Sex peptide receptor-regulated polyandry mediates the balance of pre- and post-copulatory sexual selection in Drosophila

Polyandry prolongs sexual selection on males by forcing ejaculates to compete for fertilisation. Recent theory predicts that increasing polyandry may weaken pre-copulatory sexual selection on males and increase the relative importance of post-copulatory sexual selection, but experimental tests of this prediction are lacking. Here, we manipulate the polyandry levels in groups of Drosophila melanogaster by deletion of the female sex peptide receptor. We show that groups in which the sex-peptide-receptor is absent in females (SPR-) have higher polyandry, and – as a result – weaker pre-copulatory sexual selection on male mating success, compared to controls. Post-copulatory selection on male paternity share is relatively more important in SPR- groups, where males gain additional paternity by mating repeatedly with the same females. These results provide experimental evidence that elevated polyandry weakens pre-copulatory sexual selection on males, shifts selection to post-copulatory events, and that the sex peptide pathway can play a key role in modulating this process in Drosophil

No evidence for precopulatory inbreeding avoidance in Drosophila melanogaster

Inbreeding depression can lead to the evolution of inbreeding avoidance before or after mating. However, despite widespread evidence of inbreeding depression, studies of inbreeding avoidance have generated different results across populations or species. These differences could potentially reflect the confounding effects of factors such as magnitude of inbreeding depression, sex, social familiarity, state of primary sexual receptivity and mating history. We examined the influence of these proximate factors on precopulatory inbreeding avoidance in a laboratory-adapted, outbred population of Drosophila melanogaster. We found a significant but low coefficient of inbreeding depression based on egg-adult viability measures. Controlling for sex-specific responses, familiarity, sexual receptivity and mating history, we found no evidence of precopulatory inbreeding avoidance. Mate choice of virgins was random with respect to relatedness and measurements of courtship frequency, mating latency and mating duration did not indicate any preference for unrelated partners. In fact, the only evidence for differential sexual behaviour in response to relatedness was that males first mated to unrelated females were significantly faster to remate with related females than with unrelated females. These results suggest that inbreeding avoidance may be limited in outbred populations of D. melanogaster, and fit theoretical predictions that inbreeding is not selected against in either sex when the coefficient of inbreeding depression is relatively low. © 2012 The Association for the Study of Animal Behaviour

Effects of habitat alteration and disturbance by humans and exotic species on fosa Cryptoprocta ferox occupancy in Madagascar's deciduous forests

Anthropogenic habitat alteration and invasive species are threatening carnivores globally. Understanding the impact of these factors is critical for creating localized, effective conservation programmes. Madagascar's Eupleridae have been described as the least studied and most threatened group of carnivores. We investigated the effects of habitat degradation and the presence of people and exotic species on the modelled occupancy of the endemic fosa Cryptoprocta ferox, conducting camera-trap surveys in two western deciduous forests, Ankarafantsika National Park and Andranomena Special Reserve. Our results indicated no clear patterns between habitat degradation and fosa occupancy but a strong negative association between cats Felis sp. and fosas. Cat occupancy was negatively associated with birds and positively associated with contiguous forest and narrow trails. In contrast, dog Canis lupus familiaris occupancy was best predicted by wide trails, degraded forest and exotic civets. Our results suggest fosas are capable of traversing degraded landscapes and, in the short term, are resilient to contiguous forest disturbance. However, high occupancy of cats and dogs in the landscape leads to resource competition through prey exploitation and interference, increasing the risk of transmission of potentially fatal diseases. Management strategies for exotic carnivores should be considered, to reduce the widespread predation of endemic species and the transmission of disease

Activity patterns of sympatric living exotic and endemic carnivores (the fosa) in Western Madagascar's deciduous forests

Western Madagascar's deciduous forest is an important, threatened habitat to little-known Eupleridae, such as the fosa Cryptoprocta ferox. Using camera-trap grids established in two important deciduous forests, Ankarafantsika National Park and Andranomena Special Reserve, we explore the activity patterns of endemic and exotic carnivores and evaluate how exotics may be influencing fosa temporal activity across these two protected areas. Three methodologies, kernel density, circular and wave analysis, were used to evaluate the activity pattern overlap between exotic free-ranging cats Felis sp. and dogs Canis familiaris, exotic small Indian civets Viverricula indica and the endemic fosa. Our results showed fosas to be cathemeral, peaking in activity in the evening and at dawn. Cats were nocturnal, whilst also highly active at dusk. Civets did not display a dominant period of activity, but were relatively more active in the night, and at dusk. In contrast, dogs were diurnal and also active at dawn, in alignment with human activity. Fosa activity significantly overlapped with the nocturnal cat and civet, whilst being distinct from the diurnal dog and humans. Our results suggest that there is potentially a competitive impact of exotic free-ranging dogs and cats when present across fosas’ dry forest habitat. This highlights the need for further examination into the impact of Madagascar's exotic carnivores, and the experimental trial to investigate the impact of their removal (or reduced abundance), on Madagascar's wildlife

Regional airline capacity, tourism demand and housing prices: A case study of New Zealand

