Papers by Gerald Wilkinson
Genetics, 1997
Analysis of mitochondrial DNA control region sequences from 41 species of bats representing 11 fa... more Analysis of mitochondrial DNA control region sequences from 41 species of bats representing 11 families revealed that repeated sequence arrays near the tRNA-Pro gene are present in all vespertilionine bats. Across 18 species tandem repeats varied in size from 78 to 85 bp and contained two to nine repeats. Heteroplasmy ranged from 15% to 63%. Fewer repeats among heteroplasmic than homoplasmic individuals in a species with up to nine repeats indicates selection may act against long arrays. A lower limit of two repeats and more repeats among heteroplasmic than homoplasmic individuals in two species with few repeats suggests length mutations are biased. Significant regressions of heteroplasmy, θ and π, on repeat number further suggest that repeat duplication rate increases with repeat number. Comparison of vespertilionine bat consensus repeats to mammal control region sequences revealed that tandem repeats of similar size, sequence and number also occur in shrews, cats and bighorn sheep...
Genetics, 1991
Length variation in D-loop mitochondrial DNA was observed after amplification with the polymerase... more Length variation in D-loop mitochondrial DNA was observed after amplification with the polymerase chain reaction (PCR) in 28% of 195 evening bats, Nycticeius humeralis, from seven colonies. Nucleotide sequences of PCR products show that this heteroplasmy is characterized by an 81-bp region which is tandemly repeated five to eight times. Southern blots using PCR products as probes on HaeIII genomic digests confirm the presence of heteroplasmy. Furthermore, densitometry of electrophoresed PCR products from 109 mother-offspring pairs indicate that heteroplasmy is stably transmitted from mother to offspring with one exception: a heteroplasmic offspring had a homoplastic mother and sib. Nucleotide sequences from this family reveal that a repeat duplication and deletion occurred. The observed mutation rate per generation, mu, for length polymorphism is comparable to an independent estimate, mu = 10(-2), based on hierarchical diversity statistics. With the exception of the repeat nearest t...
Current Biology, 2018
Highlights d Miniature GPS-microphone tags allow monitoring wild bats' movement and interactions ... more Highlights d Miniature GPS-microphone tags allow monitoring wild bats' movement and interactions d Bats foraging on ephemeral resources move in groups in variable movement patterns d Bats foraging on predictable resources move alone and in fixed movement patterns d Results support the hypothesis that resource predictability shapes group foraging
Molecular Ecology Notes, 2002
Artibeus jamaicensis is one of the most common bat species in the neotropics, with a welldefined ... more Artibeus jamaicensis is one of the most common bat species in the neotropics, with a welldefined polygynous social structure in caves. In order to study behaviour and to examine patterns of paternity and relatedness between different harem groups, we developed 14 microsatellite loci from two different enriched genomic libraries. We screened 125 individuals from two different bat colonies and found that polymorphism ranged from five to 13 alleles. Heterozygosity ranged from 63 to 95%. The primers amplified across 14 bat species, indicating their potential utility for population-level studies in several closely related bat species.
Biology Letters, 2017
Helping kin or nonkin can provide direct fitness benefits, but helping kin also benefits indirect... more Helping kin or nonkin can provide direct fitness benefits, but helping kin also benefits indirect fitness. Why then should organisms invest in cooperative partnerships with nonkin, if kin relationships are available and more beneficial? One explanation is that a kin-limited support network is too small and risky. Even if additional weaker partnerships reduce immediate net cooperative returns, individuals extending cooperation to nonkin can maintain a larger social network which reduces the potential costs associated with losing a primary cooperation partner. Just as financial or evolutionary bet-hedging strategies can reduce risk, investing inquantityof social relationships at the expense of relationshipquality(‘social bet-hedging’) can reduce the risks posed by unpredictable social environments. Here, we provide evidence for social bet-hedging in food-sharing vampire bats. When we experimentally removed a key food-sharing partner, females that previously fed a greater number of unr...
Proceedings. Biological sciences / The Royal Society, Jan 22, 2015
Regurgitations of blood among vampire bats appear to benefit both direct and indirect fitness. To... more Regurgitations of blood among vampire bats appear to benefit both direct and indirect fitness. To maximize inclusive fitness, reciprocal food sharing should occur among close kin. Why then do females with kin roost-mates help non-kin? We tested the hypothesis that helping non-kin increases a bat's success at obtaining future donations by expanding its network of potential donors. On six occasions, we individually fasted 14 adult females and measured donations from 28 possible donors. Each female was fasted before, during and after a treatment period, when we prevented donations from past donors (including 10 close relatives) by simultaneously fasting or removing them. This experiment was designed to detect partner switching and yielded three main results. First, females received less food when we prevented donations from a past donor versus a control bat. Donors within a group are therefore not interchangeable. Second, the treatment increased the variance in donors' contribu...
