Changes in parrot diversity after human arrival to the Caribbean.

Humans did not arrive on most of the world's islands until relatively recently, making islands favorable places for disentangling the timing and magnitude of natural and anthropogenic impacts on species diversity and distributions. Here, we focus on Amazona parrots in the Caribbean, which have close relationships with humans (e.g., as pets as well as sources of meat and colorful feathers). Caribbean parrots also have substantial fossil and archaeological records that span the Holocene. We leverage this exemplary record to showcase how combining ancient and modern DNA, along with radiometric dating, can shed light on diversification and extinction dynamics and answer long-standing questions about the magnitude of human impacts in the region. Our results reveal a striking loss of parrot diversity, much of which took place during human occupation of the islands. The most widespread species, the Cuban Parrot, exhibits interisland divergences throughout the Pleistocene. Within this radiation, we identified an extinct, genetically distinct lineage that survived on the Turks and Caicos until Indigenous human settlement of the islands. We also found that the narrowly distributed Hispaniolan Parrot had a natural range that once included The Bahamas; it thus became "endemic" to Hispaniola during the late Holocene. The Hispaniolan Parrot also likely was introduced by Indigenous people to Grand Turk and Montserrat, two islands where it is now also extirpated. Our research demonstrates that genetic information spanning paleontological, archaeological, and modern contexts is essential to understand the role of humans in altering the diversity and distribution of biota.

Intraguild processes drive space-use patterns in a large-bodied marine predator community.

Interspecific interactions, including predator-prey, intraguild predation (IGP) and competition, may drive distribution and habitat use of predator communities. However, elucidating the relative importance of these interactions in shaping predator distributions is challenging, especially in marine communities comprising highly mobile species. We used individual-based models (IBMs) to predict the habitat distributions of apex predators, intraguild (IG) prey and prey. We then used passive acoustic telemetry to test these predictions in a subtropical marine predator community consisting of eight elasmobranch (i.e. shark and ray) species in Bimini, The Bahamas. IBMs predicted that prey and IG prey will preferentially select habitats based on safety over resources (food), with stronger selection for safe habitat by smaller prey. Elasmobranch space-use patterns matched these predictions. Species with predator-prey and asymmetrical IGP (between apex and small mesopredators) interactions showed the clearest spatial separation, followed by asymmetrical IGP among apex and large mesopredators. Competitors showed greater spatial overlap although with finer-scale differences in microhabitat use. Our study suggests space-use patterns in elasmobranchs are at least partially driven by interspecific interactions, with stronger spatial separation occurring where interactions include predator-prey relationships or IGP.

Human arrival and landscape dynamics in the northern Bahamas.

The first Caribbean settlers were Amerindians from South America. Great Abaco and Grand Bahama, the final islands colonized in the northernmost Bahamas, were inhabited by the Lucayans when Europeans arrived. The timing of Lucayan arrival in the northern Bahamas has been uncertain because direct archaeological evidence is limited. We document Lucayan arrival on Great Abaco Island through a detailed record of vegetation, fire, and landscape dynamics based on proxy data from Blackwood Sinkhole. From about 3,000 to 1,000 y ago, forests dominated by hardwoods and palms were resilient to the effects of hurricanes and cooling sea surface temperatures. The arrival of Lucayans by about 830 CE (2σ range: 720 to 920 CE) is demarcated by increased burning and followed by landscape disturbance and a time-transgressive shift from hardwoods and palms to the modern pine forest. Considering that Lucayan settlements in the southern Bahamian archipelago are dated to about 750 CE (2σ range: 600 to 900 CE), these results demonstrate that Lucayans spread rapidly through the archipelago in less than 100 y. Although precontact landscapes would have been influenced by storms and climatic trends, the most pronounced changes follow more directly from landscape burning and ecosystem shifts after Lucayan arrival. The pine forests of Abaco declined substantially between 1500 and 1670 CE, a period of increased regional hurricane activity, coupled with fires on an already human-impacted landscape. Any future intensification of hurricane activity in the tropical North Atlantic Ocean threatens the sustainability of modern pine forests in the northern Bahamas.

A vertebrate adaptive radiation is assembled from an ancient and disjunct spatiotemporal landscape.

