Mainland Florida Research Articles

Population Genetic Structure of a Rare Butterfly in a Fragmented South Florida Ecosystem.

We investigated the genetic structure and diversity between populations of a rare butterfly, the Florida duskywing (Ephyriades brunnea floridensis E. Bell and W. Comstock, 1948) (Lepidoptera: Hesperiidae) across a network of South Florida pine rockland habitat fragments. Based on 81 individuals from seven populations and using multiple polymorphic microsatellite loci, our analyses support the presence of mainland Florida (peninsular) and Florida Keys (island) population groupings, with a moderate, asymmetrical gene flow connecting them, and the presence of private alleles providing unique identities to each. We additionally found that despite a prevalence in many Lepidoptera, the presence of Wolbachia was not identified in any of the samples screened. Our findings can be used to inform conservation and recovery decisions, including population monitoring, organism translocation, and priority areas for management, restoration or stepping-stone creation to help maintain the complex genetic structure of separate populations.

Ensemble Models for Tick Vectors: Standard Surveys Compared with Convenience Samples.

Ensembles of Species Distribution Models (SDMs) represent the geographic ranges of pathogen vectors by combining alternative analytical approaches and merging information on vector occurrences with more extensive environmental data. Biased collection data impact SDMs, regardless of the target species, but no studies have compared the differences in the distributions predicted by the ensemble models when different sampling frameworks are used for the same species. We compared Ensemble SDMs for two important Ixodid tick vectors, Amblyomma americanum and Ixodes scapularis in mainland Florida, USA, when inputs were either convenience samples of ticks, or collections obtained using the standard protocols promulgated by the U.S. Centers for Disease Control and Prevention. The Ensemble SDMs for the convenience samples and standard surveys showed only a slight agreement (Kappa = 0.060, A. americanum; 0.053, I. scapularis). Convenience sample SDMs indicated A. americanum and I. scapularis should be absent from nearly one third (34.5% and 30.9%, respectively) of the state where standard surveys predicted the highest likelihood of occurrence. Ensemble models from standard surveys predicted 81.4% and 72.5% (A. americanum and I. scapularis) of convenience sample sites. Omission errors by standard survey SDMs of the convenience collections were associated almost exclusively with either adjacency to at least one SDM, or errors in geocoding algorithms that failed to correctly locate geographic locations of convenience samples. These errors emphasize commonly overlooked needs to explicitly evaluate and improve data quality for arthropod survey data that are applied to spatial models.

Dataset for Mosquitoes (Diptera: Culicidae) from Cross Key, Monroe County, Florida, USA

The Florida Keys Mosquito Control District deploys dry ice-baited light traps to monitor mosquito populations throughout the Florida Keys. Cross Key is an island directly north of Key Largo and via bridges it serves as a link between Key Largo and mainland Florida. This paper describes a data set compiled from trap collections on Cross Key, Florida, between September 23, 2002 and March 1, 2016.

Validating Species Distribution Models With Standardized Surveys for Ixodid Ticks in Mainland Florida.

Tick-borne pathogens are of growing concern. The U.S. Centers for Disease Control and Prevention (CDC) developed guidelines standardizing surveys of tick vectors to better monitor the changes in their occurrences. Unbiased surveillance data, from standardized surveys, are presumed critical to generate valid species distribution models (SDMs). We tested previously generated SDMs from standardized protocols for three medically important ticks [Amblyomma americanum (Linnaeus, Ixodida, Ixodidae), Ixodes scapularis (Say, Ixodida, Ixodidae), and Dermacentor variabilis (Say, Ixodida, Ixodidae)]. These previous models ruled out a quarter to half of the state as having these species, with consensus occurrence in about a quarter of the state. New surveys performed throughout 2019 on 250 transects at 43 sites indicated the rule-out functions were 100% accurate for I. scapularis and D. variabilis and 91.9% for A. americanum. As SDM concordance increased, the proportion of transects yielding ticks increased. Independent surveys of SDMs provide external validation—an aspect missing from many SDM studies.

