title: Population structure and interspecific hybridisation of two invasive blowflies (Diptera: Calliphoridae) following replicated incursions into New Zealand

authors: Croft, Lillian

subjects: biological invasion

abstract: Rates of biological invasion are increasing globally, with associated negative effects on native biodiversity and ecosystem services. Among other genetic processes, hybridisation can facilitate invasion by producing new combinations of genetic variation that increase adaptive potential and associated population fitness. Yet the role of hybridisation (and resulting gene flow) in biological invasion in invertebrate species is under‐studied. Calliphora hilli and Calliphora stygia are blowflies proposed to have invaded New Zealand separately from Australia between 1779 and 1841, and are now widespread throughout the country. Here, we analysed genome‐wide single nucleotide polymorphisms (SNPs), generating genotyping‐by‐sequencing data for 154 individuals collected from 24 populations across New Zealand and Australia to assess the extent of gene flow and hybridisation occurring within and between these blowflies and to better understand their overall population structure. We found that New Zealand populations of both species had weak genetic structure, suggesting high gene flow and an absence of dispersal limitations across the country. We also found evidence that interspecific hybridisation is occurring in the wild between C. hilli and C. stygia in both the native and invasive ranges, and that intraspecific admixture is occurring among populations at appreciable rates. Collectively, these findings provide new insights into the population structure of these two invasive invertebrates and highlight the potential importance of hybridisation and gene flow in biological invasion.

text: Population structure and interspecific hybridisation of two invasive blowflies (Diptera: Calliphoridae) following replicated incursions into New Zealand Rates of biological invasion are increasing globally, with associated negative effects on native biodiversity and ecosystem services. Among other genetic processes, hybridisation can facilitate invasion by producing new combinations of genetic variation that increase adaptive potential and associated population fitness. Yet the role of hybridisation (and resulting gene flow) in biological invasion in invertebrate species is under‐studied. Calliphora hilli and Calliphora stygia are blowflies proposed to have invaded New Zealand separately from Australia between 1779 and 1841, and are now widespread throughout the country. Here, we analysed genome‐wide single nucleotide polymorphisms (SNPs), generating genotyping‐by‐sequencing data for 154 individuals collected from 24 populations across New Zealand and Australia to assess the extent of gene flow and hybridisation occurring within and between these blowflies and to better understand their overall population structure. We found that New Zealand populations of both species had weak genetic structure, suggesting high gene flow and an absence of dispersal limitations across the country. We also found evidence that interspecific hybridisation is occurring in the wild between C. hilli and C. stygia in both the native and invasive ranges, and that intraspecific admixture is occurring among populations at appreciable rates. Collectively, these findings provide new insights into the population structure of these two invasive invertebrates and highlight the potential importance of hybridisation and gene flow in biological invasion.

year: 2024-01-07

title: Environmental pollutants from the Scott and Shackleton expeditions during the ‘Heroic Age’ of Antarctic exploration

authors: Blanchette, Robert A.

subjects: Antarctica

abstract: Early explorers to Antarctica built wooden huts and brought huge quantities of supplies and equipment to support their geographical and scientific studies for several years. When the expeditions ended and relief ships arrived, a rapid exodus frequently allowed only essential items to be taken north. The huts and thousands of items were left behind. Fuel depots with unused containers of petroleum products, asbestos materials, and diverse chemicals were also left at the huts. This investigation found high concentrations of polyaromatic hydrocarbons in soils under and around the historic fuel depots, including anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, fluorene, and pyrene, as well as benzo[a]anthracene, benzo[a]pyrene, and fluoranthene, which are recognized carcinogens. Asbestos materials within the huts have been identified and extensive amounts of fragmented asbestos were found littering the ground around the Cape Evans hut. These materials are continually abraded and fragmented as tourists walk over them and the coarse scoria breaks and grinds down the materials. A chemical spill, within the Cape Evans hut, apparently from caustic substances from one of the scientific experiments, has caused an unusual deterioration and defibration on affected woods. Although these areas are important historic sites protected by international treaties, the hazardous waste materials left by the early explorers should be removed and remedial action taken to restore the site to as pristine a condition as possible. Recommendations are discussed for international efforts to study and clean up these areas, where the earliest environmental pollution in Antarctica was produced.