To investigate the origins and stages of vertebrate adaptive radiation, we reconstructed the spatial and temporal histories of adaptive alleles underlying major phenotypic axes of diversification from the genomes of 202 Caribbean pupfishes. On a single Bahamian island, ancient standing variation from disjunct geographic sources was reassembled into new combinations under strong directional selection for adaptation to the novel trophic niches of scale-eating and molluscivory. We found evidence for two longstanding hypotheses of adaptive radiation: hybrid swarm origins and temporal stages of adaptation. Using a combination of population genomics, transcriptomics, and genome-wide association mapping, we demonstrate that this microendemic adaptive radiation of novel trophic specialists on San Salvador Island, Bahamas experienced twice as much adaptive introgression as generalist populations on neighboring islands and that adaptive divergence occurred in stages. First, standing regulatory variation in genes associated with feeding behavior (prlh, cfap20, and rmi1) were swept to fixation by selection, then standing regulatory variation in genes associated with craniofacial and muscular development (itga5, ext1, cyp26b1, and galr2) and finally the only de novo nonsynonymous substitution in an osteogenic transcription factor and oncogene (twist1) swept to fixation most recently. Our results demonstrate how ancient alleles maintained in distinct environmental refugia can be assembled into new adaptive combinations and provide a framework for reconstructing the spatiotemporal landscape of adaptation and speciation.

Expanding records of occurrence of the whale shark (Rhincodon typus) in The Bahamas and a call for sustainable tourism practices.

This report updates our understanding of whale shark occurrences in The Bahamas by drawing upon a variety of data sources. Our findings reveal previously unreported sighting locations, often associated with tourism activities, underscoring the pivotal role played by nontraditional data sources in addressing knowledge gaps. These revelations emphasize the ongoing necessity for monitoring efforts. Additionally, we have found cases that raise concerns related to unregulated human-shark interactions in the region, highlighting the pressing need for sustainable tourism practices within Bahamian waters.

Grooming Time Predicts Survival: American Kestrels, Falco sparverius, on a Subtropical Island.

AbstractAnimals have evolved a variety of adaptations to care for their body surfaces, such as grooming behavior, which keeps the integument clean, parasite-free, and properly arranged. Despite extensive research on the grooming of mammals, birds, and arthropods, the survival value of grooming has never been directly measured in natural populations. We monitored grooming and survival in a population of marked American kestrels (Falco sparverius) on San Salvador Island, Bahamas. We found a strong association between time spent grooming and survival over a 2-year period. The quadratic relationship we show is consistent with stabilizing natural selection on grooming time. To our knowledge, this is the first evidence for a correlation between grooming time and survival in a natural population. Grooming time may predict the survival of many animal taxa, but additional studies are needed to determine the shape and strength of the relationship among birds, mammals, and arthropods.

The Difficulty of Predicting Evolutionary Change in Response to Novel Ecological Interactions: A Field Experiment with Anolis Lizards.

AbstractDetermining whether and how evolution is predictable is an important goal, particularly as anthropogenic disturbances lead to novel species interactions that could modify selective pressures. Here, we use a multigeneration field experiment with brown anole lizards (Anolis sagrei) to test hypotheses about the predictability of evolution. We manipulated the presence/absence of predators and competitors of A. sagrei across 16 islands in the Bahamas that had preexisting brown anole populations. Before the experiment and again after roughly five generations, we measured traits related to locomotor performance and habitat use by brown anoles and used double-digest restriction enzyme-associated DNA sequencing to estimate genome-wide changes in allele frequencies. Although previous work showed that predators and competitors had characteristic effects on brown anole behavior, diet, and population sizes, we found that evolutionary change at both phenotypic and genomic levels was difficult to forecast. Phenotypic changes were contingent on sex and habitat use, whereas genetic change was unpredictable and not measurably correlated with phenotypic changes, experimental treatments, or other environmental factors. Our work shows how differences in ecological context can alter evolutionary outcomes over short timescales and underscores the difficulty of forecasting evolutionary responses to multispecies interactions in natural conditions, even in a well-studied system with ample supporting ecological information.

Jaw size variation is associated with a novel craniofacial function for galanin receptor 2 in an adaptive radiation of pupfishes.