Establishment ofAedes(Ochlerotatus)scapularis(Diptera: Culicidae) in Mainland Florida, With Notes on the Ochlerotatus Group in the United States

Aedes scapularis (Rondani), a widespread neotropical vector mosquito species, has been included in the mosquito fauna of Florida on the basis of just three larval specimens that were collected in the middle Florida Keys in 1945. Here, we report numerous recent collections of immature and adult Ae. scapularis from multiple locations in two counties of southern Florida. These specimens represent the first records of Ae. scapularis from mainland Florida and the first records of the species in the state since the initial detection of the species 75 yr ago. Collections of both larvae and adults across several years indicate that Ae. scapularis is now established in Broward and Miami-Dade Counties. These contemporary records of this species in Florida may represent novel dispersal and subsequent establishment events from populations outside the United States or a recent reemergence of undetected endemic populations. To confirm morphological identification of Ae. scapularis specimens from Florida, the DNA barcoding region of the cytochrome c oxidase subunit I gene (COI) was sequenced and compared to all other Ochlerotatus Group species from the United States, specifically Aedes condolescens Dyar and Knab (Diptera: Culicidae), Aedes infirmatus Dyar and Knab (Diptera: Culicidae), Aedes thelcter Dyar (Diptera: Culicidae), Aedes tortilis (Theobald) (Diptera: Culicidae), and Aedes trivittatus (Coquillett) (Diptera: Culicidae). Molecular assays and sequencing confirm morphological identification of Ae. scapularis specimens. Maximum likelihood phylogenetic analysis of COI and ITS2 sequences place Florida Ae. scapularis in a distinct clade, but was unable to produce distinct clades for Florida specimens of Ae. condolescens and Ae. tortilis.

Back to the Future: Updates on the Invasion History of Junonia Butterflies in Florida and the Mystery of Chokoloskee

The tropical buckeye, Junonia zonalis (Lepidoptera: Nymphalidae) is a recent addition to the butterfly fauna of mainland Florida. It appears that this species began to invade the mainland from the Florida Keys or Cuba by the 1930s, hybridizing with J. coenia and bringing with it mitochondrial haplotype group A, which is common in the Caribbean but is essentially absent from North American Junonia. By the 1940s, J. zonalis appears to have established populations in Miami, but eventually may have been extirpated. Later, new populations of J. zonalis may have become established on mainland Florida by subsequent waves of J. zonalis migrants. Substantial fluctuations in both population size and mitochondrial haplotype group A frequency seem to be characteristic of Florida mainland populations of J. zonalis. Populations of J. zonalis in the Florida Keys and Cuba have maintained nearly constant mitochondrial haplotype group A frequencies over many decades and may be more stable than those on the Florida mainland. Junonia zonalis specimens attributed to Chokoloskee, Florida, from the early 1900s have questionable provenance. Based on their haplotype frequency and other evidence these Chokoloskee specimens may have been collected in Cuba. Similarly, one specimen of J. zonalis likely collected during the 1880s and labeled “Indian River, Fla.” probably also originated from outside of Florida.

Ecological Plasticity and the Future of the Argentine Giant Tegu (Salvator merianae Dumeril and Bibron, 1839) in the Southeastern US

Salvator merianae (Argentine Giant Tegu) is an invasive exotic species established in 2 as yet unconnected populations in central and southern Florida. Despite intense trapping, this mid-level carnivore remains well-established in a portion of extreme southern mainland Florida where it was first released 20 y ago. High fecundity, nest-guarding, rapid growth to large body size, and broad trophic width by which it negatively impacts wildlife contribute to its success as a colonizing species. Native to more temperate habitat, it experiences a defined winter and summer in South America unlike the wet–dry seasons of southern Florida. We conducted a qualitative comparison of key life-history traits from source areas to those of southern Florida that provided a measure of its ecological plasticity and formed the basis for expectations associated with northward expansion. Our examination of 1168 specimens collected during 2011–2017 revealed an overlap between the sexes in timing of fat storage prior to brumation and late-winter–early-spring peak in gonadal size. Females were ovigerous during March–May and possibly June, and clutch size averaged 28.6 eggs. Hatching was possible during May–August, and both sexes reached sexual maturity by 2 y of age. In this subtropical system, length of seasonal activity, gonadal cycles, and size and age at sexual maturity differed from those of source areas, indicative of the degree of plasticity among these traits over a short period of time. We found that the climate of the Southeast is amenable to the colonization of this vagile species. Our findings are suggestive that a return to the strongly selected seasonal activity and gonadal cycles of central Argentina will accompany the Argentine Giant Tegu in its northward dispersal into more temperate conditions even as it retains a somewhat relaxed cycle in southern Florida.

