title: Suboptimal Choice Behaviour in Hens

authors: Ngatai, Karmen Louise

subjects: Suboptimal Choice

abstract: Choice performances of six Brown Shaver hens were studied across three series of conditions, using a partial replication of Stagner and Zentall’s (2010) procedure.  Hens chose between two alternatives during choice-trials.  Choice of the low-probability alternative provided one of two stimuli that reliably predicted 100% reinforcement on 20% of the trials, and 0% reinforcement on the remaining 80% of trials.  Choice of the non-discriminative alternative provided one of two unreliable stimuli that non-differentially signalled 50% reinforcement, regardless of the stimulus presented.  In Conditions 1-4 and Condition 6, the stimuli and reinforcement contingencies associated with the side keys were repeatedly reversed across conditions.  In Condition 5, stimulus and reinforcement contingencies were each equated at 50%.  Results replicated Stagner and Zentall’s (2010) findings demonstrating that choice for the low-probability alternative for most hens remained almost exclusive across reversals, except Condition 5 where previous choice performances for all subjects, was disrupted.  In Conditions 7-11, the reliability of the low-probability stimuli was gradually decreased across conditions.  Results showed that the decreasing reliability of the low-probability stimuli did not deter many hens from choosing suboptimally.  Conditions 12 and 13 reversed Conditions 8 and 11, respectively.  Results showed that choice performances for most hens in Condition 13 varied considerably from Condition 11.  The main finding from this study is that hens do not exclusively choose signals that reliably signal a reinforcing outcome.  This is because choice for the low-probability alternative for many hens was not affected when the reliability of those signals decreased.  This suggests that the signals themselves may be more reinforcing than their subsequent outcome which may have implications for human gambling behaviour.

text: Suboptimal Choice Behaviour in Hens Choice performances of six Brown Shaver hens were studied across three series of conditions, using a partial replication of Stagner and Zentall’s (2010) procedure.  Hens chose between two alternatives during choice-trials.  Choice of the low-probability alternative provided one of two stimuli that reliably predicted 100% reinforcement on 20% of the trials, and 0% reinforcement on the remaining 80% of trials.  Choice of the non-discriminative alternative provided one of two unreliable stimuli that non-differentially signalled 50% reinforcement, regardless of the stimulus presented.  In Conditions 1-4 and Condition 6, the stimuli and reinforcement contingencies associated with the side keys were repeatedly reversed across conditions.  In Condition 5, stimulus and reinforcement contingencies were each equated at 50%.  Results replicated Stagner and Zentall’s (2010) findings demonstrating that choice for the low-probability alternative for most hens remained almost exclusive across reversals, except Condition 5 where previous choice performances for all subjects, was disrupted.  In Conditions 7-11, the reliability of the low-probability stimuli was gradually decreased across conditions.  Results showed that the decreasing reliability of the low-probability stimuli did not deter many hens from choosing suboptimally.  Conditions 12 and 13 reversed Conditions 8 and 11, respectively.  Results showed that choice performances for most hens in Condition 13 varied considerably from Condition 11.  The main finding from this study is that hens do not exclusively choose signals that reliably signal a reinforcing outcome.  This is because choice for the low-probability alternative for many hens was not affected when the reliability of those signals decreased.  This suggests that the signals themselves may be more reinforcing than their subsequent outcome which may have implications for human gambling behaviour.

year: 2013

title: Assessing dispersal among habitats for three New Zealand aquatic insects using mitochondrial DNA (COI) sequences

