title: Does invasiveness predict competition outcomes between ecologically similar invasive blowflies?

authors: Nunn, Daniel

abstract: Biological invasion is a complex puzzle, and its significance is at an all-time high. Current research highlights that the success of invasive species is partly due to their superior performance in key behavioural traits, such as aggression and boldness, especially when compared to ecologically similar native species. However, less attention has been given to differences in these traits among invasive species themselves. Not all invaders are created equal; they vary in their degree of invasiveness, often characterised by the extent of their global spread. If behavioural traits are crucial for invasiveness, it stands to reason that more invasive species - those with greater success - should outperform less invasive ones.

I tested this hypothesis using larval competition between differentially invasive blowfly species. Calliphora stygia has a limited distribution, found only in Australia and New Zealand, whereas Lucilia sericata and Lucilia cuprina (Lucilia spp.) are invaders with almost global distributions. Under direct laboratory competition, the highly invasive Lucilia spp. exhibited fewer body size reductions than C. stygia, regardless of intra- or interspecific competition levels. These findings suggest that competitive traits may exist along a continuum from native to invasive species, increasing predictably with invasiveness. This insight highlights invasiveness as a potentially reliable metric for predicting competition outcomes between ecologically similar sympatric invaders.

text: Does invasiveness predict competition outcomes between ecologically similar invasive blowflies? Biological invasion is a complex puzzle, and its significance is at an all-time high. Current research highlights that the success of invasive species is partly due to their superior performance in key behavioural traits, such as aggression and boldness, especially when compared to ecologically similar native species. However, less attention has been given to differences in these traits among invasive species themselves. Not all invaders are created equal; they vary in their degree of invasiveness, often characterised by the extent of their global spread. If behavioural traits are crucial for invasiveness, it stands to reason that more invasive species - those with greater success - should outperform less invasive ones.

I tested this hypothesis using larval competition between differentially invasive blowfly species. Calliphora stygia has a limited distribution, found only in Australia and New Zealand, whereas Lucilia sericata and Lucilia cuprina (Lucilia spp.) are invaders with almost global distributions. Under direct laboratory competition, the highly invasive Lucilia spp. exhibited fewer body size reductions than C. stygia, regardless of intra- or interspecific competition levels. These findings suggest that competitive traits may exist along a continuum from native to invasive species, increasing predictably with invasiveness. This insight highlights invasiveness as a potentially reliable metric for predicting competition outcomes between ecologically similar sympatric invaders.

year: 2024

title: Examining the Association between Cannabis Use and Working Memory, Processing Speed, and Sub-Psychotic Subjective Experiences

authors: Vaka, Wabuya

subjects: Cannabis

abstract: New Zealand has among the top two highest prevalence of cannabis use in the world. Additionally, the strings of cannabis on offer in the market of New Zealand is among the most potent ones available. With these two factors at play within New Zealand society, it is important to know the effects of cannabis on mental health. Studies have suggested that regular/heavy use of cannabis can lead to psychosis, however other studies have presented findings contrary to this. Studies consistently found that individuals with psychosis performed much poorer on working memory measure via the digit-symbol subset of the WAIS. Thus this study aimed to investigate how cannabis use may relate with performance of digit-symbol performance and sub-clinical psychotic experiences.
Method: A quantitative design was used to investigate relationships:  between cannabis use, digit-symbol performance, and ratings of the Sub-Psychotic Subjective Experiences Scale (SPSES). Fifty one voluntary random sample participants (n=51) were included in the results of the study. 69% were aged 18-24 years, 84% of the sample population were students, and majority Europeans. Males and females were equally represented. The research sessions were conducted in an office-type laboratory environment. The first part entailed participants completing Wechsler Abbreviated Scale of Intelligence 2nd edition (WASI-II), and Wechsler Adult Intelligence Scale 3rd edition (WAIS-III) digit-symbol subtest with the researcher on a desk. Participants then moved to the computer to complete the questionnaires on background and history, cannabis use (Cannabis Use Problem Identification Test (CUPIT) and Cannabis Abuse Screening Test (CAST) questionnaires for cannabis users), and the Sub-Psychotic Subjective Experiences (SPSES) questionnaire.
Results: Participants were apportioned into four cannabis use groups using self-rating measures obtained from CUPIT and CAST scores. The user groups were 1: non-users, 2: previous uses, 3: non-regular users, and 4: regular users.
An overall  one-way (4 cannabis use groups) MANOVA conducted on the outcome variables digit-symbol scores, and SPSES scores, with  depression scores and IQ scores as covariates) revealed no significant main effects, significant interactions or any significant covariates. Subsequent Spearman’s Rank-Order coefficient, however, indicated significant correlations of cannabis use with CUPIT scores, CAST scores, and use of other recreational drugs. Pearson’s correlation coefficient was used for correlation analyses for all other ratio and interval variables. There were no significant Pearson’s correlations found.
Conclusion: The study found no significant association between regular cannabis use and digit-symbol performance; nor was there a significant association between cannabis use and sub-psychotic subjective experiences ratings. Therefore, the student-majority sample did not present any significant deficits in cognitive function depending on cannabis use. Cannabis use was also not related to IQ scores or depression scores; and absence thereof.