A tale of two islands: evidence for impaired stress response and altered immune functions in an insular pit viper following ecological disturbance.

The frequency and intensity of ecological perturbations affecting wild animal populations is expected to increase in the future with animals facing numerous global threats. Seahorse Key is a continental island off mainland Florida that has historically been a major rookery for several species of waterbirds. As a result of an unknown disturbance, the entire rookery abandoned Seahorse Key in April 2015 and shifted nesting activities to nearby Snake Key, resulting in an influx of food resources in the form of fish carrion to resident Florida cottonmouth snakes (Agkistrodon conanti), while snakes on Seahorse Key experienced a drastic reduction in food resources. Our objective was to assess plasma corticosterone concentrations, corticosterone negative feedback using dexamethasone, blood glucose, body condition, packed cell volume, natural antibody agglutination, white blood cell counts and ratios and erythrocyte sedimentation rate to characterize the long-term effects of differential resource availability in these two snake populations 3years after this major ecological disturbance. We collected blood samples at three time points from cottonmouths on Seahorse Key (n = 6 individuals) and Snake Key (n = 13 individuals) in fall 2018. In due consideration of the small sample size, our study shows evidence that 3years after the shift in waterbird nesting Seahorse Key cottonmouths exhibit a dampened acute stress response and presumptive impaired innate immune functions relative to cottonmouths on Snake Key. These results highlight the context-dependent nature of biomarkers and implicate the significant decrease in food resources on Seahorse Key in altering hormonal stress responses and innate immune functions, possibly leading to unknown long-term downstream effects. This study assessed the response of a wild population of pit viper to ecological disturbance in situ with the aim to improve our understanding of how animals cope with such perturbations and improve our capacity to make informed decisions for conservation.

A Survey of Tick-Borne Bacterial Pathogens in Florida.

Within the past three decades, new bacterial etiological agents of tick-borne disease have been discovered in the southeastern U.S., and the number of reported tick-borne pathogen infections has increased. In Florida, few systematic studies have been conducted to determine the presence of tick-borne bacterial pathogens. This investigation examined the distribution and presence of tick-borne bacterial pathogens in Florida. Ticks were collected by flagging at 41 field sites, spanning the climatic regions of mainland Florida. DNA was extracted individually from 1608 ticks and screened for Anaplasma, Borrelia, Ehrlichia and Rickettsia using conventional PCR and primers that amplified multiple species for each genus. PCR positive samples were Sanger sequenced. Four species of ticks were collected: Amblyomma americanum, Amblyomma maculatum, Dermacentor variabilis, and Ixodes scapularis. Within these ticks, six bacterial species were identified: Borrelia burgdorferi, Borrelia lonestari, Ehrlichia ewingii, Rickettsia amblyommatis, Rickettsia andeanae, Rickettsia parkeri, and Rickettsia endosymbionts. Pathogenic Borrelia, Ehrlichia, and Rickettsia species were all detected in the North and North-Central Florida counties; however, we found only moderate concordance between the distribution of ticks infected with pathogenic bacteria and human cases of tick-borne diseases in Florida. Given the diversity and numerous bacterial species detected in ticks in Florida, further investigations should be conducted to identify regional hotspots of tick-borne pathogens.

Standardized Ixodid Tick Survey in Mainland Florida.

A statewide survey of questing ixodid ticks in mainland Florida was developed consistent with U.S. CDC standards to maximize the amount of epidemiologic and environmental data gathered. Survey sites were stratified by climatic zones and proportional to recognized land cover categories. A total of 560 transects on 41 sites within the state were sampled repeatedly by flagging between 2015 and 2018. Four tick species were collected; Amblyomma americanum, Amblyomma maculatum, Ixodes scapularis and Dermacentor variabilis. All species were more commonly found in northern and central regions of the state than in southern and western regions. Adult I. scapularis were active from autumn through spring and complementary to adult A. americanum and D. variabilis. Standardized survey methods help reduce sampling biases and better characterize risk from the species surveyed. However, differences in the attractiveness of collection methods for different tick species makes cross-species comparisons a continuing challenge.