Evolutionary Psychology, 2013
Comparative studies of language are difficult because few language precursors are recognized. In ... more Comparative studies of language are difficult because few language precursors are recognized. In this paper we propose a framework for designing experiments that test for structural and semantic patterns indicative of simple or complex grammars as originally described by Chomsky. We argue that a key issue is whether animals can recognize full recursion, which is the hallmark of context-free grammar. We discuss limitations of recent experiments that have attempted to address this issue, and point out that experiments aimed at detecting patterns that follow a Fibonacci series have advantages over other artificial context-free grammars. We also argue that experiments using complex sequences of behaviors could, in principle, provide evidence for fully recursive thought. Some of these ideas could also be approached using artificial life simulations, which have the potential to reveal the types of evolutionary transitions that could occur over time. Because the framework we propose has sp...
Philosophical transactions of the Royal Society of London. Series B, Biological sciences, Jan 19, 2015
Multicellularity is characterized by cooperation among cells for the development, maintenance and... more Multicellularity is characterized by cooperation among cells for the development, maintenance and reproduction of the multicellular organism. Cancer can be viewed as cheating within this cooperative multicellular system. Complex multicellularity, and the cooperation underlying it, has evolved independently multiple times. We review the existing literature on cancer and cancer-like phenomena across life, not only focusing on complex multicellularity but also reviewing cancer-like phenomena across the tree of life more broadly. We find that cancer is characterized by a breakdown of the central features of cooperation that characterize multicellularity, including cheating in proliferation inhibition, cell death, division of labour, resource allocation and extracellular environment maintenance (which we term the five foundations of multicellularity). Cheating on division of labour, exhibited by a lack of differentiation and disorganized cell masses, has been observed in all forms of mul...
The hypothesis that the time required to detect an approaching predator varies inversely with col... more The hypothesis that the time required to detect an approaching predator varies inversely with colony size was tested. Ninety-five attacks by Loggerhead Shrikes (Lanius ludovicianus) and American Kestrels (Falco sparverius) were simulated at six Cliff Swallow (Petrochelidon pyrrhonota) colonies. Colony size, which ranged from 18 to 320 nests, did not explain a significant portion of the variance in the time it took to detect approaching predator models, even when effects due to wind velocity, breeding stage, nest exposure, and air temperature were removed. Only air temperature proved to be a significant predictor of detection time. To determine whether or not large colonies might reduce the relative amount of predation more effectively than small colonies, we conducted periodic predator censuses around each colony and observed actual predator attacks. Relative predator density increased only five-fold, while colony size increased by a factor of 20. Further, we found no relationship between attack rate and colony size. Consequently, we suggest that larger colonies may dilute the effect of local predators and thereby suffer less nestling predation on a per nest basis.
Food Sharing in Vampire Bats
Sci Am, 1990
Food Sharing in Vampire Bats Two nights without a blood meal and a vampire bat starves to deathu... more Food Sharing in Vampire Bats Two nights without a blood meal and a vampire bat starves to deathunless it can solicit food from a roostmate. Л buddy system ensures that food distribution among the bats is equitable by Gerald S. Wilkinson At nightlong after most visual /\ ...
Proceedings of the Royal Society B: Biological Sciences, 2013
Common vampire bats often regurgitate food to roost-mates that fail to feed. The original explana... more Common vampire bats often regurgitate food to roost-mates that fail to feed. The original explanation for this costly helping behaviour invoked both direct and indirect fitness benefits. Several authors have since suggested that food sharing is maintained solely by indirect fitness because non-kin food sharing could have resulted from kin recognition errors, indiscriminate altruism within groups, or harassment. To test these alternatives, we examined predictors of food-sharing decisions under controlled conditions of mixed relatedness and equal familiarity. Over a 2 year period, we individually fasted 20 vampire bats ( Desmodus rotundus ) and induced food sharing on 48 days. Surprisingly, donors initiated food sharing more often than recipients, which is inconsistent with harassment. Food received was the best predictor of food given across dyads, and 8.5 times more important than relatedness. Sixty-four per cent of sharing dyads were unrelated, approaching the 67 per cent expected ...
