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Simple Summary: Problem behaviours are a leading cause of relinquishment of pets. Clinical animal behaviourists (CABs) have to make behavioural assessments and give advice to help owners address problem behaviours. CABs use information presented about a case to make an assessment, which in turn guides their recommendations, but little is known about how CABs make an assessment from the information presented. This study explored this process, particularly in relation to fear and frustration, two emotions that frequently contribute to problem behaviours and can present in superficially similar ways (e.g., as aggression). Interviews with CABs explored their perception of fear and frustration and how they differentiate these in practice. Interviewees generally agreed on the nature of fear; however, there was little consensus about frustration, and many struggled to explain how the two could be differentiated. Typically, personal judgement and intuition were used when making an assessment, with a range of flaws being apparent in their reasoning. This work not only highlights the current inconsistencies in the use of terminology but also issues with the processes used to make an assessment. Therefore, there is clearly a need to develop consensus definitions and a consistent framework for the assessment of emotions in clinical behaviour practice to help pets with problem behaviours. Fear and frustration are two emotions thought to frequently contribute to problem behaviour, often leading to relinquishment. Inferring these emotions is challenging as they may present with some similar general signs, but they potentially require different treatment approaches to efficiently address the behaviour of concern. Although behavioural assessment frameworks have been proposed, it is largely unknown how clinical animal behaviourists (CABs) assimilate information about the emotional state of an animal to inform their behavioural assessment. In other fields (such as both in human and veterinary medicine), the use of intuition and gut feelings, without the concurrent use of an assessment framework, can lead to higher rates of error and misdiagnosis. Therefore, this study used semi-structured interviews of ten CABs and qualitative methods to explore the ways they conceptualise, recognise and differentiate fear and frustration in dogs. Although interviewees perceived fear and frustration as negative affective states that lead to changes in an animal's behaviour, there was little consensus on the definition or identification or differentiation of these emotions. The use of a scientific approach (i.e., hypothesis-driven and based on falsification of competing hypotheses) for behavioural assessment was highly variable, with individual assessment processes often characterised by tautology, intuition, circular reasoning and confirmation bias. Assessment was typically based on professional judgment, amalgamating information on interpretation of communicative signals, motivation, learning history, breed, genetics and temperament. Given the lack of consensus in the definition of these states, it is clearly important that authors and clinicians define their interpretation of key concepts, such as fear and frustration, when trying to communicate with others. [ABSTRACT FROM AUTHOR]

Sexual selection is known to play a major role in the evolution of insect sperm size, whereas natural selection is thought to be a major driver of insect egg size. Despite these differing forms of selection operating, it is possible coevolution between male and female gametes can occur owing to their vital interactions during fertilization. We tested egg–sperm coevolution in insects and found that longer sperm correlated to longer and wider eggs. Moreover, the size of the entry point of sperm into insect eggs (micropyles), was positively related to the diameter of sperm, on average being approximately three times the diameter of the sperm. This suggests a function in reducing and channelling sperm entry, but potentially still leaving space for movement. Our work suggests that greater attention needs to be paid to egg–sperm interactions prior to the point of fertilization as they may influence the evolution of gametes. [ABSTRACT FROM AUTHOR]

Reconstructing biological invasions from historical sources can provide insights into how they occur but are difficult to do when invasions are poorly documented. Genetic signatures left by invaders can also offer insights into invasion routes, points of origin and general biology but often present conclusions that are contradictory to expectations. Here, we test the ability of continental‐wide microsatellite genotype data from 29 loci and 3122 samples to reconstruct the well‐documented invasion of red foxes Vulpes vulpes from the United Kingdom into Australia over 150 years ago, an invasion that has led to the extinction of many native species. Our analysis reveals several key signals of invasion evident in Australian foxes. They display lower levels of diversity than foxes sampled from the UK, exhibit clines in diversity from the point of introduction (south‐east Australia) to the edge of their range, and show strong evidence of allele surfing in westerly and north‐easterly directions. These characteristics are consistent with a single point of origin followed by rapid expansion in westerly and north‐easterly directions as suggested by historical records. We also find little genetic structure in foxes across Australia with only the vast Nullarbor Plains and Great Victoria Desert region presenting a detectable barrier to their dispersal. As such, no mainland region within the current range of foxes can be considered genetically isolated and therefore appropriate for localised eradication efforts. Overall, our analyses demonstrate the ability of comprehensive population genetic studies to reconstruct invasion histories even after more than 80 years since colonisation was stabilised. [ABSTRACT FROM AUTHOR]

Simple Summary: Anticoagulant rodenticides are commonly used as a method of rodent population control. Unfortunately, many non-target species are exposed to rodenticides. The route by which non-target animals are poisoned is not always clear, which can hinder conservation efforts. It has been suggested that insectivorous species may be exposed to rodenticides via the consumption of contaminated insect prey. This study examined whether rodenticide baits mixed with the biomarker rhodamine B can be used to track invertebrate consumption of rodenticide baits in a natural environment, and, in doing so, we assessed whether insects could be a source of rodenticide poisoning in insectivores. The rhodamine B baits created an observable response; molluscs were the most frequent consumers of bait. Maximum temperature, distance from baits, the addition of copper tape to boxes, and proximity to buildings were all found to affect their rate of uptake. Other invertebrates rarely showed signs of uptake. This has provided valuable insights into the mechanisms by which insectivores experience rodenticide poisoning, which is necessary in developing effective mitigation measures to aid conservation efforts. We suggest that further investigation into using mollusc repellents around bait boxes should be considered. Non-target species are commonly exposed to anticoagulant rodenticides worldwide, which may pose a key threat to declining species. However, the main pathway of exposure is usually unknown, potentially hindering conservation efforts. This study aimed to examine whether baits mixed with the biomarker rhodamine B can be used to track invertebrate consumption of rodenticides in a field environment, using this to observe whether invertebrate prey are a potential vector for anticoagulant rodenticides in the diet of insectivores such as the European hedgehog (Erinaceus europaeus). Rhodamine B baits were found to create an observable response. Uptake was negligible in captured insects; however, 20.7% of slugs and 18.4% of snails captured showed uptake of bait. Maximum temperature, distance from bait, proximity to buildings, and the addition of copper tape to bait boxes all influenced the rate of bait uptake in molluscs. Based on these data, it seems likely that molluscs could be a source of rodenticide poisoning in insectivores. This research demonstrates which prey may pose exposure risks to insectivores and likely environmental factors, knowledge of which can guide effective mitigation measures. We suggest that further investigation into using mollusc repellents around bait boxes should be considered. [ABSTRACT FROM AUTHOR]

The size and shape of red blood cells (erythrocytes) is determined by key life history strategies in vertebrates. They have a fundamental role to deliver oxygen to tissues, and their ability to do so is shaped by the tissue's need and their shape. Despite considerable interest in how other components of blood are shaped by ecology and life history, few studies have considered erythrocytes themselves. We tested how erythrocyte size and shape varied in relation to energetically demanding activities using a dataset of 631 bird species. We found that in general, birds undergoing greater activities such as long distance migration had smaller and more elongated cells, while those with greater male-male competition had smaller and rounder cells. Smaller, more elongated erythrocytes allow more rapid oxygenation/deoxygenation and support greater aerobic activity. The rounder erythrocytes found in species with strong male–male competition may stem from younger erythrocytes deriving from androgen-induced erythropoiesis rates. Finally, diving species of bird had larger erythrocytes, indicating that erythrocytes are acting as a vital oxygen store. In summary, erythrocyte size and shape in birds are driven by the need to deliver oxygen during energetically costly activities. [ABSTRACT FROM AUTHOR]