Understanding the genetic basis of novel adaptations in new species is a fundamental question in biology. Here we demonstrate a new role for galr2 in vertebrate craniofacial development using an adaptive radiation of trophic specialist pupfishes endemic to San Salvador Island, Bahamas. We confirmed the loss of a putative Sry transcription factor binding site upstream of galr2 in scale-eating pupfish and found significant spatial differences in galr2 expression among pupfish species in Meckel's cartilage using in situ hybridization chain reaction (HCR). We then experimentally demonstrated a novel role for Galr2 in craniofacial development by exposing embryos to Garl2-inhibiting drugs. Galr2-inhibition reduced Meckel's cartilage length and increased chondrocyte density in both trophic specialists but not in the generalist genetic background. We propose a mechanism for jaw elongation in scale-eaters based on the reduced expression of galr2 due to the loss of a putative Sry binding site. Fewer Galr2 receptors in the scale-eater Meckel's cartilage may result in their enlarged jaw lengths as adults by limiting opportunities for a circulating Galr2 agonist to bind to these receptors during development. Our findings illustrate the growing utility of linking candidate adaptive SNPs in non-model systems with highly divergent phenotypes to novel vertebrate gene functions.

Seagrass production around artificial reefs is resistant to human stressors.

Primary production underpins most ecosystem services, including carbon sequestration and fisheries. Artificial reefs (ARs) are widely used for fisheries management. Research has shown that a mechanism by which ARs in seagrass beds can support fisheries and carbon sequestration is through increasing primary production via fertilization from aggregating fish excretion. Seagrass beds are heavily affected by anthropogenic nutrient input and fishing that reduces nutrient input by consumers. The effect of these stressors is difficult to predict because impacts of simultaneous stressors are typically non-additive. We used a long-term experiment to identify the mechanisms by which simultaneous impacts of sewage enrichment and fishing alter seagrass production around ARs across non-orthogonal gradients in human-dominated and relatively unimpacted regions in Haiti and The Bahamas. Merging trait-based measures of seagrass and seagrass ecosystem processes, we found that ARs consistently enhanced per capita seagrass production and maintained ecosystem-scale production despite drastic shifts in controls on production from human stressors. Importantly, we also show that coupled human stressors on seagrass production around ARs were additive, contrasting expectations. These findings are encouraging for conservation because they indicate that seagrass ecosystems are highly resistant to coupled human stressors and that ARs promote ecosystem services even in human-dominated ecosystems.

Bird populations and species lost to Late Quaternary environmental change and human impact in the Bahamas.

Comparing distributional information derived from fossils with the modern distribution of species, we summarize the changing bird communities of the Bahamian Archipelago across deep ecological time. While our entire dataset consists of 7,600+ identified fossils from 32 sites on 15 islands (recording 137 species of resident and migratory birds), we focus on the landbirds from four islands with the best fossil records, three from the Late Pleistocene (∼25 to 10 ka [1,000 y ago]) and one from the Holocene (∼10 to 0 ka). The Late Pleistocene sites feature 51 resident species that have lost one or more Bahamian populations; 29 of these species do not occur in any of the younger Holocene sites (or in the Bahamas today). Of these 29 species, 17 have their closest affinities to species now or formerly living in Cuba and/or North America. A set of 27 species of landbirds, most of them extant somewhere today, was more widespread in the Bahamas in the prehistoric Holocene (∼10 to 0.5 ka) than they are today; 16 of these 27 species were recorded as Pleistocene fossils as well. No single site adequately captures the entire landbird fauna of the combined focal islands. Information from all sites is required to assess changes in Bahamian biodiversity (including endemism) since the Late Pleistocene. The Bahamian islands are smaller, flatter, lower, and more biotically depauperate than the Greater Antilles, resulting in more vulnerable bird communities.

A new species of the hagfish genus Eptatretus (Myxinidae) from the Bahamas, western North Atlantic.

A new species of the hagfish genus Eptatretus (Myxinidae) is described based on two specimens (407-433 mm total length) collected off the northern Bahamas, between depths of 910 and 1153 m. The new species is distinguished from its congeners by having seven pairs of gill apertures well-spaced and arranged in a near straight line, a 3/2 multicusp pattern of teeth, 10-11 anterior unicusps, 50-51 total cusps, 12-14 prebranchial pores, 48-52 trunk pores, 79-84 total pores, and no nasal-sinus papillae. An identification key for the species of Eptatretus from the western Atlantic Ocean is also provided.

Thirty-five years of tiger shark Galeocerdo cuvier relative abundance near Bimini, The Bahamas, and the Southeastern United States with a comparison across jurisdictional bounds.