text: Environmental pollutants from the Scott and Shackleton expeditions during the ‘Heroic Age’ of Antarctic exploration Early explorers to Antarctica built wooden huts and brought huge quantities of supplies and equipment to support their geographical and scientific studies for several years. When the expeditions ended and relief ships arrived, a rapid exodus frequently allowed only essential items to be taken north. The huts and thousands of items were left behind. Fuel depots with unused containers of petroleum products, asbestos materials, and diverse chemicals were also left at the huts. This investigation found high concentrations of polyaromatic hydrocarbons in soils under and around the historic fuel depots, including anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, fluorene, and pyrene, as well as benzo[a]anthracene, benzo[a]pyrene, and fluoranthene, which are recognized carcinogens. Asbestos materials within the huts have been identified and extensive amounts of fragmented asbestos were found littering the ground around the Cape Evans hut. These materials are continually abraded and fragmented as tourists walk over them and the coarse scoria breaks and grinds down the materials. A chemical spill, within the Cape Evans hut, apparently from caustic substances from one of the scientific experiments, has caused an unusual deterioration and defibration on affected woods. Although these areas are important historic sites protected by international treaties, the hazardous waste materials left by the early explorers should be removed and remedial action taken to restore the site to as pristine a condition as possible. Recommendations are discussed for international efforts to study and clean up these areas, where the earliest environmental pollution in Antarctica was produced.

year: 2004

title: Defining indigenous trade: A working paper incorporating Māori and indigenous perspectives

authors: McLellan, Georgia

abstract: This working paper is part of a New Zealand Government–funded research project titled ‘Tauhokohoko: Enabling mana motuhake through Indigenous trade’ (Tauhokohoko), which was developed by the University of Waikato and Te Rōpū Taumata Charitable Trust (Te Taumata). The paper was prepared by the Tauhokohoko Research Aim 1.3 team and sets out a working definition of ‘Indigenous trade’.

The Tauhokohoko Research Aim 1.3 team acknowledges that the term ‘Indigenous’ can be problematic, since it collectivises the experiences of all Indigenous peoples. The project acknowledges the diverse realities of Indigenous peoples and strives to use the term in an inclusive way. Despite the existence of fraught relations between Indigenous peoples and postcolonial trade practices, Indigenous peoples have always had their own trade practices and relations grounded in Indigenous ways of being, knowing and doing. Within contemporary economies, Indigenous peoples are increasingly turning to international trade to meet their economic, social and cultural aspirations.

The Tauhokohoko Research Aim 1.3 team believes that Indigenous trade, when practiced in the right way, can be used as a tool for enhancing Indigenous self-determination and collective wellbeing. This paper outlines a tentative definition of ‘Indigenous trade’ for research purposes and provides grounded examples of Indigenous trade that fit within that tentative definition. The Tauhokohoko project is concerned primarily with the involvement of Indigenous peoples in international trade as a financial activity; however, the tentative definition encompasses financial, non financial, tangible and non-tangible forms of exchange. The paper ends by outlining the key literature that informs the working definition of ‘Indigenous trade’, including perspectives on the origins of international trade and Indigenous trade, international business and entrepreneurship, and Indigenous economies.

text: Defining indigenous trade: A working paper incorporating Māori and indigenous perspectives This working paper is part of a New Zealand Government–funded research project titled ‘Tauhokohoko: Enabling mana motuhake through Indigenous trade’ (Tauhokohoko), which was developed by the University of Waikato and Te Rōpū Taumata Charitable Trust (Te Taumata). The paper was prepared by the Tauhokohoko Research Aim 1.3 team and sets out a working definition of ‘Indigenous trade’.

The Tauhokohoko Research Aim 1.3 team acknowledges that the term ‘Indigenous’ can be problematic, since it collectivises the experiences of all Indigenous peoples. The project acknowledges the diverse realities of Indigenous peoples and strives to use the term in an inclusive way. Despite the existence of fraught relations between Indigenous peoples and postcolonial trade practices, Indigenous peoples have always had their own trade practices and relations grounded in Indigenous ways of being, knowing and doing. Within contemporary economies, Indigenous peoples are increasingly turning to international trade to meet their economic, social and cultural aspirations.

The Tauhokohoko Research Aim 1.3 team believes that Indigenous trade, when practiced in the right way, can be used as a tool for enhancing Indigenous self-determination and collective wellbeing. This paper outlines a tentative definition of ‘Indigenous trade’ for research purposes and provides grounded examples of Indigenous trade that fit within that tentative definition. The Tauhokohoko project is concerned primarily with the involvement of Indigenous peoples in international trade as a financial activity; however, the tentative definition encompasses financial, non financial, tangible and non-tangible forms of exchange. The paper ends by outlining the key literature that informs the working definition of ‘Indigenous trade’, including perspectives on the origins of international trade and Indigenous trade, international business and entrepreneurship, and Indigenous economies.

year: 2025-12-10