Water relations of an insular pit viper

Colonization of novel habitats often requires plasticity or adaptation to local conditions. There is a critical need to maintain hydration in terrestrial environments having limited water. Atypical populations of Florida cottonmouth snakes, Agkistrodon conanti, inhabit continental islands with no permanent sources of fresh water. Here, we report investigations related to how these insular snakes maintain water balance considering the mainland conspecifics are semi-aquatic and typically associate with freshwater mesic habitats. We tested three hypotheses related to water relations of insular populations of cottonmouth snakes compared with those on the mainland. (1) Voluntary drinking of fresh water in free-ranging insular snakes should reflect a relationship to recency of rainfall more strongly than in mainland snakes. (2) Insular snakes will tolerate greater dehydration before drinking than will mainland snakes. (3) Insular snakes will avoid drinking seawater more strongly than will those from the mainland. Between 2001 and 2018, we quantitatively estimated the hydration status of 337 individual cottonmouth snakes from insular populations and 30 cottonmouth snakes from mainland Florida, as judged by the tendency of wild-caught snakes to drink fresh water immediately following capture. We found that insular cottonmouth snakes had a higher incidence of dehydration than did mainland cottonmouth snakes (64% versus 23%), and the hydration status of the insular snakes correlated with patterns of precipitation. We also determined experimentally the dehydration threshold for drinking fresh water in insular (mean±s.d. -5.64±4.3%, n=34) and mainland cottonmouth snakes (-5.74±4.5%, n=21), and these were not significantly different. Discrimination tests for drinking serially from a graded series of brackish water showed that mainland snakes did not discriminate against the highest brackish value (10.5ppt or 30% seawater), whereas insular snakes showed a preference for <15% seawater. Naive neonates from insular and mainland cohorts behaved similarly. The preference of insular snakes for fresh water represents an important aspect of the maintenance of water balance that differs from the mainland conspecifics and is likely a habituated or adaptive response to dependence on rainfall.

Resurrection of Scolopendra longipes Wood and Scolopendra cubensis Saussure from synonymy with Scolopendra alternans Leach (Chilopoda, Scolopendromorpha, Scolopendridae): an enigmatic species-group needing phylogeographic analysis, with an overview on the origin and distribution of centipedes in the Caribbean region.

Resurrection of Scolopendra longipes Wood, 1862, and Scolopendra cubensis Saussure, 1860, from junior synonymy with Scolopendra alternans Leach, 1815, is proposed. A neotype specimen of Scolopendra longipes is designated. Scolopendra longipes has a restricted range from the Dry Tortugas up through the Florida Keys of Monroe County into the mainland Florida counties of Collier and Dade southeast to the Bahamas, while Scolopendra cubensis is endemic to Cuba. Characters distinguishing S. longipes, and S. cubensis from S. alternans are illustrated and compared using digital photography, micrography and morphometric data. It is suggested that what has been considered Scolopendra alternans from southern Florida through the Caribbean and into northern South America is probably an evolving species-group that has undergone major diversification sometime during the Paleocene and early Eocene ~65.5-50 million years ago (Ma), mainly due to geographic isolation caused by a combination of plate tectonics and 100,000 year cycles of glaciation/deglaciation.

Towering cumulonimbus clouds over mainland Florida, viewed from Anna Maria Island, Florida

Towering cumulonimbus clouds over mainland Florida, viewed from Anna Maria Island, Florida

Geographic Distribution ofTrachymyrmex jamaicensis(Hymenoptera: Formicidae)

Trachymyrmex jamaicensis (Andre) (Hymenoptera, Formicidae) is a rarely encountered fungus-growing ant known only from the West Indies and South Florida. I compiled and mapped >100 site records for T. jamaicensis, documenting the earliest known records for 15 geographic areas (coun tries, U.S. states, and major West Indian islands). Populations of T. jamaicensis have an essentially continuous range from the island of St. Vincent in the south (13.1°N) to Florida and the Bahamas in the north (up to 27.0°N). Almost all records from Florida come from the Florida Keys, south of 25.5°N; there are only 2 records of T. jamaicensis from mainland Florida. Based on the scarcity of records of T. jamaicensis in Florida, the Florida Committee on Rare Endangered Plants and Animals (FCREPA) officially designated T. jamaicensis as rare species.