Abundances of large sharks are reported to have declined worldwide, and in response various levels of fisheries management and conservation efforts have been established. For example, marine-protected areas have been suggested as a means to protect large expanses of ocean from fishing and other industrial activities (e.g., habitat destruction), and in 2011 The Commonwealth of The Bahamas established The Bahamas Shark Sanctuary. Nonetheless, assessing the effectiveness of conservation efforts is challenging because consistent long-term data sets of shark abundances are often lacking, especially throughout the Caribbean and The Bahamas. In this study, the authors investigated the catch rates and demographics of tiger sharks Galeocerdo cuvier caught in a fishery-independent survey near Bimini, The Bahamas, from 1984 to 2019 to assess relative abundance trends following the banning of longline fishing in 1993 and the subsequent establishment of the shark sanctuary. To contextualize the relative abundance trends near Bimini, the authors compared this to the relative abundance of tiger sharks in a fishery-dependent survey from the Southeastern USA (SE USA), conducted from 1994 to 2019. The data of this study suggest that local abundance of tiger sharks has been stable near Bimini since the 1980s, including after the ban of longline fishing and the implementation of the shark sanctuary. In comparison, the abundance near the SE USA has slowly increased in the past decade, following potential declines in the decade preceding the USA Shark Management Plan. The results of this study provide some optimism that current conservation efforts in The Bahamas have been effective to maintain local tiger shark abundance within the protected area. In addition, current fisheries management in the SE USA is allowing this species to recover within those waters.

Extensive hybridization and past introgression between divergent lineages in a quasi-clonal hermaphroditic fish: Ramifications for species concepts and taxonomy.

Extreme inbreeding is expected to reduce the incidence of hybridization, serving as a prezygotic barrier. Mangrove rivulus is a small killifish that reproduces predominantly by self-fertilization, producing highly homozygous lines throughout its geographic range. The Bahamas and Caribbean are inhabited by two highly diverged phylogeographic lineages of mangrove rivulus, Kryptolebias marmoratus and a 'Central clade' closely related to K. hermaphroditus from Brazil. The two lineages are largely allopatric, but recently were found in syntopy on San Salvador, Bahamas, where a single hybrid was reported. To better characterize the degree of hybridization and the possibility of secondary introgression, here we conducted a detailed genetic analysis of the contact zone on San Salvador. Two mixed populations were identified, one of which contained sexually mature hybrids. The distribution of heterozygosity at diagnostic microsatellite loci in hybrids showed that one of these hybrids was an immediate offspring from the K. marmoratus x Central clade cross, whereas the remaining five hybrids were products of reproduction by self-fertilization for 1-3 generations following the initial cross. Two hybrids had mitochondrial haplotypes of K. marmoratus and the remaining four hybrids had a haplotype of the Central clade, indicating that crosses go in both directions. In hybrids, alleles of parental lineages were represented in equal proportions suggesting lack of recent backcrossing to either of the parental lineages. However, sympatric populations of two lineages were less diverged than allopatric populations, consistent with introgression. Results are discussed in terms of applicability of the biological species concept for isogenic, effectively clonal, organisms.

Curvivirga aplysinae gen. nov., sp. nov., a marine bacterium isolated from the sea sponge Aplysina fistularis.

A Gram-stain-negative, strictly aerobic, motile bacterium, designated strain RKSG073T, was isolated from the sea sponge Aplysina fistularis, collected off the west coast of San Salvador, The Bahamas. Cells were curved-to-spiral rods with single, bipolar (amphitrichous) flagella, oxidase- and catalase-positive, non-nitrate-reducing and required salt for growth. RKSG073T grew optimally at 30-37 °C, pH 6-7, and with 2-3 % (w/v) NaCl. The predominant fatty acids of RKSG073T were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) and C16 : 0. Major isoprenoid quinones were identified as Q-10 and Q-9. Phylogenetic analyses of nearly complete 16S rRNA genes and genome sequences positioned strain RKSG073T in a clade with its closest relative Aestuariispira insulae AH-MY2T (92.1 % 16S rRNA gene sequence similarity), which subsequently clustered with Hwanghaeella grinnelliae Gri0909T, Marivibrio halodurans ZC80T and type species of the genera Kiloniella, Thalassospira and Terasakiella. The DNA G+C content calculated from the genome of RKSG073T was 42.2 mol%. On the basis of phylogenetic distinctiveness and polyphasic analysis, here we propose that RKSG073T (culture deposit numbers: ATCC collection = TSD-74T, BCCM collection = LMG 29869T) represents the type strain of a novel genus and species within the family Kiloniellaceae, order Rhodospirillales and class Alphaproteobacteria, for which the name Curvivirga aplysinae gen. nov., sp. nov. is proposed.

