Kin-recognition abilities, first demonstrated 25 years ago in toad tadpoles, now appear to be widespread among amphibians. In some vertebrates kin recognition is based, at least in part, on highly polymorphic major histocompatibility complex (MHC) genes. Besides protecting animals from disease resistance, MHC genes regulate social behaviour. They allow relatives to recognise one another so that they can cooperate for mutual benefit. These two seemingly distinct functions of MHC genes may be integrally related, because animals need to outbreed to optimise the immune systems of their offspring. The ability to discriminate MHC-type is therefore likely to facilitate kin discrimination in tadpoles. I tested association preferences of African clawed-frog (Xenopus laevis) tadpoles in a laboratory choice apparatus. As in other anuran species, I found that tadpoles at earlier developmental stages preferentially associate with unfamiliar siblings over unfamiliar non-siblings but that this preference reverses during development. Tadpoles approaching metamorphosis demonstrated a reversal in their preference; they preferentially school with non-kin rather than kin. The ontogenetic switch in larval schooling preferences coincides with the onset of thyroid hormone (TH) controlled development and may be indicative of decreased fitness benefits associated with schooling with kin at later developmental stages. These may result from an increase in intraspecific competition, predation, or disease susceptibilities of prometamorphic individuals. Alternatively, the kin avoidance behaviours observed at later larval stages might reflect disassociative behaviour that facilitates inbreeding avoidance at reproductive maturity. This is the first study to find a shift from an association preference for kin to non-kin during amphibian larval development. Using allele-specific PCR techniques to MHC-type tadpoles, I tested association preferences among siblings based on shared MHC haplotypes. By using only full siblings in experimental tests, I controlled for genetic variation elsewhere in the genome that might influence schooling preferences. I found that X. laevis tadpoles discriminate among familiar full siblings based on differences at MHC genes. Subjects from four families preferentially schooled with MHC-identical siblings over those with which they shared no or one haplotype. Furthermore, the strength of tadpoles’ MHC-assortative schooling preferences significantly correlated with amino acid differences in the peptide-binding region (PBR) of both the MHC class I and II loci. Since MHC-PBR polymorphisms determine the pool of peptides that can serve as ligands for MHC molecules, these findings support the hypothesis that MHC peptide ligands mediate MHC type discrimination. As test subjects were equally familiar with all stimulus groups, tadpole discrimination appears to involve a self-referent genetic recognition mechanism whereby individuals compare their own MHC type with those of conspecifics. I also found that non-MHC-linked genetic differences contribute to tadpole association preferences in tests that contrast MHC and kinship. Tadpoles did not discriminate between MHC-similar non-siblings and MHC-dissimilar siblings and preferentially associated with MHC-dissimilar non-siblings rather than MHC-similar non-siblings. Although the MHC may be not solely responsible for the genetically determined cues that direct tadpole association preferences, it certainly is important in facilitating discrimination among conspecifics in X. laevis tadpoles. MHC-based discrimination may be retained through ontogeny and serve to maintain MHC-polymorphisms by facilitating disassortative mating.

To assess the context dependence of kin discriminating behavior, I examined kin-biased aggregation behavior in tadpoles of R. cascadae in different ecological conditions. I manipulated food distribution, predator presence, thermal heterogeneity, and relatedness in a multifactorial mesocosm experiment. All four factors interacted to influence tadpole dispersion. My results suggest that kinship is an important factor in aggregation behavior dependent upon ecological conditions. Kin-biased predator defense mechanisms have been proposed as a possible functional explanation for kin discrimination in anuran larvae. Tadpoles may better cooperate in predator vigilance while in kin groups or release kin specific alarm pheromones when attacked by a predator. I examined predator avoidance and alarm response behavior in tadpoles of the Cascades frog (Rana cascadae) and tested whether such behavior is influenced by kinship factors. I found no evidence of an alarm response behavior in R. cascadae. My results suggest that crushed tadpoles appear to initiate a feeding response rather than an alarm response as has been previously proposed. Kin-biased competitive interactions have been proposed as a possible functional explanation for kin discrimination in anuran larvae. Tadpoles may direct competitive interactions away from kin. I examined the role of kinship in growth and development of tadpoles of the Cascades frog (Rana cascadae) in both laboratory and field studies. In the laboratory, individuals reared in kin groups had a significantly smaller mass at metamorphosis than individuals reared in mixed groups. However, kinship effects in the field depended upon the treatment context. Depending upon tadpole density and access to flocculent substrate, tadpoles survived better (after adjusting for differences in mass) in kin groups than in mixed groups. My results demonstrate that kinship factors can affect growth and development in tadpoles, depending upon the ecological conditions. Furthermore, my results provide a functional explanation for the kin discriminating behavior observed in R. cascadae and suggest why such behavior may be context dependent. / Graduation date: 1995