Ants of the Florida Keys: species accounts, biogeography, and conservation (Hymenoptera: Formicidae).

As a tropical archipelago, the Florida Keys provide an ideal environment to examine the historic and short-term processes that structure and influence biological diversity. Through a new survey of the ants of the Florida Keys, we increase our knowledge of the number of species to 94 representing 34 genera and 8 subfamilies. Through detailed collection information, we provide an in depth picture of the distribution of each species across the Keys. On the basis of these data and information on the native and known distributions of each species, we confirm the historical trend toward continued immigration of nonnative species into the Florida Keys and present these findings in the context of the proportion of native to nonnative species. We find a similar number of species introduced from the Old World and Neotropical mainland and discuss the probable immigration of mainland Florida species during the exposure of the Florida Shelf during the last glacial episode and the subsequent isolation of some populations as sea level rose following the last glaciation. Lastly, we discuss the possible threats to these populations due to rapid climate change and other human influences.

Identifying Effective Attractants and Rodenticide Baits for Gambian Giant Pouched Rats

F ollowing the escape of 8 Gambian giant pouched rats (Gambian rats) from an exotic pet breeder in 1999, Gambian ra ts became an established invasive species that persists in the wild on Grassy Key, Florida. Because of their large body size, the free/ranging Gambian rats pose a serious threat to native species and agricultural crops, especially if they find their way into mainland Florida. Initiated in 2005, the USDA Wildlife Services has been conducting an eradication and detection program in the Florida Keys. Today however, detecting, baiting, trapping, and removing the now sparse population of Gambian rats are proving difficult. Therefore, we conducted a laboratory trial with wild/captured Gambian rats from Grassy Kay to test 15 potential materials that could be used for attracting the remaining free/ranging population. We found that a conspecific scent (i.e., feces and urine) from other Gambian rats was the most attractive, but also peanut butter, anise, ginger, and fatty acid scent seemed to attract Gambian rats. In an additional study, we tested the efficacy of 6 commercially available rodenticide baits (all with different formulations of active ingredients) in multiple/choice food trials. We found that brodifacoum (second/generation anticoagulant) and zinc phosphide (acute rodenticide) formulated baits were highly effective. Using these various attractants and rodenticides could be useful for eliminating the sparse population of invading Gambian rats in the Florida Keys.

Potential attractants for detecting and removing invading Gambian giant pouched rats (Cricetomys gambianus)

Native to Africa, Gambian giant pouched rats (Gambian rats; Cricetomys gambianus Waterh.) are a threatening invasive species on a Florida island, Grassy Key. Gambian giant pouched rats shifted from a domestic pet to invading species after suspected release from a pet breeder. Because of the large size of Gambian rats (weighing up to 2.8 kg), they pose a serious threat to native species (particularly nesting species) and agricultural crops, especially if Gambian rats invade mainland Florida. Also, Gambian rats pose a threat from disease, as they were implicated in a monkeypox outbreak in the midwestern United States in 2003. The United States Department of Agriculture's Wildlife Services has initiated eradication and detection efforts in the Florida Keys, but trapping the sparse population of Gambian rats has proven difficult. Fifteen attractants that could be used in traps for capturing or detecting single or paired Gambian rats were tested. It was found that conspecific scents (i.e. feces and urine) from other Gambian rats were the best treatment for attracting single and paired Gambian rats. Single Gambian rats explored more attractant types than paired Gambian rats. Effective attractants for use with Gambian rats have been identified, and multiple attractant types should be used to capture or detect the sparse population. It is recommended that mainly urine and feces from Gambian rats be used, but peanut butter, anise, ginger and fatty acid scent could also be useful for attracting the currently small population of Gambian rats on Grassy Key.

