϕST=0.21) only played a marginal role.

opencc-zeroDec 2009View details →

Data from: Significant genetic boundaries and spatial dynamics of giant pandas occupying fragmented habitat across southwest China

Understanding population history and genetic structure are key drivers of ecological research. Here we studied two highly fragmented and isolated populations (Xiaoxiangling and Daxiangling) of giant pandas (Ailuropoda melanoleuca) at the extreme southwestern edge of their distribution. This area also contains the Dadu River, national road 108 and various human infrastructure and development, providing an ideal region in which we can identify the effects of different barriers on animal movements. We used partial mitochondrial control region (mtDNA) and nine microsatellite loci (nuclear DNA) data derived from 192 fecal and one blood sample collected from the wild. We found 136 genotypes corresponding to 53 unique multilocus genotypes and eight unique control region haplotypes (653 bp). Significant genetic boundaries correlated spatially with the Dadu River (K=2). We estimate that a major divergence took place between these populations 26 000 YBP, at around the similar time the rock surface of valley bottom formed in Dadu River. The national road has resulted in further recent population differentiation (Pairwise FS on mtDNA and nuclear DNA) so that in effect, four smaller sub-populations now exist. Promisingly, we identified two possible first generation migrants and their migration paths, and recommended the immediate construction of a number of corridors. Fortunately, the Chinese government has accepted our advice and is now planning corridor construction.

opencc-zeroDec 2013View details →

Data from: Temporally dynamic habitat suitability predicts genetic relatedness among caribou

Landscape heterogeneity plays a central role in shaping ecological and evolutionary processes. While species utilization of the landscape is usually viewed as constant within a year, the spatial distribution of individuals is likely to vary in time in relation to particular seasonal needs. Understanding temporal variation in landscape use and genetic connectivity has direct conservation implications. Here, we modelled the daily use of the landscape by caribou in Quebec and Labrador, Canada and tested its ability to explain the genetic relatedness among individuals. We assessed habitat selection using locations of collared individuals in migratory herds and static occurrences from sedentary groups. Connectivity models based on habitat use outperformed a baseline isolation-by-distance model in explaining genetic relatedness, suggesting that variations in landscape features such as snow, vegetation productivity and land use modulate connectivity among populations. Connectivity surfaces derived from habitat use were the best predictors of genetic relatedness. The relationship between connectivity surface and genetic relatedness varied in time and peaked during the rutting period. Landscape permeability in the period of mate searching is especially important to allow gene flow among populations. Our study highlights the importance of considering temporal variations in habitat selection for optimizing connectivity across heterogeneous landscape and counter habitat fragmentation.

opencc-zeroDec 2022View details →

Effects of habitat types on the dynamic changes of allocation in carbon and nitrogen storage of vegetation-soil system in sandy grasslands

<p>The progressive restoration of degraded vegetation in semiarid and arid desertified areas undoubtedly formed different habitat types. The most plants regulate their growth by fixing carbon with their energy deriving from photosynthesis, carbon (C) and nitrogen (N) play the crucial role in regulating plant growth, community structure and function in the vegetation restoration progress. However, it is still unclear how habitat types affect the dynamic changes of allocation in C and N storage of vegetation-soil system in sandy grasslands. Here, we investigated plant community characteristics and soil properties across three successional stages of habitat types: semi-fixed dunes (SFD), fixed dunes (FD) and grasslands (G) in 2011, 2013 and 2015. We also examined the C and N concentrations of vegetation-soil system, and estimated their C and N storage. The C and N storage of vegetation system, soil and vegetation-soil system remarkably increased from SFD to G. The litter C and N storage in SFD, N storage of vegetation system in SFD and N storage of soil and vegetation-soil system in FD increased from 2011 to 2015, while aboveground plant C and N storage of FD were higher in 2011 than in 2013 and 2015. Most of C and N were sequestered in soil in the vegetation restoration progress. These results suggest that the dynamic changes of allocation in C and N storage in vegetation-soil systems varied with habitat types. Our study highlights that SFD has higher N sequestration rate in vegetation, while FD has the considerably N sequestration rate in the soil.</p>

opennotspecifiedFeb 2023View details →

FIG. 3 in Breeding Population Dynamics of Threatened Crawfish Frogs Inform Targets for Habitat Management

FIG. 3. Correlation between tadpole survival and the instantaneous population growth rate (k) for 1,000 points drawn randomly from 1,000 simulations of stochastic population simulations of Nate's Pond with (left panel) and without (right panel) immigration included in the simulation model. The white line is a third order polynomial function fitted to the data, and the gray band represents the 95% confidence interval. The horizontal dashed line indicates a k of 1. The distributions of tadpole survival rates and k values are provided as marginal plots.

opennotspecifiedFeb 2023View details →

FIG. 2 in Breeding Population Dynamics of Threatened Crawfish Frogs Inform Targets for Habitat Management

FIG. 2. Percent change in the instantaneous population growth rate (k) in response to a percent change in female Crawfish Frog tadpole, juvenile, or adult survival rates for a population located in southwest Indiana, USA, between 2009–2013. Percent change in each vital rate represents the general range of that vital rate observed in this study. Change was estimated by varying the focal rate while holding all other rates constant.

opennotspecifiedFeb 2023View details →

FIG. 1 in Breeding Population Dynamics of Threatened Crawfish Frogs Inform Targets for Habitat Management

FIG. 1. (A) Post-birth, females-only, stage matrix model of Crawfish Frogs that accommodates age and state-specific transition probabilities and the ''temporary emigration'' of individuals that skip breeding or breed at other sites. (B) Projection matrix of the model used to estimate elasticities and sensitivities of vital rates. Parameters in the matrix model: embryonic survival (Se), tadpole survival (St), metamorph and juvenile survival (Sj), adult survival following the first breeding event (Sa1), adult survival following two or more breeding events (Sa2), probability that a one-year-old juvenile matures at age 2 (p), probability that a two-year-old juvenile matures at age 3 (q), the probability that a mature individual emigrates to become a non-breeding individual (c22), probability that a non-breeding individual remains a non-breeding individual (c'), and clutch size multiplied by 0.5 to represent half of all eggs developing into females (C). We assumed that all individuals mature by age 4. Individuals that emigrate to become a nonbreeding individual may either skip reproduction or breed at another site.