Kin-recognition abilities, first demonstrated 25 years ago in toad tadpoles, now appear to be widespread among amphibians. In some vertebrates kin recognition is based, at least in part, on highly polymorphic major histocompatibility complex (MHC) genes. Besides protecting animals from disease resistance, MHC genes regulate social behaviour. They allow relatives to recognise one another so that they can cooperate for mutual benefit. These two seemingly distinct functions of MHC genes may be integrally related, because animals need to outbreed to optimise the immune systems of their offspring. The ability to discriminate MHC-type is therefore likely to facilitate kin discrimination in tadpoles. I tested association preferences of African clawed-frog (Xenopus laevis) tadpoles in a laboratory choice apparatus. As in other anuran species, I found that tadpoles at earlier developmental stages preferentially associate with unfamiliar siblings over unfamiliar non-siblings but that this preference reverses during development. Tadpoles approaching metamorphosis demonstrated a reversal in their preference; they preferentially school with non-kin rather than kin. The ontogenetic switch in larval schooling preferences coincides with the onset of thyroid hormone (TH) controlled development and may be indicative of decreased fitness benefits associated with schooling with kin at later developmental stages. These may result from an increase in intraspecific competition, predation, or disease susceptibilities of prometamorphic individuals. Alternatively, the kin avoidance behaviours observed at later larval stages might reflect disassociative behaviour that facilitates inbreeding avoidance at reproductive maturity. This is the first study to find a shift from an association preference for kin to non-kin during amphibian larval development. Using allele-specific PCR techniques to MHC-type tadpoles, I tested association preferences among siblings based on shared MHC haplotypes. By using only full siblings in experimental tests, I controlled for genetic variation elsewhere in the genome that might influence schooling preferences. I found that X. laevis tadpoles discriminate among familiar full siblings based on differences at MHC genes. Subjects from four families preferentially schooled with MHC-identical siblings over those with which they shared no or one haplotype. Furthermore, the strength of tadpoles’ MHC-assortative schooling preferences significantly correlated with amino acid differences in the peptide-binding region (PBR) of both the MHC class I and II loci. Since MHC-PBR polymorphisms determine the pool of peptides that can serve as ligands for MHC molecules, these findings support the hypothesis that MHC peptide ligands mediate MHC type discrimination. As test subjects were equally familiar with all stimulus groups, tadpole discrimination appears to involve a self-referent genetic recognition mechanism whereby individuals compare their own MHC type with those of conspecifics. I also found that non-MHC-linked genetic differences contribute to tadpole association preferences in tests that contrast MHC and kinship. Tadpoles did not discriminate between MHC-similar non-siblings and MHC-dissimilar siblings and preferentially associated with MHC-dissimilar non-siblings rather than MHC-similar non-siblings. Although the MHC may be not solely responsible for the genetically determined cues that direct tadpole association preferences, it certainly is important in facilitating discrimination among conspecifics in X. laevis tadpoles. MHC-based discrimination may be retained through ontogeny and serve to maintain MHC-polymorphisms by facilitating disassortative mating.

Thesis (M.S.)--Michigan State University. Dept. of Zoology, 2008. / Title from PDF t.p. (viewed on July 27, 2009) Includes bibliographical references. Also issued in print.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 61-70).

Thesis (M.Sc. Biological Sciences)--University of Waikato, 2007. / Title from PDF cover (viewed February 21, 2008) Includes bibliographical references (p. 79-85)

Thesis advisor: Eric Strauss / Thesis advisor: Peter Auger / Northern Diamondback Terrapin (Malaclemys terrapin terrapin) hatchlings from the Great Marsh of Barnstable, Massachusetts on Cape Cod were studied as part of a headstarting program at Boston College. Although headstarting programs are relatively common methods to revive wild turtle populations, concern exists over the ability of headstarted terrapins to exhibit normal behavior when released into the wild. Observations of terrapins in the wild and in the laboratory suggest that terrapins are highly social and that these social interactions are modulated by kinship relations. This study investigated the social behavior of juvenile terrapins while they were basking on a restricted site. Groups of familiar kin and nonkin, and unfamiliar kin and nonkin were tested. Familiar kin were found to bask in larger groups and showed a willingness to share the limited basking site. Unfamiliar nonkin also interacted, but were more aggressive. Unfamiliar kin and familiar nonkin were not distinguishable in their behaviors. These results suggest that terrapins form social groups based on both familiarity and relatedness. Learning how captive headstarted terrapins form social groups and share resources may provide key information for their survival and recovery efforts in Massachusetts. / Thesis (BS) — Boston College, 2007. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Biology. / Discipline: College Honors Program.

This thesis examines whether juvenile feral pigeons, Columba livia, form sibling alliances when competing for access to a defensible food source. When tested as a flock at a non-depletable column feeder, with room for either one or two birds to feed, siblings associated with each other more often than expected by chance. Frequency of aggression between siblings at these feeders tended to be lower than expected on the basis of their association. Removal experiments showed that sibling presence had a positive effect on relative feeding success at the single column feeder: a juvenile who lost to another juvenile on a one-to-one basis tended, in the presence of its sibling, to lose less badly to, or even beat, that same juvenile. In contrast, presence of the winner's sibling tended not to affect the relative feeding success of competitors. These results support the hypothesis that pigeon siblings form aggressive alliances when competing for food that is defensible.

Thesis (M. Sc.)(Zoology)--University of Pretoria, 2005. / Includes bibliographical references. Available on the Internet via the World Wide Web.

No description available.