text: Examining the Association between Cannabis Use and Working Memory, Processing Speed, and Sub-Psychotic Subjective Experiences New Zealand has among the top two highest prevalence of cannabis use in the world. Additionally, the strings of cannabis on offer in the market of New Zealand is among the most potent ones available. With these two factors at play within New Zealand society, it is important to know the effects of cannabis on mental health. Studies have suggested that regular/heavy use of cannabis can lead to psychosis, however other studies have presented findings contrary to this. Studies consistently found that individuals with psychosis performed much poorer on working memory measure via the digit-symbol subset of the WAIS. Thus this study aimed to investigate how cannabis use may relate with performance of digit-symbol performance and sub-clinical psychotic experiences.
Method: A quantitative design was used to investigate relationships:  between cannabis use, digit-symbol performance, and ratings of the Sub-Psychotic Subjective Experiences Scale (SPSES). Fifty one voluntary random sample participants (n=51) were included in the results of the study. 69% were aged 18-24 years, 84% of the sample population were students, and majority Europeans. Males and females were equally represented. The research sessions were conducted in an office-type laboratory environment. The first part entailed participants completing Wechsler Abbreviated Scale of Intelligence 2nd edition (WASI-II), and Wechsler Adult Intelligence Scale 3rd edition (WAIS-III) digit-symbol subtest with the researcher on a desk. Participants then moved to the computer to complete the questionnaires on background and history, cannabis use (Cannabis Use Problem Identification Test (CUPIT) and Cannabis Abuse Screening Test (CAST) questionnaires for cannabis users), and the Sub-Psychotic Subjective Experiences (SPSES) questionnaire.
Results: Participants were apportioned into four cannabis use groups using self-rating measures obtained from CUPIT and CAST scores. The user groups were 1: non-users, 2: previous uses, 3: non-regular users, and 4: regular users.
An overall  one-way (4 cannabis use groups) MANOVA conducted on the outcome variables digit-symbol scores, and SPSES scores, with  depression scores and IQ scores as covariates) revealed no significant main effects, significant interactions or any significant covariates. Subsequent Spearman’s Rank-Order coefficient, however, indicated significant correlations of cannabis use with CUPIT scores, CAST scores, and use of other recreational drugs. Pearson’s correlation coefficient was used for correlation analyses for all other ratio and interval variables. There were no significant Pearson’s correlations found.
Conclusion: The study found no significant association between regular cannabis use and digit-symbol performance; nor was there a significant association between cannabis use and sub-psychotic subjective experiences ratings. Therefore, the student-majority sample did not present any significant deficits in cognitive function depending on cannabis use. Cannabis use was also not related to IQ scores or depression scores; and absence thereof.

year: 2017

title: Aihe Pepene

authors: Hart, Philip

abstract: Sharing the same illustrious whakapapa as his brother Reha Aperahama, Aihe Pepene was prominent when living in the Thames district before settling at Te Aroha in 1878. When speculators tried to acquire the Thames foreshore from Pepene and others in 1870, he became involved in the subsequent legal actions over unpaid promissory notes. Later he would acquire interests in many blocks of land, and received a steady income by leasing or selling these plus his share in the goldfields revenue. When the Aroha Block was considered by the land court for the last time, in 1878, he conducted the case for Ngati Rahiri.
He invested in four Hauraki goldfields, and was briefly an owner and skipper of two small river steamers, an unsuccessful endeavour that resulted in his being forced to sell more land to meet his debts. Once his 1880 and 1881 financial difficulties were resolved, no more such problems recurred. 
A leading rangatira in Hauraki generally as well as at Te Aroha, he would be elected to a Maori Committee that was soon revealed to have no significance. Closely involved with Pakeha, he assisted settlement, and his loyalty to the Crown was illustrated by his becoming an officer in the Thames Native Volunteer Corps. A member of the Church of England for many years, like many Maori he became a Mormon, a faith perhaps more appropriate to his private life, for he had more than one wife, notoriously eloping with the wife of a more senior rangatira despite already being married.

text: Aihe Pepene Sharing the same illustrious whakapapa as his brother Reha Aperahama, Aihe Pepene was prominent when living in the Thames district before settling at Te Aroha in 1878. When speculators tried to acquire the Thames foreshore from Pepene and others in 1870, he became involved in the subsequent legal actions over unpaid promissory notes. Later he would acquire interests in many blocks of land, and received a steady income by leasing or selling these plus his share in the goldfields revenue. When the Aroha Block was considered by the land court for the last time, in 1878, he conducted the case for Ngati Rahiri.
He invested in four Hauraki goldfields, and was briefly an owner and skipper of two small river steamers, an unsuccessful endeavour that resulted in his being forced to sell more land to meet his debts. Once his 1880 and 1881 financial difficulties were resolved, no more such problems recurred. 
A leading rangatira in Hauraki generally as well as at Te Aroha, he would be elected to a Maori Committee that was soon revealed to have no significance. Closely involved with Pakeha, he assisted settlement, and his loyalty to the Crown was illustrated by his becoming an officer in the Thames Native Volunteer Corps. A member of the Church of England for many years, like many Maori he became a Mormon, a faith perhaps more appropriate to his private life, for he had more than one wife, notoriously eloping with the wife of a more senior rangatira despite already being married.

year: 2016