Pleistocene aridification underlies the evolutionary history of the Caribbean endemic, insular, giant Consolea (Opuntioideae).

PREMISE: The Caribbean islands are in the top five biodiversity hotspots on the planet; however, the biogeographic history of the seasonally dry tropical forest (SDTF) there is poorly studied. Consolea consists of nine species of dioecious, hummingbird-pollinated tree cacti endemic to the West Indies, which form a conspicuous element of the SDTF. Several species are threatened by anthropogenic disturbance, disease, sea-level rise, and invasive species and are of conservation concern. However, no comprehensive phylogeny yet exists for the clade. METHODS: We reconstructed the phylogeny of Consolea, sampling all species using plastomic data to determine relationships, understand the evolution of key morphological characters, and test their biogeographic history. We estimated divergence times to determine the role climate change may have played in shaping the current diversity of the clade. RESULTS: Consolea appears to have evolved very recently during the latter part of the Pleistocene on Cuba/Hispaniola likely from a South American ancestor and, from there, moved into the Bahamas, Jamaica, Puerto Rico, Florida, and the Lesser Antilles. The tree growth form is a synapomorphy of Consolea and likely aided in the establishment and diversification of the clade. CONCLUSIONS: Pleistocene aridification associated with glaciation likely played a role in shaping the current diversity of Consolea, and insular gigantism may have been a key innovation leading to the success of these species to invade the often-dense SDTF. This in-situ Caribbean radiation provides a window into the generation of species diversity and the complexity of the SDTF community within the Antilles.

Origins and genetic legacies of the Caribbean Taino.

The Caribbean was one of the last parts of the Americas to be settled by humans, but how and when the islands were first occupied remains a matter of debate. Ancient DNA can help answering these questions, but the work has been hampered by poor DNA preservation. We report the genome sequence of a 1,000-year-old Lucayan Taino individual recovered from the site of Preacher's Cave in the Bahamas. We sequenced her genome to 12.4-fold coverage and show that she is genetically most closely related to present-day Arawakan speakers from northern South America, suggesting that the ancestors of the Lucayans originated there. Further, we find no evidence for recent inbreeding or isolation in the ancient genome, suggesting that the Lucayans had a relatively large effective population size. Finally, we show that the native American components in some present-day Caribbean genomes are closely related to the ancient Taino, demonstrating an element of continuity between precontact populations and present-day Latino populations in the Caribbean.

A new species of the genus Acyrtus on the eastern Pacific: A cornerstone for the evolution and biogeography of the genus.

The genus Acyrtus Schultz, 1944 currently includes four species distributed in the western Atlantic (WA), three occurring from the Bahamas to the southern Caribbean, and one endemic to the Fernando de Noronha Archipelago in north-east Brazil. We describe a new species of Acyrtus based on morphology and genetics from several individuals caught at artificial hard substrates deployed between 10 and 16 m deep at Malpelo Island, Colombian Pacific. The Malpelo clingfish, Acyrtus arturo new species, differs from all its WA congeners by a combination of morphology, meristics and genetics. This species is unique within Acyrtus in having the greatest number of caudal rays (12-13). It can also be distinguished by the greater body height (19.8-27.8% standard length), its longer disc (34.0-39.1% standard length) and the greater distance between anus and disc (13.9-18.1% standard length). A. arturo sp. nov. is the first Acyrtus so far recorded from the eastern Pacific and adds to the already high number of fishes endemic to Colombia's remote oceanic territory of Malpelo.

Comparing global and local maps of the Caribbean pine forests of Andros, home of the critically endangered Bahama Oriole.