authors: Riding, Morgan Alexandra

subjects: Dispersal

abstract: Dispersal of aquatic insects is a key process allowing colonization of new habitat and linking existing populations among habitats. Studying the dispersal of freshwater taxa directly is logistically challenging and assessments of population genetic structure using DNA sequence fragments have provided an alternative means to examine the dispersal and connectivity of natural populations. Here, I used mitochondrial cytochrome c oxidase subunit I (COI) DNA sequences to assess the genetic similarity for aquatic insect species across both small (<50km) and large (>1000km) spatial scales. For the first study, I examined genetic similarity among source and restored stream habitats in Taranaki Region, New Zealand. Three common species were targeted based on differences in dispersal capabilities: Archichauliodes diversus (Megaloptera; active larvae, weak flight), and Hydropsyche colonica and Pycnocentrodes aeris (Trichoptera; sessile larvae, strong flight). Archichauliodes diversus showed the greatest sequence diversity (19 haplotypes) followed by P. aeris (14 haplotypes) and H. colonica (4 haplotypes). Despite relatively high levels of genetic diversity, A. diversus was genetically similar throughout the study area, suggesting adequate dispersal among source and restored habitats. Individuals of H. colonica, with much lower levels of haplotype diversity, were also genetically similar between source and restored habitats. In contrast, P. aeris had one haplotype that was more common in source versus restored habitats. I concluded that taxa were relatively well connected between source and restored habitats and that COI sequences can provide a useful indicator for tracking restoration efforts within relatively small geographic areas. In the second study, I focused on large-scale patterns of diversity for A. diversus which is widespread throughout both the North and the South Islands of New Zealand and compared this with available sequences from a congeneric Australian species. I found sequence divergences between the New Zealand A. diversus and Australian Archichauliodes sp (11.8% divergence), and between New Zealand North Island and South Island A. diversus (3% divergence). In the South Island, there were 8 haplotypes restricted to individual sites and 4 haplotypes that were shared among sites. For the North Island, individuals there were 21 haplotypes restricted to one of more sites and 1 common haplotype shared among Taranaki sites. There were 12 missing mutational steps between haplotypes from the North Island and the South Islands. The Australian Archichauliodes sp was further separated by 70 missing mutational steps from the South Island of New Zealand. Differentiation was also observed within the South Island with shared haplotypes observed at distances of > 150 km. On this basis, I suggested that despite potentially weak flight, individuals of A. diversus can regularly disperse distances of up to 150 km. However, they also appear limited by geographic barriers such as the Cook Strait between the North and South Islands (<25 km). Molecular clock estimates between New Zealand and Australian Archichauliodes sp. suggested that isolation of individuals occurred around 5 Mya and isolation between the North and South A. diversus occurred within the last 2 Mya; corresponding with the Pliocene and Pleistocene, respectively.  On the basis of both studies, I concluded that COI gene sequences can provide a useful method for assessing the genetic similarity of aquatic insect populations on both small (<50km) and large (>1000km) spatial scales and that these data can then be used to test ecological and evolutionary hypotheses.

text: Assessing dispersal among habitats for three New Zealand aquatic insects using mitochondrial DNA (COI) sequences Dispersal of aquatic insects is a key process allowing colonization of new habitat and linking existing populations among habitats. Studying the dispersal of freshwater taxa directly is logistically challenging and assessments of population genetic structure using DNA sequence fragments have provided an alternative means to examine the dispersal and connectivity of natural populations. Here, I used mitochondrial cytochrome c oxidase subunit I (COI) DNA sequences to assess the genetic similarity for aquatic insect species across both small (<50km) and large (>1000km) spatial scales. For the first study, I examined genetic similarity among source and restored stream habitats in Taranaki Region, New Zealand. Three common species were targeted based on differences in dispersal capabilities: Archichauliodes diversus (Megaloptera; active larvae, weak flight), and Hydropsyche colonica and Pycnocentrodes aeris (Trichoptera; sessile larvae, strong flight). Archichauliodes diversus showed the greatest sequence diversity (19 haplotypes) followed by P. aeris (14 haplotypes) and H. colonica (4 haplotypes). Despite relatively high levels of genetic diversity, A. diversus was genetically similar throughout the study area, suggesting adequate dispersal among source and restored habitats. Individuals of H. colonica, with much lower levels of haplotype diversity, were also genetically similar between source and restored habitats. In contrast, P. aeris had one haplotype that was more common in source versus restored habitats. I concluded that taxa were relatively well connected between source and restored habitats and that COI sequences can provide a useful indicator for tracking restoration efforts within relatively small geographic areas. In the second study, I focused on large-scale patterns of diversity for A. diversus which is widespread throughout both the North and the South Islands of New Zealand and compared this with available sequences from a congeneric Australian species. I found sequence divergences between the New Zealand A. diversus and Australian Archichauliodes sp (11.8% divergence), and between New Zealand North Island and South Island A. diversus (3% divergence). In the South Island, there were 8 haplotypes restricted to individual sites and 4 haplotypes that were shared among sites. For the North Island, individuals there were 21 haplotypes restricted to one of more sites and 1 common haplotype shared among Taranaki sites. There were 12 missing mutational steps between haplotypes from the North Island and the South Islands. The Australian Archichauliodes sp was further separated by 70 missing mutational steps from the South Island of New Zealand. Differentiation was also observed within the South Island with shared haplotypes observed at distances of > 150 km. On this basis, I suggested that despite potentially weak flight, individuals of A. diversus can regularly disperse distances of up to 150 km. However, they also appear limited by geographic barriers such as the Cook Strait between the North and South Islands (<25 km). Molecular clock estimates between New Zealand and Australian Archichauliodes sp. suggested that isolation of individuals occurred around 5 Mya and isolation between the North and South A. diversus occurred within the last 2 Mya; corresponding with the Pliocene and Pleistocene, respectively.  On the basis of both studies, I concluded that COI gene sequences can provide a useful method for assessing the genetic similarity of aquatic insect populations on both small (<50km) and large (>1000km) spatial scales and that these data can then be used to test ecological and evolutionary hypotheses.

