63 research outputs found
Directional Footing, Degeneracy, and Alignment
No full textThis paper argues from an Optimality Theory perspective that no one-to-one correspondence exists between directional footing effects and individual constraints. Recent work in OT claims that directional footing effects are best captured by the constraints All-Feet-Left (Ft-Left) and All-Feet-Right (Ft-Right) in (1) (e.g. McCarthy & Prince 1993b, 1994; Kirchner 1993; Cohn & McCarthy 1994; Crowhurst & Hewitt, in press; Hewitt 1994a; Kager 1994).
(1) a. All-Feet-Left: Align(Foot, L, PrWd, L)
b. All-Feet-Right: Align(Foot, R, PrWd, R)
This paper argues that the relationship between the alignment constraints in (1) and directional footing is more complicated than has been envisioned. In fact, the OT account presented here reveals directional effects to be epiphenomenal: either of the constraints in (1) may yield rightward or leftward footing, depending on its interaction with constraints requiring syllable-to-foot parsing and binary foot structure (see below). We also show that directionality and stray syllable parsing at edges are dependent: right-to-left and left-to-right effects under Ft-Left dominance co-occur with either the presence or the absence of a degenerate foot, but not with both. This relationship is inverted when Ft-Right dominates Ft-Left. One outcome of this study is that interactions among a small number of constraints leads to a modified typological view of metrical patterns familiar from earlier work.The definitive version of this paper was published in NELS 25: Proceedings of the North East Linguistics Society (1995) and is available at http://glsa.hypermart.net/Crowhurst, M., & Hewitt, M. S. (1995). Directional footing, degeneracy, and alignment. In J. N. Beckman (Ed.), NELS 25: Proceedings of the North East Linguistics Society (pp. 47-61). Amherst, MA: GLSA (Graduate Linguistic Student Association), Dept. of Linguistics, University of Massachusetts
Using simulations to evaluate Mantel‐based methods for assessing landscape resistance to gene flow
No full textMantel-based tests have been the primary analytical methods for understanding how landscape features influence observed spatial genetic structure. Simulation studies examining Mantel-based approaches have highlighted major challenges associated with the use of such tests and fueled debate on when the Mantel test is appropriate for landscape genetics studies. We aim to provide some clarity in this debate using spatially explicit, individual-based, genetic simulations to examine the effects of the following on the performance of Mantel-based methods: (1) landscape configuration, (2) spatial genetic nonequilibrium, (3) nonlinear relationships between genetic and cost distances, and (4) correlation among cost distances derived from competing resistance models. Under most conditions, Mantel-based methods performed poorly. Causal modeling identified the true model only 22% of the time. Using relative support and simple Mantel r values boosted performance to approximately 50%. Across all methods, performance increased when landscapes were more fragmented, spatial genetic equilibrium was reached, and the relationship between cost distance and genetic distance was linearized. Performance depended on cost distance correlations among resistance models rather than cell-wise resistance correlations. Given these results, we suggest that the use of Mantel tests with linearized relationships is appropriate for discriminating among resistance models that have cost distance correlations <0.85 with each other for causal modeling, or <0.95 for relative support or simple Mantel r. Because most alternative parameterizations of resistance for the same landscape variable will result in highly correlated cost distances, the use of Mantel test-based methods to fine-tune resistance values will often not be effective
Locality of Conjunction
No full textThis article accounts for locality of conjunction (Smolensky 1995) in terms of the locus function for constraint violations (McCarthy 2003, Riggle & Wilson 2004). A formal account is given of the idea that the locally conjoined constraints need to share their locus of violation. In addition, markedness reversals are discussed (Ito & Mester 2002). This proposal is found superior to previous approaches to restricting local conjunction, such as fulcrum (Bakovic 1999, Hewitt & Crowhurst 1996) and domain (Lubowicz 2002, Moreton & Smolensky 2002, Smolensky 1993).The definitive version of this paper was published in WCCFL 24: Proceedings of the 24th West Coast Conference on Formal Linguistics (2005) and is available at http://www.lingref.com/cpp/wccfl/24
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Landscape features affecting genetic diversity and structure in East African ungulate species
No full textHabitat loss and fragmentation is a crisis affecting wildlife worldwide. In Tanzania, East Africa, a dramatic and recent (<80 years) expansion in human settlement and agriculture threatens to reduce gene flow among protected areas for many species of large mammals. Wildlife linkages can mitigate population isolation, but linkage designs lacking empirical justification may be controversial and ineffective. Connectivity conservation requires an understanding of how biogeographic factors shaped gene flow prior to habitat loss or fragmentation, however the history of interaction among populations is rarely known. The goal of my study was to provide context for connectivity conservation in central and southern Tanzania by identifying landscape features that have shaped gene flow for three ungulate species with different dispersal capabilities.
