title: Photobiont selectivity for lichens and evidence for a possible glacial refugium in the Ross Sea Region, Antarctica

authors: Jones, Tracey C.

subjects: algae

abstract: Lichens are a symbiosis consisting of heterotrophic, fungal (mycobiont) and photosynthetic algal or cyanobacterial (photobiont) components. We examined photobiont sequences from lichens in the Ross Sea Region of Antarctica using the internal transcribed spacer region of ribosomal DNA and tested the hypothesis that lichens from this extreme environment would demonstrate low selectivity in their choice of photobionts. Sequence data from three targeted lichen species (Buellia frigida, Umbilicaria aprina and Umbilicaria decussata) showed that all three were associated with a common algal haplotype (an unnamed Trebouxia species) which was present in all taxa and at all sites, suggesting lower selectivity. However, there was also association with unique, local photobionts as well as evidence for species-specific selection. For example, the cosmopolitan U. decussata was associated with two photobiont species, Trebouxia jamesii and an unnamed species. The most commonly collected lichen (B. frigida) had its highest photobiont haplotype diversity in the Dry Valley region, which may have served as a refugium during glacial periods. We conclude that even in these extreme environments, photobiont selectivity still has an influence on the successful colonisation of lichens. However, the level of selectivity is variable among species and may be related to the ability of some (e.g. B. frigida) to colonise a wider range of habitats.

text: Photobiont selectivity for lichens and evidence for a possible glacial refugium in the Ross Sea Region, Antarctica Lichens are a symbiosis consisting of heterotrophic, fungal (mycobiont) and photosynthetic algal or cyanobacterial (photobiont) components. We examined photobiont sequences from lichens in the Ross Sea Region of Antarctica using the internal transcribed spacer region of ribosomal DNA and tested the hypothesis that lichens from this extreme environment would demonstrate low selectivity in their choice of photobionts. Sequence data from three targeted lichen species (Buellia frigida, Umbilicaria aprina and Umbilicaria decussata) showed that all three were associated with a common algal haplotype (an unnamed Trebouxia species) which was present in all taxa and at all sites, suggesting lower selectivity. However, there was also association with unique, local photobionts as well as evidence for species-specific selection. For example, the cosmopolitan U. decussata was associated with two photobiont species, Trebouxia jamesii and an unnamed species. The most commonly collected lichen (B. frigida) had its highest photobiont haplotype diversity in the Dry Valley region, which may have served as a refugium during glacial periods. We conclude that even in these extreme environments, photobiont selectivity still has an influence on the successful colonisation of lichens. However, the level of selectivity is variable among species and may be related to the ability of some (e.g. B. frigida) to colonise a wider range of habitats.

year: 2013

title: An investigation into the persistence-strengthening effects of differential reinforcement of alternative (DRA) behaviour

authors: Layton, Karen Lorraine

subjects: differential reinforcement of alternative (DRA) behaviour

abstract: Ten experiments used hens to investigate the effects of different disruptive events and ways of introducing differential reinforcement of alternative behaviour (DRA), on the persistence of responding. Of interest was the persistencestrengthening effects of DRA on the target, or problem, behaviour, and whether this could be reduced by training an alternative behaviour in a separate context to that of the target behaviour. A DRA was compared to the effects of a procedure where the alternative and target behaviours were trained in the same context (traditional DRA). The different behaviours were pecking at different coloured keys, and responding was maintained by food reinforcement.
Baseline training involved a three-component multiple schedule; one component with two yellow keys available (DRA analogue using VI 37.5 s and 150 s) and the other two with one key available in each (analogous to target (blue and VI 150 s) and alternative (green and VI 37.5 s) behaviours trained separately). A disruptor test followed, also using three-component multiple schedules. This disruptor test included a component with the two yellow keys (Concurrent/DRA Component) and one which combined the, previously single, green and blue keys (Combined Component). In each experiment, the sequence of baseline followed by a disruptor test was repeated with different components in each test. Persistence was measured as the responses in the test as a proportion of baseline responses for that behaviour.
In Experiment 1 the disruptor was extinction and this showed that separate training reduced persistence of the target behaviour and extinction burst, as in previous research. Experiments 2 and 3 used the same procedures but the hens were exposed to a centre key alone (associated with one of VI 150 s (red centre key), 75 s (white centre key) or 37.5 s (pink centre key) schedule) prior to each baseline and this centre key then acted as the disruptor. Reinforcement was available on all keys in the tests. These found that the red key worked as a disruptor, and there were similar effects on persistence as in Experiment 1, regardless of the red key schedule. Experiment 4, using the same procedures but with no formal disruptor, also found the separate training gave reduced persistence of the target but not the alternative behaviour in the tests. Experiment 5 to 7 examined different disruptors (flashing light, sound, and a separate chamber), all with reinforcement continuing in tests. Target response persistence was reduced as a result of the separate training. Experiment 8 compared the effects on target persistence of separate training with the training schedule thinned prior combining and after combining. This found there was reduced target behaviour persistence when the schedules were thinned prior to being combined. Experiment 9 added a baseline with the target behaviour alone, prior to the previous procedure, and showed the same reduced target persistence even when both the target keys were initially presented alone. Experiment 10 showed the results were robust when each component was associated with a physically separate context. All experiments showed that training a target behaviour in a separate context to the alternative behaviour was successful at reducing the persistence-strengthening effects of DRA.