Proceedings of the Royal Society of London. Series B: Biological Sciences, 2001
The relationship between cultural and genetic evolution was examined in the yellow-naped amazon A... more The relationship between cultural and genetic evolution was examined in the yellow-naped amazon Amazona auropalliata. This species has previously been shown to have regional dialects de¢ned by large shifts in the acoustic structure of its learned contact call. Mitochondrial DNA sequence variation from a 680 base pair segment of the ¢rst domain of the control region was assayed in 41 samples collected from two neighbouring dialects in Costa Rica. The relationship of genetic variation to vocal variation was examined using haplotype analysis, genetic distance analysis, a maximum-likelihood estimator of migration rates and phylogenetic reconstructions. All analyses indicated a high degree of gene £ow and, thus, individual dispersal across dialect boundaries. Calls sampled from sound libraries suggested that temporally stable contact call dialects occur throughout the range of the yellow-naped amazon, while the presence of similar dialects in the sister species Amazona ochrocephala suggests that the prop ensity to form dialects is ancestral in this clade. These results indicate that genes and culture are not closely associated in the yellow-naped amazon. Rather, they suggest that regional diversity in vocalizations is maintained by selective pressures that promote social learning and allow individual repertoires to conform to local call types.
Molecular Ecology, 1996
We used sequence variation within 297 bp of control region mitochondrial DNA (mtDNA) amplified fr... more We used sequence variation within 297 bp of control region mitochondrial DNA (mtDNA) amplified from 53 lesser long-nosed bats, Leptonycteris curasoae (Phyllostomidae: Glossophaginae) captured at 13 locations in southwestern United States and Mexico and one site in Venezuela to infer population structure and possible migration routes of this endangered nectar-and fruit-eating species. Phylogenetic analysis using maximum parsimony and U P G M A confirmed species and subspecies distinctions within Leptonycteris and revealed two clades exhibiting 3% sequence divergence within the Mexican subspecies, L. c. yerbabuenae. Even though many roosts contained L. c. yerbabuenae from both clades, weak population structure was detected both by a correlation between genetic differentiation, F st , and geographical distance and by a cladistic estimate of the number of migration events required to align bat sequences with geographical location on maximum parsimony, as compared to random, trees. Three results suggest that L. c. yerbabuenae are more likely to migrate between sites along the Pacific coast of Mexico or along the foothills of the Sierra Madre Occidental than between these regions. (1) Seventeen of 20 bats which shared an identical sequence were captured up to 1800 km apart but within the same putative migration corridor. (2) Residuals from a regression of F st on distance were greater between than within these regions. (3) Fewer migration events were required to align bats with these two groups than expected from random assignment. We recommend analysing independent genetic data and monitoring bat visitation to roost sites during migration to confirm these postulated movements.
Bulletin of Mathematical Biology, 1987
Behavioral Ecology and Sociobiology, 2011
In several bird and mammal species, contact calls are utilized to maintain group cohesion and coo... more In several bird and mammal species, contact calls are utilized to maintain group cohesion and coordinate group movement. From a signal design perspective, contact calls typically exhibit acoustic features that make them easily localizable and encode information about individual or group identity. Pallid bats (Antrozous pallidus) are unusual among vespertilionids in that they often emit a loud, partially audible frequency-modulated social call several times in rapid succession while in flight. This call appears to function as a contact call in that it is frequently given when bats return from foraging and perform circular flights before entering a crevice roost. However, the degree to which pallid bats respond to the calls of conspecifics and what information is provided in the call is unknown. Thus, the goal of this study was to investigate pallid bat calling behavior to determine if calls attract roostmates or elicit responses from them and provide sufficient information for individual recognition. In playback studies, we found that contact calls elicit calls and approaches and that free-flying bats respond more to familiar than unfamiliar calls. In addition, analysis of frequency and temporal measurements of calls collected from multiple sites and spectral cross correlation analysis of calls recorded from the same radiotagged bats on multiple evenings revealed that the frequency pattern of contact calls is highly repeatable over time within individuals but exhibits significant differences among individuals. Thus, contact call structure appears to be unique to individuals and stable through time, which makes these calls well-suited for roostmate recognition. Keywords Communication. Signature call. Fission-fusion. Vespertilionid bat Benefits of group living in animals include predator detection, information transfer about foraging sites, and social thermoregulation (Krebs and Davies 1993). To obtain these benefits, a mechanism to maintain group cohesion is necessary, especially when individuals in the group are highly mobile. One such mechanism utilized by several bird and mammal species is the use of a specialized vocal signal, typically designated as a contact call. From a signal design perspective, contact calls are often high in amplitude and easily localizable, with the broadcast range of the call often closely tied to the dispersion of the group. In addition, variation in frequency modulation, temporal pattern, and harmonic structure can encode information about the individual or the social composition of its group (Bradbury and Vehrencamp 1998). For example, northern resident killer whales (Orcinus orca) live in stable family groups and produce contact calls that are specific to groups, and to a lesser extent, individuals (Nousek et al. 2006). Alternatively, in more fluid societies, there is little benefit to maintain group signatures due to the frequent immigration and emigration of individuals. Thus, contact calls often encode individual signatures, which may aid in maintaining non-random associations among group members (Cortopassi and Bradbury 2006). For example, fission-fusion social structure is characteristic of many avian and mammalian societies where subgroups are part of a larger group that frequently splits or merges together (Couzin 2006), and many species with this type of social system produce individually specific contact calls [e.g., spider monkeys, Ateles geoffroyi (Ramos-Fernandez 2005); orange-fronted parakeets, Aratinga canicularis (Cortopassi and Bradbury Communicated by G. Jones