Raccoon (Proycon lotor) removal and the rapid colonization of the green iguana (Iguana iguana) on a public land in South Florida: A conservation opportunity for the Caribbean

The greeni iguana (Iguana iguana) is a highly invasive exotic lizard that is firmly established in southern Florida. We documented the colonization pattern of this species at Hugh Taylor Birch State Park (HTBSP) in southern mainland Florida. First seen at the park in 1994, individual lizards were few in number, large in body size, and seen only in trees well above the ground. Shortly after the removal of an extremely high-density raccoon population at HTBSP in November 2000, mixed size-classes of green iguanas were observed often and in high numbers. Results of a survey conducted during August 2006–January 2007 corroborated the high relative abundance and size-structure of a growing population of green iguanas, and their increased terrestrialism following the removal of a native mammalian predator. Conversely, we hypothesize that indigenous threatened green iguana populations in the Caribbean would be beneficiaries of exotic raccoon removal, particularly on relatively isolated sites similar to that investigated in this study.

PREDICTING WOODY-PLANT SPECIES RICHNESS IN TROPICAL DRY FORESTS: A CASE STUDY FROM SOUTH FLORIDA, USA

Tropical dry forests are one of the world's most endangered forest types. Currently there are no comparative data on extent or levels of species richness for remaining forest fragments. This research identifies landscape metrics and spectral indices that can be applied at the stand and patch level to predict woody-plant species richness in tropical dry forests. This study was undertaken in 18 stands of tropical dry forest with nine sites in the Florida Keys and nine sites within an urban–agricultural matrix in mainland Florida, USA. Woody-plant species richness was quantified at the stand level (belt transects totaling 500 m2) and patch level (presence/absence data for 65 native tropical plants ≤2.5 cm dbh) for all study sites. Landsat Enhanced Thematic Mapper Plus (ETM+) satellite images (pixel resolution 30 × 30 m) were used to assess the utility of landscape metrics (forest patch area, nearest neighbor distance, shape index, boundary complexity) and spectral indices (normalized-difference vegetation index [NDVI] for nine pixels and 500 pixels directly over transects, and all pixels in the forest patch area) for predicting stand- and patch-level species richness. The 18 stands of tropical dry forest sampled in this study included 4248 woody plants, representing 71 species. Islands in the Florida Keys had higher levels of woody-plant species richness than mainland sites. There was a significant positive relationship between mean NDVI for the nine pixels over each stand and stand species richness and a significant negative relationship between species richness and standard deviation of NDVI for nine pixels over each stand. The density of evergreen plants explained 66% of the variability in mean NDVI. At the patch level, forest patch area and mean NDVI at the stand, 500-pixel, and patch level were all positively associated with patch species richness. However, combining forest patch area with NDVI significantly improved the prediction of patch species richness. Results from this study support the species–energy theory at the level of a forest stand and patch and suggest that a first-order approximation of woody-plant species richness in stands and patches of tropical dry forest is possible in biodiversity hot spots.

An exploratory assessment of Cuban Treefrog (Osteopilus septentrionalis) tadpoles as predators of native and nonindigenous tadpoles in Florida

The introduction and establishment of nonindigenous species is a significant threat to native biodiversity worldwide (Vitousek et al., 1996; Mack et al., 2000). The adverse ecological impacts of such species on native taxa are generally attributed to several basic mechanisms, perhaps the most obvious of which is the direct predation of native organisms by a nonindigenous species (Simberloff, 1997). In the most extreme cases, predation by nonindigenous species has caused the extinction of native and endemic faunas (e.g., Honegger, 1981; Savidge, 1987; Atkinson, 1989). Although the impacts of nonindigenous predators are not always this severe, they are nonetheless worrisome if native community structure is significantly altered. For these reasons the study of the impacts of potentially injurious invasive predators is an essential component of biodiversity conservation. The nonindigenous Cuban Treefrog, Osteopilus septentrionalis, has been established in mainland Florida, USA since at least 1951 (Schwartz, 1952) and has since spread to occupy much of peninsular Florida where it occurs syntopically with several native anurans (Meshaka, 2001). Anecdotal reports of lo-