© 2019 Elsevier Ltd Tourism is one of the most important economic activities in New Zealand as tourists commonly travel by air to the various regions of this geographically isolated archipelago. This paper aims to investigate: (i) how regional tourism demand and airline capacity affect each other; and (ii) how both affect the housing prices in New Zealand's smaller regions. The paper empirically examines these inter-relationships between regional tourism demand and air transport, and their joint effects on the housing prices by constructing a three-stage least squares (3SLS) structural model employing a panel dataset of New Zealand's six smaller airports and regions from January 2008 to December 2014. Empirical results showed that increased regional tourism activity raises airline capacity and vice versa. Importantly, domestic airline capacity has a statistically significant impact on regional housing prices but not regional tourist demand (with the exception of Queenstown as a major and popular tourist centre). Policy implications of the key findings for regional tourism and air transport developments are discussed

Understanding the environmental and anthropogenic correlates of tiger presence in a montane conservation landscape

Management of tigers is a response to a global conservation crisis. Range contraction, population decline, habitat fragmentation, prey loss, and poaching cause and aggravate this crisis. There is a debate as to whether conserving source sites or maintaining landscape connectivity is the greater priority. Both approaches rely on understanding environmental and anthropogenic factors. We used a large dataset from a nation-wide camera trapping survey to investigate factors affecting habitat use of tigers across the montane landscape of Bhutan. We tested the effects of environmental and anthropogenic covariates on habitat use while accounting for imperfect detection using a hierarchical occupancy model. Tiger habitat use showed a strong positive association with closeness to protected area, greater distance from human settlement and availability of abundant large prey. Our findings can help to identify the drivers of tiger decline and contribute to the refinement of conservation strategies to combat that decline in this montane conservation landscape. We provide a general approach to tiger conservation by highlighting the importance of understanding the basic ecology of this apex predator, including the relationship between environmental and anthropogenic variables and habitat use. Bhutan, with unusually strong environmental legislation, and a high percentage of its area protected and under contiguous forest cover, set the global standard in large carnivore conservation and is an important component of a wider conservation complex in South Asia

Identifying important conservation areas for the clouded leopard Neofelis nebulosa in a mountainous landscape: Inference from spatial modeling techniques

The survival of large carnivores is increasingly precarious due to extensive human development that causes the habitat loss and fragmentation. Habitat selection is in-fluenced by anthropogenic as well as environmental factors, and understanding these relationships is important for conservation management. We assessed the en-vironmental and anthropogenic variables that influence site use of clouded leopard Neofelis nebulosa in Bhutan, estimated their population density, and used the results to predict the species’ site use across Bhutan. We used a large camera-trap dataset from the national tiger survey to estimate for clouded leopards, for the first time in Bhutan, (1) population density using spatially explicit capture–recapture models and (2) site-use probability using occupancy models accounting for spatial autocorrela-tion. Population density was estimated at ̂DBayesian=0.40 (0.10 SD) and ̂Dmaximum−likelihood=0.30 (0.12 SE) per 100 km2. Clouded leopard site use was positively associated with forest cover and distance to river while negatively associated with elevation. Mean site-use probability (from the Bayesian spatial model) was ̂ψspatial=0.448 (0.076 SD). When spatial autocorrelation was ignored, the probability of site use was overestimated, ̂ψnonspatial=0.826 (0.066 SD). Predictive mapping al-lowed us to identify important conservation areas and priority habitats to sustain the future of these elusive, ambassador felids and associated guilds. Multiple sites in the south, many of them outside of protected areas, were identified as habitats suitable for this species, adding evidence to conservation planning for clouded leopards in continental South Asia

Within-group male relatedness reduces harm to females in Drosophila

To resolve the mechanisms that switch competition to cooperation is key to understanding biological organization. This is particularly relevant for intrasexual competition, which often leads to males harming females. Recent theory proposes that kin selection may modulate female harm by relaxing competition among male relatives. Here we experimentally manipulate the relatedness of groups of male Drosophila melanogaster competing over females to demonstrate that, as expected, within-group relatedness inhibits male competition and female harm. Females exposed to groups of three brothers unrelated to the female had higher lifetime reproductive success and slower reproductive ageing compared to females exposed to groups of three males unrelated to each other. Triplets of brothers also fought less with each other, courted females less intensively and lived longer than triplets of unrelated males. However, associations among brothers may be vulnerable to invasion by minorities of unrelated males: when two brothers were matched with an unrelated male, the unrelated male sired on average twice as many offspring as either brother. These results demonstrate that relatedness can profoundly affect fitness through its modulation of intrasexual competition, as flies plastically adjust sexual behaviour in a manner consistent with kin-selection theory

Within-group male relatedness reduces harm to females in Drosophila

To resolve the mechanisms that switch competition to cooperation is key to understanding biological organization. This is particularly relevant for intrasexual competition, which often leads to males harming females. Recent theory proposes that kin selection may modulate female harm by relaxing competition among male relatives. Here we experimentally manipulate the relatedness of groups of male Drosophila melanogaster competing over females to demonstrate that, as expected, within-group relatedness inhibits male competition and female harm. Females exposed to groups of three brothers unrelated to the female had higher lifetime reproductive success and slower reproductive ageing compared to females exposed to groups of three males unrelated to each other. Triplets of brothers also fought less with each other, courted females less intensively and lived longer than triplets of unrelated males. However, associations among brothers may be vulnerable to invasion by minorities of unrelated males: when two brothers were matched with an unrelated male, the unrelated male sired on average twice as many offspring as either brother. These results demonstrate that relatedness can profoundly affect fitness through its modulation of intrasexual competition, as flies plastically adjust sexual behaviour in a manner consistent with kin-selection theory