year: 2016

title: HIV diagnoses in indigenous peoples: comparison of Australia, Canada and New Zealand

authors: Shea, Beverley

subjects: HIV

abstract: In industrial countries, a number of factors put indigenous peoples at increased risk of HIV infection. National surveillance data between 1999 and 2008 provided diagnoses for Aboriginal and Torres Strait Islanders (Australia), First Nations, Inuit and Métis (Canada excluding Ontario and Quebec) and Māori (New Zealand). Each country provided similar data for a non-indigenous comparison population. Direct standardisation used the 2001 Canadian Aboriginal male population for comparison of five-year diagnosis rates in 1999–2003 and 2004–2008. Using the general population as denominators, we report diagnosis ratios for presumed heterosexual transmission, men who have sex with men (MSM) and intravenous drug users (IDU). Age standardised HIV diagnosis rates in indigenous peoples in Canada in 2004–2008 (178.1 and 178.4/100 000 for men and women respectively) were higher than in Australia (48.5 and 12.9/100 000) and New Zealand (41.9 and 4.3/100 000). Higher HIV diagnosis rates related to heterosexual contact among Aboriginal peoples, especially women, in Canada confirm a widening epidemic beyond the conventional risk groups. This potential of a generalised epidemic requires urgent attention in Aboriginal communities; available evidence can inform policy and action by all stakeholders. Although less striking in Australia and New Zealand, these findings may be relevant to indigenous peoples in other countries.

text: HIV diagnoses in indigenous peoples: comparison of Australia, Canada and New Zealand In industrial countries, a number of factors put indigenous peoples at increased risk of HIV infection. National surveillance data between 1999 and 2008 provided diagnoses for Aboriginal and Torres Strait Islanders (Australia), First Nations, Inuit and Métis (Canada excluding Ontario and Quebec) and Māori (New Zealand). Each country provided similar data for a non-indigenous comparison population. Direct standardisation used the 2001 Canadian Aboriginal male population for comparison of five-year diagnosis rates in 1999–2003 and 2004–2008. Using the general population as denominators, we report diagnosis ratios for presumed heterosexual transmission, men who have sex with men (MSM) and intravenous drug users (IDU). Age standardised HIV diagnosis rates in indigenous peoples in Canada in 2004–2008 (178.1 and 178.4/100 000 for men and women respectively) were higher than in Australia (48.5 and 12.9/100 000) and New Zealand (41.9 and 4.3/100 000). Higher HIV diagnosis rates related to heterosexual contact among Aboriginal peoples, especially women, in Canada confirm a widening epidemic beyond the conventional risk groups. This potential of a generalised epidemic requires urgent attention in Aboriginal communities; available evidence can inform policy and action by all stakeholders. Although less striking in Australia and New Zealand, these findings may be relevant to indigenous peoples in other countries.

year: 2011