Forest loss is occurring at alarming rates across the globe. The pine rockland forests of Andros, The Bahamas, likely represent some of the largest stands of Bahamian subspecies of Caribbean pine in the world. Given the unique species that inhabit these pine forests, such as the endemic and critically endangered Bahama Oriole, monitoring habitats on Andros is crucial to inform conservation planning. We developed a 2019 land classification map to assess the status of nine terrestrial habitats on Andros. Our Random Forest classification model predicted habitat classes with high overall accuracy. Caribbean pine was the dominant land class making up roughly one-third of the total terrestrial area. Whereas much of the pine forest area was found as small patches, most were close to other patches of pine suggesting isolation of forest patches is low. We compared our known intact forest areas to recent forest loss identified by the Hansen et al. Global Forest Change product and assessed areas of habitat disturbance in high-resolution imagery. Our results suggest that this global map overpredicted forest loss on Andros. The small degree of true forest loss on Andros was driven mostly by anthropogenic activity. A cross-tabulation of the Hansen forest loss with fire data showed that understory fires were frequently associated with falsely classified deforestation. Given the threats of climate change to this open forest type-intensifying fire regimes, strengthening hurricanes, and sea level rise-monitoring changes in open forest extent is a critical task across the Caribbean region and the world.

Validity of the Food Insecurity Experience Scale and prevalence of food insecurity in The Bahamas.

INTRODUCTION: Despite UN recommendations to monitor food insecurity using the Food Insecurity Experience Scale (FIES), to date there are no published reports of its validity for The Bahamas, nor have prevalence rates of moderate or severe food insecurity been reported for the remote island nation. At the same time, food security is a deep concern, with increasing incidence of natural disasters and health concerns related to diet-related disease and dietary quality plaguing the nation and its food system. This article aims to examine the validity of the FIES for use in The Bahamas, the prevalence of moderate and severe food insecurity, and the sociodemographic factors that contribute to increased food insecurity. METHODS: The FIES survey was administered by randomized and weighted landline telephone survey in Nassau in The Bahamas to 1000 participants in June and July 2017. The Rasch modelling procedure was applied to examine tool validity and prevalence of food insecurity. Equating procedures calibrated this study's results to the global FIES reference scale and computed internationally comparable prevalence rates of both moderate and severe food insecurity. A regression analysis assessed the relationship between household variables and food security. RESULTS: The FIES met benchmarks for fit statistics for all eight items and the overall Rasch reliability is 0.7. As of 2017, Bahamians' prevalence of moderate and severe food insecurity was 21%, and the prevalence of severe food insecurity was 10%. Statistically significant variables that contribute to food insecurity included education, age, gender, and presence of diabetes, high blood pressure, or heart disease. Results also indicated that Bahamians experience food insecurity differently than populations across the globe, likely due in large part to the workings of an isolated food system heavily dependent on foreign imports. Responses showed that by the time a Bahamian worries they will not have enough food to eat, they have already restricted their meals to a few kinds of foods and begun to limit their intake of vegetables and fruits. CONCLUSION: This study, which is among the first to comprehensively measure food security in The Bahamas, provides a baseline for further research and evaluation of practices aimed at mitigating food insecurity in small island developing states. Further, this study provides a benchmark for future research, which may seek to understand the impacts of Hurricane Dorian and COVID-19, disasters further isolating the remote island nation. Post-disaster food security data are needed to further understand the extent to which food security is impacted by natural disasters and identify which sectors and stakeholders are most vital in restructuring the agricultural sector and improving food availability following catastrophic events.

Consumer Responses to Experimental Pulsed Subsidies in Isolated versus Connected Habitats.

AbstractIncreases in consumer abundance following a resource pulse can be driven by diet shifts, aggregation, and reproductive responses, with combined responses expected to result in faster response times and larger numerical increases. Previous work in plots on large Bahamian islands has shown that lizards (Anolis sagrei) increased in abundance following pulses of seaweed deposition, which provide additional prey (i.e., seaweed detritivores). Numerical responses were associated with rapid diet shifts and aggregation, followed by increased reproduction. These dynamics are likely different on isolated small islands, where lizards cannot readily immigrate or emigrate. To test this, we manipulated the frequency and magnitude of seaweed resource pulses on whole small islands and in plots within large islands, and we monitored lizard diet and numerical responses over 4 years. We found that seaweed addition caused persistent increases in lizard abundance on small islands regardless of pulse frequency or magnitude. Increased abundance may have occurred because the initial pulse facilitated population establishment, possibly via enhanced overwinter survival. In contrast with a previous experiment, we did not detect numerical responses in plots on large islands, despite lizards consuming more marine resources in subsidized plots. This lack of a numerical response may be due to rapid aggregation followed by disaggregation or to stronger suppression of A. sagrei by their predators on the large islands in this study. Our results highlight the importance of habitat connectivity in governing ecological responses to resource pulses and suggest that disaggregation and changes in survivorship may be underappreciated drivers of pulse-associated dynamics.