I investigated historical patterns of connectivity for Maasai giraffe (Giraffa camelopardalis tippelskirchi), impala (Aepyceros melampus), and eland (Tragelaphus oryx) by estimating genetic structure among four to eight protected areas per species. Genetic structure changes very slowly among large populations and thus is likely to reflect historical processes instead of recent anthropogenic influences. I collected noninvasive DNA samples and generated microsatellite genotypes at 8 to 15 loci per species, then estimated genetic diversity metrics (allelic richness, AR, and expected heterozygosity, H[subscript E]) for each population (defined by reserve). I also calculated genetic distance (F[subscript ST] and Nei's unbiased genetic distance, D[subscript hat]) and an estimate of gene flow (Nm) between all population pairs for each species.
To elucidate the possible causes of genetic structure between these populations, I tested for isolation by distance and isolation by resistance based on a suite of biogeographic factors hypothesized to affect gene flow. To do this, I created GIS-based resistance surfaces that assigned different costs of movement to landscape features. I created one or more resistance surfaces for each hypothesis of landscape effect. I used circuit theory to estimate the cumulative resistance between each pair of reserves for each weighting scheme, and then performed Mantel tests to calculate the correlation between these resistances and the observed population pairwise genetic distances (D[subscript hat]). I chose the optimal resistance model for each species as the model that was most highly correlated with observed genetic patterns. To verify that the correlation of resistance models with genetic distance was not an artefact of geographic distance, I performed partial Mantel tests to calculate correlation while controlling for the effect of geographic distance. Finally, I compared historical gene flow patterns to the distribution of contemporary human activity to predict areas that are at risk of a loss of connectivity.
Indices of genetic diversity were moderate for all three species and comparable to previously reported values for other savannah ungulates. Diversity (both H[subscript E] and A[subscript R]) was highest in eland and lowest in giraffe for these populations, and was not consistently correlated with reserve size as has been reported for other species in East Africa. Although patterns in genetic distance were broadly similar across all three species there were also striking differences in connectivity, highlighting the importance of cross-species comparisons in connectivity conservation.
At this scale, resistance models based on slope strongly predicted population structure for all three species; distance to water was also highly correlated with genetic distance in eland. For all three species, the greatest genetic distances occurred between populations separated by the Eastern Arc Mountains, suggesting that the topography
of this area has long acted as a barrier to gene flow, but this effect is present in varying degrees for each species. I observed high levels of historical gene flow between centrally located populations (Ruaha National Park and Rungwa Game Reserve) and those in the southwest (Katavi National Park and Rukwa Game Reserve). Although human settlement in this area has been low relative to other areas, the connection between the Katavi/Rukwa and Ruaha ecosystems may be threatened by increased human activity and warrants conservation.
High levels of historical gene flow were also seen between reserves in the northeast (Tarangire National Park, Swagaswaga Game Reserve) and the central and southwest populations. These connections appear highly threatened due to current land use practices, and may have already suffered a loss of gene flow. Field surveys in the lands surrounding the northeastern reserves are needed to quantify current levels of connectivity and determine whether corridors could be established to maintain or restore gene flow with other reserves
Critical incident sparks critical incident sparks critical incident: an ‘<i>a</i>resolutionist’ method
No full textWorking with same-sex attracted young people in order to minimize harassment and support to sexual diversity
No full textThis article reports on interviews with same-sex attracted young people enrolled in a secondary school. The author reports particularly on same- sex attracted males but notes that the study relates to females and transgender young people as well. The author considers discrimination, constraints for interviewees, the status of being gay and living in the community
Working through tension: a response to the concerns of lesbian, gay and bisexual secondary school students
No full textDeposited with permission of the author. © 2001 Michael CrowhurstThe experiences of lesbian, gay, bisexual and transgender (LGB)(T) secondary school students are often problematic. The literature documents that LGB(T) students often experience harassment in secondary school settings. The participants in this study identify that issues around subject content, the need to address bullying and strategies around support are three key issues that might be targeted if LGB(T) school experiences are to improve. This thesis responds to participant perspectives by outlining a broad approach that is anchored by their concerns
Two women, two murders : stigmatised media representations of violence against sex workers
No full textThis chapter employed a specific Australian case study to document the structural stigma that is pervasive in in relation to the sex industry and replicated and facilitated within media representation of sex workers as deviant and blameworthy social pariahs. Our comparison of media responses to the murders of Jill Meagher, the happily married woman, and Tracy Connelly, the transgressive street-based sex worker, emphasizes the power of entrenched belief systems about women’s sexuality and the partiality towards antiquated gender norms. Taken together, these case emphasize how dominant cultural forms generate media and public sympathy generated for the victims of violence who meet gendered cultural expectations while tacitly legitimising violence against sex workers
Bighorn genotypes 2013-2015
No full textThis file is in GENEPOP format, which is easily converted to a variety of formats. It contains individual genotypes from desert bighorn sheep samples collected from 2013-2015 (duplicates from the same individuals were removed), and includes all 16 microsatellite loci. Note that the 3rd locus- BL4- was removed for a subset of the analyses in the paper
Bighorn genotypes 2000-2003
No full textThis file is in GENEPOP format, which is easily converted to a variety of formats. It contains individual genotypes from desert bighorn sheep samples collected from 2000-2003 (duplicates from the same individuals were removed), and includes all 16 microsatellite loci. Note that the 3rd locus- BL4- was removed for a subset of the analyses in the paper
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