The Auk, 2006
EѣќљѢѡіќћюџѦ ѡѕђќџіђѠ ќѓ longevity predict that average life span should increase as the rate of ... more EѣќљѢѡіќћюџѦ ѡѕђќџіђѠ ќѓ longevity predict that average life span should increase as the rate of extrinsic mortality decreases (Austad and Fischer 1991). For example, the ability to fl y may contribute to long life span in birds and bats through decreased vulnerability to environmental contingency (Holmes and Austad 1994). Probability of dying from extrinsic factors, such as predation, disease, or accidents, is believed to infl uence life span because the force of natural selection decreases with age. If extrinsic sources 108
Artificial Life, 2001
In the research described here we extend past computational investigations of animal signaling by... more In the research described here we extend past computational investigations of animal signaling by studying an artificial world in which a population of initially noncommunicating agents evolves to communicate about food sources and predators. Signaling in this world can be either beneficial (e.g., warning of nearby predators) or costly (e.g., attracting predators or competing agents). Our goals were twofold: to examine systematically environmental conditions under which grounded signaling does or does not evolve, and to determine how variations in assumptions made about the evolutionary process influence the outcome. Among other things, we found that agents warning of nearby predators were a common occurrence whenever predators had a significant impact on survival and signaling could interfere with predator success. The setting most likely to lead to food signaling was found to be difficult-to-locate food sources that each have relatively large amounts of food. Deviations from the s...
The name Cholamonas cyrtodiopsidis gen. n., sp. n., is created for a mycophagous heterotrophic fl... more The name Cholamonas cyrtodiopsidis gen. n., sp. n., is created for a mycophagous heterotrophic flagellate isolated and cultivated from the intestine of a diopsid fly. Flagellates were subanteriorly biflagellate, uninucleate, and naked. Golgi dictyosomes were anterior to the nucleus, and a reticulate paranuclear body posterior to it. Two groups of refractile bodies were present, one at the anterior end of the cell, the other in the vicinity of the nucleus. Numerous elongate, unbranched mitochondria with tubular cristae were distributed around the periphery and parallel to the long axis of the cell. The kinetid consisted of two symmetrical subunits, each with two basal bodies (one of which was associated with a stubby flagellum), a compound microtubular root, and associated fibers and bands. Cytoskeletal microtubules emanated from the cell anterior and were not associated with any kinetid element. Feeding, on yeast, was accomplished by rapid pseudopodial action at the posterior end of the cell. Cholamonas cyrtodiopsidis is referred to Cercomonadida because it possesses a paranuclear body and has a kinetid architecture similar to some species of Cercomonas. It differs from all other cercomonads in its endocommensal habitat, mycophagy, doubled kinetid, distribution of refractile granules and mitochondria, and minimal production of pseudopodia.
mulated data on the lifespans of 65 species of bats. The current list of species-speci c maximum ... more mulated data on the lifespans of 65 species of bats. The current list of species-speci c maximum longevities is surprisingly extensive (see Wilkinson and South, 2002, appendix; Gaisler et al., 2003), considering that these data are obtained from the fortuitous recapture of individuals that were tagged during their birth year. From these data, it is clear that bats are relatively long-lived mammals. On average, bats live three times longer than non ying eutherian mammals of similar body size and metabolic rate (Austad and Fischer, 1991). While this extreme longevity poses intriguing questions for researchers interested in determinants of longevity and senescence, it also poses practical obstacles to the investigation of biological phenomena in which age is a critical factor. Determining the age of wild, untagged mammals can be di cult. This di culty is particularly poignant in bats because with such extended longevities, it is likely that they experience more environmental and physiological variation (particularly that associated with age) than short-lived mammals and this variation may confound several aspects of bat biology that we aim to investigate. In this chapter, we describe techniques for age determination and discuss senescence and longevity in bats. We present methods currently available for the determination of age in juvenile and adult bats, highlight the advantages and disadvantages of each, and provide guidelines to use when selecting a par tic u lar method. We also suggest new ideas, which, with proper research and the development of standards, may result in novel techniques that can overcome some of the limitations of current methods and thus enhance our ability to determine chronological and/or biological age of bats. Finally, we brie y summarize current research on bat longevity and senescence research that often requires knowledge of chronological age of individuals and present ideas for future investigations in this line of research. Methods for Age Estimation and the Study of Senescence in Bats anja k. brunet-rossinni gerald s. wilkinson 15 550-38447_ch04_1P.indd 315 550-38447_ch04_1P.indd 315
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Papers by Gerald Wilkinson