text: An investigation into the persistence-strengthening effects of differential reinforcement of alternative (DRA) behaviour Ten experiments used hens to investigate the effects of different disruptive events and ways of introducing differential reinforcement of alternative behaviour (DRA), on the persistence of responding. Of interest was the persistencestrengthening effects of DRA on the target, or problem, behaviour, and whether this could be reduced by training an alternative behaviour in a separate context to that of the target behaviour. A DRA was compared to the effects of a procedure where the alternative and target behaviours were trained in the same context (traditional DRA). The different behaviours were pecking at different coloured keys, and responding was maintained by food reinforcement.
Baseline training involved a three-component multiple schedule; one component with two yellow keys available (DRA analogue using VI 37.5 s and 150 s) and the other two with one key available in each (analogous to target (blue and VI 150 s) and alternative (green and VI 37.5 s) behaviours trained separately). A disruptor test followed, also using three-component multiple schedules. This disruptor test included a component with the two yellow keys (Concurrent/DRA Component) and one which combined the, previously single, green and blue keys (Combined Component). In each experiment, the sequence of baseline followed by a disruptor test was repeated with different components in each test. Persistence was measured as the responses in the test as a proportion of baseline responses for that behaviour.
In Experiment 1 the disruptor was extinction and this showed that separate training reduced persistence of the target behaviour and extinction burst, as in previous research. Experiments 2 and 3 used the same procedures but the hens were exposed to a centre key alone (associated with one of VI 150 s (red centre key), 75 s (white centre key) or 37.5 s (pink centre key) schedule) prior to each baseline and this centre key then acted as the disruptor. Reinforcement was available on all keys in the tests. These found that the red key worked as a disruptor, and there were similar effects on persistence as in Experiment 1, regardless of the red key schedule. Experiment 4, using the same procedures but with no formal disruptor, also found the separate training gave reduced persistence of the target but not the alternative behaviour in the tests. Experiment 5 to 7 examined different disruptors (flashing light, sound, and a separate chamber), all with reinforcement continuing in tests. Target response persistence was reduced as a result of the separate training. Experiment 8 compared the effects on target persistence of separate training with the training schedule thinned prior combining and after combining. This found there was reduced target behaviour persistence when the schedules were thinned prior to being combined. Experiment 9 added a baseline with the target behaviour alone, prior to the previous procedure, and showed the same reduced target persistence even when both the target keys were initially presented alone. Experiment 10 showed the results were robust when each component was associated with a physically separate context. All experiments showed that training a target behaviour in a separate context to the alternative behaviour was successful at reducing the persistence-strengthening effects of DRA.

year: 2018

title: Māori transitions into tertiary education

authors: Amundsen, Diana Leigh

subjects: Maori

abstract: This thesis critically examines Māori transitions into tertiary education. The research explored the lived transition experiences of 20 Māori tertiary education students in the Bay of Plenty region. Historical and contemporary factors in Aotearoa influencing effective Māori student transitions into tertiary education were investigated. Data were collected and analysed through repeated semistructured interviews and focus groups over the 2016-2018 period with 20 Māori students enrolled in a wānanga, a polytechnic and a university. Participants experienced their transition as a journey, continuously evolving their identities and agency in relation to the tertiary education environments and social structures they encountered.
The findings suggest that transitions to tertiary education for Māori students involve a reciprocal interplay of identity, agency and structure which support or constrain transition experiences. Effective transition experiences were underpinned by processes of continuity enabling identity growth. Support was central to how well participants perceived their transition—racism and lack of support were significant barriers; suitable support was a significant enabler.
An over-riding theme from this research related to the interplay of power relations and Māori identity. How effectively participants developed a sense of belonging (or alienation) and identity growth linked to the tertiary education environments they encountered during their transition. Within wānanga, participants felt their Māori cultural identity was highly valued; within polytechnics, there was a sense that Māori culture is included but more could be done; within universities, a need for more inclusive practices to support Māori learner requirements was identified.
Lastly, this research was conducted by a Pākehā researcher working across kaupapa Māori spaces within interpretive and critical paradigms. Unexpected moments of struggle, discomfort and vulnerability opened up new and deeper understanding of implications for Pākehā educators and researchers engaging across Māori research spaces. This thesis argues for Pākehā to use their privilege to foster more equitable social structures. Equitable social structures would be beneficial for Māori transitions into tertiary education environments.

text: Māori transitions into tertiary education This thesis critically examines Māori transitions into tertiary education. The research explored the lived transition experiences of 20 Māori tertiary education students in the Bay of Plenty region. Historical and contemporary factors in Aotearoa influencing effective Māori student transitions into tertiary education were investigated. Data were collected and analysed through repeated semistructured interviews and focus groups over the 2016-2018 period with 20 Māori students enrolled in a wānanga, a polytechnic and a university. Participants experienced their transition as a journey, continuously evolving their identities and agency in relation to the tertiary education environments and social structures they encountered.
The findings suggest that transitions to tertiary education for Māori students involve a reciprocal interplay of identity, agency and structure which support or constrain transition experiences. Effective transition experiences were underpinned by processes of continuity enabling identity growth. Support was central to how well participants perceived their transition—racism and lack of support were significant barriers; suitable support was a significant enabler.
An over-riding theme from this research related to the interplay of power relations and Māori identity. How effectively participants developed a sense of belonging (or alienation) and identity growth linked to the tertiary education environments they encountered during their transition. Within wānanga, participants felt their Māori cultural identity was highly valued; within polytechnics, there was a sense that Māori culture is included but more could be done; within universities, a need for more inclusive practices to support Māori learner requirements was identified.
Lastly, this research was conducted by a Pākehā researcher working across kaupapa Māori spaces within interpretive and critical paradigms. Unexpected moments of struggle, discomfort and vulnerability opened up new and deeper understanding of implications for Pākehā educators and researchers engaging across Māori research spaces. This thesis argues for Pākehā to use their privilege to foster more equitable social structures. Equitable social structures would be beneficial for Māori transitions into tertiary education environments.

year: 2019